Summer brings its own set of challenges for extremely sensitive-skinned horses, as insects, sweat, humidity, and even insect repellent products can trigger skin irritation.

Photo by niku16/Adobe Stock

Prioritize Insect Control

Horses with insect allergies may develop equine eosinophilic collagenolytic granulomas—round, firm, raised nodules that are often covered by normal-looking hair. Consistent insect management, including fly sheets, masks, boots, fans, and topical insect repellent products like fly spray, may help reduce reactions in susceptible horses.

When sensitive–skinned horses are bitten by insects, the resulting itching and inflammation can lead to rubbing, scratching or biting. This trauma weakens the skin barrier, providing an entry point for bacteria and increasing the risk of secondary skin problems, including rain rot and staph infections.

Choose Fly Spray Carefully

For some sensitive–skinned horses, fly control presents a catch-22: Insect bites trigger irritation, but the fly spray used to prevent them may also cause a reaction. Certain horses may be sensitive to the active ingredients or carriers used in a particular formula, including the ingredients that distinguish water-based from oil-based fly sprays.

Water-based fly sprays are typically lighter, dry more quickly, and leave less residue, making them a useful option for horses that have skin reactions to oil-based products.

Oil-based formulas often last longer and resist sweat or light rain, but they can leave an oily buildup that traps dirt and sweat against the coat, which can lead to secondary skin conditions or allergic reactivity.

Regardless of the formula, patch-test every new fly spray on a small area for 24 to 48 hours before applying it all over the horse. This can prevent a localized sensitivity from becoming a widespread reaction.

Stop using any product that causes redness, swelling, hives, itching, or hair loss, secondary infections, and hose the horse’s skin down immediately if they do react. Because frequently rotating products can make skin triggers difficult to identify, introduce only one new product at a time.

Sweat, Humidity and Summer Skin Flare-Ups

Summer heat, humidity and frequent insect exposure can keep a sensitive horse’s skin damp and irritated for hours.

After riding or turnout, remove sweat and dirt from high-friction areas such as beneath the saddle, girth, mane and between the hind legs. Hose off, bathe, or wipe the coat as needed, then allow it to dry completely before applying fly sheets, fly boots, etc.

Check the skin regularly for early crusting, scabs, itching, swelling, or hair loss in the summer, especially during very hot and humid weather. Persistent moisture from humidity, insect bites, and rubbing can weaken the skin barrier and contribute to rain rot or secondary bacterial infections.

Clean grooming tools, tack, and saddle pads regularly to prevent sweat, dirt, product residue, and infectious organisms from building up and further irritating sensitive skin.

The post Summer Survival Guide for Horses with Extremely Sensitive Skin appeared first on Horse Illustrated Magazine.

“These insects make their appearance in the spring and become sparse in the cold winter months, but generally they remain active year-round, especially in places like Florida, contributing to the chronic causes of allergic skin disease in some horses,” says Caitlyn Henderson, DVM, of Peterson Smith Equine Hospital in Ocala, one of Florida’s largest equine clinics.

The condition is often seasonal with chronic relapses, but horses in warmer climates may be affected year-round.

Photo by Bob Langrish

Clinical Signs of Insect Bite Hypersensitivity in Horses

Horses suffering from IBH often present with recurrent hives and/or chronic itching (pruritus). Clinical signs of IBH can include:

◆ Circular areas of crusting caused by inflammation (bacterial folliculitis)

◆ Blisters (papules)

◆ Hair loss (alopecia)

◆ Raised, hard, thickened areas of skin

◆ Broken hairs with sores in mane and tail head

◆ Self-trauma from rubbing

◆ Pigmentary alterations

◆ Behavioral changes due to discomfort

“Signs can often start as very subtle, especially when under the mane or at the tail head,” says Henderson. “Broken hairs are easy to miss in the beginning.”

Intense itching can cause allergic horses to rub bald spots and sores into their manes and tails. Photo by Christiane Slawik

Skin lesions develop where insects feed. This is typically along the horse’s ventral chest and abdomen, under the mane, along the withers and back (dorsum), tail base, and inguinal areas (between the hind legs), as well as on the face and ears.

