How Fly Spray Works

Although fly spray is a familiar product to horse owners, you may not have given much thought to how it works or what’s in the bottle.

“Fly repellents work by either repelling flies or killing them upon contact,” says Erika T. Machtinger, Ph.D., assistant professor of entomology at Pennsylvania State University in State College, Penn. “Repellents contain active ingredients that emit an odor or taste that flies find unpleasant and will try to avoid. Some fly repellents work by combining both repelling and killing properties. These repellents contain a combination of active ingredients that repel flies and contain insecticides that kill them upon contact.”

Active Ingredients

Most companies will list features and benefits on the front of the label, says Casey White, an entomologist and senior director of technical services and innovation for Central Life Sciences, Farnam’s research and development division.

“If it’s something that kills and repels, it’ll say ‘kills and repels’ or ‘insecticide and repellent.’ Often, it’ll call out major species of insects or arthropods, such as ticks, that the product is effective against.”

The small print is where you should pay attention to the listed ingredients, including the number and type of active ingredients and their percent concentration. The active ingredients are what give the product its killing and repelling power.

Active ingredients can be either natural or synthetic. Pyrethrins are a natural insecticide derived from the chrysanthemum flower. These offer knockdown benefits but break down quickly when exposed to sunlight. Pyrethroids are synthetic versions designed to have longer-lasting action; these include permethrin, cypermethrin, tetramethrin, and others.

Essential oils such as citronella, geraniol, eucalyptus, thyme, cedar oil, lemongrass, rosemary oil, and clove oil are natural options to repel insects. Fatty acids are another type of natural repellent, including octonoic, nonanoic, and decanoic acid.

Other ingredients include synergists, which work to amplify the active ingredients to provide greater killing power and/or longer-lasting protection. One of the most common is piperonyl butoxide (PBO). Others include butoxypolypropylene glycol and n-octyl bicycloheptene dicarboximide (MGK 264).

Comparing Products

Looking at the list of active ingredients and their percentages is one way to compare products and select the one that you think will work best for your needs.

“Formulas that use newer technology and a higher level of active ingredients cost more to make,” says Amy Cairy, vice president of marketing for W.F. Young, makers of Absorbine. For these reasons, you can expect many of the best-selling fly sprays to come with a higher price tag, she notes.

Along with comparing the levels of active ingredients, it’s also important to look at the recommended application rate, says White. A product may look like it’s half the concentration of a comparative product, but if you have to apply twice as much of it, he points out that you’re essentially applying the same amount of active ingredient—just in a more dilute form.

Fly Spray Formulation

In addition to the active ingredients, a product’s formulation is another difference to consider. Most fly sprays can be categorized as oil- or water-based, and there are pros and cons to each type.

Oil-based sprays have staying power, but can attract dirt and dust and may be irritating to horses with sensitive skin. If you see “contains petroleum distillate” on the list of ingredients, that’s the tipoff that it’s an oil-based spray.

Water-based sprays are non-irritating and less of a magnet for dust, but will likely need to be reapplied more frequently.

Many horse owners prefer all-natural formulas using essential oils and plant extracts as an alternative to chemical sprays.

Long-lasting sweat and water-resistant formulas contain ingredients that help the product stick to the hair shaft. These are designed to hold up well to rain and sweat under normal turnout and working conditions, says Cairy.

However, she notes that if you rinse your horse with a hose, sponge him off, or bathe him with shampoo, you are removing the product from the horse’s hair and should reapply the fly spray afterward.

Coat conditioners and sunscreen are other bonus ingredients you might find in a fly spray.

Choosing the Right Fly Spray

The right fly spray can depend on several factors.

“First, consider the type of flies that are prevalent in your area and choose a spray that targets those specific types of flies,” says Machtinger. “Next, consider your horse’s individual needs, such as any skin sensitivities or allergies. It’s also important to consider the spray’s effectiveness and how long it will last, and finally the ease of application and whether it requires dilution or not.”

