Thiabendazole

Thiabendazole is an older benzimidazole anthelmintic used against selected gastrointestinal and respiratory nematodes. Historical veterinary applications include equine strongyles and some ruminant worms. It also has local antifungal uses in selected combination preparations. Parasite response varies with species, life stage and resistance pattern.

Group

Benzimidazole anthelmintic

Mechanism of Action

Thiabendazole interferes with parasite microtubule function through binding to beta-tubulin. Disrupted intracellular transport and nutrient handling impair glucose utilization and deplete energy stores, contributing to parasite death. Effects on parasite energy pathways may also contribute. Its local antifungal activity is pharmacologically separate from the clinical objective of systemic nematode treatment.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Respiratory parasites	30–70 mg/kg	PO	Every 12 h

Horses

Use / stage	Dose	Route	Schedule	Instructions
Nematodes	44 mg/kg	PO	Once

Sheep

Use / stage	Dose	Route	Schedule	Instructions
Nematodes	44 mg/kg	PO	Once
Selected nematode infections	67 mg/kg	PO	Once

Goat

Use / stage	Dose	Route	Schedule	Instructions
Nematodes	44 mg/kg	PO	Once
Selected nematode infections	67 mg/kg	PO	Once

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Nematodes	67 mg/kg	PO	Once
Severe nematode infection	111 mg/kg	PO	Once

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Nematodes	67–90 mg/kg	PO		Baby pigs; repeat schedule unspecified.

Indications

Treatment of selected susceptible gastrointestinal nematodes in horses or ruminants.
Historical treatment of selected canine respiratory nematodes with a supported regimen.
Local treatment of selected superficial fungal or otic infections with an appropriate thiabendazole-containing combination product.

Adverse effects

Adverse effects are uncommon in the clinical guidance.

Monitoring and Administration

Assess fecal response and parasite susceptibility. Commercial availability and resistance can limit usefulness; protect products from light.

Dogs: 50 mg/kg every 24 hours for 3 days, repeated in 1 month; route is not explicitly stated for this regimen.

Cats: 125 mg/kg every 24 hours for 3 days; route is not explicitly stated for this regimen.