Suspected levamisole intoxication in calves

Area of Science:

• Veterinary Pharmacology
• Animal Toxicology
• Ruminant Health

Background:

• Anthelmintics are widely used in livestock for parasite control.
• Levamisole is a common anthelmintic, but its narrow safety margin poses a risk.
• Calf management practices, including transport and yarding, can induce stress and dehydration.

Purpose of the Study:

• To investigate cases of suspected levamisole intoxication in young cattle.
• To identify risk factors associated with adverse drug events from anthelmintic treatment.
• To highlight the importance of accurate drug administration in veterinary medicine.

Main Methods:

• Observation of clinical signs in Friesian and Hereford calves post-anthelmintic administration.
• Post-mortem examination and adverse drug event investigation.
• Analysis of anthelmintic formulation, quality, and drench gun function.

Main Results:

• Calves exhibited severe nicotinic-type symptoms including hypersalivation, tremors, and central nervous system depression.
• Two Hereford calves died after treatment, with two Friesian calves succumbing later.
• Anthelmintic quality and drench gun function were confirmed to be within specifications.

Conclusions:

• Dehydration and stress increase susceptibility to levamisole toxicity in calves.
• Levamisole has a narrow safety margin, making accurate weight-based dosing essential.
• Overdosing can occur if calf health status is not considered during treatment.