Journal watch18 February 2024
Author(s): Logan, F., McAloon, C.G., Ryan, E.G., Duane, M., Deane, B. and McAloon, C.I.
Published in: Journal of Dairy Science
Date: December 2023
DOI: https://doi.org/10.3168/jds.2023-23928
Type of access: Open access
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Our summary
Logan, F. et al. (2023) Sensitivity and specificity of mobility scoring for the detection of foot lesions in pasture based Irish dairy cows. Journal of Dairy Science.
The aim of this observational study was to determine the sensitivity and specificity of mobility scoring for the detection of foot lesions on commercial pasture-based dairy cows.
A convenience sample of twelve pasture-based dairy herds in Ireland were recruited to take part in the trial in Summer 2021 with a randomised sample of 50 cows per herd enrolled in the study. Each farm received two visits, two weeks apart, the first visit was related to another study. On the second visit, the recruited cows were separated from the rest of the herd following milking for visual assessment and assignment of a mobility score (MS) using the AHDB Dairy mobility scoring system. A foot inspection was then carried out for each cow with all four feet lifted, cleaned, and examined for foot lesions. Any detected foot lesion was identified and graded using scales which were based on existing severity scales that had been modified according to the clinical experience of the study authors.
Cows with detected foot lesions were categorised into one of three case definitions 1: any lesion present; 2: moderate lesions present; 3: severe lesions present. Lesions type and severity scales were mapped to these case definitions based on a consensus agreement of the study authors. Sensitivity and specificity of MS were calculated based on the proportion of cows for each of the case definitions that had a MS ≥2.
The final study population was 595 cows. Of these 235 cows (39%) had a MS of 0 (good mobility); 290 cows (49%) an MS of 1 (imperfect mobility) 61 cows (10%) an MS of 2 (impaired mobility); and 9 cows (2%) an MS of 3 (severely impaired mobility). Of cows with MS=0, 43% had one or more foot lesions, and 56% of cows with MS=1; 82% of cows with MS=2; and all 9 (100%) of cows with MS=3 had one or more foot lesions. Overall, 54%, 21% and 15% of cows had foot lesions meeting the criteria for case definition 1 (Low), 2 (Moderate) and 3 (High) respectively.
Of the cows with foot lesions, 77% had non-infectious lesions, 9% had an infectious lesion and 14% had both infectious and non-infectious. Digital dermatitis was the most prevalent infectious lesion, and claw overgrowth and white line disease were the most prevalent non-infectious lesions.
The overall sensitivity and specificity of MS at detecting cows with foot lesions meeting the criteria for case definition 1 was 0.18 and 0.96, respectively, for case definition 2 was 0.35 and 0.94, respectively, and for case definition 3 was 0.43 and 0.94, respectively, thus the sensitivity of MS was low across all case definitions whilst specificity was high across all case definitions. Sensitivity for MS varied substantially by parity.
Limitations of the study include the dairy cattle population was from a small number of herds based on a pasture-based system recruited from a convenient sample of herds in one region of Ireland. Therefore the results from this study may not be generalisable to other herds on other systems in different geographic locations.
Take home
This study provides some evidence that mobility scoring has poor sensitivity for the detection of foot lesions in cows in a pasture-based system. More effective lameness identification methods with improved sensitivity and specificity are needed for the detection of foot lesions in cows.
The following may also be of interest
InFOCUS: Spotlight on quality of life assessment tools: pain assessment tools: species specific pain assessment tools: farm animals [RCVS Knowledge] [online] Available from: https://infocus.rcvsknowledge.org/qol-quality-of-life-assessment-tools-pain-assessment-species-specific-assessment-tools-farm-animals/ [Accessed 16 February 2024]
Mobility scoring: how to score your cows [AHDB] [online] Available from: https://ahdb.org.uk/knowledge-library/mobility-scoring-how-to-score-your-cows [Accessed 16 February 2024]
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