Below, we’ll examine what heat stress looks like, the warning signs, what to do if your horse overheats, and how to prevent dehydration from heat stress.

What Causes Heat Stress in Horses?

Horses primarily create heat while digesting their feed and during any activity that requires their muscles to work. Even light activity in extremely hot, humid weather could cause your horse to overheat.

You may notice that your horse’s blood vessels appear larger and distended when it’s hot outside. This reaction is normal, as it shunts the blood to the skin to rid the body of excess heat; however, this doesn’t provide adequate cooling if the air temperature is warmer than the horse’s body temperature.

Other than humans, horses are the only mammals that sweat. During hotter conditions, they primarily use this mechanism to wet the body and allow cooling via evaporation. The problem occurs when the sweat doesn’t evaporate to allow adequate cooling, potentially leading to heat stress.

“Horses are pretty efficient at dissipating heat compared to species that don’t sweat,” says Kris Hiney, Ph.D., associate professor and Equine Extension Specialist at Oklahoma State University. “But they can still get heat stress [during] prolonged periods of high temperatures or working in high temperatures. Very young or infirm horses are more likely to suffer from heat stress.”

Detecting Heat Stress

Hot skin and profuse sweating or less sweating than expected for the activity could be warning signs of heat stress. Hiney advises looking for high body temperature, an elevated heart rate, and a respiration rate beyond what’s expected for the workload.

“Working in hot temperatures may not be completely avoidable,” she says. “[But] it’s important to recognize the signs that your horse may be overheating.”

Hiney recommends practicing the following techniques ahead of time so both you and your horse will be familiar with them when needed.

◆ Use a rectal thermometer (keep one with you if you’re far from a barn) to monitor heat load. Body temperature will normally increase with exercise, and body temperatures of 104 degrees to 106 degrees Fahrenheit are common for some events.

However, horses with these body temperatures need to be cooled carefully. If a horse’s temperature is over 106 degrees, take immediate action to cool the horse. Temperatures reaching 107 degrees may require veterinary assistance.

◆ Check your horse’s heart rate, either with a stethoscope or manually. When the horse is allowed to rest, his heart rate should noticeably begin to drop. It should return to 40 to 50 beats per minute within 15 minutes. Failure of the heart rate to drop quickly indicates heat stress.

“Flared nostrils and heaving flanks while breathing are not only from work, but also from the increased heat load,” Hiney explains. “Allow the horse to rest and watch carefully for a reduction in breathing rate and intensity.”

◆ Assess the amount and location of sweat. Normal sweating patterns include along the neck, flanks and between the hind legs. With intense exercise or extreme temperatures, the horse may be completely covered in sweat and will need help being cooled.

A horse that has ceased sweating is most likely suffering from heat exhaustion and is in critical need of care.

How to Treat Heat Stress

If you suspect your horse is overheating, it’s vital to stop exercising and move him to a cooler setting right away. You will likely need to help him cool down to prevent heat stress from turning into heat stroke, which can have dire consequences.

“Evaporation through sweat is the major way horses dissipate heat, but high humidity levels will limit the effectiveness of sweating,” says Hiney. “Increase airflow to the skin by removing all tack and equipment and use a sweat scraper to remove excess sweat.

“Cool running water can greatly aid in cooling,” she continues. “Apply water or even ice along major blood vessels like the neck, chest and inside of the legs. Blood will cool as it passes through these areas and then return to the trunk of the body to help dissipate the heat load. Continual application of cool, running water will prevent the warming of the water on the horse’s skin. Otherwise, use a scraper to remove the warm water and increase the rate of cooling. Water left on the skin will warm rapidly and trap heat against the horse’s body.”

Hiney says that you can still help your horse cool down even when you don’t have access to running water by using a sponge to wet the major blood vessels. Again, you should concentrate on the neck and chest. She also suggests adding rubbing alcohol to the water to increase evaporation and aid in cooling.

If you need to cool your horse while riding if you’re not near running water, Hiney suggests using a squirt bottle to apply cool water along the major exposed blood vessels in the neck and chest. You can refill your water bottle from streams, lakes or stock tanks.

“Air movement is another major way that animals lose heat,” she says. “Supplying fans or keeping the horse in a breezy area is ideal. Fans with higher velocities provide more effective cooling. If you have access to electricity, put a fan near the arena to aid in cooling during rest periods. This fan can greatly assist with continuing normal training during the summer. Even so, be sure that the horse’s heart rate and respiration rate have dropped before returning to work.

“Simple strategies like keeping the horse in the shade or riding in shaded areas prevent heat gain directly from the sun,” Hiney adds. “Standing under trees is even more useful, as the horse will radiate heat up to the leaves, which are continually cooled by their own evaporation.”

She warns that heat stress can quickly turn to heat stroke. If you feel this is happening, cease work, strip tack off the horse, and get him into the shade immediately. When facing heat stroke, veterinary care with IV fluids may be necessary.

Heat Index

Through appropriate management, heat stress can be prevented. Start by paying attention to the heat index in your area to understand when it’s dangerous to work your horse. Although different horses may tolerate heat differently, follow general guidelines to ensure you’re not putting your horse in danger.

“Pay attention to heat and humidity,” Hiney advises. “A good rule of thumb is to add the values of the temperature [in degrees Fahrenheit] and humidity [relative percentage] to get the horse’s comfort index. Horses cool themselves normally—unless dehydrated or fatigued—if the combined values are below 130.

“If the combined temperature and humidity is over 150 (such as 90 degrees Fahrenheit with 60 percent humidity), horses will need assistance in cooling,” she continues. “If temperatures and humidity are expected to reach 170, it may be best to plan early morning riding or skip intense work. Even riding in the evening may not see a large drop in temperature until the sun has been down for several hours.”

Dangerous Dehydration

High heat or excessive sweating can cause dehydration in horses. If your horse doesn’t replace the fluid lost during sweating by drinking adequate water, he can become dehydrated, which can be life-threatening.

“Horses can become dehydrated in as little as two to three hours under the right conditions,” says Hiney. “Horses need to be well-hydrated before beginning to work, for example, horses that have come off of a long trailer ride.”

She explains that some warning signs of dehydration include prolonged capillary refill time (checked by pressing your finger into the horse’s gums) and tenting when skin is pulled from the neck or over the eye. The horse may also have a gaunt or tucked-up appearance.

Colic and overheating are possible, but if the horse gets an electrolyte imbalance due to dehydration, tying up and even death could occur.

“The primary mechanism horses use to dissipate heat is through sweating,” says Hiney. “Sweating leads to dehydration if the horse isn’t allowed to replenish, and the rate of sweating can outstrip the ability to keep up.

“Warm body temperatures encourage horses to drink, so allow access to water in the cool-down period,” she continues. “Allow frequent sips of cool water. Saline can also help replenish water and electrolytes, but be sure to have plain water available, too.”

Key Takeaway

Luckily, horses usually bounce back after a bout of heat stress or dehydration without any lasting effects. However, both can become very serious conditions in a relatively short span and, if left untreated, can lead to death.

It’s best for your horse’s health to not allow either to begin with by ensuring he always has access to clean, fresh water and avoiding exercise in extremely hot weather.

Ride in the morning when it’s coolest, and reduce ride time and intensity when it’s hot and humid, or refrain altogether if the temperature and humidity are above safe levels.

This article about heat stress appeared in the July 2023 issue of Horse Illustrated magazine. Click here to subscribe!

The post Heat Stress in Horses appeared first on Horse Illustrated Magazine.

Professional equine grooms Cat Hill and Emma Ford believe there are no hard and fast rules about blanketing. The lifelong horsewomen have managed barns and horses for top riders in all disciplines, including Olympians. Together they run World-Class Grooming and share their expertise through clinics and books, including the top-selling equine title World-Class Grooming.

“The biggest rule is that you have to remember that horses are individuals just like people,” says Hill. “There are many horses that grow great coats and are really comfortable being unblanketed in many climates, all the way up to Alaska. But there are also horses that really struggle without being covered in some way.”