“These lesions all come with a degree of itching, which feeds the cycle of lesion development, eventually causing severe scarring, permanent hair loss, and depigmentation,” says Henderson.

Why It Happens 

With IBH, a half-ton horse can’t hold his own against tiny insects.

The horse’s immune system is triggered by proteins and enzymes in the insects’ saliva as they feed. The horse’s body identifies those salivary enzymes and proteins as foreign, which causes the allergic response.

“The immune system releases antibodies, specific immune cells, and inflammatory mediators that drive inflammation and cell migration to peripheral tissues near the bite site, which then drives itching and swelling,” says Henderson. “Histamine is also released from mast cells sent by the immune system at the bite site, and they release more enzymes that irritate nerves nearby, further driving the urge to itch.”

It’s a nasty cycle that will only continue unless the horse is treated and the cause addressed.

Diagnosing Insect Bite Hypersensitivity

Because IBH is often bundled with other environmental allergies, there isn’t a single test to definitively diagnose the condition.

 Veterinarians base their diagnosis on the horse’s history (including travel, exposure, housing, and environment), clinical signs, duration, severity, and frequency of those signs, previous treatment, and diagnostics. The goal is to rule out other skin diseases and determine the best response to treatment.

“Many practitioners will still reach for intradermal allergen testing to support their diagnosis, which is helpful if clients are looking for a more direct approach,” says Henderson. “Serum allergy testing has proven to be of little benefit for horses with their broad range of allergen exposure. It’s like sending your kiddo to daycare for the first time and then testing them to see what germs they picked up while they were there.”

Treatment Protocol 

There is no one-size-fits-all protocol. Medical treatment can soothe the irritated skin and provide relief, but fly control or insect avoidance is considered the mainstay of both treatment and prevention.

“No amount of bathing, fish oil, and cetirizine in the world will help a horse with IBH if we aren’t trying everything we can to reduce the insect population in their environment,” says Henderson. “It doesn’t matter how much Benadryl you give your child after playing in an ant pile if you don’t get them out of the ant pile first.”

Limiting places where flies can make contact with a horse through use of fly sheets, masks, and boots helps sensitive horses enjoy outdoor time. Photo by Christiane Slawik

She advises horse owners to prioritize reducing the insect population and limiting insect-horse contact. This includes:

◆ On-horse insect repellent containing 2% permethrin

◆ Fly masks with ear covers

◆ Fly sheet

◆ Fly boots

◆ Automatic fly spray systems in barns

◆ Fly traps (including sticky traps)

◆ Bug zappers

◆ Strong indoor fans

◆ Keeping horses stabled during peak insect feeding times

◆ Eliminating standing water in paddocks and barn area

◆ Diligent manure management and removal 

Strong indoor fans discourage flies from landing on horses. Photo by Terri Cage/Adobe Stock

Bathing the horse with medicated shampoo is recommended. Look for products that contain ingredients that support healthy coats and reduce dryness, as well as ketoconazole and chlorhexidine to reduce bacterial and fungal growth in the skin that can contribute to itching.

“Many veterinarians want to reach for systemic glucocorticoids, such as dexamethasone or prednisolone, and antihistamines,” says Henderson. “There is little research that supports the efficacy of these drugs for horses with IBH, but anecdotally they show promise in limiting the itch-inflammation cycle. Cetirizine (Zyrtec), another antihistamine, also has little research supporting efficacy against itching and clinical signs associated with IBH, but it is considered safer for horses than systemic glucocorticoids. Regardless, your veterinarian should consider your horse’s general health, risk factors, and clinical signs when starting therapy.”

If you want to try an oral supplement, omega-3 fatty acid supplements have been shown to improve skin lesions, but don’t help with itching.

Diligent manure removal takes away fly breeding grounds. Photo by Christiane Slawik

Secondary Infections 

IBH lesions disrupt the skin’s protective barrier and the population of healthy microbiota. When this happens, opportunistic bacteria and pathogens sometimes infect deeper tissues, causing secondary infections.

“Now, instead of just controlling the itch and giving the skin time to heal, you have to eliminate the bacterial infection before the itching resolves and the healing can finally begin,” says Henderson.

