Pathology of ruminal acidosis in cattle

Area of Science:

• Veterinary Pathology
• Ruminant Medicine
• Gastroenterology

Background:

• Rumen acidosis (RA) is a common alimentary disease in ruminants.
• It results from excessive feed fermentation in the reticulorumen.
• Understanding microscopic lesions is crucial for diagnosis and management.

Purpose of the Study:

• To characterize and compare microscopic lesions in acute and subacute RA in cattle.
• To evaluate histomorphometric differences between RA forms and controls.
• To identify key pathological markers for differentiating RA severity.

Main Methods:

• Retrospective analysis of 52 cattle with rumen fluid pH ≤5.5.
• Classification of cases into acute or subacute RA based on clinical history.
• Histologic examination and histomorphometry of ruminal papillae, epithelium, and stratum corneum.
• Comparison using univariable linear mixed models with 7 control animals.

Main Results:

• Acute RA cases showed minimal changes, primarily shorter ruminal papillae compared to controls.
• Subacute RA cases exhibited shorter, wider papillae, epithelial hyperplasia, and parakeratotic hyperkeratosis.
• Numerous intraepithelial pustules were observed in 79% of subacute RA cases.
• Subacute RA cases had more numerous, wider papillae and thicker epithelium than acute RA cases.

Conclusions:

• Distinct microscopic lesions and histomorphometric profiles differentiate acute and subacute RA in cattle.
• Subacute RA is associated with more severe and widespread histopathologic changes in the rumen.
• These findings aid in the diagnosis and understanding of RA pathogenesis in cattle.