From the evidence on your fleece jacket and truck upholstery, it’s clear: Shedding season has begun. Although it’s technically still winter, shedding—which is triggered by the length of the days rather than temperatures—begins in some horses by mid-February. Other horses may start later, but by the end of March every horse in your barn should be losing his winter coat. 

It’s important to note which horses aren’t shedding. Holding on to a thick, winter coat is a hallmark of the metabolic disorder pituitary pars intermedia dysfunction (PPID, Cushing’s disease). If your hairy horse hasn’t been diagnosed with PPID, ask your veterinarian about the possibility. 

Also call the veterinarian if your horse has been diagnosed with PPID and is under treatment but still seems to be shedding slowly—his medication dose may need to be adjusted. Finally, although it’s much more rare than metabolic disease, horses with significant blindness may also be slow to shed because their eyes cannot register the daylight cues that trigger the process.

Some horses are patchy shedders, meaning they will lose large swaths of hair on one part of their body and then another. This looks odd—or even unsightly—for a few weeks, but it isn’t a sign of illness. It’s just a congenital quirk. Likewise, some horses will lose fine, outer layers of skin as they shed, which can look alarming but also is harmless. If you’re concerned with how your shedding horse looks, take a photo, send it to your veterinarian and ask if it’s time to worry. 

This article was originally published the Volume 474 of EQUUS magazine