A 10-year-old Warmblood gelding in New Zealand was referred to a veterinary clinic with two masses on his left fetlock. The masses were each over an inch in diameter and had hard, rough surfaces. They grew rapidly in the three weeks since the horse’s owner had discovered them. A piece of one of the masses was sent for microscopic evaluation and Drs. John Munday, Michael Hardcastle and Melissa Sim determined that a novel papillomavirus caused the lesions.
Papillomaviruses are double-stranded DNA viruses that tend to be host specific. There are nine equine papillomaviruses that have been sequenced; the first to be sequenced was Equus caballus type 1 (EcPV1), which causes papillomas in horses.
The masses the gelding had were most similar to EcPV1, but they didn’t present in the same way: EcPV1 generally causes small masses around the face. Veterinarians treated the masses with imiquimod ad the lesions resolved in 14 weeks.
The study team noted that papillomas only develop when a host is infected by a papillomavirus for the first time, which is why warts (papillomas) typically develop in young horses. This is an additional indication that the virus that caused the lesions in the older horse is new.
Read the full study here.
Read more at HorseTalk.
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