How Horses Stay Warm

Horses can weather winter quite well in most situations.

“Horses are well equipped to handle the cold, provided they are able to acclimate and stay dry enough to fluff the hair,” says Karen L. Waite, Ph.D., who serves as coordinator of the Michigan State University (MSU) Horse Management Program in East Lansing, Mich. She is also the director of undergraduate education in the MSU Department of Animal Science. “Horses stay warm in several ways: through the digestion of forages like hay, which produces body heat; by growing a thick winter haircoat, which starts to develop around August or September as day length starts to shorten; and by fluffing up their hair coat as the need arises.”

That “fluff factor” traps warm air against the skin, allowing the horse’s hair coat to provide natural insulation, much like a cozy down comforter. However, if the horse gets wet, that ability diminishes.

“A wet horse in 45-degree weather may be more uncomfortable than a dry horse with a full winter coat would be in sub-zero temperatures,” says Waite.

Additionally, a horse that moves from Florida to Minnesota in the middle of winter may not have a hair coat extensive enough to handle that level of cold.

“Most horses don’t actually need blankets to stay warm if they are allowed to develop a winter coat suitable to conditions,” says Waite. “The exception would be horses without adequate body condition or hair coat development, and occasionally older horses.”

Hill emphasizes the need to keep a close eye on senior horses.

“Just like older people, horses lose the ability to thermoregulate,” she says. “A horse who has lived without a blanket his entire life may suddenly need blanketing to retain condition when he gets into his 20s. He may not necessarily look cold. He may grow a huge, thick, heavy coat. But [some horses] really start to drop weight in the wintertime, and that’s because their body is burning energy to keep them warm.”

Hill recalls the story of an Arabian mare who lived at her family’s farm in upstate New York.

“Until she was in her mid-20s, she’d never worn a blanket and had always been very comfortable, happy, and hardy living out 24/7 with a run-in shed,” she says. “And then she got to a certain age where we really struggled with her weight in the winters. We bought her a heavyweight blanket that we put on her once it was consistently below freezing, and we had another 10 years of happy, healthy life with her. So as your horse ages, you may need to re-evaluate his blanketing needs.”

Why You May Consider Blanketing Your Horse

In addition to the weather and your horse’s age, coat and health status, there are a variety of other factors to consider in your blanketing decision.

An extreme temperature swing may warrant blanketing even for horses that normally go au naturel because they are not acclimated to that level of cold.

“If the horse has a full haircoat and is generally healthy, I would only blanket if temperatures were extreme, and outside the normal ranges for the area, unless he was old or had issues with body condition,” says Waite.

Access to shelter from wind and rain is another deciding factor in a horse’s blanketing needs.

“Rain is one of the hardest things for horses to handle without adequate shelter, because that squishes down the hair,” explains Hill. Even a healthy horse struggles when he can’t get away from the wet, she says.

Standing in wet or muddy conditions can also increase the need for blanketing, says Hill.

“When horses’ legs get wet, they struggle to bring their body temperature back up,” she says. “If a horse is standing out in a muddy field, you may need to put a warm blanket on him. Not just something to protect his back from the rain, but something with insulation as well.”

Horses that have been fully or partially body clipped will require blanketing. Hill and Ford firmly believe that if you have done any sort of partial clip, you still need to blanket. As Hill points out, the reason we clip particular areas such as the neck and chest is because they have underlying large veins, which help to cool the horse.

“When you get a cold wind over those veins, you’re putting a lot of stress on the horse’s body. So even if you just clipped up his neck, you really need to put some sort of protection back over the horse to help keep him at a [warm] base temperature,” says Hill.

Another reason you might want to blanket in winter is cleanliness. There’s nothing wrong with blanketing for the convenience of keeping a horse tidy, say Hill and Ford. If you have limited time and you live in an area where mud is a real issue in the winter, blanketing can make things easier on both you and your horse.

“Your horse is going to have a healthier and happier winter if you blanket him so that you can groom the areas that are exposed, but you’re not having to spend an enormous amount of time getting the mud or dirt out of his coat,” says Hill.

However, blanketing must be managed appropriately, which requires time and commitment. You’ll need to keep a close eye on the weather forecast, consider temperature fluctuations, and blanket accordingly.

“The biggest factor that people need to consider is that blankets need to be checked daily and changed as needed,” notes Waite.

Considering the Denier and Fill of Blankets

Blankets come in a mind-boggling variety. The first step is to select the right blanket type for your horse’s lifestyle. Any blanket that will be worn outdoors must be waterproof; wearing a soggy blanket is uncomfortable and will make your horse cold.

Turnout blankets are waterproof, durable and can be worn inside the barn or out in the elements. Stable blankets are not fully waterproof, and are meant to be worn indoors only.

When it comes to blanket shopping, the technical terminology can get complicated, but to help clarify the basics, Lauren Donohue, assistant merchant and horse clothing product expert with Dover Saddlery headquartered in Littleton, Mass., says to start by understanding what denier, fill and material you need.

“Denier” refers to the toughness of the fabric, while “fill” refers to the weight and warmth a blanket offers, measured in grams (g).

“The highest standard denier we typically see on the market is 1680d, and that’s meant for horses that are really rough on their blanket; the higher the denier, the tougher the outer material is,” says Donohue. “Sheets with 0g fill won’t offer any insulation—it’s just like putting on a raincoat. The more fill a blanket has, the warmer it is.”

Outer material also affects the durability of the blanket, which can be made of polyester, polypropylene, or ballistic nylon.

When building a blanket wardrobe, horse owners should look for versatility that will keep most horses comfortable in most situations. Donohue recommends starting out with a turnout blanket, noting that the two most popular fill weights are 50g (lightweight) and 200g (medium or midweight).

“The 50g can be worn when it’s a little warmer, [such as if] you get a summer rain, and it can be nice for those fall days when a horse might be feeling excited in turnout,” she says. “The 200g can be worn in a lot of scenarios. I keep my horse’s 200g blanket on until deep winter in New England comes around.”

Because a blanket and even a sheet has weight to it, Hill points out that it can flatten the horse’s haircoat. For this reason, she is a fan of using a 150g turnout versus a turnout sheet with no insulation.

“Sometimes it can be counterintuitive that adding a lightweight rain sheet or blanket can actually make a horse colder because they can no longer ‘poof up’ their coat,” she says. “We’re huge fans of the 150g-weights as rain sheets, because the light insulation does a great job of keeping the horse warm and dry and reversing the effects of the flattening of the hair. That really hits the sweet spot for those horses that need just a little bit of blanketing.”

Hill and Donohue both recommend having a neck cover as well. For colder climates, adding a heavyweight blanket (300g-plus) should build a basic wardrobe.

Too Hot, Too Cold, Just Right

Knowing which blanket to put on your horse can be tricky. World-Class Grooming has a blanketing chart (see below) that goes from below 30 degrees Fahrenheit to above 60, for wet or dry conditions, from full body clip to hairy beast and everything in between. Still, it’s important to know your own horse and consider each horse’s needs individually to blanket appropriately.

How do you know if your horse is comfortable in his blanket? Shivering or sweating can be obvious signs that something is amiss. Putting your hand under the blanket can help tell you if a horse is overly warm (if you detect tackiness or sweat). However, a method Hill prefers to assess if a horse is warm enough is to feel his extremities: legs, ears and face.

“If those areas on his skin feel cool, then your horse is cold,” she says. “If the tips of his ears are cold under the hair, he’s cold. The tips of their ears and their legs should feel the same temperature as the rest of the horse if they are properly blanketed.”

If you’re unsure of the appropriate weight blanket for the weather conditions, Waite advises that you may want to err on the side of less, given that overheating and dehydration can also cause significant problems.

Healthy Blanketing for Your Horse

Improper blanketing can lead to a variety of health problems.

If blankets get wet, they need to be removed, as hypothermia or skin infections (such as rain rot) may develop, notes Waite.

“If horses or blankets get wet, that causes more issues than anything else,” she says.

