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How to Prevent and Treat Horse Fly Bites on Livestock

Updated: Apr 13

How to Prevent and Treat Horse Fly Bites on Livestock

Did you know that horse flies can cause serious injury to your livestock? If you've ever seen a horse fly bite, you'll know that it's quite painful for the animal—and these bites are more than just an annoyance. They can lead to allergic reactions, skin irritation, and secondary infections of the skin, which can lead to serious health issues.

The good news is that there are ways to prevent horse fly bites from happening in the first place. If your livestock is already suffering from these pests, there are treatments available that can help alleviate their pain and discomfort while also preventing further damage! In this article we will go over some precautions and treatments for horse flies and horse fly bites.

If your livestock has been bitten by horse flies (or any other insect), here are some tips on how to treat the bites and prevent future attacks:

How do horse fly bites affect livestock?

If you're a farmer, horse fly bites can be an unwelcome nuisance. Not only are they painful for your livestock, but they can lead to other health problems as well.

Here's what you need to know about preventing and treating horse fly bites in horses and cattle:

Horse flies are blood-sucking insects that attack livestock, such as horses and cattle. They lay eggs on grassy areas like pastures or meadows where the larvae will grow into adult flies within three weeks of hatching. Horse flies have a lifespan of two months but may migrate during colder seasons if there’s not enough food around them locally.

The bite of a horse fly is known as myiasis because it involves an insect feeding off your animal’s body tissue instead of just sucking up some liquid blood—and this particular type of insect causes pain when it bites!

It’s possible for these wounds to become infected if they aren't properly cleaned out daily with warm water mixed with soap or disinfectant until healed over completely.

Clean the bite immediately to prevent infection

In most cases, your livestock will not have a severe allergic reaction to horse fly bites. If you notice that your livestock has been bitten by a horse fly, you should clean the bite site immediately to prevent infection. Remove any dirt or debris, then wash with soap and water.

If you have access to an antibiotic ointment, apply it liberally and cover the bite with a gauze pad. Keep the area clean and dry at all times until all signs of swelling disappear.

Call a veterinarian if there is severe swelling around the bite

If you notice that the animal has severe swelling around the bite site (the size of a grapefruit), you should contact your veterinarian immediately.

If you notice signs of anaphylactic shock, such as trouble breathing and swelling around the face and neck, follow the steps below to treat an allergic reaction to horse fly bites.

What is anaphylactic shock?

Anaphylaxis is a severe allergic reaction that is caused when the immune system overreacts to allergens. In response, the body produces antibodies that cause swelling of the airways, hives, and itchy skin. In severe cases, anaphylaxis can cause death within minutes.

Anaphylactic shock occurs when blood pressure drops rapidly due to low blood volume (hypotension) and low blood flow through the heart (bradycardia).

How to treat anaphylactic shock in livestock

Anaphylactic shock is an acute and potentially life-threatening condition. The most common cause of anaphylactic shock in livestock is stings from insects like bees, wasps, and horse flies.

If you suspect that your animal has anaphylaxis, the first thing to do is remove the irritant, if possible. Look for swollen eyes and face, severely constricted airway, wheezing, coughing, and other signs of trouble breathing.

As soon as you notice any one of these symptoms of anaphylaxis in your animal, the best thing to do is call your veterinarian right away. You should also move the animal to a space where they cannot hurt themselves and others.

When the vet arrives, they will most likely administer a medication called epinephrine (adrenaline) to combat the effects of anaphylaxis. Epinephrine is used to treat low blood pressure and shock associated with anaphylaxis.

Get veterinary help when treating anaphylactic shock in livestock

If your animal is suffering from anaphylactic shock, get veterinary help immediately. Call your veterinarian first, then call the local emergency veterinarian.

It’s also smart to call the local animal control office and any other appropriate local resources that might be able to help you treat anaphylactic shock in livestock.

If possible, try calling the local poison control center as well; they may be able to give instructions over the phone on how best to treat this kind of allergic reaction in animals.

If you can't reach a veterinarian or other qualified expert for advice about how best to treat your animal, call 911 and ask them what steps they would take if confronted with this type of situation themselves.

If you have epinephrine on-farm and are unable to reach a veterinarian, follow these steps:

  • Remove all pressure from the airway by gently holding their head down and tilting it so that any fluid drains out of their mouth.

  • If possible, administer a dose of epinephrine immediately to reverse anaphylactic shock. You can administer it immediately via a needless syringe, then give the animal IV fluids at 20 mL/kg per hour until veterinary help arrives.

  • Keep the animal warm and calm until help arrives.

How to prevent horse fly bites on livestock

There are a few different steps you can take to make sure that your livestock are protected from horse flies.

Horse flies are attracted to carbon dioxide, so if you can reduce the amount of CO2 that's released into the air around your animals (i.e., by keeping them indoors), then there will be fewer horse flies swarming around them.

Additionally, horse flies like to lay eggs on manure piles—so if you want to keep them away from your livestock, then it's best to avoid creating these breeding grounds for horse flies as much as possible.

Another simple step you can take to reduce the number of horse flies on your property is ensuring that your livestock’s water tanks are always clean. Dirty or muddy water will attract flies. This goes for stalls and pastures, too—pick up manure often to prevent the likelihood of insects.

Use essential oils to repel horse flies

Essential oils work by giving off an odor that is repulsive to insects like horse flies. They have been shown to be effective in repelling flies, and they can be used in many different ways.

For example, a simple way to apply them is by adding 1 teaspoon of essential oil per gallon of water, then spraying this mixture on the animal’s body or around its stall or paddock.

You can also use essential oils to treat horse fly bites after they've occurred: mix 1 part coconut oil with 3 parts lavender or cedar wood oil; apply directly to bites as needed to relieve itching and inflammation.

Use fly repellent products

One of the best ways to prevent horse fly bites on livestock is to use fly repellent products. These generally work to prevent all types of flying insects from landing on your animals and potentially biting them.

Use a fly repellent on your animal’s legs and belly to deter horse fly attacks, especially during the summer months when they are most active.

There are also ingestible fly repellent supplements that can be added to your livestock’s feed ration.

Take caution when using insecticides on pregnant animals, as some of them contain chemicals that can cause birth defects in their offspring.

Keep track of your use of these repellent products with Farmbrite. Farmbrite keeps track of tasks, treatments, feedings and more for many types of livestock and crops. Take a look today for free.


If your livestock has been bitten by a horse fly, now you know how to treat the bites and prevent future attacks.

If you're unsure about what kind of bite it is or if your pet is showing signs of an allergic reaction, call a veterinarian immediately. They will be able to help you determine what treatment plan will be best suited for your animal's needs.


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