Avermectin toxicity in bovines less than thirty days old

Area of Science:

• Veterinary Pharmacology
• Toxicology
• Animal Science

Background:

• Avermectins, including abamectin and ivermectin, are widely used antiparasitic agents in livestock.
• Young animals, particularly bovines under four months, are considered more susceptible to avermectin toxicity.
• Limited data exists on the safety of specific avermectin dosages in neonatal calves.

Purpose of the Study:

• To evaluate the safety and potential adverse effects of different subcutaneous dosages of abamectin and ivermectin-abamectin combinations in calves less than one month of age.
• To assess clinical signs and biochemical parameters in blood and cerebrospinal fluid (CSF) following avermectin administration.

Main Methods:

• Thirty-five calves (<30 days old) were divided into seven groups, receiving either a control substance or varying doses of abamectin or ivermectin-abamectin.
• Clinical observations and biochemical analyses (total protein, AST, GGT, alkaline phosphatase in blood; CSF analysis including protein, glucose, CK, ALT, LDH) were performed on days 0, 1, 7, and 14 post-treatment.

Main Results:

• No neurological toxicity was observed in any treatment group.
• No significant biochemical alterations were detected in blood or cerebrospinal fluid that could be attributed to the avermectin treatments.
• Calves tolerated abamectin up to 600 μg/kg and ivermectin (450-1350 μg/kg) + abamectin (250-750 μg/kg) combinations without adverse effects.

Conclusions:

• The tested avermectin formulations and dosages were found to be safe in calves less than 30 days of age.
• The multiple drug resistance gene (MDR1 - ABCB1) may play a role in the observed tolerance.
• Further research is warranted to fully elucidate the safety profile and potential influencing factors of avermectin use in young bovines.