Equine hoof canker is a destructive infection that affects the external and underlying structures of the hoof. The disease is diagnosed by its typical clinical appearance: cauliflower-like proliferation of the hoof matrix with a foul smell and white, cheesy fluid – nice! Current treatment involves removing the infected parts of the hoof and followed by a careful antiseptic cleaning program and in some cases antibiotics. This is very time consuming, taking several months, and clinical signs often return within a year. The successful treatment of this disease is hindered by the fact that the cause of this infection has not been identified.
Recent research has shown that the DNA and RNA of bovine viruses (papillomaviruses), which can cause tumours, have been detected in canker tissue samples, whereas no viral DNA was detected in horses without canker lesions.1 A short communication recently published in Veterinary Record documents a new and promising therapy for canker using a topical formulation of cisplatin chemotherapy, aimed at reducing the length of hospitalisation and short-term recurrence of the disease.2 Cisplatin is one of the most potent chemotherapy agents used in human and veterinary medicine and intralesional cisplatin chemotherapy with and without surgery is a well-documented and successful therapy for common equine skin tumors (sarcoids). It works by binding to certain sequences of DNA/RNA, making it unable to replicate.
Ten horses (19 hooves) diagnosed with canker were included in the study. Hooves were thoroughly cleaned, trimmed and kept in disinfectant bandages until surgery, when affected tissues were removed. If healthy tissue appeared a few days later in the absence of any suspected canker, the topical cisplatin therapy was started. This included 10 applications of cisplatin paste, made up of cisplatin injection solution, EucillinB crème and metronidazole-saccharose (two antibiotics). Treated hooves were bandaged until a layer of horn had formed or the hooves were fitted with a treatment plate. Horses were kept in hospital on an average of 32 days and follow-up investigations (between 0 and 14 months) found that nine of 10 horses had not any recurrence of the infection.
The authors, Veronika Apprich and Theresia Licka, noted that, after this treatment regimen, uncontrolled growth of the canker was easily controlled, with a low incidence of short to medium-term recurrence. They also add that in contrast to other cancer treatments, topical cisplatin chemotherapy could be cost effective by reducing hospital time.
Attempting to study a disease considered to be rare may have seemed ambitious to some; Theresia told us, ‘In our clinic, research into canker, thought to be rare, was regarded as a bit of a long-term project, and we were regarded as a very patient research team (if slightly crazy). We were looking forward to having two canker horses a year for this study. Since we have started, and word spread, we have been inundated with patients as well as international requests for information on canker treatment, and our students now graduate with the (probably erroneous) impression it is about as common as pus in the foot!’
The team is now working on several related projects, one of which is an infection study, in an attempt to discover the origins of this disease.
References
1. Brandt, S., Schoster, A., Tober, R., Kainzbauer, C., Burgstaller, J. P., Haralambus, R. & others (2010) Consistent detection of bovine papillomavirus in lesions, intact skin and peripheral blood mononuclear cells of horses affected by hoof canker. Equine Veterinary Journal 43, 202-209