Udder cleft dermatitis (UCD; also bovine ulcerative mammary dermatitis or foul udder) is an inflammation of the udder skin and is most often located between the frontquarters and at the transition of the frontquarters and the abdominal wall. Cows with UCD may have an increased risk of clinical mastitis, and associations between UCD and digital dermatitis has been suggested. The lesions can impair animal welfare, milk production, and milk quality and can lead to death and premature culling. Thus preventive measures are warranted, but in daily practice, UCD is not always adequately detected by farmers and their cattle veterinarians.
The objective of this study was to investigate the prevalence of cows with complicated UCD on postmortem examination, associated with embolic pneumonia as the most likely cause of death.
Material and Methods
Royal GD’s registered veterinary pathologists diagnosed 39 dairy cows from different Dutch dairy herds with mild to severe UCD from 1 January 2019–31 December 2019 based on postmortem examination in the necropsy room.
Histological examination and microscopy, as well as additional bacteriology testing, were carried out in the GD laboratory. The pathology department is part of the GD laboratory, which is ISO 17025 accredited for a large number of laboratory tests and based on these accredited procedures the postmortem examinations were performed. Photographs were taken from the relevant lesions.
From 20 of the 39 dairy cows (51%) with UCD on postmortem examination in 2019 it is most likely that a complicated UCD was the fatal cause of death, due to the fact that no other causal factor for death was identified by the veterinary pathologists. Based on histology from the udder skin, a necrotic inflammation of the subcutaneous abdominal (milk) vein was observed with many bacteria involved, besides an ulcerative dermatitis of the skin. A comparable inflammation of the blood vessels in the lungs, with extension to the surrounding tissue, was observed, which is typical for embolic pneumonia. Bacteriological culture of the lung tissue revealed seven times Helcococcus spp., 12 times Trueperella pyogenes, and in two cases a mixed infection of these bacteria was isolated. In some cases, E. coli, streptococci, and/or anaerobic bacteria were cultured from the diseased lung tissue. All the isolated bacteria can be considered as opportunistic bacteria.
Interestingly, in all of these 20 cases, the clinical signs during the life of these cows (that were reported by the veterinarian on the accompanying submission form) were fever, respiratory distress, milk drop and death, despite antimicrobial treatment. In only one case the history taken by the veterinarian reported UCD.
From 19 of the 39 dairy cows (49%) with UCD on postmortem external examination in 2019 passed the necropsy room with uncomplicated UCD. In these cows, ulcerative dermatitis was described, although there was no related embolic pneumonia observed, but other most likely causes that led to the death of these cows.