Skin lesions develop where insects feed, such as under the mane, and may not be noticed until the hair is rubbed out. Photo by Christiane Slawik

Immunotherapy

People get allergy shots, but do they work on horses?

Henderson says allergen-specific immunotherapy (ASIT) has shown promise in horses when administered over a period of two years, but so far treatment protocols have not been standardized, so results vary.

“ASIT is especially beneficial for horses who cannot avoid their allergens or who are exposed to their allergens for extended periods, often resulting in further hypersensitization of the allergic response,” says Henderson. “Horses in Florida, for example, are exposed to mosquitoes and biting insects nearly year-round, so those horses that have moderate to severe IBH even in our peak ‘winter’ are good candidates for ASIT.”

It typically takes three to six months to see if the horse will have a positive response to treatment. In some cases, immunotherapy has resulted in remission of the allergy. Your veterinarian can determine if your horse is a good candidate for immunotherapy.

“Immune-modulating therapies, such as Cytopoint (lokivetmab), Apoquel (oclacitnib), and allergy shots are still undergoing safety and efficacy studies in horses,” says Henderson.

Finally, don’t subject your horse to the questionable suggestions you may find when searching for home remedies for IBH. Applying used motor oil, bacon grease, or similar concoctions to your horse’s mane, tail, or coat won’t cure the condition, and can end up increasing skin irritation. 

This article about insect bite hypersensitivity in horses appeared in the May/June 2025 issue of Horse Illustrated magazine. Click here to subscribe!

The post Insect Bite Hypersensitivity in Horses appeared first on Horse Illustrated Magazine.

Algae blooms are the bane of summer, turning your horse’s drinking water into an unappealing green slime. Photo by Richard/Adobe Stock

How to Reduce Water Trough Algae

While unsightly, many types of algae don’t pose a direct health concern. However, certain types of blue-green algae release toxins that can lead to colic and diarrhea in horses. In humans, it can mean skin irritation, stomach upset, and nervous system problems.

Water sources that have a lot of algae can be less desirable to horses and lead to reduced water intake. For all these reasons, it’s good horse-keeping practice to keep algal blooms to a minimum in your troughs with a regular plan of attack.

Algae are plant-like organisms that are photosynthetic. This means they need nutrients and sunlight to grow. When we can reduce or eliminate these, we have a better chance of slowing algae growth and keeping the slime at bay.

Here are a few ways:

◆ Seek shade. Ideally, place the water trough or tank in a shady or covered area. Moving it out of the sun reduces the water temperature and makes the environment less attractive to algae.

◆ Reduce contaminants. If you can, keep the water container away from feeding areas and manure piles. This will help (but not eliminate) pieces of hay, dirt, manure and insects from getting into the water.

◆ Skim daily. Using an aquarium net or pool skimmer, make a daily habit of skimming off anything floating on the surface and scooping up what you can near the bottom of the tank before these particles start to decompose and feed the green monster.

Additives to Try

To help keep water troughs clean, here are a few ideas that might be worth a try, including a couple important caveats.

◆ Barley straw. Prepackaged in small bundles or bales, barley straw is thought to produce a chemical that impacts the pH of the water and reduces the potential for new algae growth (but doesn’t reduce existing algae). Submerge the bundle on the bottom of a clean tank using a brick or other horse-safe weight and replace as indicated on the package.

◆ Copper. The chemical properties of copper inhibit photosynthesis in algae and can help to control it.

Important note! Copper is safe for horses, cattle and dogs, but it is toxic to sheep. Avoid using copper if your horses share water sources with sheep.

Small pieces of copper pipe are one option. Another form of copper is copper sulfate crystals, which, along with zinc sulfate crystals, have been used for years by livestock producers to help reduce algae. Ask your veterinarian for application rates and follow label directions carefully, including dissolving in warm water before thoroughly mixing into the water trough.

◆ Aeration. Algae thrives in still water, so an aerator keeps the water moving. This can discourage both algae formation and mosquito larvae, but be warned that curious horses may see the aerator as a toy. Attach it to the tank or put it in the center of a large stock tank where they can’t reach it.

◆ Commercial additives. A variety of equine water trough products are available, some containing enzymes and other ingredients. Always check with your veterinarian and follow the manufacturers’ recommendations for use.

