Page 40 - Speedhorse Canada Spring 2020

Ringworm, or dermatophytosis, is a fungal organism that lives on skin and can spread to humans and other animals. Signs include patchy hair loss, typically on the trunk, head and neck, and the hair can easily be pulled out in tufts around the edges of the hairless area.
chemical treatments simultaneously. The horse owners or trainers are trying to do what they can and may get carried away because there are many people giving different advice and opinions on treatments.
“Here at our clinic we have a pharmacy technician who does
a lot of our compounding,” says Evans. “Our scratches ointment is
a mixture of zinc ointment, a little furacin, penicillin, and a little bit of corticosteroid to help decrease the swelling and reactivity of the skin. We use this cream fairly liberally at first, to soften the crusts so we can take them off and get them out of the way. Once we get the wound cleaned up so there
are no crusts or debris, we use it more sparingly to allow dry air and sunlight to get to the area. I think sunlight and fresh air can help it heal. This not only helps scratches, but also some of the other skin lesions like ringworm.
“Many skin problems will readily heal—and we call those
self-limiting—if the horse is out in the sunlight, whereas if the horse is blanketed all the time and kept in a barn where it’s damp and there’s ammonia in the air, this makes things worse.”
Sometimes other infections,
like bacterial folliculitis, can look similar to scratches but is not as common. “It is similar to what is seen in dogs and humans, with bacterial infections of the hair follicles and secretory glands of the skin,” he says. “There are some types of bacteria that are normally found on the horse’s skin, such
as various staphylococcus and streptococcus species. If there is trauma to the skin, or if the horse has a lot of fly bites, the bacteria have access and can invade the follicles. It’s like acne in that it can appear almost anywhere on the horse. It tends to look a little like scratches at first, but has a greater distribution. Scratches (pastern
dermatitis) is almost always limited to the back of the pastern initially, whereas these other infections may start anywhere on the body or face.
“There are usually multiple
firm nodules. Sometimes there
is crusting. There may or may
not be any hair loss. The lesions usually are not itchy, but the client is generally worried about the spreading nodules. For diagnosis, we take a skin scraping or skin biopsy to view under a microscope. We usually identify a lot of white blood cells and sometimes we can see active bacteria.
“Most of the time when I arrive at this diagnosis, the client has been treating it as scratches (and maybe didn’t involve the veterinarian) and has become frustrated. When I look at it, I can see that it’s not typical scratches and do a biopsy. Then the pathologist finds a staph infection. Those require a different course of treatment,” Evans explains.
Urticaria, or hives/welts, is a hypersensitivity reaction and can appear any time of the year. Hives can occur because of an environmental allergen, such something new the horse has come into contact with, or a drug/vaccine sensitivity.
40 SPEEDHORSE CANADA Spring 2020
EQUINE HEALTH