Etiology and epidemiology of digital dermatitis in Australian dairy herds

Andrew McPherson; Bill Tranter; Ash Phipps; Richard Laven; John House; Ruth N Zadoks; Sam Rowe

doi:10.3168/jds.2023-24258

Etiology and epidemiology of digital dermatitis in Australian dairy herds

J Dairy Sci. 2024 Feb 6:S0022-0302(24)00075-4. doi: 10.3168/jds.2023-24258. Online ahead of print.

Authors

Andrew McPherson¹, Bill Tranter², Ash Phipps³, Richard Laven⁴, John House¹, Ruth N Zadoks¹, Sam Rowe⁵

Affiliations

¹ Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales, 2570, Australia.
² College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia; Tableland Veterinary Service, Malanda, Queensland, Australia.
³ Rochester Veterinary Practice, Rochester, Victoria, Australia.
⁴ Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4474, New Zealand.
⁵ Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales, 2570, Australia. Electronic address: samuel.rowe@sydney.edu.au.

PMID: 38331178
DOI: 10.3168/jds.2023-24258

Abstract

Bovine digital dermatitis (BDD) is an important cause of lameness in dairy cows worldwide. However, there is very little known about this disease in Australian herds, which are predominantly managed on pasture. The primary objectives of this cross-sectional study were to describe the presence and prevalence of BDD in Australian dairy herds and to characterize the microbiota of healthy skin and M4 lesions of BDD-affected, pasture-managed cows. Cows from 71 dairy herds were examined at milking time to identify the presence of BDD lesions. True prevalence was estimated using Bayesian methods with informative priors for sensitivity and specificity. Biopsy samples (n = 60) were collected from cows with and without BDD-lesions in 7 pasture-based herds. The microbiota in the superficial and deep strata of each tissue biopsy were characterized via sequencing of the V3-V4 region of the bacterial ribosomal RNA gene. Lesions were detected in 1,817 (11.5%) of 15,813 cows, and in 68 of 71 (95.8%) herds. The median herd-level apparent and true prevalences of BDD were 8.5 and 18.1%, respectively, but this varied considerably between farms. On farms with BDD, M4 lesions accounted for 70 to 100% of all lesions (interquartile range = 95.1 to 100%, median = 100%). M2 lesions (i.e., large ulcerative lesions) were observed at low prevalence (<2.2%) in the few herds (7/71, 9.9%) where they were found. There was a statistically significant difference in the composition of the microbiota between healthy skin and M4 lesions but not between superficial and deep tissue layers. Several gut- and effluent-associated bacterial taxa, including Lentimicrobium and Porphyromonas, which have previously been associated with BDD, were abundant in BDD lesions but not in control biopsies. Our study supports the idea that such taxa are involved in, though possibly not essential to, lesion development and persistence in pasture-managed cows in Australia. Our results also suggest that Dichelobacter may contribute to the disease process. We conclude that BDD is likely to occur in most Australian dairy farms, but that further studies are needed to identify its impact on cow welfare and productivity. Further investigation of the etiology of BDD in Australian dairy herds is also necessary to inform prevention and control strategies.

The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).