Ovine white-liver disease (OWLD). Pathology

Area of Science:

• Veterinary Pathology
• Animal Nutrition
• Biochemistry

Background:

• Ovine enzootic ataxia (OEA) is a significant disease in lambs grazing pastures.
• The precise pathological mechanisms and contributing factors to OEA require further elucidation.
• Cobalt and vitamin B12 are essential micronutrients for ruminant health.

Purpose of the Study:

• To investigate the microscopic liver changes associated with Ovine enzootic ataxia (OEA) in lambs.
• To determine the role of cobalt/vitamin B12 deficiency in the pathogenesis of OEA.
• To identify potential co-factors or triggers exacerbating liver damage in affected lambs.

Main Methods:

• Histopathological examination of liver tissues from lambs grazing OEA-associated pastures.
• Comparison of pathological findings between supplemented and unsupplemented lambs.
• Assessment of lambs with subclinical deficiencies on control pastures.

Main Results:

• Microscopic liver changes, including fatty change and Councilman bodies, were observed within one month on affected pastures.
• 83% of lambs on OEA pastures exhibited typical or suspect pathological changes.
• Cobalt/vitamin B12 supplementation prevented specific OEA-related liver lesions, while subclinically deficient lambs showed milder features.

Conclusions:

• Ovine enzootic ataxia (OEA) is a manifestation of vitamin B12 deficiency, exacerbated by factors initiating hepatic fatty change.
• Early hepatic fatty change compromises intracellular homeostasis, increasing hepatocyte vulnerability.
• Copper and other elements may play a role in the progression of liver damage in OEA.