Prospective cohort study of the association between early lactation mastitis and the presence of sole ulcers in dairy cows
Watson, C, et al. (2022) Prospective cohort study of the association between early lactation mastitis and the presence of sole ulcers in dairy cows. Vet Record, e1387.
The main aim of this prospective cohort study was to investigate the association between clinical mastitis (CM) in the first 30 days in milk (DIM) and presence of sole ulcers (SU) in dairy cows in early lactation. Additionally, the study aimed to investigate (a) whether these SU were new lesions that appeared after the case of CM, (b) to evaluate whether CM in the first 30 DIM was associated with the presence of both sole haemorrhage (SH) and SU, and (c) to investigate the association of somatic cell counts (SCC) in the first 30 DIM with the presence of SU in early lactation.
A convenience sample of four dairy farms in Northwest England and North Wales was selected to participate. The farms were visited weekly and data from feet examination were collected at three time points for each cow at: pre-calving, post-calving (within 14 days), and early lactation (after 30 DIM). All four feet were examined at every time point except the calving check on one farm when only hind feet were examined, most examinations were carried out by the same veterinary surgeon. Multivariable logistic regression models were used for data analysis.
A total of 2,353 Holstein-Friesian cows and heifers were included; of these, 131 cows had SU in early lactation and 49 cows had a first case of CM recorded in the first 30 DIM. The odds of having SU in early lactation were 2.44 times greater for cows that had CM in the first 30 DIM compared to cows that did not. When cows that had SU at pre-calving or calving checks were excluded, this numeric trend still existed but was no longer significant. A high SCC in the first 100 DIM was also associated with the presence of SU in early lactation.
Limitations of the study include the reliance on farm records for diagnosis of CM cases, meaning there was a possibility of misclassification bias with unrecorded cases of cows with SU in early lactation and CM in the first 30 DIM. In addition, the convenience sample of farms may not be representative of all dairy farms in the UK.
The study found an association between CM in the first 30 DIM and the presence of SU in early lactation. While this association was no longer statistically significant if cows with SU at the pre-calving or calving check were excluded, the numeric trend still existed. There was also a significant association between presence of SU in early lactation and high SCC at any time in the first 100 DIM. Future studies focusing on the mechanisms behind these associations would improve the understanding of the diseases and could lead to additional preventive strategies.
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