Page 148 - April_2023

VETERINARY VIEWS
PROTECTION OF THE EYES, EARS, AND FACE
by Nancy S. Loving, DVM
AS much as a horse loves to have his face scratched to get at the itch spots that can’t be reached, he hates to be bothered by the
tickle of insects buzzing about his head. Flies are not just irritants, but they can also create health problems for a horse. Luckily, there are some easy and preventive remedies.
EYE CONCERNS
Face flies are notoriously persistent about feeding on eye secretions, tending to congregate at the corners where the tears abound. Their presence elicits an inflammatory response in a horse’s eye, causing the conjunctival membranes to redden and swell. Eye
inflammation creates
more tear production,
thereby increasing the
attraction for flies.
Chronic eye irritation may induce a horse to scratch his eye on a solid object with the potential to develop an abrasion on the cornea that may form
an ulcer. Recurring inflammation in the external portions of an eye may pervade more deeply to cause anterior uveitis, referred to most familiarly as moon blindness.
Persistent eye irritation, or exposure to ultraviolet rays from the sun, amplifies the risk of developing cancer, such as squamous cell carcinoma, in the non-pigmented mucous membranes of the eye, especially on the sclera (white of the eye) or the third eyelid.
EAR CONCERNS
A number of fly species congregate about the face and head. Black flies, called ear gnats or
buffalo gnats, specialize in feeding on the inner surface (pinnae) of the ears, creating bloody and crusty spots where they have done their damage. This can be sufficiently annoying to a horse to make him head-shy and sensitive to touch of his ears and head, even leading to bridling problems.
Some horses develop an allergy to insect saliva, resulting in an inflammatory response that is blown far out of proportion to the original problem. Cauliflower-like plaques may grow inside the ears, sometimes worse on one ear than the other. This allergic reaction may continue even through the winter in the absence of flies.
It can be difficult to differentiate such reaction to ear gnats from equine sarcoid (benign tumor) or warts that also develop commonly within the ears. A biopsy may be necessary for a specific diagnosis and appropriate treatment.
PHOTO-ACTIVATED VASCULITIS
Horses with white on their faces or legs
are prone to developing sunburn or photo- activated vasculitis, which causes the non- pigmented skin beneath white fur to redden, ooze, and ulcerate. In many cases, horses develop this photoactivated hypersensitivity reaction subsequent to ingestion of legume hay or pasture, or other toxic plants in pasture. The best solution relies on strategies that eliminate those types of plants from the diet and to protect a horse’s skin from exposure to ultraviolet radiation. Ideally, such measures depend on covering the areas of concern – like tube socks on the lower legs – rather than having to stall a horse during daylight hours.
146 SPEEDHORSE
April 2023
pMoon Blindness can be caused by recurring inflammation in the external portions of the eye.
tHorse flies can cause numerous problems for horses, including eye and ear infections.
uHorses with white on their face or legs are prone to sunburn or photo-activated vasculitis and benefit from covering areas of concern.