Ahh, spring. Fields grow greener, leafy trails beckon, and … "Bzzzz!" What’s that? The bugs are back. They’re biting. And they’ve got plenty of misery-causing company.

Having their basis in bug and plant prevalence and weather conditions, many of the skin problems that plague horses are seasonal. This month, with the help of two veterinary dermatologists–one based in Texas, the other in Canada–we’ll offer ways to recognize and respond to five skin ailments likely to appear in spring or early summer: insect hypersensitivity, sweet itch, contact dermatitis, scratches, and rain rot. Then in October we’ll do the same for problems typically arising in cooler weather.

Insect Hypersensitivity

As spring temperatures warm, several biting insect species–black flies, horn flies, stable flies, mosquitoes, and (of course) horseflies–hatch, proliferate, and seek nourishment. "Insect hypersensitivity is the most common equine allergy," says Christine Rees, DVM, Dipl. ACVD, who taught for 13 years at Texas A&M’s veterinary school before opening an equine/small animal dermatology practice in Dallas. More specifically, Ontario Veterinary College associate professor of dermatology Anthony Yu, DVM, MS, Dipl. ACVD, designates spring and summer insect hypersensitivity as insect-bite hypersensitivity, in which the bite introduces saliva that allows the insect to access more blood flow and sometimes triggers an allergic reaction