Alimentary and Respiratory Tract Lesions in Eight Medically Fragile Holstein Cattle with Bovine Leukocyte Adhesion Deficiency (BLAD)

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Abstract
Lesions in the alimentary tract were studied in eight medically fragile Holstein cattle homozygous for the bovine leukocyte adhesion deficiency (BLAD) allele as determined by polymerase chain reaction and restriction endonuclease analysis. These cattle received institutional medical care but died or were euthanatized because of chronic debilitation associated with diarrhea (6/8) and pneumonia (4/8). The six cattle with diarrhea had acute (n = 3) or chronic (n = 3) intestinal ulcers, but the other two remained relatively healthy for 3 years and did not develop intestinal tract ulcers. Ulcerated areas were present in the small intestine in six animals, and two of these also had ulcers in the large intestine. Ulcers were covered by thick exudates that, in chronic lesions, partially occluded the intestinal lumen. Intramural and serosal fibrosis also contributed to lumen constriction. Pseudomonas aeruginosa was isolated from the intestine of four cattle. Bovine viral disease virus and Salmonella were not isolated from the five cattle that were tested. Respiratory tract lesions consisted of dense infiltrates of neutrophils in bronchi, bronchioles, and alveoli. This study suggests that intestinal lesions are integral to the demise of BLAD cattle that receive intensive medical care and that neutrophils do infiltrate the lung and enter airway lumina, despite the adhesion deficiency.

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