# Methocarbamol: veterinary dose and monograph

> Methocarbamol is a veterinary drug. Centrally acting skeletal-muscle relaxant whose most important veterinary role is in TREMORGENIC TOXICOSES — it is a first-line drug to control the muscle tremors and rigidity of permethrin (cat), metaldehyde (snail bait), tremorgenic… Indications include tremorgenic toxicoses — permethrin (cats), metaldehyde, tremorgenic mycotoxins, strychnine, pyrethroids; acute muscle spasm / muscle pain (e.g. with intervertebral disc disease); adjunct relaxation in tetanus (muscle rigidity). This monograph lists 4 reference doses for dogs, cats and horses, each with route, frequency and source.

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

## At a glance

- **Drug class:** Veterinary drug
- **Also known as:** Robaxin, Robinax
- **Species with doses:** Dogs, Cats and Horses
- **General dose range:** 20–45 mg/kg PO q8h (titrate to effect) — check the species tables for the indication
- **Routes:** IV, PO
- **Last reviewed:** 1 October 2026

## Indications

- Tremorgenic toxicoses — permethrin (cats), metaldehyde, tremorgenic mycotoxins, strychnine, pyrethroids
- Acute muscle spasm / muscle pain (e.g. with intervertebral disc disease)
- Adjunct relaxation in tetanus (muscle rigidity)

## Methocarbamol 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

*Methocarbamol doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Tremorgenic toxicosis (metaldehyde, mycotoxin) | 55–220 mg/kg | IV | to effect (max ~330 mg/kg/day) | — |
| Muscle spasm / IVDD pain (oral) | 15–44 mg/kg | PO | q8h | — |

- Tremorgenic toxicosis (metaldehyde, mycotoxin): Papich 5e and Plumb’s p.805 (label): severe conditions 55–220 mg/kg IV — half rapidly, the rest to effect — maximum 330 mg/kg/day; mycotoxin tremors no faster than 2 mL/min (Schell 2000); caffeine/guarana 50–220 mg/kg slowly IV.
- Muscle spasm / IVDD pain (oral): Papich 5e (label): 44 mg/kg q8h PO, then 22–44 mg/kg q8h, not beyond 14–21 days. Plumb’s p.805: label 132 mg/kg/day divided q8–12h, then 61–132 mg/kg/day; IVDD muscle relaxation 15–20 mg/kg PO three times daily (Morgan). Stop if no response in 5 days.

### Cats

*Methocarbamol doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Permethrin / tremorgenic toxicosis | 55–220 mg/kg | IV | to effect (max ~330 mg/kg/day) | — |

- Permethrin / tremorgenic toxicosis: Papich 5e and Plumb’s p.805 (label): moderate conditions 44 mg/kg IV; severe (strychnine, tetanus) 55–220 mg/kg IV — give half rapidly, then the rest to effect; do not exceed 330 mg/kg/day. Permethrin toxicity: 50–150 mg/kg IV, first half over 5–10 min, then to effect; can be given as a CRI over 24 h in severe cases (Boag 2009). Bathe/decontaminate and support.

### Horses

*Methocarbamol doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Muscle spasm / tying-up adjunct | 4.4–25 mg/kg | IV | as needed | — |

- Muscle spasm / tying-up adjunct: Papich 5e and Plumb’s p.805 (label): moderate conditions 4.4–22 mg/kg IV to effect (q8h); severe 22–55 mg/kg IV; acute rhabdomyolysis 15–25 mg/kg by slow IV infusion, up to four times daily (Hanson 1999). Oral: 2–3 times the IV dose. Above 30 mg/kg IV causes depression. ARCI Class 4.

## Contraindications

Renal impairment (the IV formulation's polyethylene glycol vehicle is a concern; oral generally fine). Do not exceed the maximum daily dose (~330 mg/kg/day). Rapid IV bolus (CNS depression, recumbency). Known hypersensitivity. Ensure airway protection in heavily affected toxicosis patients.