Important note! Horses are highly sensitive to the slightest change in the taste or smell of their water, and they may refuse to drink if it changes. This can lead to significant health effects, including dehydration and colic. If you do choose to use additives, work with your veterinarian to implement the change slowly and safely.

Maximize Elbow Grease

While additives and biological treatments can help with algae, the tried-and-true method of keeping buckets and tanks clean is elbow grease: regular dumping and scrubbing. However, this can waste a lot of water and create a breeding ground for flies and mosquitoes in the process.

Here are tips to address both:

◆ Use right-sized troughs. If you have just one or two horses in separate pens, opting for smaller troughs or buckets means they can be refilled daily and dumped and scrubbed daily or every few days. Timed well, this can reduce the amount of wasted water. If you have multiple horses or don’t want the daily water bucket chore, opt for a larger trough or stock tank. You still will need to dump and scrub—likely at least once a week, depending on the temperature and other factors—so be sure the tank is small enough to work with.

◆ Pro-Tip: Create an exit ramp. There’s nothing like the horror of heading to the barn in the morning and seeing a drowned animal floating in your stock tank. Build an exit ramp out of clean wood that attaches to the top of your tank, or drill a hole in each end of a clean 2×4. Tie a brick to one end and submerge it in the tank, and tie the other end to the fence or wall behind the tank.

◆ Dump with care. Experiment with keeping troughs and tanks filled only partway and letting your horse drink down the water before you need to dump and scrub. When it’s time to drain, clean and refill, see if you can route the water away—maybe even watering a lawn area or landscape plants. This also prevents creating a mud hole that’s a breeding ground for flies and mosquitoes.

If your tank has a drain plug, attach a hose and let the water drain elsewhere. If your tank doesn’t have a drain plug, use a syphon hose attached to a longer garden hose. Simple syphons use a marble in a copper fitting that you shake up and down to start the flow of water. When nearly all the water has been syphoned out, then move the tank away from the area and dump the rest.

The right size trough, not overfilling, and scrubbing with bleach between refills will help keep the algae at bay. Photo by pimmimemom/Adobe Stock

Clean a Water Trough the Right Way

Starting with a sparkly clean water trough, rather than topping it off, will help the water stay clean longer. Here’s a recommended approach:

1. Empty the tank completely and remove all debris.

2. Scrub it clean with a stiff brush.

3. Rinse the tank with a 1:10 diluted bleach solution (1 part bleach to 9 parts water), or about 1.5 cups bleach in 1 gallon of water. Be sure to use unscented and regular bleach, not the “splashless” versions. Swirl the scrub brush around the bottom and up the sides.

4. Let the bleach solution sit for 15 minutes.

5. Rinse the tank twice with clean water.

6. Refill the tank. The horses can safely drink from it right away.

While summer brings the potential for water trough algae, with a little planning and the right approach, your horse can enjoy clean, fresh water and you can win the battle of the slime.

This article about water trough algae appeared in the May/June 2025 issue of Horse Illustrated magazine. Click here to subscribe!

The post Win the Battle Against Water Trough Algae appeared first on Horse Illustrated Magazine.

Photo by Александр Ульман/Adobe Stock

Ignoring any part of a horse’s nutrient intake can threaten digestive health, immune system support and overall wellness, but a lack of water for even a short amount of time will quickly lead to significant health risks.  

With water intake, however, it’s not just about drinking. A horse’s hydration needs will vary according to diet, nutrition needs and performance demands. 

“The right nutritional balance starts with high-quality hay and pasture. That essential fiber supports proper digestive function and sustains hydration and electrolytes that a horse needs, especially a performance horse,” said Kristyn Sturken, Sentinel® Product Manager. 

Though using diet to influence hydration starts with hay and forage, it doesn’t end there. The type of feed you provide can also positively impact your performance horse’s water intake. 

Guidance for Keeping a Horse Hydrated 

Simply giving access to water does not guarantee a horse will drink enough. Water taste, smell and temperature all affect a horse’s desire to drink, and diet must also be considered. For example, a horse that is eating a lot of pasture, with a high moisture content, may drink less than if he’s consuming primarily hay, which is drier and could induce thirst. 