The local climate and weather conditions, such as heat and humidity, as well as what you are doing with your horse also influence your choice of fly spray. You may want to have a few different kinds in your kit with different features and formulations. The fly spray you use right before you go in the show ring might be different than the one you’d use to turn your horse out in the field.

“For example, if you have a horse that is easily bothered by a wide variety of flies or is reactive to insect bites, you’ll want to find a long-lasting, broad-spectrum fly spray that both kills and repels insects,” says Cairy. “Or if you live where it’s hot and humid or have a horse that is prone to heavy sweating, you’ll want to reach for a fly spray that binds to the horse’s hair shaft and won’t sweat off.”

Not Enough

One of the biggest fly spray mistakes is simply user error. Either not applying enough, not using the product according to the directions, or selecting the wrong type of product for the insect species you are dealing with.

How do you know if you’re applying the recommended amount of fly spray? Cairy suggests counting sprays and measuring how many it takes to reach the recommended amount, then using that for future reference. (About 45 sprays is what she has found it takes to reach a typical 2-ounce application.)

Pest Resistance

If you find that your go-to fly spray doesn’t seem to be as effective, there may be a reason for that.

“In addition to the method of application, the effectiveness of these products can depend on the toxicity of the active ingredient to flies, and local pest resistance,” says Machtinger. “Flies can quickly develop a resistance to the active ingredients in many fly sprays (or already are resistant to them), reducing or in some cases eliminating their effectiveness.”

Pesky house flies are among the most affected by insecticide resistance. Fortunately, Machtinger reports, newer fly spray formulations using natural ingredients such as fatty acids and plant extracts have proven to be effective and longer-lasting in laboratory tests. The 2019 published study she led also suggests that formulation differences among pyrethroid products can significantly affect their efficacy.

“We do see some resistance to fly sprays, particularly permethrin,” says Cairy. “When horse owners start thinking, ‘My fly spray isn’t working the way it used to,’ we recommend that they rotate to one with a different formulation.”

When rotating products, look for something with an active ingredient that works differently than what you have been using, such as a different chemical class, advises White.

“Many of the on-animal sprays have the same mode of action, which makes incorporating other fly management tools even more important.”

Other Fly Management

There are many other things horse owners can do to help keep fly populations down, including good sanitation and manure management, and taking steps to eliminate fly breeding habitats and disrupt their life cycle.

“Scatterbaits, fly traps, feed-through larvicidal products and larvicides applied directly to fly development areas are other options that should be incorporated into a good integrated pest management (IPM) program,” says White.

It might seem like a fly is just a fly, but it’s important to try to identify what fly species you are dealing with, because they aren’t all created equal when it comes to fly control.

“To prevent flies on horses, it’s important to first understand which species of fly is the pest,” says Machtinger. “Each species will have different methods of control that are effective.”

She emphasizes the need to use a variety of tools in combination, such as good stable management and hygiene, fly masks and sheets, and species-specific fly traps.

Flies are a nuisance, but armed with the right knowledge and tools, it’s possible to fight back.

Further Reading
◆ Hoof Problems Caused by Fly Stomping
◆ Flies, Worms and Yucky Things
◆ Using Parasitoids for Fly Control
◆ Understanding Fly Spray Labels

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

The post Fly Spray 101 appeared first on Horse Illustrated Magazine.

While many experts agree that fleas are an uncommon parasite for horses, ticks can be prevalent and potentially present a danger to your horse’s health.

Ticks are becoming an increasingly significant problem for horse owners in many areas of the country. These parasites can invade your pasture, but they also hang out in places you might routinely ride, such as cool, shady areas near creek beds or among tall grass where they wait to hitch a ride.

Protect your equine by watching for signs of flea or tick problems and treating issues right away or preventing them altogether.

How Common Are Tick Infestations with Horses?

“Horses aren’t the preferred hosts for fleas like dogs, cats and foxes are,” says Laura Stern, DVM, DABVT, director of training and quality assurance for the ASPCA Animal Poison Control Center. “The reason horses aren’t commonly affected by fleas, but do get ticks, is simple: They’re in places where they commonly encounter ticks, but not fleas. Fleas like dark areas, like dens. Those aren’t the places where horses like to be. However, ticks like long grass and wooded areas—places where horses are commonly found—making them a common target for ticks.”

