# Mebendazole: veterinary dose and monograph

> Mebendazole is a veterinary antiparasitic. A broad-spectrum benzimidazole anthelmintic for GI nematodes (and some cestodes) in horses, ruminants and poultry. Indications include GI nematodes in horses (strongyles, ascarids, pinworms), ruminants and poultry; some cestode (tapeworm) infections; broad-spectrum benzimidazole deworming (large animals/poultry). This monograph lists 4 reference doses for dogs, horses, sheep and poultry, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

Source: https://vetmasterji.com/drugs/mebendazole · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Antiparasitic
- **Also known as:** Mebex, Wormin, Vermox
- **Species with doses:** Dogs, Horses, Sheep and Poultry
- **General dose range:** 10–20 mg/kg PO single dose (repeat per cycle) — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- GI nematodes in horses (strongyles, ascarids, pinworms), ruminants and poultry
- Some cestode (tapeworm) infections
- Broad-spectrum benzimidazole deworming (large animals/poultry)

## Mebendazole dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Dogs

*Mebendazole doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| GI nematodes / Taenia | 22 mg/kg | PO | q24h (with food) | 3 days; may repeat in 3 weeks |

- GI nematodes / Taenia: Papich 5e: 22 mg/kg mixed with food q24h for 3 days, repeated in 3 weeks if needed. Rare idiosyncratic hepatotoxicity reported.

### Cattle

*Mebendazole doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — |

- No reference dose for this species: Papich 5e gives mebendazole doses only for dogs and horses and Plumb’s has no monograph.

### Horses

*Mebendazole doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| GI nematodes | 8.8 mg/kg | PO | single dose | — |

- GI nematodes: Papich 5e: 8.8 mg/kg PO. Not in Plumb’s. Check faecal egg-count reduction — benzimidazole resistance is common in cyathostomins.

### Goats

*Mebendazole doses for goats*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — |

- No reference dose for this species: Papich 5e gives mebendazole doses only for dogs and horses and Plumb’s has no monograph.

### Sheep

*Mebendazole doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| GI nematodes | Oral drench at the label dose | PO | single dose | — | Withdrawal NOT established — treat as extra-label |

- GI nematodes: Label-sourced — Papich 5e gives only dog and horse doses and Plumb’s has no monograph. Follow the local product label for dose and withdrawal.

### Poultry

*Mebendazole doses for poultry*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| GI nematodes / some cestodes | In feed or water at the label inclusion rate | PO | per label | — | Withdrawal NOT established — treat as extra-label |

- GI nematodes / some cestodes: Label-sourced (no Papich 5e poultry dose, no Plumb’s monograph). Follow the local label for dose, meat withdrawal and egg restrictions.

### Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

*Mebendazole doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — |

- No reference dose for this species: Papich 5e gives mebendazole doses only for dogs and horses and Plumb’s has no monograph.

## Contraindications

Dogs (idiosyncratic hepatotoxicity — use fenbendazole instead). Early pregnancy at high/repeated doses (benzimidazole teratogenicity concern at high doses). Known hypersensitivity. Confirm benzimidazole susceptibility where resistance is suspected. Observe food-animal withdrawal.

## Species-specific warnings

> **Caution:** Dogs: Associated with idiosyncratic, sometimes fatal hepatotoxicity in dogs — do NOT use for canine deworming; fenbendazole is the safe benzimidazole choice.

## Adverse effects

- Mild transient GI effects (uncommon) in large animals/poultry
- Idiosyncratic HEPATOTOXICITY in dogs (why it is avoided there)
- Reduced efficacy where benzimidazole resistance exists

## Drug interactions

- No major systemic therapeutic interactions
- Cross-resistance with other benzimidazoles (fenbendazole, oxfendazole, albendazole)

## Pregnancy and lactation

Benzimidazoles are generally regarded as safe in pregnancy at label doses; avoid very high/repeated dosing in early gestation.

## Monitoring

- Faecal egg count reduction (efficacy/resistance)
- Withdrawal compliance; class rotation
- (If ever used in dogs — not recommended — liver values)

## Toxicity and overdose

Wide safety margin in target large-animal/poultry species (overdose usually only mild GI upset). The notable exception is DOGS, where idiosyncratic hepatotoxicity (sometimes fatal) has occurred — hence fenbendazole is preferred for canine deworming.

Management: Supportive — fluids if needed. For suspected canine hepatotoxicity, discontinue and provide hepatoprotection/monitoring. No specific antidote (wide margin in target species).

## Clinical pearls

- A broad benzimidazole for horses, ruminants and poultry — but AVOID in dogs (idiosyncratic, sometimes fatal hepatotoxicity); use fenbendazole for canine deworming
- Benzimidazole resistance is widespread in equine/small-ruminant strongyles — do FECRTs and rotate classes
- Wide safety margin in target species, but still dose to body weight and observe withdrawals

## Mechanism of action

Binds parasite β-tubulin and inhibits microtubule polymerisation, disrupting the worm's cytoskeleton, glucose uptake and energy metabolism — killing GI nematodes (and damaging some cestodes). Mammalian tubulin has much lower affinity, giving the wide safety margin; the canine hepatotoxicity is an idiosyncratic (non-mechanism-based) reaction.

## Formulations and products

- Oral paste / suspension / granules
- 100 mg tablet (human)
- Mebendazole equine paste (Various) — Mebendazole paste/suspension, Paste / suspension
- Mebex / Vermox — 100 mg tablet; suspension, Tablet / suspension (human-label)

## Storage

Paste/suspension/tablets: 15–30 °C, protect from light; shake suspension.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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## Frequently asked questions

### What is the dose of Mebendazole for dogs?

Reference doses for Mebendazole in dogs: 22 mg/kg PO q24h (with food) for 3 days; may repeat in 3 weeks (GI nematodes / Taenia). Confirm against the label and the patient before use.

### Can Mebendazole be given to cattle?

Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species (No reference dose for this species).

### What is the dose of Mebendazole for horses?

Reference doses for Mebendazole in horses: 8.8 mg/kg PO single dose (GI nematodes). Confirm against the label and the patient before use.

### What is the withdrawal period for Mebendazole?

Sheep, PO (GI nematodes): Withdrawal NOT established — treat as extra-label; Poultry, PO (GI nematodes / some cestodes): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Mebendazole not be used?

Dogs (idiosyncratic hepatotoxicity — use fenbendazole instead). Early pregnancy at high/repeated doses (benzimidazole teratogenicity concern at high doses). Known hypersensitivity. Confirm benzimidazole susceptibility where resistance is suspected. Observe food-animal withdrawal.

### What are the side effects of Mebendazole in animals?

Mild transient GI effects (uncommon) in large animals/poultry; Idiosyncratic HEPATOTOXICITY in dogs (why it is avoided there); Reduced efficacy where benzimidazole resistance exists.

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.