Page 880 - The Veterinary Care of the Horse

infect other young horses through small abrasions on the lips and muzzle. It is also spread

through direct contact with an infected animal and on equipment such as brushes and feed
VetBooks.ir buckets. Occasionally, older horses develop papillomas.

PREVENTION AND CONTROL

• Avoid grazing youngsters on infected paddocks.

• Good pasture management should control spiky vegetation which could scratch the soft

skin of the muzzle and lips, allowing entry of the virus.

PROGNOSIS

The prognosis for verrucose warts is excellent. There is a congenital form (the foal is born

with them) and this can be more persistent, as are those that develop on adult horses. If the
lesions fail to regress, they can be surgically removed or treated with cryosurgery. However,

this can lead to scarring and loss of skin pigmentation.

Aural plaques

These occur on the inner surface of the ear and occasionally on the genitalia. They look like

grey/white plaques and can be single or multiple, smooth or raised (Figure 18.30).
Occasionally they proliferate and the plaques become up to 1 cm ( in) thick. They may join

up and extend over most of the hairless skin inside the horse’s ear. They are thought to be
caused by a papilloma virus and are transmitted by black flies (Simulium sp) biting and
feeding inside the ears. Many horse owners mistakenly think it is a fungus.