With that in mind, here are some tips for making sure a horse stays properly hydrated: 

• Offer water: Encouraging a horse to drink can help stimulate thirst. 

• Monitor sweat loss: High temperatures, humidity and intense exercise make a horse sweat, which might require adjusting electrolyte supplementation to offset what’s been lost. 

• • • A horse that is sweating normally will have a lightly moist, shiny coat, particularly under the saddle. 

• • • Sweat will spread to the neck, chest and legs in a horse that is exercising harder. 

• Supplement with electrolytes: Giving a horse a well-balanced electrolyte supplement can help replenish minerals lost during exercise. 

• Forage: Forage provides a significant source of potassium, which can help horses maintain water balance.  

Additionally, it’s essential to know the signs of dehydration. While fatigue, illness or reduced performance are worrying, if dehydration is not tended to promptly, it could result in grave health issues. 

Look for these signs of dehydration and take action immediately if found:

• Elevated heart rate or pulse exceeding 40 beats per minute  

• Changes in gum color or loss of moisture on the gums 

• Loss of skin elasticity; pinch along the neck in front of the shoulder to test—it should retract without delay 

Helping a Horse by Soaking Extruded Feed 

Extruded feed is different from pelleted feed; it is pressure cooked with moisture, which produces light, airy nuggets that encourage more chewing and, subsequently, more saliva production. Slower chewing and increased saliva production help maintain the precise nutrient balance healthy horses require and can support hydration. 

In addition to easy digestibility making nutrients more accessible to the horse, extruded feeds can be easily soaked and prepared as a mash. This can be done much quicker than it takes to soak pellets and can provide extra hydration in horses who are not drinking enough water, which can also help prevent choke. 

Getting a horse to drink more water may help prevent certain digestive upsets associated with high-stress, high-intensity conditions performance horses might experience. 

High-Quality H2O and Electrolytes 

Performance horses are particularly susceptible to electrolyte imbalances because of significant fluid losses from sweat. Electrolytes are minerals that, when dissolved in water, are vital for a multitude of bodily functions, including nerve transmission, muscle contraction and fluid balance.  

Competitive horses face an increased risk of fatigue, reduced muscle efficiency and worsened nerve function if their electrolytes are not replenished. In severe cases, serious health complications can arise. 

Key electrolytes and their function: 

• Sodium (Na): Regulates fluid balance and is essential for nerve impulse transmission. 

• Chloride (Cl): Works alongside sodium to maintain fluid balance and is a component of stomach acid, aiding digestion. 

• Potassium (K): Crucial for muscle function and helps maintain the body’s acid-base balance. 

• Calcium (Ca²): Necessary for muscle contractions, nerve function and blood clotting. 

• Magnesium (Mg²): Involved in muscle relaxation and energy production. 

Supplementing Electrolyte Intake 

You can buy supplements to help restore your horse’s electrolyte balance. These are available as additives for your horse’s water, or even as an oral gel or paste. When using, always follow the label instructions. 

Providing salt is another way to help maintain electrolyte balance. In addition to acting like an electrolyte, salt can also stimulate thirst and encourage a horse to drink more water. 

Whichever method you choose, your horse needs free access to water. Electrolytes can encourage your horse to drink water. 

Also keep in mind that some horses do not like water with additives in it, so when adding electrolytes to their drinking supply, make sure to have a separate, fresh water source available. 

Keep a Horse Hydrated for His Health and Wellness 

A horse must stay well-hydrated to maintain proper nutrient balance and support his diet, workload and lifestyle needs. It’s important to recognize the signs of dehydration and understand what behaviors and conditions increase the risk. There are many effective strategies to help keep your horse hydrated. By actively managing your horse’s water intake, you can help prevent serious health issues and ensure they stay healthy, comfortable and performing at their best.  

This article is a web exclusive for Horse Illustrated magazine. Click here to subscribe!

The post Proper Hydration Maximizes Your Horse’s Nutrient Intake appeared first on Horse Illustrated Magazine.

