CattleReview

Udder cleft dermatitis

Udder cleft dermatitis (UCD) is a common dermatological condition affecting the udder skin in dairy cows. It is generally regarded as a multifactorial disease and is discussed in a relatively limited body of literature.

However, this literature has recently been reviewed in an open-access paper by Vermeersch et al (2025) (https://doi.org/.org/10.3168/jds.2024-25086) who state that its cow and within-herd prevalence ranges widely between studies depending on the study characteristics, environment and cattle breed. Known risk factors include husbandry practices and environmental factors, such as cubicle (freestall) housing, the use of mattresses as cubicle bases and foot bathing. Cow-related elements, such as udder conformation, parity and lactation parameters are well-known risk factors for developing UCD. Despite being associated with a high incidence of veterinary-treated clinical mastitis and culling because of udder disease, the somatic cell count of the milk is not influenced by UCD. Severe UCD lesions are characterised by chronic and persistent, dysregulated inflammation accompanied by hampered skin healing and an impaired skin barrier. There is a decrease in microbial diversity followed by dysbiosis and a concomitant overgrowth of opportunistic bacteria negatively affecting beneficial commensal bacteria. Concurrently, a shift in virulence factors most likely contributes to the creation of an environment favourable to pathogens. Anecdotally, mange mites have been associated with UCD, but current literature refutes this. The role of treponemes remains inconclusive. Multiomics analysis of both transcriptomic and metagenomic severe UCD datasets revealed the negative interaction of the facultative pathogen Streptococcus pyogenes with microbiome-associated virulence factors and the patient's transcriptome. All in all, UCD is a painful skin disease for which an array of miscellaneous risk factors has been identified. In conclusion, no efficient curative treatments nor prevention strategies have been identified, although alginogel products have been described to have a positive effect on the healing process of severe lesions.

Bovine tuberculosis

A review by Wiseman et al (2024) (https://doi.org/10.1016/j.tvjl.2024.106266) examines how the different stages of Mycobacterium bovis infection in cattle may contribute to the failure to diagnose infected animals using conventional testing methodologies and the attendant risk this poses in creating prolonged or recurrent herd breakdowns. The dynamics of M. bovis infection in cattle can influence the proportion of infected animals that are diagnosed by ante-mortem tests in routine bTB surveillance and monitoring programmes. Although the current diagnostic tests based on cell-mediated or serological responses are imperfect, they are effective in diagnosing most infected animals. However, the lack of perfect sensitivity and specificity also leads to failure to diagnose all infected animals leading to the persistence of infection in herds. The terms residual, subclinical, latent and anergy have been used interchangeably to denote the presence of continued undiagnosed M. bovis infection within cattle herds, which ultimately hinders the eradication of bTB and imposes substantial financial burdens on farming communities and national economies. Epidemiological data suggests the existence of M. bovis-infected, but often undetected, cattle within herds contribute to eradication failure. This has similarities with human tuberculosis, caused by Mycobacterium tuberculosis, where latent infection is defined as the persistence of viable but quiescent bacilli for extended periods in patients without clinical symptoms but with a detectable immune response to M. tuberculosis antigens. If a similar infection state exists in cattle infected with M. bovis, the persistence of such animals in disease-managed herds is unlikely to be common given that those found to have positive immune responses to M. bovis antigens are routinely culled to minimise future risk of transmission. Apart from contributing to the burden of herd infection, such residual infection without detection may also ‘seed’ recipient herds following animal movements, and potentially play an important role in the overall epidemiology of bTB as the prevalence of disease decreases and the attendant altered predictive value of the diagnostic tests result in a greater proportion of infected animals remaining undetected.