Horn flies cause ventral midline dermatitis, a condition characterized by spontaneous balding, rawness, crusting and skin thickening. To soothe the condition, gently remove the scabs and wash the area with mild soap; then treat the lesions with an antibiotic and corticosteroid ointment twice a day for several days. To prevent renewed irritation, coat the midline with petroleum jelly and use fly repellant to deter the horn flies.
If your horse is contorting himself to scratch his mane or tail, and you notice droplets of wet or dried serum near the roots of the mane and tail hairs, ticks are probably biting him. Louse powder will kill the parasites, and vegetable or mineral oil applied to the base of the mane and tail discourages tick attachment.
Bites from lice, which crop up in winter, cause extreme itchiness, a heavy, waxy dandruff and bald patches. If your horse's mane and tail are balding slightly and shedding dry dandruff, mites are likely to blame. Dust or wash the infected horse, plus everything and everyone he touches, with an insecticidal preparation.
The horsefly-sized insects known as warbles lay eggs on their hosts' legs. Once the warble larvae hatch, they burrow into the skin and migrate through the tissues. When they reach a likely spot-usually the horse's back-they form anthill shaped lumps on the skin surface. Each larva's apartment has a tiny breathing hole that oozes pink fluid. Getting rid of warbles is tricky, since crushing one in the skin can set off a possibly fatal allergic reaction. A veterinarian must carefully widen the breathing holes and then draw the larvae out. Ivermectin kills warble larvae before they can migrate.
Historical Hints
If you're still not sure about your horse's skin abnormality, take time to consider when you first noticed it and how it has changed since. Make a written record of all pertinent details:
- When did the problem start and how quickly has it progressed? Skin conditions that grow fast and worsen continually, especially if they cause open lesions or crustiness, are more likely to be serious.
- What were the characteristics of the condition at each stage, and what effects have attempted treatments had?
- Has the problem occurred before? Does it come and go with certain seasons or under particular conditions?
- Was your horse exposed to chemicals, detergents, unusual foliage or any other potential irritant?
- Has there been a recent change in his routine, environment, grooming equipment/supplies, feed or medication?
- Do herdmates have the same problem? Are his relatives similarly affected?
If fever, appetite loss, fatigue, depression, general edema, diarrhea, or elevated pulse and respiration accompany any skin condition, call your veterinarian at once.
This article originally appeared in the August 1998 issue of EQUUS magazine.
