Clinical and diagnostic comparisons of bovine foot rot and bovine digital dermatitis lesions and management differences in feedlot cattle in Alberta.

Background: Bovine foot rot (BFR) and bovine digital dermatitis (BDD) are infectious foot lesions with overlapping clinical features that complicate diagnosis.

Objective: Our objective was to differentiate BFR and BDD using quantitative and qualitative techniques. Populations of BFR- and BDD-associated bacteria were compared across sampling strategies, histopathological features described, and risk factors assessed via surveys.

Animals and procedure: Lame cattle were assessed and bacteria in punch biopsy samples (PB-samples), swabs, and subcutaneous samples (SC-samples) were quantified using quantitative real-time PCR. In addition, PB-samples were used for hematoxylin and eosin and Warthin-Faulkner staining. Feedlot records and producer surveys captured risk factors and producers' opinions on management practices.

Results: Swabs and SC-samples had varying bacterial abundances compared to PB-samples. Histopathology and risk factors were not diagnostic for BFR versus BDD.

Conclusion and clinical relevance: Higher bacterial loads in swabs compared to PB-samples suggested careful consideration of their use as an alternative to punch biopsies in studying BFR and BDD. Furthermore, histology did not differentiate these diseases. Fusobacterium spp. population differences in dermis and SC-samples could indicate distinct, species-level roles in BFR pathogenesis. In addition, risk factors such as weight and lameness scores could not distinguish between BFR and BDD.