Fortunately canker is now a rare disease in horses. It affects the frog area of the foot but can extend further into the sole and in very severe cases can even start to affect the hoof wall. One or more of the feet can be affected. Although this disease is one of the oldest recognised ailments of the horse it is still poorly understood. It is believed to be caused by an infection with anaerobic (live without oxygen) bacteria or papilloma virus, and occurs mainly in horses where the feet have been exposed to damp or unhygienic conditions. In some cases an auto-immune problem underlies the disease.
There is often an unpleasant odour. Frequently it is misdiagnosed as thrush and treated with oxytetracycline spray (as in the case above). Unfortunately this is usually unsuccessful.
Early diagnosis is important – the sooner correct treatment is instigated the higher the success rate.
Contaminated / infected tissue should be cut away – this is best done with the aid of a ‘nerve block’ (so the horse cannot feel the foot) and sedation.
The foot should then be disinfected daily with hydrogen peroxide and coated with metronidazole paste. In the cases where an auto-immune problem is suspected, corticosteroid treatment might be necessary.
The foot must be kept clean and dry thereafter until complete resolution of the lesion.