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What is Bug Bite Allergy?

Bugs are everywhere; no matter where you live they are a pest to your horse during one season or another.  Some horses can have a hypersensitivity to the saliva of the bug.  This means instead of a typical small bump that usually appears if at all, your horse will have severe itching, inflammation at the site of the puncture, development of lesions, hair loss from constant scratching, and more.  If this is the case for your horse, it is important you get your veterinarian involved.  She can diagnose his condition properly, administer treatments in the form of medication and additional therapies, and discuss prevention with you.  If treated properly, prognosis of recovery for your horse is good.

Your horse can be allergic to bug bites from a variety of species.  If you notice bumps or lesions on your horse, or just discomfort in general, contact your veterinarian.

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Symptoms of Bug Bite Allergy in Horses

Symptoms are often seasonal when the insects are alive and flourishing, such as the spring through the fall.  Symptoms may include:

  • Pruritus 
  • With or without crusted papules
  • Erosions
  • Ulcers 
  • Hair loss
  • Lichenification
  • Pigmentary disturbances 

Symptoms can begin at the mane and go all the way down to the base of the tail.  It can also affect the thorax, face, pinna, neck and shoulders.  Self trauma can lead to the increased severity of the symptoms. 

Types

Horses usually show patterns of skin disease due to insect hypersensitivity.  Depending on the insect’s preference of feeding region, patterns can be of a dorsal or ventral distribution or a combination of the two.  The dorsal pattern is the most common form of insect bite allergy.

Causes of Bug Bite Allergy in Horses

Bug bite allergies can occur in any horse.  Studies have been conducted to try and find a correlation with those with hypersensitivity but none can be found.  Horses with the allergy can be male or female, any breed, any age, and any color.  In typical cases, the first sign of clinical reaction occurs at the age of 3 to 4 years old.

Diagnosis of Bug Bite Allergy in Horses

Diagnosis of a bug bite allergy in your horse can often be done by physical examination alone.  Your veterinarian may need to clip the affected area in order to get a better look at the affected skin.  If the insect is a large one, you may be able to see a puncture mark.  If it is something small like a mosquito, you will not see the puncture but you will see the inflamed area it leaves behind.

In cases where the veterinarian is unsure if it is indeed a bug bite allergy, she may want to collect a skin sample for biopsy testing to rule out other causes.  This will be helpful if determining the lesion or growth associated with the area is a tumor or not.  For those with bug bite allergies, the specimen is usually composed mainly of eosinophils with lymphocytes.  Changes to indicate a secondary bacterial infection may also be seen. 

In addition to this, she may collect a serum sample to measure the immunoglobulin E concentration against various insect allergies.  There are certain laboratories in the country that have panels to test your horse’s immune reaction to common allergens; this can include a parasitic panel.

Treatment of Bug Bite Allergy in Horses

Decreasing your horse’s exposure to insects is ideal.  There are sprays you can purchase and apply to your horse and his environment.  Reduction of insects in the environment is also important.  Mosquito larvae develop in standing water; it is important you minimize the amount of standing water where your horse spends his time. 

Treating the site of skin reaction is also important.  The site of skin reaction and severity of the issue will determine the treatment.  If small papules are present, a topical steroid can be used to decrease the itching.  By decreasing the amount of your horses scratching, you will lower his chances of developing a secondary bacterial infection.  In more severe reactions, the veterinarian may choose to employ oral steroids.  Antihistamines and antibiotics may also be prescribed depending on the appearance of your horse’s skin.

You can utilize natural or herbal treatments if desired.  An easy fix most people have in their pantry involves making a paste out of baking soda and water and apply it to the bite.  It draws out the toxin and relieves the itch quickly.  You can also use natural ingredient lotions to relieve the itching and encourage tissue healing.  

Prevention of the bug bites is the most ideal treatment option.  You can add screens or mesh netting to your stall windows and entrances to decrease the amount of access points for insects.  You can also install fans in your horse’s area to create a constant breeze; this discourages insects from landing on your horse.  If they cannot land on him, they cannot bite him.  There are also certain coverings he can wear if he is out on pasture to decrease the amount of flesh the bugs have access to.

Recovery of Bug Bite Allergy in Horses

Treating the lesions specifically is very important.  You will want to clean them and medicate them in order to prevent a secondary bacterial infection from developing.  You will also want to treat your horse’s system as a whole and calm down the allergic reaction.  As long as you follow the veterinarian’s instructions for care his prognosis of recovery is good.

Bug Bite Allergy Questions and Advice from Veterinary Professionals

Belle
Tennessee Walking
13
Mild condition
0 found helpful
Mild condition

My 13 year old mare is showing loss of hair and skin redness with some bleeding in the forehead and ear regions. She is very resistant to any treatment to the affected area. We were able, with difficulty, to spray the infected area with antiseptic. This worked well on my other two gelding males.
She is now showing unusual signs. She is is acting tired and unusually calm. I am afraid that she is getting an infection. Is it safe to administer antibiotics to her?

Health Expert
Dr. Callum Turner, DVM
1720 Recommendations
Without examining Belle, I cannot advise the use of antibiotics as they are a prescription medication and should be used under the direction of an attending Veterinarian. Whilst it is possible that there may be a secondary infection or an infection introduced by a vector, this would need to be seen by your Veterinarian to determine whether antibiotics are required and which specific antibiotic would be most appropriate. Regards Dr Callum Turner DVM

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