Usually associated with heavy breeds and unsanitary conditions, canker can actually affect any horse, any age and in any living condition. Yards with the best stable management can fall foul to this tumorous-like growth on hooves. Known as Hypertrophic Pododermatitis canker is unlike thrush, which is a necrotic process destroying tissue, it spreads in live tissue without the help of oxygen. Some research suggests it is part of the Bacteriodes species (this includes those that cause foot rot in sheep). Other studies found spirochete (spiral-shaped) bacteria in the epithelium. This is similar to findings in cows and sheep with digital dermatitis.
More recent studies would appear to prove it to be a virus.* Abnormal keratin production, or overgrowth, occurs underneath the hoof horn as the infection spreads through the epithelial layer. The first signs usually appear in the sulci region as white or grey matter which is moist and spongy.
How to successfully resolve canker can be learnt on the WHP Level 3 course. It has been our experience that dealing with the virus alone is not the answer, and as such we have now successfully resolved 3 cases of canker with no recurrence. 9 other cases that we know of have also been successfully resolved under guidance of our protocol.
Consistent detection of bovine papillomavirus in lesions, intact skin and peripheral blood mononuclear cells of horses affected by hoof canker
S. BRANDT*, A. SCHOSTER2, R. TOBER1, C. KAINZBAUER1, J. P. BURGSTALLER3, R. HARALAMBUS1, R. STEINBORN1,
C. HINTERHOFER1 and C. STANEK1
Reasons for performing the study: Equine hoof canker is a chronic proliferative pododermatitis of as yet unknown aetiology. Like equine sarcoid disease, canker is a therapy-resistant disorder characterised by hyperkeratosis, acanthosis and a marked tendency to recur.
Hypothesis: There is an association of sarcoid-inducing bovine papillomaviruses of types 1 and 2 (BPV-1, BPV-2) with hoof canker disease.
Methods: Using PCR-based techniques, we assessed canker tissue, intact skin and/or peripheral blood mononuclear cells (PBMCs) of 25 canker-affected horses for the presence of sarcoid-associated BPV-1 and -2.
Results: Conventional PCR revealed BPV-1/-2 DNA in 24/24 canker, 12/13 skin and 10/11 PBMC DNA isolates. Using inverse PCR, full-length BPV episomes were detected in 1/5 canker specimens. Sequencing of viral early and late genes amplified from canker, intact skin and PBMC DNA of 2 cases revealed an overall identity of 98% to BPV-1. Viral DNA loads amounted to ≤16 copies per cell in canker tissue and intact skin, and to ≤0.35 copies per PBMC, as determined by quantitative PCR. Using RT-PCR, the viral major oncogene E5 was shown to be transcribed in 2/4 canker tissue specimens and 5/7 PBMC isolates. Immunocapture PCR from 7 canker and 6 skin extract supernatants revealed capsomere-associated viral DNA in one canker and one skin sample. Hoof tissue, skin and PBMCs collected from 13 individuals with no signs of canker or BPV-related malignancies scored negative throughout the experiments.
Conclusion: These findings suggest that the observed presence of BPV-1/-2 in canker-affected horses is not coincidental but indicative of an active contribution to hoof canker disease.
Potential relevance: The use of antivirals and/or immune modulators may help improving canker therapy.
(Photos from Google with no names available to give credit to photographers - or poor horses!)