Waite also emphasizes the importance of proper blanket fit, as sores may result from blankets rubbing. A blanket that is too small may result in the horse being unable to move about or rise normally, while a blanket that is too big can also cause injuries if the horse becomes tangled in it.

Because the constant weight of wearing a blanket can cause rubs and pressure points, Hill and Ford like to do what they call a daily reset. They take the blanket off and put it back on to make sure it’s sitting in the right place, while at the same time checking underneath for any sore spots, swelling or rubs.

“The most problematic areas are the withers, points of the hip, and points of the shoulders,” says Ford.

If you’re not careful, it’s possible to cause more harm than good with blankets.

“If you can let the horse grow a full haircoat and shed naturally, that causes the fewest issues in the long run,” says Waite.

If you opt to blanket your horse, she agrees that it’s critical to check underneath blankets daily, and to check body condition regularly. Consistent grooming is also needed to keep horses healthy.

While the main reason for blanketing should be for the horse’s health and wellbeing, Hill acknowledges that it can also be a horsekeeping issue—to keep the horse clean and make grooming and riding easier—and that’s OK if it’s done mindfully.

Safe Blanketing Procedure

Getting your horse properly dressed for winter weather requires some small but important details that are often overlooked.

There’s a correct “order of operations” to putting a blanket on and off safely. According to Cat Hill and Emma Ford, authors of World-Class Grooming, you should always secure a blanket from front to back: first chest straps, then belly straps, and finally leg straps. If there is a neck cover, secure this last.

When removing the blanket, reverse the process: neck cover; leg straps, if any, should be undone and hooked back up while not around the leg; then belly straps; and finally, chest fasteners.

“If the horse spooks or runs forward, you don’t want the belly or leg straps still on while the chest is undone, because the blanket can slide back and cause a panic situation,” says Hill. “A horse can get seriously injured from getting tangled in a blanket that way.”

Remember, too, that you must train a horse to wear a blanket, just like any other piece of equipment. Go slow, says Hill. If you don’t know that a horse has been blanketed before, having a helper halter him and hold the lead rope is beneficial.

One of Ford’s biggest safety concerns is leaving a blanket’s leg straps undone during the blanketing process. She emphasizes that you should always hook them back up so that they’re not dangling down when you’re putting the blanket on or off a horse.

“They basically turn into flying weapons,” she says. “Many of them are on elastic; when you go to put the blanket over the top of the horse they get caught on stuff, the horse can step on them, they can whack into the horse’s legs, and all sorts of things. They should always be connected to both rings, and the only time they come off is when you’re unclipping them and putting them around the leg and hooking them back on.”

Since horses like to itch and rub themselves against things, Hill and Ford warn that any snap on a blanket that is facing away from the horse has the potential to be caught on something. When the blanket is on, it’s important that the “trigger,” or opening part of the snap, should face inward toward the horse.

Best Blanket Fit

Fitting blankets is like buying jeans—every brand has its own fit and shape. Brands that work for some won’t work for others, says Lauren Donohue, assistant merchant and horse clothing product expert with Dover Saddlery. Here is her best advice on fitting a blanket.

The two major measurements to consider are the length and drop of the blanket. Horse blankets are usually sized based on the length of the horse’s side measurement, listed in inches or sometimes centimeters. To measure the length, start with a fabric tape measure from the middle of your horse’s chest. Go across the shoulder to the middle of the tail.

The drop on a blanket is measured from the middle of the spine to the bottom of the blanket (on one side).

“Each brand will have their own drop measurement for the blanket, and this will differ by brand. If your horse is [round and] well-sprung in the ribs, you will want to ensure the drop length of the blanket is sufficient coverage for your horse,” she says.

If your horse is on the line between sizes, Donohue says to consider whether you will be layering underneath the blanket at all, and if your horse is prone to rubs. If the answer is yes to either of these, she recommends sizing up.

It may take some trial and error to find the blanket that fits your horse the best.

“All of these tips for fit are helpful, but my biggest secret is to buy from a retailer with a return policy!” shares Donohue.

Blanketing Horses at Home vs. Boarding Barns

Hill and Ford have worked in barns large and small, with blanketing recommendations for each scenario. Blanketing options vary when it comes to keeping horses at home or at boarding barns, and for the policies a boarding barn may offer.

For people who care for their own horses and are not blanket-changing multiple times throughout the day, they recommend one of the interchangeable blanketing systems as a good cost-effective option. These typically include a waterproof outer layer with liners that clip in. The liners are usually less expensive than a blanket, and you can swap them out to keep them clean and dry.

“A clean blanket is really important to keep a horse warm, because if the polyfill absorbs oil from the horse’s coat and packs down, it no longer has air pockets and is no longer is warm,” explains Hill. “I always talk about ‘clean underpants’—we like to keep a sheet on the horse next to the skin. I keep two cheap cotton sheets that I can wash easily because then I don’t have to wash my big, heavy blankets as often.”

If barn staff are the ones blanketing and unblanketing your horse, it’s important to be considerate.

“If you keep your horse at a large boarding barn where somebody other than you is in charge of changing 20 horse blankets in a day, the blanketing systems are a pain for them because they have to take the whole thing off, change the layers, and put it back on,” says Ford.

In that situation, she recommends having a lightweight (100g or 150g fill weight), a medium, and a heavy because you can layer between those three. The barn worker can put these on or off as needed, and they can go in whatever order.

“At the end of the day, what is most convenient for the staff is going to mean your horse is blanketed appropriately if you’re not the one in charge of it,” says Ford. Ask them what they prefer and works best for them.

Key Takeaway

While there is no one-size-fits-all solution to blanketing, understanding your horse’s individual needs is key. Blanketing can be beneficial, but it certainly requires attention to detail. By following these best practices, blanketing can be a useful tool to help your horse thrive during the winter months.

This article about horse blanketing practices appeared in the November/December 2023 issue of Horse Illustrated magazine. Click here to subscribe!

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Depending on whether you and your horses live in Maine, Kentucky, Montana, or California, winter in each area manifests itself differently. Each region has unique patterns; winter pastures in Montana look whiter than those in Northern California, which might be soggy and green. Experts tell us one principle is the same for winter horse pasture management no matter where you live: Overgrazing and allowing horses on soggy, wet soils are the bane of winter horse pasture management.

The Off Season

“There is always an ‘off season,’ no matter where you live,” says Jay Mirro, senior resource planner for the King Conservation District outside of Seattle, Wash. Mirro develops farm plans for horse and livestock owners; farm plans are basically a road map for managing land and animals.

His tenet for winter horse pasture management is to never graze on wet soils and never graze below 3 inches of forage stubble height—the height of a plant after grazing or mowing.

“The off season is when you don’t put horses on pastures out of concern of degrading the health and productivity of your pasture,” he explains.

Wet Soils + Grazing = Compaction

“Ideally, it’s best for the pasture if you don’t do anything to it in the winter when the ground is wet and not frozen,” says Mirro. “Grazing ground that is saturated and soggy creates compaction. Compacted soils don’t drain as well and have less oxygen for plant roots to respire, creating an environment that promotes weeds instead of grass.”

All this reduces soil health, microbial life, and nutrient cycling of manure and urine, explains Mirro, who is himself also the owner of a 34-acre farm with seven acres of pasture for his beef cows, sheep, and goats.

“Grazing when the soils are wet makes for a higher chance that horse hooves will physically damage sod, tearing the grass out of the ground,” creating depressions and uneven pock marks in the soil surface, he says. “Next summer when you mow the field, you will curse because the ground is so uneven.”

Compacted ground is a bad deal if your intention is to grow a productive pasture. Compacted soils are much less absorbent, which causes water to run off, carrying soil sediment along with nutrients and pathogens from manure and urine. All of this is labeled as non-point pollution, and it can potentially harm waterways and the animals that live there.

“If the ground is wet enough that you wouldn’t consider driving [equipment] on it, then it’s too wet for animals to use it,” explains Marty Chaney, an agronomist and pasture management specialist with the Natural Resources Conservation Service (NRCS) in Olympia, Wash. She was named Pasture Conservationist of the Year in January 2023, and is fondly known as “The Grass Whisperer.”