For many riders, summer brings the most time to spend in the saddle. Days are longer and horse activities abound. This season is also typically when heat-related risks are highest. With intense exercise in hot weather, the horse’s internal temperature can briefly climb as high as 108° Fahrenheit. To recover, the horse is not just battling the ambient temperature, but also his body’s ability to cool itself. So how hot is too hot to ride?

When you’re training toward a goal, consistency is important, but be mindful when you ride to avoid overheating—or worse. For practical advice on summer riding, we turned to veterinarians in two hot—but very different—regions, the Southeast and Southwest.

Photo by ccestep8/Adobe Stock

Hot and Dry

Summer temps in the desert Southwest can easily climb to 120° Fahrenheit, so riding between mid-morning and late afternoon is strongly discouraged.

“Ride early and be done by 10 a.m. or break it into two sessions,” advises Christine Staten, DVM, a large animal veterinarian and owner of Adobe Veterinary Center in Tucson, Ariz. “[You can] ride early in the morning and late in the day, instead of one long session.”

Photo by By adogslifephoto/Adobe Stock

In addition to shorter rides, don’t hesitate to head for the shade for quick breaks.

“In dry environments, just getting under shade can reduce the temperature by 20 degrees,” she notes.

“This advice is as much for riders as it is for horses,” says Staten. “We see more heatstroke in riders in the middle of a hot day than in horses. Every year in Tucson, we have people die from heatstroke on the trail.”

Hot and Humid

Heat and humidity alone can be challenging for horses. Add exercise to the equation and health risks increase.

“The coastal humidity in Florida multiplies the heat index substantially because it reduces the body’s ability to dissipate heat through evaporation or sweating,” explains Caitlyn Henderson, DVM, of Peterson Smith Equine Hospital in Ocala, one of Florida’s largest equine clinics. “It’s akin to trying to breathe and cool yourself from under a hot, wet blanket.”

In addition to not riding during midday, Henderson always advises having a shaded area where horse and rider can take short breaks. Keep buckets of cool water available so the horse can drink. When humidity climbs, it helps to add a misting fan if the area has access to electricity.

Quick Math to Determine If It’s Too Hot to Ride

For a simple assessment on riding safety, add the air temperature to the humidity percentage.

When the combined total is under 130, a healthy horse can effectively cool himself. When the combined total is between 130 to 150, the horse’s ability to cool himself is decreased.

If the combined total is over 150, this ability is greatly reduced. Once the combined total is over 180, conditions can be life threatening for any horse under physical stress.

A good rule of thumb is to avoid riding if the air temperature and humidity combined total over 150.

Horses at Risk of Overheating

Certain horses are more vulnerable to overheating. These include:

• Old or very young
• Not acclimated to climate
• Out of condition
• Heavily-muscled, thicker body types
• Diagnosed with an endocrine disease, like PPID (Cushing’s disease)
• History of equine asthma
• Recovering from a recent respiratory challenge
• Diagnosed with anhidrosis (partial or total inability to sweat)

“If your horse shows any signs of heat stress, have your veterinarian evaluate him to determine if there are underlying issues,” says Staten. “If this is happening, there’s probably something going on that needs to be addressed so we can come up with a plan to remedy it.”

Heavily muscled body types are more susceptible to overheating. Photo by Terri Cage/Adobe Stock

Acclimation

Whether you live in a hot, arid region or where it’s hot and humid, it’s critical that your horse be acclimated to those conditions before strenuous exercise.

After 25 years of equine practice in Tucson, Staten has never seen a healthy, acclimated horse have heatstroke. The problems she sees are in horses that have recently moved to the area or have an endocrine disease, like PPID, or have anhidrosis.

Staten finds the best season to move a horse to the desert Southwest is fall or winter, as this gives the most time to acclimate. If you move in spring, expect acclimation to take at least a couple of months.

Horses coming to hot climates adjust best if moved in fall or winter and allowed several months to acclimate. Photo by Richard Nantais/Adobe Stock

“Dark-colored horses struggle more when trying to acclimate to our weather. If a horse is still shedding a winter coat in spring, that can make it rough on them,” she cautions.

“It’s recommended that human athletes take six weeks, minimum, to acclimate to a new climate, and no less than that should be afforded to our equine athletes,” says Henderson.