“Fleas don’t like horses,” agrees Garrett Metcalf, DVM, DACVS-LA, an equine veterinarian at Pine Ridge Equine Hospital in Glenpool, Okla. “Fleas are species-specific, and horses aren’t a suitable host for fleas, so it’s rare to have fleas on horses. Ticks are a common problem and rather good at transmitting diseases to horses.”

Signs of a Tick Problem with Your Horse

Horse owners are very protective of their animals, and typically attuned to changes in their behavior. However, a tick’s small size makes it easier for them to hide, so it’s essential to be aware of signs you might blame on something else that could indicate a tick issue.

The first step is to stay alert and physically look for ticks on your horse’s body while being aware of any potentially serious side effects of a tick bite. Besides the actual tick body, Stern says to look for a raised, hard bump where a tick was feeding. She says you might see your horse rubbing a particular spot where a tick is or was, and experience hair loss due to excessive rubbing.

“If your horse has a severe tick infestation or if he seems weak, wobbly or has pale gums, contact your veterinarian immediately before trying to remove any ticks, as you may cause damage to the skin or stress the horse in his weakened condition,” she cautions.

Metcalf advises looking around the groin, head, and region under the tail where ticks often like to accumulate. He says that you might notice swelling in areas where ticks have bitten a horse and edema around the bite site.

“If a horse is head-shy while haltering, lethargic, or has a fever, and ticks are present on the horse, it would be best to have the horse examined by a veterinarian,” he says. “Ticks are a common [cause of] swelling and pain around the ears, and most tick-borne diseases will cause fever and lethargy as the main clinical signs.”

Health Hazards of Infestation

Ticks infected with serious diseases don’t usually transmit those pathogens immediately. Instead, they usually must feed on the host—namely your horse—for a while before disease transmission occurs. This delay in disease transition makes it extremely important to remove ticks as soon as possible.

While less critical issues such as itchiness, hair loss, poor hair coat and local irritation can occur, Stern stresses that more serious problems such as infection at the site of tick attachment, anemia from blood loss in severe cases, and tick-transmitted disease could occur.

“Ticks can transmit a number of diseases to horses, including Lyme disease, equine granulocytic anaplasmosis and equine piroplasmosis,” says Stern. “Rarely, we may also see tick paralysis. There’s typically a delay of 24 hours between when the ticks attach and when they can transmit diseases, which makes it very important to find them quickly and remove them before they have the chance to transmit any diseases.”

An Ounce of Prevention

Prevention is always preferable to treatment, which is true of fleas and ticks. If you can keep your stable and pasture free of these parasites, you avoid having to remove ticks from your horse and could prevent potentially serious problems.

Metcalf suggests using permethrin-based products, which he says are the best store-bought products to combat fleas or ticks on horses.

“It’s rather difficult to prevent ticks from getting onto horses,” he cautions. “Concentrated, topically applied permethrin products may be the best option at this time. Some of these products need to be applied every three weeks.

“Natural remedies aren’t very effective against reducing ticks on horses,” he continues. “Some essential oil recipes use geranium oil as a possible tick repellent. Physical barriers, such as fly boots, may help reduce ticks from getting onto the limbs of horses.”

Stern also touts various tick repellents and products that kill ticks. She says there are some sprays you can use before a ride and topical spot-on products that work longer for horses more consistently at risk of encountering ticks.

“You can use a repellent to help keep ticks off your horses,” says Stern. “Repellents often contain a pyrethroid insecticide, such as permethrin or cypermethrin. Repellents have the advantage of not requiring the ticks to bite and take a blood meal. Avermectins, such as moxidectin and ivermectin, can also kill ticks, but [the ticks] need to take a blood meal first.”

She cautions the importance of always reading the label of any flea and tick product you use to ensure it’s appropriate for use on horses.