The Cutoff Point

Northern climes that experience a white winter still need to be careful when grazing pastures.

“Snow insulates the soil,” says Chaney. “It’s possible that there is a layer of wet, unfrozen soil under the snow, which can be damaged. Even if there is no snow, frozen plant crowns can be subject to injury [from overgrazing].”

Pasture grasses do not grow during the winter months, so care must be taken to avoid animal consumption of available grass, as grass won’t grow back for months.

“By allowing horses to graze and harvest forage, you are reducing the insulation that grass provides, causing further chilling of the soil. Spring regrowth will be slower,” she explains, because of the required warming of the soil, which will be necessary after the lack of insulation during cold weather.

“If a pasture gets grazed down to the ground, it takes longer to regrow” once spring rolls around again, says Chaney. “Most grass species don’t like to be grazed below 3 inches.”

Confinement Areas

In the winter, you’re basically trying to protect the soil and plants. The two together will give you a healthier pasture throughout the year.

“Instead, create a good confinement area,” says Mirro. “This provides a great solution to horsekeeping in the winter.”

The confinement area becomes your horse’s outdoor living quarters, and it’s where you keep your horse when pasture growth has slowed, so your pastures don’t get grazed below 3 inches.

“A confinement area, roughly 1,000 square feet per horse with 6″ of a well-draining gravel product [for footing], will have stability,” he says.

Guidelines for Limited Grazing

This doesn’t mean no pasture in the winter.

“There are still opportunities when horses can graze in the winter,” says Mirro, as long as you are careful to keep horses off wet soils and keep turnout times short.

He offers a few guidelines for judicious winter grazing:

◆ Limit turnout time to 30-60 minutes max.

◆ Besides the concern for overgrazing or compacting wet soils, also be aware of significantly changing your horse’s diet, which can upset his gut biome, leading to metabolic disorders like colic.

◆ Choose your highest and driest fields.

◆ Be mindful of the weather; if it’s been dry for a few days, that’s the best time to do some limited turnout.

“If you absolutely have to use the pasture, it’s just 30 minutes twice a day,” Chaney agrees. “When you are starting to think about rototilling your garden” in the springtime when the ground is firmer, that is the time to slowly begin integrating pasture back into your horse’s diet.

Getting Help for Winter Horse Pasture Management

Both your NRCS office and your local conservation district can offer free, non-regulatory education and technical assistance (see “Know Your Resources” below).

Two other sources of information can also provide management guidance:

◆ Soil Type: The Web Soil Survey is an online database operated by the USDA that provides information about the unique properties of each landowner’s soil.

“The front page is self-explanatory, and they have links that explain characteristics of soils,” says Chaney. Some examples include texture, ability to drain, parent material, and distribution over a landscape.

◆ Soil Nutrient Testing: “It’s good to get one done every few years to see what’s going on,” says Chaney. “Most labs will provide advice, too, on how to manage your pasture based on your soil testing results.”

Contact your conservation district or NRCS office for more help.

“Take a walk regularly in your pastures to see what’s happening,” Chaney suggests.

She often tells landowners to photograph a section of their land and compare it over the years.

“You will more easily see the changes in types of plants and productivity, both positive and negative, this way. This will give you feedback on how your management is affecting the field.”

Winter Horse Pasture Management: Key Takeaways

“We need to balance the needs of the horse with the needs of the pasture,” says Mirro. “Many horse and livestock owners treat pastures as turnout exercise areas, and we don’t want to get to the point where we don’t have any grass in a pasture, because that’s not ecologically sustainable.

“We need to be thinking about pastures with their effect on soil health, runoff, and the local environment. There are ways we can graze in the winter, but you just want to be mindful that you aren’t doing damage or increasing potential problems,” he concludes.

“Pasture plants in more northern climates actually start their annual growth in the fall, so how you manage them in the winter will have a significant effect on how they perform the following spring and summer,” adds Chaney.

Winter horse pasture management is critical to maintaining both healthy horses and thriving pastures, no matter where you live. While it’s important to provide winter grazing opportunities when appropriate, careful attention must be paid to soil and forage conditions to prevent harm to both the pasture and the horse’s health.

This article about winter horse pasture management appeared in the November/December 2023 issue of Horse Illustrated magazine. Click here to subscribe!

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It’s that time of year when the grass gets greener and starts growing fast. But is it time to open the gates and let your horses graze the pastures you’ve carefully fenced off all winter? Putting horses out too soon in the spring can reduce the productivity of your pastures this coming summer, plus letting horses graze too much too quickly can be dangerous for horse health.

Here is some guidance for horse pasture maintenance to keep in mind at the start of grazing this spring.

1. Use a Confinement Area

You can greatly improve the health and productivity of your pastures by creating and using a paddock or heavy-use area for confining your horses. An enclosure, such as a corral, run, or pen becomes your horse’s outdoor living quarters.

Your horses should be confined here during the winter months when pasture grasses are dormant and not growing. In springtime, confine horses here when soils are still wet (more on this in a moment).

In the summer, use the confinement area to keep pastures from becoming overgrazed—never below 3 or 4 inches—and to keep your horses from becoming overweight.

A good location for a confinement area is in a high, well-drained area that has chore-efficient access so it’s easy to feed horses and clean paddocks. Make sure that paddocks slope gently away from the stall or shelter for good drainage, and consider putting down some type of footing, such as crushed rock or coarse sand to help prevent erosion and mud.

A good location for a confinement area is in a high, well-drained area that has chore-efficient access so it’s easy to feed horses and clean paddocks. Make sure that paddocks slope gently away from the stall or shelter for good drainage, and consider putting down some type of footing, such as crushed rock or coarse sand to help prevent erosion and mud.

Implementing a regular manure management program will help prevent a buildup of muck as well as getting a source of compost lined up for your pastures.

2. Give Pastures Time Off

One of the key tenants of pasture management is the time you keep horses off the pasture. Saturated soils and dormant pasture plants simply cannot survive continuous grazing and trampling.

When soils are wet, they are easily compacted, suffocating the roots of grass plants. Over time, these plants die out and weeds and mud will take their place. A simple test for sogginess is to walk out by yourself onto your fields to see if you are creating a footprint as you go along. If so, you know it’s too wet and the weight of a horse will surely compact the soil.

Instead, wait until your pastures dry out more and try the foot-printing test again.

3. Separate the Wettest Areas

In the spring, you can let horses onto the higher dry areas first and save the wet areas until later in the summer when they dry out.

Temporary fencing using self-insulating step-in plastic posts and electric tape is best for something like this, as you can simply adjust the shape of your grazing areas as you need it.

4. Apply a Green Band-Aid

Encourage a thick, healthy stand of grass by hand-spreading grass seed in areas that are bare or where grass isn’t growing as thick as you’d like. Otherwise, those same bare spots provide a growing site for summer weeds and can mean more mud next winter.

For most parts of North America, a mix of horse pasture seeds containing orchard grass, endophyte-free tall fescue, perennial rye grass and/or timothy work best. Warmer parts of the country should mix in warm-season species like brome.

For help selecting grasses specific to your region, consult your local conservation district, extension office, or the Natural Resources Conservation Service.

5. Test the Soil

Fertilizer is almost always overused—and may not be needed at all. Just because it’s spring doesn’t mean it’s time to fertilize. Applying fertilizer when your pasture grass doesn’t need it means wasted time and money, plus excess fertilizer will most likely be washed into nearby streams or lakes, or it can seep into ground water.

The best way to find out if your pastures need to be fertilized is to do a soil test. By finding out what your soil needs, you will be able choose a fertilizer with the right amount of nitrogen, phosphorous, and potassium. Fertilizers high in nitrogen may not be what your grass plants need in the spring. Nitrogen promotes plant top growth, which grass plants are already doing vigorously on their own.

Do an Internet search to find soil testing labs or reach out to your local conservation district, Natural Resources Conservation Service office, or extension office for advice on the best way to take a soil sample. If you find that you need to fertilize, fertilizing in mid-spring and/or late fall is usually sufficient.

