Summertime Skin Problems

Summertime has a tendency to bring sunshine, heat, humidity, and insects to a horse barn. These three things can be hard on a horse's skin, and can lead to the development of several common issues.


Increased day length and a hotter sun can spell trouble for horses lacking pigment on their face, nose, and ears. Intense sunlight can cause redness, swelling, and increased sensitivity. It can be unsightly and is no doubt painful for the horse.

Certain plants such as ragwort, St. John's wort, and buckwheat contain chemicals that cause horses to be unusually sensitive to the sun. Medications like tetracycline also can make horses more photosensitive.

If your horse is showing signs of sunburn, the first and most logical step is to limit exposure to the most intense hours of sunlight by stabling during these times. Sunscreen or zinc oxide is effective for horses and can be used in the affected areas of the nose and face. Many grooming products and fly sprays might have sunscreen already added.

Eliminating photosensitizing plants from the horse's pasture or hay, and awareness of possible side effects of medications also might solve the problem.

Insect Allergies

Besides being responsible for the transmission of many infectious diseases, insect bites can result in serious skin problems in some horses. Many horses develop allergies to the saliva of biting gnats and flies. These often appear as itchy, raised lesions along the back or belly of the horse. It also might involve the mane and tail, with hair loss resulting from the intense itching. In more serious cases, bacterial skin infections can result because the horse is scratching and causing trauma to the skin.

The most commonly documented culprit is the biting midge (Culicoides sp). Others include blackflies, horn flies, and mosquitoes. Allergies to these insects can be a frustrating occurrence, but there are several counteractive measures that can be taken. The most effective therapy is avoiding or minimizing your horse's contact with the insects. Stabling horses from dusk until after dawn is important, as dusk and dawn are prime feeding times for biting insects. The use of fans while your horse is in the stall can reduce the number of flying insects in the building. Using permethrin-based fly control products one to three times a week can also make a difference.

In addition to these management changes, medications prescribed by your veterinarian such as glucocorticoid anti-inflammatories can be quite effective. Some studies also have shown promising results from immunotherapy or allergy shots specific to the insect causing the problem.

Dermatophilosis or Rain Scald

Horses exposed to hot, humid, or rainy conditions are at risk for development of rain scald. Rain scald (rain rot, dermatophilosis, or streptothricosis) is a summertime skin disease caused by the organism Dermatophilus congolensis. It is an organism with properties of both fungi and bacteria that infects the hair follicles. Because there is damage to the hair follicle and shaft, the hair will pull out easily in small clumps leaving pink skin. The lesions also might become scabbed over or contain pus. It is most common over the back, rump, fetlock, and cannon bone.

The organism is contagious and can be spread by tack, equipment, or insects. Keeping horses clean and dry is effective for both prevention and treatment. It is also important to disinfect all tack and equipment to prevent spreading the organism. Antibacterial shampoos and rinses containing agents like chlorhexidine are effective for both equipment and animals. The use of ointments is not advised, as they tend to hold moisture in, while the goal of treatment is to keep these lesions dry.

Summer conditions can make for an excellent time to enjoy your horse, but they can be harmful in extreme cases. Remember that avoiding the extreme summer elements is the key to preventing skin problems.

Article courtesy of Purdue University School of Veterinary Medicine,  

About the Author

Justin Sellon, DVM

Justin Sellon, DVM, is associated with Dr. Weldy’s Veterinary Service. He returned to North Central Indiana after graduating from Purdue University, and he resides in Nappanee with his wife, Mandy and daughter Stella.

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