There's no need to sound the alarm if you find grayish or skin-colored bumps on the nose of your young horse. Papillomas, which can appear overnight, are a type of equine warts. And sure, they look unsightly, but they shouldn't cause excessive worry.
In fact, baby warts (sometimes referred to as "teenage acne" in the horse world) are simply a nuisance, especially when you want your horse to be well turned out for the ring. That said, let the breakout run its course, as warts are rarely painful and will surely disappear as your horse matures.
What Are Papillomas?
Papillomas refer to small, gray, irregular bumps that looks like warts. They are most commonly seen on a horse's nostrils and muzzle or on thinly-haired areas of its body (such as the eyelids, or front legs). This form of "acne" results from a viral infection with the equine herpes virus. These warts are contagious to other young horses but will resolve on their own in one to nine months without treatment.
Symptoms of Papilloma in Horses
Viral papilloma can pop up quite suddenly. One day, your horse seems fine; and upon further inspection, you find strange bumps that seem to spread easily and almost overnight. A whole region on your horse may look encrusted with cauliflower-like bumps. Watch this closely, as other young horses in the same pasture or barn may break out, as well.
It's also not unusual for the skin to crack and bleed, or for papilloma warts to break off in areas that are mobile, like on the lips and nose. Some horse owners believe that once they bleed and scab, the warts will go away faster. However, any open wound must be closely monitored to prevent infection.
Causes of Papilloma
Similar to the warts humans contract, horse papillomas are caused by the equine papillomavirus, a herpes virus. But this type of wart is not zoonotic (a disease that exists in animals but can be transferred to people), so you don't have to worry about contracting the virus from your horse. And certainly, you cannot make your horse sick either.
Equine warts can, however, be transferred from horse to horse and a young mare can transfer them to her foal as it nurses. Young horses can also catch the virus from buckets, fences, or any other place a curious young horse may stick its nose into or brush up against. Papillomas mostly affect horses less than 18 months old, and it is very rare—yet, not impossible—for an older horse to get them.
Since warts are common, most seasoned horse owners can diagnose them themselves without the help of a veterinarian. But for questionable lesions, a veterinarian can take a biopsy to make sure the bumps aren't sarcoids (a type of skin tumor) or another type of infection or tumor.
On young horses, treatment is not necessary as papillomas will go away within a few months, as the horse develops its own resistance to the virus. Really, it's as if the warts disappear as mysteriously as they come.
If a wart-infected area become inflamed and sore, you may consider treating these spots with over-the-counter antiseptics or a topical moisturizing lotion for cracked skin, and keep the section clean. A lotion like a diaper rash ointment may help—and is totally harmless—should your horse become uncomfortable. Otherwise, it’s fine to simply let the papillomas run its course. If you are concerned that your horse is uncomfortable or that an affected area might be infected, call your veterinarian for advice.
How to Prevent Papillomas
Other than basic stable hygiene, there's little that can be done to prevent horses from contracting warts. However, if one horse gets them, you can keep it quarantined and use separate buckets, feed bins, and other equipment to prevent the virus from spreading. Sometimes the virus may be present before you see the signs, however, so this precaution may not be entirely effective.
After an outbreak, barns, feeding troughs, buckets, and tack should all be disinfected to kill lingering organisms. A diluted bleach solution can be used on feeding equipment and stall walls and tack can be scrubbed with soap and water.
And don't worry about older horses, as they rarely get warts. Still, be aware that lumps and bumps in older horses can be signs of other problems.
Skin Diseases Refresher Papillomatosis (viral warts). American Association of Equine Practitioners.