6. Spread Compost

Once soils are no longer saturated and you are able to drive equipment out on your pastures without risk of compaction, do your horses and pasture a favor by spreading compost. The many micro and macro nutrients, organic material, beneficial bacteria, and fungi in the compost will help your grass plants become more productive.

Spread a thin layer, approximately ¼ to ½ inch thick, and no more than about 3 to 4 inches total in the same area per season. Compost can be spread by hand or with a manure spreader. Go back through with a harrow (a drag) to break up clumps and spread compost thinly. If you don’t own a harrow and tractor, use a garden rake and go through by hand, raking thicker areas so plants aren’t smothered with compost.

7. Introduce Grazing Gradually

Once horses begin grazing pastures again, limit turnout time. Too much spring grass can cause very serious digestive issues when the microbes in a horse’s gut are not yet adapted to the diet change. Start with about an hour at a time and work up to several hours over a period of weeks. For additional questions on how much grazing time is safe for your horse, consult your veterinarian.

Also be careful not to allow your grass to be grazed below about 3 to 4 inches in height. The most concentrated sugar (the plant’s food source) is in the bottom few inches of grass plant. Above that is the more fibrous portion of the plant, which is healthier for a horse to consume. It’s also detrimental to the grass plant to remove its food source.

Let grass plants grow to 6 to 9 inches in height before turning horses out on them, and remove horses from any area once it is grazed down to 4 inches.

We are all excited to see green pastures in the spring. Prioritizing good maintenance of them will help ensure their health this coming summer, which makes for happy horses.

This article about spring horse pasture maintenance appeared in the March 2023 issue of Horse Illustrated magazine. Click here to subscribe!

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As temperatures drop, feeding your horse presents a new set of challenges. Instead of grazing all day on nutritious green grass, he’ll probably be switching to a diet of hay. Many horses lose weight without access to unlimited pasture. In addition, impaction colic due to dehydration presents a very real risk. Read on to stay ahead of these risks this winter.

Hay Keeps Your Horse Warm in the Winter

Not only does hay meet your horse’s forage needs, it also helps keep him warm. The process of digesting fiber in the hindgut produces tremendous amounts of heat, almost like carrying around a little wood stove. Don’t believe anyone who tells you to feed corn to keep your horse warm—it doesn’t!

While round-bale hay presents a convenient method of feeding many horses for a long time in the winter, be picky about quality when buying it. Many are stored outdoors, which is OK for cattle use, but hay for horses must be stored under cover to avoid mold spores that cause respiratory disease and illness.

Additionally, cattle-quality hay is very stemmy and tends to be unpalatable and wasted through trampling. Shop around for round bales that resemble your small-bale hay quality. Using a bale feeder will help prevent much of the hay from being wasted.

Hay Alternatives

If you don’t have room to store hay for the entire winter and find yourself faced with a hay shortage, there are some alternatives available. Beet pulp, senior feed, hay cubes and hay pellets are all good ways to provide forage and stretch your hay supply. Keep in mind that none of these provide long-stem forage, so start using them to stretch your hay supply before you run out completely.

Vitamins & Minerals

Without access to green grass, horses may become deficient in vitamins A and E, which are the first to go after grass is baled into hay and stored for long periods. A ration balancer or vitamin/mineral supplement are options to consider for winter feeding if your horse isn’t fed a commercial equine grain mix, which is already fortified with vitamins and minerals.

Additionally, your horse should always have free access to salt. Since ice-cold salt blocks can become unappealing to lick, the best option is a feeder with loose salt. Horses tend to regulate their salt intake very well, and this also keeps them drinking plenty of water.

Hydration Nation

The most important nutrient in your horse’s diet is water. Without staying properly hydrated, the contents of the intestines can dry out as they pass through, causing impaction colic. Although this is often the easiest type to resolve with a vet’s assistance, every horse owner would prefer to steer clear of a case of colic.

If your temperatures regularly fall below freezing, check water troughs at least twice a day, breaking up any surface ice. Better yet, use insulated buckets or float a trough heater in the water. Although horses will drink very cold water, they will drink more if it is in the 40 to 65-degree Fahrenheit range.

Be extra-careful about trough heater cords, making sure they’re wrapped in wire or conduit so mice and horses can’t nibble on them. Stick your hand in daily to check for any wayward electric current, which will stop horses from drinking immediately.

Winter Weight Maintenance for Your Horse

Many horses shed pounds in the winter as they burn more calories to maintain their core temperature. Be prepared for this and have extra hay and grain on hand if you need to increase rations.

You may also consider switching to alfalfa hay or supplementing your grass hay with it (as opposed to adding more grain). Alfalfa boosts the calories per pound of hay, while still ensuring enough forage is in the diet.

If you are prepared for the challenges of feeding your horse in the winter, you won’t be taken by surprise when Mother Nature throws you a curveball this season.

This article about feeding your horse in winter appeared in the November/December 2022 issue of Horse Illustrated magazine. Click here to subscribe!

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If you live in an area where sunlight is plentiful and horses spend hours outside, you’ve most likely seen white faces turn pink as warmer weather takes hold. Like humans, horses are susceptible to sunburn, which occurs when skin is exposed to too much ultraviolet (UV) light. Horses most likely to be affected by too much sun are those with white hair/pink skin on their faces and large swaths of white or lighter colors on their bodies, like Paint Horses and Appaloosas. Though most of us are familiar with sunburn and its manifestation in horses, there is an equine condition that causes what looks like sunburn on steroids, called photosensitization, or photosensitivity.

Photosensitization occurs when certain photodynamic compounds in the skin are exposed to sunlight, which causes a chemical reaction that damages cells. The injured area will become ulcerated, fluid-filled and painful. Like sunburn, this condition often affects areas on the horse that are lightly pigmented and have sparse hair covering, like the muzzle, eyes, tips of ears, and base of the tail.

There are multiple types of photosensitivity; the type a horse is experiencing is classified by the source of the photodynamic compound. The kinds that most often impact horses are systemic photosensitivity (often called primary photosensitivity) and hepatogenous sensitivity (also called secondary photosensitivity).

No matter the cause, the signs of photosensitivity are similar, though the time between exposure and onset of signs may vary.

Feel the Burn

Photosensitization is often seen in summer months when sunlight is most intense and pasture grasses are thriving. Mild photosensitization or cases in early stages may be difficult to discern from sunburn, but advanced cases are easy to recognize.

Light and white areas of the horse affected by photosensitivity can often be so damaged that an owner may worry that the horse got tangled in something, like a wire fence. The skin can be red and blistered, as well as swollen and hot to the touch. Photosensitivity on the legs can also look like scratches (also known as dew poisoning, mud fever, greasy heel or pastern dermatitis).

The blisters eventually break, leaving oozing, raw areas that will become crusty and eventually peel away. Horses experiencing photosensitivity may rub or scratch affected areas, further damaging skin. The wounds can easily become infected without diligent care.

Substances that cause photosensitization can be found in plants and drugs; some chemicals may also act photosensitizing agents. For horses, the compounds most often to blame are plant-derived.

Primary Photosensitivity in Horses

Primary photosensitivity takes place when a photodynamic agent has been ingested by the horse or injected into his body or absorbed through the skin. The agent then circulates throughout the bloodstream, but only causes skin cell damage when the horse is exposed to UV light.

One common pasture plant containing a toxin that can cause primary photosensitivity is alsike clover (Trifolium hybridum), which looks similar to red clover (Trifolium pretense) or white clover (Trifolium repens). Red and white clover are purposely planted for hay and pasture, so it’s important to identify which is which.

Other plants that can cause primary photosensitization are buckwheat, oatgrass, perennial ryegrass and St. John’s wort.

Many other plants (including other clovers and Bermudagrass) are suspected to cause primary photosensitization, but the specific toxins have not yet been identified. Hay made from any plants that cause photosensitivity may also cause a reaction, as the toxins are not destroyed by drying.