“Some cattle products can cause significant toxicity in horses,” warns Stern. “[And] some products won’t be labeled for use on certain horses, especially foals under 3 months of age. Always apply per the labeled [instructions] to minimize the risk of side effects, as well. Your veterinarian can help you determine what product will be best, based on the risk of exposure to ticks, the risk of ticks carrying disease, and your horse’s lifestyle and health history.”

Other Remedies

Besides treating your horse, you should always pay attention to his surroundings. Stern says ticks are generally more of an issue outside of barns, so you don’t typically need tick control inside your barn.

“If fleas are present in the barn, it’s generally not an issue for horses,” she says. “But you can minimize risk by preventing wildlife from entering the barn and ensuring that cats and dogs who have access to the barn are treated with flea preventatives. Treating the environment may be needed for heavy flea infestations.”

One of the best all-natural ways of minimizing tick exposure is to keep horses out of areas that contain a lot of ticks. Of course, that isn’t always possible.

“Ticks are often found in tall grasses and wooded areas,” says Stern. “They dislike hot, sunny areas with no plant cover. An easy way to minimize the number of ticks your horses are exposed to is by mowing any tall grass, removing weeds, and preventing your horse from entering wooded areas or hanging around the boundaries between woods and pasture. Preventing wildlife, especially deer, from entering pastured areas is another important step you can take to decrease the number of ticks in your pasture.”

Metcalf also suggests using pasture insecticides to help reduce fleas or ticks in your pasture. He cautions that whenever a heavy amount of wildlife traffic is present, there’s more of a reservoir of future ticks or fleas to re-establish residency in the pasture.

Tick Removal Tips

Any time you’ve been out riding—or at least once a day if your horse is on pasture—you should check him for ticks. A visual inspection is an excellent first step, but using your fingers to feel around for small ticks that might not be easy to see is also important.

“Deer ticks that transmit Lyme disease only reach 3mm when fully grown and can be hard to see,” says Stern. “The most important areas to check your horse for ticks are the chest, belly, flanks, mane, tail and ears—places where the skin is thinner and ticks can more easily attach.”

Even if you take precautions such as using tick repellents and keeping your horse out of areas ticks might frequently hang out, your horse will inevitably pick up a tick or several during tick season. Stern cautions that there are a lot of myths about the best way to remove a tick from a horse.

“You don’t want to crush the tick, use a hot match, or apply something like baby oil to try to smother it,” she says. “Instead, put on a pair of gloves and take tweezers and grasp the head of the tick close to the site of attachment to the horse. Then, slowly pull the tick away at a 90-degree angle from the horse. This will allow you to remove the entire tick.

“After you remove the tick, wash the skin in the area where the tick was attached with a mild soap and then wash your hands,” Stern continues. “Ticks should be placed in a jar of isopropyl alcohol, which can be disposed of when full. If you notice that the head of the tick wasn’t removed from the horse, contact your veterinarian, as the site can become infected.”

Metcalf agrees that physically removing ticks from horses with your fingers or a hemostat-like instrument is a safe removal method. However, he says some owners might want to kill the ticks first with a permethrin spray, then use physical removal methods.

“Your veterinarian is your best source of information about preventing or controlling ticks,” adds Stern. “They have knowledge of which products work best in your area and the best control strategy, given your horses and your facility. Having preventative measures in place before you have an issue is best. Scheduling a visit with your vet in the late winter or spring is an ideal time to get a holistic tick-control program set up for your horses, but it’s never too late in the year to reach out and get an expert opinion from your vet.”

Ticks and Horses: Key Takeaway

Because ticks can transmit serious diseases, it’s crucial for horse owners to stay vigilant by regularly checking their horses for ticks and taking preventive measures to reduce exposure. By staying informed and taking action early, you can minimize the risk of tick infestations and ensure your horse remains healthy and comfortable.

This article about ticks with horses appeared in the September 2023 issue of Horse Illustrated magazine. Click here to subscribe!

The post The Risk of Ticks with Horses appeared first on Horse Illustrated Magazine.