She finds it easier for horses to gradually acclimate to heat and humidity if they’re introduced to it in early spring, at latest.

Proceed with caution if you’ve just moved to an area where it’s significantly hotter and more humid than where your horse lived previously.

“I see a lot of riders who come here from New York and New Jersey and just want to ride, but to do this in the summer months is going to be more of a challenge,” says Henderson.

She recommends giving the horse a full week to recover from travel. Then return to light work under saddle, exercising at the coolest time of the day for at least six weeks as the horse acclimates.

She encourages riders to take it day by day, because some horses need more time than others to adjust.

Keep Horses Drinking When It’s Hot

Hydration is critical for horses in hot weather.

Electrolyte loss due to exercise or simply sweating can lead to metabolic stress and decrease the horse’s thirst response, which can result in dehydration and overheating.

In addition to access to salt (plain or trace mineral), horses may need electrolyte supplementation to replenish the sodium, potassium, calcium, and chloride lost through sweating and urination.

Henderson tells riders to prepare for summer temps by introducing electrolytes to the horse’s diet earlier in the year. The goal is to encourage water intake year-round, so horses are always well hydrated before exercising.

“If you’re at a show, offer water between classes,” says Staten. “If you’re on the trail and there’s a place to drink, let them. A horse should always be allowed to drink, even when he’s hot.”

Cool Down

Many people think the best way to cool a hot horse after exercise is just to walk him in the shade. However, research shows that the most efficient method is to continuously shower a stationary horse with cool (79° Fahrenheit) tap water. In a recent study, this method decreased the horse’s core temperature in an average of just two minutes.

“Focus water on the jugular vein and the large veins inside the legs,” says Staten, noting that this helps cool the horse’s core temperature.

Research shows that the most efficient cooling method is to continuously shower a stationary horse with cool tap water. In a recent study, this method decreased the horse’s core temperature in an average of just two minutes. Photo by Daniel/Adobe Stock

Finish cooling out by slowly walking the horse until his respiratory rate and body temperature are normal. Movement helps remove lactic acid from the system and keeps muscles from tightening up.

Always allow the horse to drink during recovery. Research shows that horses voluntarily drink more within the first hour after exercise when water is about 68° Fahrenheit.

Offer half a gallon of water at a time throughout the cool-down process until the horse doesn’t want to drink any more. Make sure there is plenty of water in his stall/corral to drink after he’s totally cooled out.

Summer Travel

Any time you trailer during the summer, pick the coolest part of the day to travel. Increase air flow by opening all vents and windows, but for safety’s sake, do not let horses put their heads outside the trailer.

“Hot metal is like an oven, so get them out of the trailer as soon as you get where you’re going,” says Staten.

Use Common Sense to Determine if It’s Too Hot to Ride

So, is it ever too hot to ride?

“If you think you are going to struggle to get through a ride due to the heat, so will your horse,” says Henderson. “If there’s ever a time you think it might just be too hot to ride, you’re probably right. Go with your gut feeling and take your horse’s health into consideration. It’s never wrong to delay a ride for a cooler time of day for the safety of your horse.”

This article about when it may be too hot to ride a horse appeared in the July 2024 issue of Horse Illustrated magazine. Click here to subscribe!

The post How Hot is Too Hot to Ride? appeared first on Horse Illustrated Magazine.

Warmer summer days can provide the ideal weather for leisurely rides on your favorite mount, but heat can take a toll on horses, just like people. When exercising or working your horse in temperatures in the 90s and 100s, overheating and heat stress can endanger your horse—and even turn deadly. Watching for heat stress signals is vital to your horse’s health.

With intense exercise in hot weather, the horse can become completely covered in sweat and need help cooling down. Photo by Shelley Paulson

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.”

Remove tack and apply continuous running water to help cool the blood and lower a horse’s temperature if you suspect heat stress. Photo by Phil Cardamone/Adobe Stock

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.”

Taking a break in the shade is important during a hot ride. Standing under a tree helps even more as leaves provide evaporative cooling. Photo by CPDPrints/Adobe Stock

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.”

In hot weather, horses can become dehydrated in as little as two to three hours. Make sure your horse begins work as well-hydrated as possible. Photo by Pimmimemom/Adobe Stock

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.