Certain drugs can also cause photosensitization, so a conversation with your horse’s veterinarian may be warranted if he is on any of the following: phenothiazine, some sulfonamides (like trimethoprim sulfa), and tetracycline.

Secondary Photosensitivity in Horses

Secondary photosensitivity is the most common photosensitivity found in horses; it takes place when a horse’s liver is compromised to the point where he can’t metabolize specific chemicals normally.

Liver damage can be caused by a myriad of things, but this type of photosensitivity often occurs when a horse ingests plants or blue-green algae that damage the liver, affecting its ability to remove photodynamic compounds from the bloodstream.

Horses most at risk of this type of photosensitization are turned out on pastures that are overgrazed and in poor condition. Oftentimes, more than one horse in a field will be affected by secondary photosensitization.

Some plants can cause both primary and secondary photosensitivity, but the more profound toxic effects, such as liver damage, come from the ingestion of plants that contain pyrrolizidine alkaloids (PAs). Plants with higher levels of PAs include buttercup, comfrey, heliotrope, kale, lanata and ragwort, among many others.

You should call a vet if your horse has no appetite, is lethargic or jaundiced, or is in poor body condition in addition to being sensitive to sunlight; these are all signs of liver damage. Additional diagnostic testing may be necessary to determine how impaired liver function is.

Treatment of Photosensitization

Treatment of the wounds caused by photosensitization is often simply management of symptoms while allowing the skin to heal. Horses experiencing photosensitization should be kept out of the sun and preferably off the pasture that caused the photosensitive reaction. The wounded area should be kept as clean as possible to minimize secondary skin infections, and it is critical to keep flies at bay.

Gentle cleaning of the affected area is recommended; scabs covering the damaged skin should be left alone because picking or removing them could prolong healing and encourage infection. A vet may prescribe steroids to relieve some of the inflammation or an antibiotic if the infection is severe.

Prevention of Photosensitization

Owners of horses with lots of chrome should be diligent in their assessment of white legs and faces (as well as bodies). It’s much easier to heal lesions caused by photosensitivity if the wounds are caught early, but it’s even better to keep sun-related injuries at bay. Try the following:

◆ Use a child-safe sunblock on the areas of the horse that are likely to burn, like around noses and eyes. As always, the higher the SPF number, the more protection the product will offer.

◆ Apply a diaper rash cream, which contains zinc oxide. The sticky product often stays in place longer than traditional sunscreens when the horse grazes in taller grass. An added bonus: These creams are so thick that an owner can tell if a spot was missed during application and bare skin remains exposed.

◆ Consider using shampoos, coat care products and fly sprays that tout their ability to help block sunlight. Remember that these products may not adequately protect a horse’s skin when used alone.

◆ Use fly masks with ear or muzzle coverings; if using a fly sheet or fly boots, opt for products with UV protection.

The wounds and pain caused by photosensitization can be significant and the healing process arduous. Though the cause may never be clear, the owner of any horse who has experienced a photosensitive episode will remain diligent in their monitoring of white patches to try to prevent it from happening again.

Removing Common Culprits of Photosensitization

Alsike clover and St. John’s wort are common causes of photosensitivity in horses, and their management in fields can be key to preventing repeat occurrences.

If alsike clover hasn’t taken over a field, it can be sprayed or removed by hand. However, if the pasture is infested, complete renovation should be considered to prevent the ongoing ingestion of the plant by horses.

St. John’s Wort spreads both by seed and underground rhizome, so it can be difficult to eradicate manually or with herbicide application. It’s also resistant to many herbicides, so a call to your local extension agent may be needed to get advice on how to eliminate it from fields. Biological controls like flea beetles, moths and midges have been used to kill St. John’s Wort, as they ingest the foliage but don’t harm other pasture grasses.

If you suspect a problem or the wounds have gotten severe, contact your vet for advice on an immediate treatment protocol.

This article about photosensitivity in horses appeared in the July 2022 issue of Horse Illustrated magazine. Click here to subscribe!

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Flies love to land on horses’ lower legs, and even the most diligent fly spray regimen can’t always prevent stomping-related cracked and chipped hooves or loose and lost shoes. There is more at stake than gallons of fly spray and dust clouds in the paddock. Are you ready to stop the stomp and help your horse?

That symphony of stomps you hear as you approach your horse’s pasture can be an ominous warning sign of hoof problems to come. If you start to see hoof health deteriorate as summer progresses, you may soon be facing increased farrier bills and even a horse that need time off.

Be a Keen Observer

What’s a horse owner to do? First, make a plan—but make it early in the summer, before the flies take over.

The first step is to understand that the sound of a horse stomping the ground may mean different things, and you must be dedicated to checking your horse several times a day.

Stomping at flies is a normal reaction for horses when flies buzz around and land on lower legs. But a horse will also stomp the ground if he has unearthed a wasp’s nest or biting-ant hill in the ground; he may need your help, especially in a small pen.

Likewise, a horse may be nervously pawing the ground, not stomping. If you hear the sound of stomping when you shouldn’t, don’t assume that your horse is reacting to flies. Always investigate unusual sounds coming from a pen or pasture.

Next, learn what is “normal” for flies in your area and on your farm. Some areas cycle through different types and densities of flies over the course of the summer.

Flies may bother horses more or less at different times of the day, or in different weather conditions. Make notes about what you notice about the flies around your horse and around your barn, in general. If your horse prefers a certain part of a paddock, it may be because there are fewer flies or the ground is softer and pounding isn’t so jarring.

If your horse is sensitive to biting flies, have topical astringents and healing ointments on hand to dab broken skin and welts. Exposed wounds on the lower legs will attract even more flies. Be prepared to call your vet if sudden swelling occurs.

Learn all you can about horse behavior in the pasture. Horses can become habitual stompers, and tales are told of fly-weary horses who kept on stomping even on windy days when no flies bothered their legs.

Fly Stomping Causes Problems for Feet

Fly stomping can wreak havoc on hooves. Shod horses may experience raised clinches, a loosening of the nails’ grip on the hoof wall. The clinches may suddenly feel rough to the touch.

Ragged clinches may cause cuts and scrapes on the hands and thighs of riders and grooms who pick up hooves for cleaning, and rip or catch on an expensive pair of breeches. They’re another good reason to wear long pants around horses in the summer.

Loose shoes are a special danger when horses are shod with clips. Clips prevent shoes from shifting, but a horse can step down on a loose shoe’s clip and damage his hoof wall or sole. A shoe that comes completely off is a danger to all the horses in a pasture, since any of them can step on its exposed nails or protruding clips.

Frayed “potato chip” feet are common in the summer and worsen as fall approaches. Stomping at flies may make brittle hoof walls worse.

Superficial wall cracks are also common in stomping horses, but a crack that penetrates the wall requires the attention of a farrier. It may worsen over the course of the summer if the horse is stomping repeatedly.

Notify your farrier if you see problems developing so they can be treated before resulting in lameness or requiring special shoeing.

Fighting Off Flies

Horses have their pet peeves. One hates wearing leg wraps. Another fears the sound of sprays and won’t stand still for application. Learn each horse’s fly-related idiosyncrasies, inform everyone who cares for the horse, and find workarounds so every horse has as ideal protection from flies as possible to prevent fly stomping.

What’s in your fly spray? Respect anyone around your barn—whether horse or human—who may be sensitive to fly-control chemicals.

Know how much and how often products should be used. Your paddock fly-control practices should suit the severity of your problem, your horse’s turnout schedule, and your environmental priorities.

10-Step Plan to Eliminate Foot Problems Related to Fly Stomping

1. Think ahead. Keep a calendar and mark when the flies start appearing, what times of day they are the worst, and dates when you notice different types and densities of flies and mosquitoes. Also mark days for manure removal. Likewise, make note of weather, and notice paddock areas that have more or fewer stomping horses.

2. Check each foot on your horse before and after turnout. Look for loose or sprung clinches, bent or gaping shoes, and traces of dried blood that indicate stomp-related skin damage. Examine the insides of legs and pasterns.