1. Manure Management

Probably the single most important way of fly control is proper disposal of horse manure. Stable flies, the most annoying of all the biting flies that bother horses, breed in manure. Houseflies also prefer manure for reproduction.

The best way to keep these fly numbers down is to frequently remove manure from your horse’s stall or paddock. Barn aisles, turnout areas and riding arenas should also be cleaned. Clean at least once a day; more often if you can.

Once manure is scooped up, it should be taken to a manure pile far away from the barn or stored in a covered dumpster until you can remove it from your property.

Soiled bedding is another favorite spot for flies to lay their eggs. Remove wet shavings or straw from your horse’s stall every day to keep the fly population down.

2. Moisture Control

Flies love moisture and seek out wet areas to breed. Search your property for leaks from faucets, sprinklers and pipes. Look for areas where rain water gathers, too.

If your horse has a favorite spot in his stall or paddock to urinate, you can bet that flies are laying their eggs there. Put down moisture-absorbing materials to help soak up the urine. In box stalls, keep urine to a minimum with frequent cleanings and by using highly absorbent bedding.

3. Biological Controls

An eco-friendly way to combat flies is to use biological methods. Tiny parasitic wasps are widely available, and work by destroying the fly larvae before it can hatch. Signing up for a monthly delivery of these predatory insects during fly season can help keep the fly population down at your barn.

Harmless to humans and so small you can barely see them, the wasps are shipped still in the egg stage. Once a few of the wasps hatch in the plastic bag after delivery, you sprinkle the contents in and around your horse’s living area.

4. Traps

Available in a variety of different types, fly traps work by attracting flies, either through color or scent. Once the fly lands on or enters the trap, it can’t escape and eventually dies.

The simplest type of fly trap uses a sticky surface to capture flies. The flies are drawn to the color—usually orange or yellow—and land on it. The glue-covered surface sticks to their feet, keeping them from flying away. Other traps use bait to lure the fly inside. Some traps have water inside, and the flies drown because they can’t escape. Others simply trap them inside the container, where they die due to lack of food and water.

Sticky fly traps can be hung anywhere flies congregate, but should be safely out of reach of curious horses. Baited traps should be placed far from stalls since they will initially attract more flies to the area before the insects become trapped.

5. Barn Fans

Flies tend to be less active when there’s a strong breeze, as wind affects their ability to fly. So create your own wind! Barn fans hung from the ceiling over each stall and in the barn aisles can do wonders for keeping flies out of the area. Freestanding fans can also be used in barn aisles.

6. Stable Management

The environment surrounding your horses can have a big effect on the number of flies at your facility. Practicing good barn keeping will keep flies to a minimum.

Start by making sure all garbage cans are securely covered. An open trash can will draw flies from near and far. Keep feed storage containers covered as well since some grains and sweet feeds can attract flies. Clean up spilled feed right away, especially if it’s wet.

Be sure to dispose of any rotting hay on the property since this is the perfect breeding environment for flies. The combination of moisture and organic material is a haven for these pests. Also, avoid using straw as bedding since wet straw is a magnet for flies.

7. Fly Sprays

Both insecticidal sprays and repellents discourage flies from landing on your horse.

Oil-based sprays have more staying power on horses than water-based products, and both are best used in conjunction with other types of fly control. They should not be used in the vicinity of parasitoid wasps, however, since the beneficial insects are also susceptible to insecticides.

When applying fly sprays, be sure to use an adequate amount as directed on the label. If you don’t coat the horse’s hair with the spray, flies can still land and bite. For applying around the eyes, ears and muzzle, spray the product onto a washcloth and wipe it onto the horse’s face. You can also use a roll-on insecticide for these delicate areas.

8. Cover-Ups

No matter how good your fly control methods, it’s impossible to get rid of every single fly. To protect your horse from these biting pests, use cover-ups.

Fly masks are the most effective way to protect your horse from flies. Face flies are notorious for feeding on the mucus in your horse’s eyes, causing irritation and potentially spreading disease. You can also use a mask with attached ear covers to keep biting gnats out of his ears.

