Treponeme-Associated Hoof Disease of Free-Ranging Elk ( Cervus elaphus) in Southwestern Washington State, USA.
Authors: Han Sushan, Mansfield Kristin G, Bradway Dan S, Besser Thomas E, Read Deryck H, Haldorson Gary J, Alt David P, Wilson-Welder Jennifer H
Journal: Veterinary pathology
Summary
# Treponeme-Associated Hoof Disease in Free-Ranging Elk: Emerging Pathology and Livestock Parallels Between 2008 and the time of publication, a debilitating hoof disease emerged in free-ranging elk populations across southwestern Washington State, characterised by progressive sole ulceration, chronic hoof overgrowth, and capsule sloughing, yet the aetiological agent remained unidentified despite initial investigation. Researchers examined elk of varying ages (3, 7, and 9 months old) alongside affected adults to trace disease progression and identify causative organisms; lesion samples underwent histopathological analysis, immunohistochemistry, bacterial culture, and PCR testing to characterise the pathology and identify infectious agents. Spirochete bacteria identified as *Treponema* species were consistently isolated from foot lesions across affected age groups, with 9-month-old animals showing chronic changes comparable to adults (sole ulcers in 3/9, overgrown/sloughed capsules in 4/9), whilst younger animals displayed earlier-stage disease ranging from ulcerative lesions with bacterial invasion in 7-month-olds (6/8 affected) to superficial coronary erosions in 3-month calves—notably, the latter were PCR-positive despite minimal histological changes. Secondary aerobic and anaerobic bacterial infections were documented alongside *Treponema*, consistent with patterns seen in bovine digital dermatitis and contagious ovine digital dermatitis, and antibody titres suggested immune responsiveness to infection. This work establishes treponeme-associated hoof disease (TAHD) as a significant emerging pathology in cervids that shares striking similarities with economically important livestock conditions, warranting investigation into transmission mechanisms, environmental factors, and whether wildlife populations may
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Practical Takeaways
- •This is a wildlife disease report with limited direct application to equine practice; however, awareness of Treponema-associated hoof disease in wild cervids helps contextualize similar spirochetal diseases in domestic livestock and horses
- •The disease demonstrates how treponeme infections cause progressive, debilitating foot pathology across species—relevant for understanding potential mechanisms in equine digital dermatitis if it occurs
- •Early lesions (superficial coronary erosions) may precede clinical signs of chronic hoof disease, suggesting screening protocols for exposed populations could detect infection early
Key Findings
- •Treponema spirochetes identified via immunohistochemistry and PCR in ulcerative foot lesions across elk age groups (9, 7, and 3 months old)
- •Disease progression characterized by underrunning of hoof capsule and heel-sole junction with suppurative inflammation and epithelial hyperplasia in older elk
- •Secondary polymicrobial bacterial colonization detected alongside Treponema in foot ulcers of 9 and 7-month-old elk
- •Treponeme-associated hoof disease in elk shares pathological similarities to bovine digital dermatitis and contagious ovine digital dermatitis