3. Try using fly boots. If using repellent, too, apply to both the inside and the outside of the leg from the knee or hock down.

4. Don’t turn out horses near manure piles in summer. Remember that flies love manure, so a horse’s feet and lower legs are already often in close range for a fly. Be diligent about picking out your paddocks so you can deprive flies of the manure they seek.

5. Walk your pastures and look for lost shoes. If you find one, note the location and date found and the name of the horse, if known. Check that horse for hoof damage. Your farrier may be able to re-use the found shoe if it’s in good shape.

6. Quickly address shoes that are partially detached. First, call your farrier. You may be instructed to secure the shoe with duct tape or cover the entire foot with Vetrap and keep the horse in a stall until it can be fixed.

7. Learn to remove a loose or bent shoe. If you’re unsure how to do this, purchase a basic set of farrier tools and ask your farrier to teach you. Store the tools in a clean, dry place and don’t use them for anything but horseshoes.

8. Have your horse on a regular trimming or shoeing schedule. Six weeks is normal, but some horses may need shorter intervals, especially in summer. Don’t be tempted to skip or reschedule an appointment in the summer. Overgrown feet and worn shoes that are left on too long put a horse at risk.

9. Not stomping may be a problem, too. Senior horses, laminitics, or ringbone sufferers will especially appreciate diligent lower-leg fly defense. Is there a horse that’s not stomping at the flies, even though he’s in the same paddock with horses who are? It’s possible that the horse is in pain and doesn’t want to slam a sore foot onto the ground.

10. Stomping feet may be only part of the problem. Make sure your horse is up to date on vaccinations for insect-related diseases. A variety of serious infectious horse diseases are carried by horse flies and mosquitoes.

Flies are a fact of life around horses in the summer. They are a nuisance, but they can also cause problems that will gradually compromise a horse’s wellbeing. Horses instinctively stomp their feet when they sense flies.

Your horse will thank you for stopping the stomp before his hooves are damaged.

This article about fly stomping affecting hooves appeared in the July 2022 issue of Horse Illustrated magazine. Click here to subscribe!

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Anhidrosis is a condition defined by the decreased ability to sweat in response to an increased body temperature. It’s often thought to be intricately tied to high heat, but its occurrence is more selective: high temperatures must be in conjunction with high humidity. This condition is cause for concern because between 65 and 70 percent of a horse’s body heat dissipates from sweating, so the inability to cool down can cause a significant impact on health.

Signs of Anhidrosis in Horses

Though horses with anhidrosis are often called “non-sweaters,” this term is misleading: The majority of horses with the condition suffer from incomplete or partial anhidrosis, meaning they don’t sweat as much as they should, or they sweat in abnormal patterns—not that they don’t sweat at all.

This condition is most often diagnosed in performance horses that are in work, but it can affect any horse, including those that are retired and not ridden. Studies have shown that darker-colored horses are often more affected by anhidrosis than their lighter-colored counterparts¹.

This condition doesn’t appear on most horse owners’ radar until their horse has a fairly serious health episode that is linked back to environmental conditions. As temperatures rise, horses suffering from anhidrosis may show a decrease in exercise tolerance and a higher-than-expected respiratory rate for the amount of exercise that was undertaken.

These horses may also have dull, dry haircoats or be seen leaving the herd to stand in the shade alone. Lack of sweating is the most serious manifestation of the disease and often occurs after other clues are present.

As with many equine diseases, it’s better to catch the condition early, when intervention has the greatest chance for impact. Martha Rodgers, VMD, owner of Shephard Hill Equine in Lexington, Ky., recommends learning your horse’s sweat patterns in different temperatures, especially if he’s located in an area with high heat and humidity.

“With a noticeable reduction in sweat capability or pattern, diagnosing the condition earlier has typically made it easier to stimulate increased sweating with the available treatments,” Rodgers says. She notes that if the horse has a complete inability to sweat, the treatment is often less effective overall or can take much longer to see any effects.

What is the Cause of Anhidrosis in Horses?

The cause of anhidrosis isn’t clear, but it’s believed to be linked to overstimulation of the horse’s sweat glands by stress hormones, often in the heat of the summer. Anhidrosis can be brought on by a plethora of triggers, including electrolyte imbalance and overtraining².

Antihistamines and macrolide antibiotic (broad-spectrum antibiotics used against many gram-positive bacteria) use can lead to temporary anhidrosis, but the condition typically abates once the drug ceases to be administered.

The form of anhidrosis most horses experience is called chronic idiopathic anhidrosis (CIA). CIA is frustrating for horse owners as it is the most difficult form to control. A treatment for complete resolution is not yet available, but steps can be taken to make the horse more comfortable.

Researchers at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) have identified a genomic marker that contributes to CIA. The scientists discovered a genetic marker pointing to a defective potassium transporter channel³. The research team hypothesizes that sweat glands trying to use these damaged channels eventually lose their ability to sweat.

Diagnosis and Management of Anhidrosis

A horse is often diagnosed with anhidrosis by clinical observation and examination, including a medical history. However, a “sweat test” can be done to quantitatively assess how well the horse can sweat.

A sweat test involves a series of intradermal terbutaline injections, which should increasingly stimulate the horse’s sweat glands as medication concentration rises. The vet will likely also run a blood panel that includes an electrolyte analysis; this may assist in the formation of a treatment plan. A skin biopsy can also be performed, but it’s rarely necessary to look at the skin microscopically to make a definitive diagnosis.

Once a horse is diagnosed with anhidrosis, he must be given supportive care to assist with thermoregulation. Management changes are often necessary to ensure the horse’s safety, as well. This doesn’t often mean moving your horse to a cooler climate, although in extreme cases, relocation may be considered.

Simple management modifications can include limiting sun exposure and minimizing turnout during the hottest time of day. Reducing training and showing schedules is often necessary, but making sure the horse isn’t ridden during the hottest part of the day may suffice and allow the horse to remain in work.

Supplements and Acupuncture

Many owners find themselves eager to try anything that could help their anhidrotic horse. You may have heard about adding a daily dark beer to his grain ration; there is no harm in this, though it hasn’t been shown to do much good.

“There are a few supplements that have shown some anecdotal success over the first few days [of use], so response to treatment can be assessed quickly,” Rodgers says. “There are other [supplements] that are typically given over a month or more, and response to treatment with those products may be harder to evaluate, as environmental conditions may change over that length of time.”

Rodgers notes that a 2010 study of Xiang Ru San, a Chinese herbal medicine, used in conjunction with acupuncture showed statistically significant benefit to all 18 horses with anhidrosis that were studied⁴. However, this study relied on owner reporting and didn’t have a control group or double-blind methodology.

A double-blind study of 44 horses conducted in 2012 by the University of Florida also found significantly improved sweat-test results from acupuncture and herbal medicine, and did have a control group. However, these results returned to baseline four weeks after stopping treatment⁵.

“Consistent use of Xiang Ru San while the horse still has some ability to sweat, albeit reduced, has been helpful in my practice,” says Rodgers. “I’ve had the most beneficial, longer-lasting results with consistent management changes and Neuro-Vet paste use soon after diagnosis.”

Unfortunately, it’s important to note that no anhidrosis treatment is one and done.

“Most of the treatments have to be ongoing until consistent increases in sweating ability are seen [which can take a month or more], or until the combined ambient heat/humidity index has declined,” says Rodgers.

Once a horse has had anhidrosis, he should be monitored whenever environmental conditions might trigger it.

Managing anhidrosis can be difficult and a drain on an owner in terms of time and finances. However, with diligent care and a dedicated veterinarian, a horse suffering from anhidrosis can often lead a safe and healthy life—no relocation necessary.

Sources

1. Hagyard Equine Medical Institute
2. University of Florida IFAS Extension
3. University of Florida IFAS Extension
4. American Journal of Traditional Chinese Veterinary Medicine
5. University of Florida

This article about anhidrosis in horses appeared in the June 2022 issue of Horse Illustrated magazine. Click here to subscribe!

