Occurrence of Treponema DNA in equine hoof canker and normal hoof tissue.
Authors: Sykora S, Brandt S
Journal: Equine veterinary journal
Summary
# Editorial Summary: Treponema DNA in Equine Hoof Canker Hoof canker remains a poorly understood chronic pododermatitis in horses, though recent case reports have implicated Treponema species in its development. Sykora and Brandt's 2015 retrospective investigation used PCR analysis with four primer sets to detect treponemal DNA across 59 canker samples from 26 affected horses and 12 biopsies from nine healthy control animals, with sequencing to identify specific Treponema phylotypes. Treponemal DNA was found in 63% of canker samples (37/59 from 19/26 cases) and notably also in 75% of healthy hoof tissue (9/12 from 7/9 controls), though the distribution of species differed between groups—canine oral Treponema and Treponema medium subspecies bovis predominated in diseased tissue, whilst T. refringens-like sequences were more common in normal hooves, and T. medium ssp. bovis was absent from all controls. Whilst the detection of treponemes phylogenetically similar to bovine digital dermatitis organisms in canker lesions is intriguing and strengthens the case for their involvement, the high prevalence in healthy tissue suggests these bacteria may be commensal rather than directly causative, indicating that additional aetiological factors or predisposing conditions warrant investigation before Treponema can be definitively implicated in canker pathogenesis.
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Practical Takeaways
- •Treponema bacteria, particularly T. medium ssp. bovis, appear associated with hoof canker and may warrant investigation as a causative agent in chronic cases resistant to conventional treatment
- •The presence of digital dermatitis-like treponemes in equine canker suggests infection control and biosecurity measures used for cattle may have application in equine practice
- •Hoof canker cases may benefit from antimicrobial therapy targeting Treponema species as part of a multi-modal treatment approach, pending further research into pathogenesis
Key Findings
- •Treponemal DNA detected in 37 of 59 canker samples (63%) from 19 of 26 cases versus 9 of 12 control samples (75%) from 7 of 9 healthy horses
- •Canine oral Treponema sp. and Treponema medium ssp. bovis were most frequently detected in canker lesions, while controls harboured mainly Treponema refringens-like sequences
- •All control samples tested negative for T. medium ssp. bovis DNA, suggesting potential disease association
- •Treponemes highly similar to bovine digital dermatitis treponemes were identified in canker lesions, indicating possible cross-species pathogenic mechanism