Canker: What Is It?

My veterinarian mentioned that she was treating a horse on a nearby farm for canker. What is it? How do you treat it?

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My veterinarian mentioned that she was treating a horse on a nearby farm for canker. What is it? Where does it come from? And how do you treat it? Is it different from thrush?

ATo the best of our knowledge, canker is an anaerobic (grows in the absence of oxygen) infection in the superficial epithelium of the hoof (the horn-producing tissues of the foot). Veterinarians believe the invading organism is a part of the bacteroides species, which is similar to what causes "footrot" in sheep. Cases usually are found in the southeastern United States, but it has been diagnosed all over the country.

The bacteria associated with canker causes abnormal keratin production, or overgrowth of the horn. This excess proliferation occurs underneath the horn, as the infection spreads throughout the epithelium. The horse’s owner will notice the presence of a white or gray matter that is moist and spongy and commonly appears in the sulci region of the hoof. If there is enough infection, heat might be felt in the hoof, but only in extreme situations.

The mystery surrounding canker is its cause. It involves a very strict anaerobic process, and seems to have a multi-factorial pathogenesis. For research we’ve tried to recreate canker in the horse, but have never been successful. Our theory at this point is that canker is caused by some sort of trauma. An infection gets inside the hoof capsule and allows the horn to proliferate. It can be tough to get it out once it gets established

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Written by:

Tracy A. Turner, DVM, MS, Dipl. ACVS, is a veterinarian with Anoka Equine Veterinary Services in Elk River, Minn. He was inducted into the International Equine Veterinarians Hall of Fame in 2004.

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