## Species-specific warnings

> **Caution:** Cats: A frontline drug for permethrin toxicosis in cats (from misapplied dog spot-ons) — titrate IV to control tremors and decontaminate the cat; this is an emergency.

## Adverse effects

- Sedation, weakness, ataxia, recumbency (dose-related)
- Hypersalivation, vomiting
- Excessive CNS depression at high dose
- Brown/green-brown urine discolouration (harmless)

## Drug interactions

- Other CNS depressants (opioids, benzodiazepines, anaesthetics): additive sedation/respiratory depression
- No major specific pharmacokinetic interactions of note

## Pregnancy and lactation

Limited data; used when needed for serious toxicosis (where maternal benefit is clear). Crosses into milk.

## Monitoring

- Tremor control vs over-sedation (titrate carefully in toxicoses)
- Respiratory status in heavily affected patients (airway protection)
- Temperature (hyperthermia from tremors; hypothermia from over-relaxation)
- Total daily dose (do not exceed ~330 mg/kg/day)

## Toxicity and overdose

Overdose causes excessive CNS depression — profound sedation, ataxia, recumbency, weakness and, at very high doses, respiratory depression. The IV vehicle can be problematic in renal impairment. Generally a wide margin and reversible with discontinuation/support.

Management: No specific antidote. Support airway/ventilation if severely depressed, IV fluids, nursing care (thermoregulation, recumbency care); effects resolve as the drug is metabolised. Reduce/stop dosing and monitor until ambulatory.

## Clinical pearls

- The muscle-relaxant of choice for tremorgenic poisonings — titrate IV to stop the tremors while keeping the patient breathing
- In permethrin-toxic cats, combine methocarbamol with decontamination (bathe off the product), thermoregulation and supportive care
- Give IV slowly and to effect; the goal is tremor control, not flat recumbency
- Respect the daily maximum (~330 mg/kg/day) and protect the airway in obtunded patients
- Harmless brown urine discolouration can alarm owners — reassure them

## Mechanism of action

A centrally acting muscle relaxant that depresses polysynaptic reflex transmission in the spinal cord and brainstem (likely via general CNS depression rather than a specific receptor), reducing skeletal-muscle hyperactivity and tremor. It does not act at the neuromuscular junction or directly on muscle, and produces relaxation/sedation without true anaesthesia or analgesia.

## Formulations and products

- 500 mg tablet
- 750 mg tablet
- Injection 100 mg/mL
- Robinax — 500 mg tablet; 100 mg/mL injection, Tablet / injection (human-label)
- Robaxin — 500 / 750 mg tablet, Tablet (human-label)

## Storage

Tablets: 15–30 °C, dry. Injection: 15–30 °C, protect from light; do not refrigerate (precipitation).

## 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 Methocarbamol for dogs?

Reference doses for Methocarbamol in dogs: 55–220 mg/kg IV to effect (max ~330 mg/kg/day) (Tremorgenic toxicosis (metaldehyde, mycotoxin)); 15–44 mg/kg PO q8h (Muscle spasm / IVDD pain (oral)). Confirm against the label and the patient before use.

### What is the dose of Methocarbamol for cats?

Reference doses for Methocarbamol in cats: 55–220 mg/kg IV to effect (max ~330 mg/kg/day) (Permethrin / tremorgenic toxicosis). Confirm against the label and the patient before use.

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

Reference doses for Methocarbamol in horses: 4.4–25 mg/kg IV as needed (Muscle spasm / tying-up adjunct). Confirm against the label and the patient before use.

### When should Methocarbamol not be used?

Renal impairment (the IV formulation's polyethylene glycol vehicle is a concern; oral generally fine). Do not exceed the maximum daily dose (~330 mg/kg/day). Rapid IV bolus (CNS depression, recumbency). Known hypersensitivity. Ensure airway protection in heavily affected toxicosis patients.

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

Sedation, weakness, ataxia, recumbency (dose-related); Hypersalivation, vomiting; Excessive CNS depression at high dose; Brown/green-brown urine discolouration (harmless).

## 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.