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Healthy Pet Care Tips

Botflies in Horses - Symptoms & Prevention

Being out in the elements, many pests may affect your horse. One of the pests we commonly see is botflies. Here, we share some information about the symptoms of botflies in horses and how to prevent this parasite from infesting your horse.

What Are Botflies?

While botflies aren't one of the worst parasites to infect horses they can still cause distress internally and externally for your equine friend, making them very uncomfortable.

The main irritation from a botfly happens externally. A botfly is fairly large and will spend its life with the goal of laying eggs in the hairs of a horse's body. While they don't bite, these annoying parasites create irritation by landing and walking around while depositing their eggs on your horse.

Types of Botflies

Here are the three types of botflies we see on horses:

Common Botflies

The eggs of common botflies are grayish-yellow to yellow in color and typically attached near the end of the horse hair in a place where the horse can reach the eggs while grooming or itching.

As the eggs hatch, the larvae make their way into the horse's mouth during these times and will eventually travel down into the stomach where they will live until the spring.

These larvae will use their hook-like mouth to remain attached to the mucous membrane of the horse's stomach until winter passes. When warmer weather arrives they are expelled with feces.

After a month in the dry soil, adult flies emerge and begin the cycle all over again. Female botflies are able to lay 500 eggs or more in a single week!

Throat Botflies

The eggs of throat botflies are typically laid near the skin and are whitish-yellow in color.

Female throat botflies aim to lay their eggs around the throat of the horse. Like the common botfly, throat botflies lay roughly 500 eggs a week.

In about three to five days the larvae hatch and crawl along the jaw, enter the mouth, and make their home in the gum line of the horse. This infestation of the gums can create distress for the horse as pockets form. At this point, the larvae begin to mature and, just as with the common botfly, they will make their way into the stomach for the winter and then be expelled in the spring to begin their lifecycle all over again.

Nose Botflies

When it comes to nose botflies the color of the egg is brownish-black, and the eggs are typically laid in the hair surrounding the nose of the horse. These botflies can be especially irritating as they will go in to lay eggs one at a time and are capable of laying roughly 160 eggs.

The eggs hatch and burrow into the lip and tongue in only two days. After 5 or 6 weeks they will make their way into the stomach and continue the cycle.

Symptoms of Botflies in Horses

Some of the signs and symptoms of a botfly infestation that may be noted in horses are:
  • loss of condition
  • impeded digestion
  • increased body temperature
  • restlessness
  • kicking at the belly
  • loss of appetite
  • intermittent diarrhea
  • constipation
It is also possible for botflies to potentially cause more severe issues such as gastritis, stomach ulcers, and more rarely, peritonitis which is an inflammation of the membrane lining the abdominal cavity and can be fatal.

How to Treat Botflies in Horses

When it comes to botflies, their life cycle lasts approximately a year and breaking this cycle is necessary for treatment to be successful.

The first and main step in the treatment process is to remove all bot fly eggs from the horse consistently. This must be done on a daily basis.

Next, you will need to treat the horse with deworming medication to irradicate the larvae thriving in the stomach.

Your vet will be crucial in this stage of treatment as they can help you manage the timing and dosage in order to provide effective treatment for your horse.

How to Prevent Botflies in Horses

One of the easiest ways to prevent botflies in horses is through effective sanitation of the area your horse spends their time. 

Here are some of the things you can do to help reduce the possibility of botflies infesting your horses:

  • Manure should be routinely cleaned up and properly composted. The heat generated during the process will kill the larvae of botflies.
  • Proper pasture management including frequent mowing and chain harrowing.
  • Utilize rotational grazing and, if possible, allow livestock to graze a pasture between horses.
  • Avoid feeding your horses from the ground.
  • Clean water, free of feces contamination, should be provided year-round.
  • Monitor your horse and keep up with egg removal as they are spotted.
  • Ensure that you keep your horse on a regular deworming program to minimize risk.

It is also recommended that you have fecal exams performed on your horse regularly to monitor for signs of any parasitic infections including botflies.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Have you noticed the signs of botflies on your horse? Book an appointment with a PetVet Care Centers member vet near you to discuss treatment and preventive measures. 

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