Consider first whether other horses are affected. Look around at your facility and consider where your horse has been and what you have been doing with them. Has it changed?

Halter the horse and start by evaluating their general health using the Whole Horse Exam. Does the horse seem healthy otherwise or do you notice other signs of illness or injury?

Assess the general quality of the hair coat? Is it consistent or patchy, shiny or dull? If there are areas that are abnormal, consider their location. Is there more than one affected area? How many are there? How large are the affected areas? Are the areas painful to touch, or do you notice the horse itching?

Is there hair loss? Is the underlying skin flaky or reddened? Does hair easily come out when you pull on it? Use your hands, feel the skin lesions. When did you first notice the problem? Is it improving or getting worse? Have you tried to treat it? If so, with what? Did it help?

Wear latex gloves to help avoid spread of infectious agents to other horses. Rarely, these agents infect people (certain skin fungi).

Do not allow skin conditions to worsen without consulting your vet. You may be able to treat simple conditions on your own, but consultation with your vet will ensure that your approach is correct and that you monitor progress appropriately.

If you treat for a week and a skin condition is not improving, then probably you are using the wrong approach. You need a veterinary DIAGNOSIS. Get help.

Allergic skin disease and skin irritation is common and is often caused by well-meaning owners' application of a variety of substances. Consider materials that might cause an adverse skin reaction. These might include topical sprays, shampoos, blankets, pads, detergents (used to wash blankets and pads), etc...

Prepare for the conversation with your vet. Dermatologic conditions are often easily photographed and sent to your vet. Be sure to take a few photos at different angles and depths in good consistent lighting conditions to ensure that you document them well. Use a ruler or show the whole horse to provide a sense of scale.