Photo by Pinkcandy/Shutterstock

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).

Advanced photosensitization is easy to recognize; red blisters break and become crusty. Photo by SunnyMoon/Shutterstock

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.

Alsike clover can be mistaken for red or white clover and is found in many horse pastures. It contains a toxin that causes primary photosensitization. Photo by Andrew Koturanov/Shutterstock

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.

Horses on overgrazed pasture containing buttercups and other weeds are at risk of secondary photosensitization, which occurs when the liver is damanged and can’t work effectively. Photo by Spline_x/Shutterstock

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.

Affected areas should be kept clean and out of the sun. It’s important to keep flies away as wounds heal. Photo by Sarah Coleman

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.

Using fly masks with ears and muzzle covers as well as sunscreen on any pink skin will help in preventing primary photo-sensitization. Photo by Patricia Barker/Shutterstock

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.

St. John’s Wort can be difficult to eradicate, but biological controls like flea beetles, moths and midges have shown success. Photo by M. Schuppich/Shutterstock

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!

The post Photosensitization in Horses appeared first on Horse Illustrated Magazine.

Photo by Kei Shooting/Shutterstock

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?

Chipped, cracked hooves can become a big problem for horses that stomp all summer long. Photo by JNix/Shutterstock

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.

If your horse alternates between the pasture and barn, take note of when flies are least active for turnout, and use a clean, shaded stall for when flies are in full force. Photo by Bettina Calder/Shutterstock

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.

Observe what times of day and weather conditions make flies more or less likely to bother your horse. Photo by ThaniT Stock/Shutterstock

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.

If using fly repellent, apply frequently to all sides of the legs according to label directions. This can help keep your horse comfortable during the summer riding season. Photo by Shelley Paulson

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.

Fly boots are available in many styles, such as loose and tight-fitting. They may help keep your horse more comfortable all summer. Photo by Shelley Paulson

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!

The post Hoof Problems Caused by Fly Stomping appeared first on Horse Illustrated Magazine.

Photo by Anaite/Shutterstock

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.

A possible sign of anhidrosis is a horse leaving the group to stand alone in the shade during hot summer days. Photo by Dee Browning/Shutterstock

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.

Learn your horse’s normal sweat patterns in different weather, especially particularly hot and humid conditions. Photo by Rolf Dannenberg/Shutterstock

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.

If a horse doesn’t sweat normally and adequate shade isn’t available outdoors, keep him inside during the day with good ventilation to stave off the negative health effects of overheating. Photo by Tomy/Shutterstock

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.

Riding in the early morning or evenings during the coolest parts of the day often enables a horse with anhidrosis to stay in work without relocating. Photo by Red On/Shutterstock

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.

Two studies have found significant improvement among horses with anhidrosis from acupuncture combined with herbal medicine. Photo by Rolf Dannenberg/Shutterstock

“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!

The post Anhidrosis in Horses appeared first on Horse Illustrated Magazine.

During hot summer days, horses may drink much more than their average 5 gallons of water per day. Photo by Sari ONeal/Shutterstock.

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.”

If you suspect your horse has become overheated, move him to a shady spot and stand him in front of a fan while contacting your vet. Photo by Clix/Shawn Hamilton.

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.

Check your horse’s temperature and respiration rate if you suspect he may be overheated. Photo by Vprotastchik/Shutterstockk.

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.

The good news about mosquito-borne diseases is that equine vaccines are extremely effective against them. Photo by frank60/Shutterstock.

“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.

Flies are not only irritating, but may also transmit pigeon fever and equine infectious anemia. Photo by Sophia Floerchinger/Shutterstock.

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.

Horses will usually avoid poisonous plants, but if grass is drying out in summer, they may be more drawn to these weeds. Find out which ones are common in your area. Photo by Brittany Mason/Shutterstock.

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.

Many areas have diamondback rattlesnakes in the summer. A bite to your horse requires swift veterinary attention. Photo by Pam Phillips Photography/Shutterstock.

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!

The post Heat Risk: Managing Horse Health in Summer Months appeared first on Horse Illustrated Magazine.