A fly sheet prevents flies from landing directly on your horse’s body. The lightweight mesh blanket protects your horse’s chest, back, sides and hindquarters from biting flies. Add mesh leg wraps to protect the lower legs, and flies will have a hard time finding a place to bite your horse.

By using these methods, you can make a big impact on the number of flies that live on your property and pester your horses.

9. Spray Systems

In a barn environment, an overhead fly spray system can be effective at keeping fly populations down. Spray systems release a repellent or insecticidal mist periodically throughout the day. The spray comes down onto the horses and prevents flies from landing and biting. The system can be designed to spray directly into both stalls and barn aisles.

After installing a spray system in your barn, choose the type of insecticide or repellent you want to use. If you are concerned about introducing chemical fly products into the environment, opt for natural formulations.

10. Supplements

Supplements designed to prevent flies from breeding in manure or to discourage flies from biting are another option for your horse. Insect growth regulators (IGR) are chemicals that disrupt the fly’s ability to reproduce by affecting the pupa stage in the life cycle. When the active ingredient in the IGR is present in the horse’s manure, the fly larvae can’t develop to adulthood.

A feed-through product containing an IGR is added daily to the horse’s food, and then passes through the horse and is deposited with the manure. The IGR has no effect on the horse, but wreaks havoc on the fly population.

Natural supplement formulas containing garlic, apple cider, yeast and other ingredients with natural fly-repelling properties are reported to discourage flies from biting. These products must be fed daily to be effective.

Further Reading on Fly Control for Horses and Barns

◆ Natural Insect Repellents for Horses
◆ Flies, Worms and Yucky Things

This article about fly control for horses and barns appeared in the July 2015 issue of Horse Illustrated magazine. Click here to subscribe!

The post 10 Ways to Banish Flies from the Barn appeared first on Horse Illustrated Magazine.

It may seem as if West Nile virus has always been a threat to horses. However, it only arrived on the Northeastern shores of the United States just two decades ago in 1999. Within a short three-year period, the virus was found across the country in 15,000 horses in 41 states. You might be asking, “How did it spread so quickly?” We’ll take a look at what West Nile virus is and how it affects your horse, the risks and how it is transmitted, plus specific preventive measures you can you take to protect your horse.

West Nile Virus Symptoms to Watch For

West Nile virus (WNV) is an infectious disease that attacks the neurological system of horses and humans, and to a lesser extent a variety of other species (goats, sheep, llamas, dogs, bears and reptiles). The blood-brain barrier normally limits access by bacteria, viruses, and fungi to the nervous system, but WNV is able to cross that barrier to cause inflammation and damage to the brain and spinal cord.

How this manifests depends on which areas of the central nervous system are affected. Common symptoms vary both in location and severity. Some horses become ataxic (uncoordinated) in the hind limbs. The horse stumbles, drags its toes, and may lilt to one side more than the other. There is often muscle twitching or tremors in the face, muzzle and lips, and/or in the neck, shoulders and chest. The horse may have trouble swallowing or experience impaired vision.

Normally tractable and calm horses might become hypersensitive to touch and/or sound. Fever and depression are common symptoms, along with limb weakness. In severe cases, the horse may wander aimlessly, develop convulsions, or become paralyzed in the rear quarters and go down on the ground, unable to rise. Death occurs in 30 to 40 percent of cases. Of those that survive, as many as 40 percent of cases persist with neurologic gait and behavior symptoms for six months, and some deficits may persist indefinitely.

Other mosquito-borne viruses, such as Eastern or Western encephalomyelitis (EEE and WEE), have similar clinical signs to West Nile virus. Blood testing provides a definitive diagnosis.

Since WNV was first seen in the United States, many companies have worked to create an effective vaccine to protect against the disease.

Going Viral

Transmission of WNV relies on interplay between birds and mosquitoes, particularly Culex species mosquitoes. Birds are the reservoir for the virus, and many (like crows, ravens, jays, house finches, owls and hawks) often succumb to the infection.

If a mosquito bites an infected bird, it can carry the virus to horse or human (and to other birds) when it takes its next blood meal.