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When it comes to summer, hot weather has its own brand of risk factors for horses. Knowing what can possibly go wrong will allow you to take proactive steps to properly manage your horse’s health in the summer.

Pay close attention to very young and very old horses, both of which are more at risk in hot weather.

Dehydration

The average 1,000-pound horse drinks a minimum of 5 gallons of water a day, often much more during hot weather. Your horse needs 24/7 access to cool, fresh water, which may require relocating water sources into the shade.

“The No. 1 heat-related issue that we see in our practice is dehydration colic,” says Christine Staten, DVM, a large animal veterinarian with Adobe Veterinary Center in Tucson, Ariz. “The GI tract is the lowest priority organ, so when your horse is even slightly dehydrated, the body sends the fluid to the highest priority organs first, which leaves the GI tract super dehydrated. When that happens, it slows down and doesn’t work to move the food and gas. This can be incredibly uncomfortable, and in the worst cases, can progress to a displacement if not addressed.

“The most important and effective treatment for these horses is water, either through a nasogastric tube or through an IV,” Staten continues. “Water is more important than any medication we could give.”

Overheating

As outdoor temps climb, it’s much easier for horses to overheat. It’s important to monitor temperature carefully as a precaution to maintain horse health in the summer.

“Horses that are overheated tend to have higher body temperatures and respiratory rates,” says Staten. “If your horse is not exercising and he is breathing faster than 20 breaths per minute or his body temperature is higher than 101.5 degrees, he is likely overheated.”

Call your veterinarian immediately if your horse shows any of the following signs:

◆ Elevated respiration even when at rest (normal range is 10 to 15 breaths per minute)
◆ Continued elevated pulse when at rest (normal range is 30 to 44 beats per minute)
◆ Irregular heartbeat or “thumps”
◆ Body temperature 103 degrees Fahrenheit or higher
◆ Profuse sweating or no sweating
◆ Dehydration
◆ Depressed, listless attitude

While waiting for the vet to arrive, get your horse into the shade. Allow him to drink as much cool water as he wants.

Using a hose, run cool water over the large blood vessels along the inside of his hind legs, belly and neck. Pouring rubbing alcohol over his back and standing him in front of a fan can also help lower body temperature.

Anhidrosis

Horses living in regions where hot temps are combined with high humidity are more at risk of anhidrosis, which is the partial or total inability to sweat. This can wreak havoc on your horse’s health in the summer.

Signs of anhidrosis include panting, rapid breathing with noticeable flaring of the nostrils, elevated temperature even at rest, decreased energy, and sparse, dry hair coat, sometimes with scaliness or thinned hair on the face, neck and shoulders.

“Anhidrosis is seriously dangerous for a horse’s life, and we do not have a cure for it. It’s primarily about managing their environment,” says Faith Hughes, DVM, DACVS, who has been with Peterson Smith Equine Hospital & Complete Care in Ocala, Fla., since 1991.

Management includes using sprinkler systems and fans, not exercising when it’s hot, feeding during cooler times of day, and making sure the horse always has cool water available. You’ll find a variety of supplements on the market designed to help manage anhidrosis.

Mosquito-Borne Disease

Another major threat to your horse’s health in the summer comes along with those buzzing pests that bother everyone at the barn. Eastern and western equine encephalomyelitis (EEE, WEE) and West Nile virus are the main mosquito-borne diseases that affect horses. Fortunately, proven vaccines are available to prevent them.

These are considered “core” vaccines, meaning all horses should receive them. In regions with heavy mosquito populations, veterinarians often recommend horses be vaccinated against these diseases twice a year to avoid this summer danger for horses.

“We have cases of EEE in Florida every year, which serves as a reminder that this disease is not gone and is not more prevalent only because of vaccination,” says Hughes. “Encephalomyelitis vaccines are more than 99 percent effective at preventing the disease when administered effectively.”

In addition to vaccinating your horse, use repellents labeled for use against mosquitoes. Cut down on mosquito breeding areas by eliminating standing water and damp vegetation.

Fly Problems

Fly control—both on-horse and in the environment—is important, not only because flies are irritating, but because they are responsible for transmitting a variety of diseases, including pigeon fever and equine infectious anemia, to mention only a couple.

House and stable flies also play a role in summer sores (cutaneous habronemiasis), weeping skin lesions caused by the infective larvae of stomach worms.

“Summer sores are very treatable, but they’re uncomfortable for the horse and annoying for the owner,” says Hughes. “Pay attention to any scratch or wound and keep them clean, since summer sores need an open sore to start.”

Hoof Concerns

Flies can also spell trouble for your horse’s hooves.

“I’ve seen horses pop clinches and loosen new shoes in just a couple days from stomping their feet at flies,” says certified journeyman farrier Jason Maki of the College of Veterinary Medicine Teaching Hospital at Texas A&M University. “With continued stomping on hard ground, barefoot horses can bruise and chip their feet.”

White line disease can also increase during the summer in both barefoot and shod horses.
“As the humidity goes up, that fungus tends to proliferate,” says Maki. “Keep an eye out for separation and any gray powder along the white line and dorsal cracks at the toe.” He says the problem is treatable with a topical chlorine dioxide product and proper trimming.
Dry, hard hooves are more susceptible to cracks and chips.

“Providing an area with moisture will help minimize the damage of excessively dry feet,” says Maki. “A classic solution is to overflow the water tank enough that there’s a place for their feet to get damp every day.”

Hooves tend to grow faster during warm weather, so you’ll likely have to shorten your trimming or shoeing cycle.

Poisonous Plants

Weeds—some of which are poisonous to horses—grow quickly during the summer, and can be a danger for horses. Generally speaking, horses will avoid eating poisonous plants, but if they are hungry (or young and curious), they may eat plants they wouldn’t otherwise.

Your local university extension office will have a list of poisonous weeds in your area. Walk turnout areas and fields regularly to identify and remove any poisonous plants.

Feed Spoilage

Feed and hay can grow mold and mildew quickly when it’s hot and humid, so buy smaller quantities. Use your eyes and nose to check for off-smelling feed and hay.

If you wet feed and hay (including hay cubes or pellets) for older horses with dental issues, realize that dampened feed products spoil quickly in the heat. Discard any leftovers promptly and clean feed tubs daily.

Snakebite

If you live in a regions with western or eastern diamondback rattlesnakes, your horse can be at risk of snakebite.

Rattlesnake venom has a necrotizing effect because it starts killing and “digesting” tissue around the bite. In addition to damaging tissue, the venom also affects the victim’s circulatory system, destroying blood cells.

A rattlesnake bite is always an emergency and requires prompt veterinary treatment.

This article about managing horse health in the summer originally appeared in the July 2021 issue of Horse Illustrated magazine. Click here to subscribe!

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Thumbs Up: Evaluating Your Horse’s Supplement Program During Changing Seasons

The weather is cooling down, and the leaves are turning colors, which means there’s something else that may be changing: your horse’s needs. If your horse’s workload, diet or living environment is changing with the seasons, he may benefit from different areas of support than he does during the summer. This is the perfect time of year to evaluate your horse’s workload, diet and living environment for the upcoming seasons and determine whether he may need different support now than he did over the summer. To learn more about why your horse’s supplement program may need to change if you’re taking it easy this winter, working harder this winter, or maintaining your regular workload this winter, check out SmartPak’s blog, “The Seasons are Changing. Are Your Horse’s Needs?”

Thumbs Down: Stopping Supplements Just Because the Seasons Have Changed

Even though the weather is cooling off, that doesn’t necessarily mean your horse’s supplement program should, too. While there are some types of supplements that you don’t need all year, many of the most popular supplements are critical even in your horse’s “off-season.” There are four areas of support that are key to your horse’s health no matter what season it is, including joint, hoof, digestion, and skin and coat. To learn why supporting your horse with these key categories is a smart investment in his health, visit SmartPak’s blog, “There is No Off Season for Your Horse’s Health.”

View more SmartPak SmartTips of the Month

The post November 2019 SmartPak SmartTip of the Month: With Changing Seasons, Should Supplements Change? appeared first on Horse Illustrated Magazine.