If you see dead birds on your property, notify your public health official and have them tested for WNV. If you have chickens on your property, move them to a location far away from the horses. Only a small amount of virus circulates in horse or human blood following a bite from an infected mosquito. This is good news because this small amount of blood-borne virus is not transmissible between horse and horse, human and human, or horse and human. Horses and humans are considered “dead-end” hosts.

Another welcome piece of good news is that not every horse or every human exposed to the virus actually develops the disease.

The Risks for West Nile Virus

All horses are at risk of contracting WNV if the right precautions aren’t taken. Other notable factors include:
◆ Horses that have not received a full series of WNV immunizations or have had inadequate number of vaccine boosters are at high risk of contracting the disease.
◆ Horses older than 15 are more at risk of developing severe neurological signs and dying as a consequence of the infection.
◆ Horses developing signs later in mosquito season (weeks 36-38) have less favorable odds of survival than horses infected with WNV clinical signs earlier (weeks 31-33).

In temperate climates, West Nile virus tends to appear in the mid to late summer months, lasting until a good killing frost that eliminates mosquitoes.

The American Association of Equine Practitioners (AAEP) considers WNV vaccine to be a core vaccine that should be given to all horses at least once a year.

Immunization

Since WNV was first seen in the United States, many companies have worked to create an effective vaccine to protect against the disease. To date, there are four or five different commercial vaccines against WNV for horses, yet none for humans.

The American Association of Equine Practitioners (AAEP) considers the WNV vaccine to be a core vaccine that should be given to all horses at least once a year. Immunization coverage is simple, with a two-dose series for adult horses. The horse is given the initial vaccine and then boosted with a second dose four to six weeks later, with the timing dependent on the type of WNV vaccine used. This is then boosted annually before mosquitoes start to hatch.

In some parts of the country where mosquitoes are abundant year-round, it may be necessary to boost the vaccine twice a year.

Foals need to be vaccinated with a three-dose series with timing that depends on the vaccination status of the mare; ask your vet for more information if you own a foal.

Property Management

Anything that can hold standing water is considered a mosquito breeding ground: gutters, flowerpots, buckets, swimming pool covers, wading pools, discarded tires, wheelbarrows, bird baths, and tractor buckets, to name a few.

DRAINAGE: Even a hoof print in mud or near a water tank is able to hold sufficient water for mosquito larvae to hatch. Turn water containers over and drill holes in the bottom to facilitate drainage when appropriate. Establish good drainage around the barn, stalls and runs. Apply gravel to areas driven over by cars and farm implements to eliminate mud and tire tracks that can hold water.

STANDING WATER: Clean stock tanks regularly to remove debris and make them less attractive to breeding mosquitoes. Ditches, creeks and ponds are also mosquito habitats; ponds can be managed with aeration systems and with larvae-eating fish.

KILL THE LIGHTS: Eliminate incandescent bulb lights around the barn and paddocks, as these are mosquito attractants. These lights placed elsewhere on the property lure mosquitoes away from horse proximity. Bug “zapper” devices kill roaming mosquitoes.

CREATE PHYSICAL BARRIERS: This is accomplished by using fl y masks, fly sheets, fly boots, and insect repellent. Permethrin-containing repellents are useful but may need frequent application.

MISTING SYSTEMS: Barns can be misted regularly with chemical insecticides. Take care to spray into cracks and corners of the barn where mosquitoes often lurk.

FANS: During active mosquito hours (dawn and dusk), it helps to aim a fan at a stalled horse to create a sufficient breeze that mosquitoes can’t negotiate. Screens on the windows and stall doors also limit mosquito access.

Attention to management details, along with immunization, is the most reliable way of protecting your horse against WNV infection.

This article on West Nile virus originally appeared in the August 2019 issue of Horse Illustrated magazine. Click here to subscribe!

Further Reading

• West Nile Still a Threat for Horses
• West Nile Virus: 10 Tips for Reducing the Risk at Your Farm

The post Warding Off West Nile: Protecting Your Horse from West Nile Virus appeared first on Horse Illustrated Magazine.