💊 Muscle Relaxant

Methocarbamol Dosage for Dogs Calculator

Veterinary methocarbamol (Robaxin-V) dosing for dogs — covering musculoskeletal spasm, tetanus, myelopathy, and toxin-induced hypertonicity with tablet breakdowns.

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Prescription drug — veterinary supervision required. Methocarbamol causes CNS depression. Avoid in dogs with myasthenia gravis, hepatic impairment, or concurrent CNS depressants. Injectable form must be given IV only — NOT SC or IM.

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About Methocarbamol (Robaxin-V)

Drug Class

Centrally-Acting Muscle Relaxant — CNS Depressant

Mechanism of Action

Methocarbamol depresses polysynaptic reflexes in the spinal cord and supraspinal areas of the brain, reducing skeletal muscle spasm. Its exact mechanism is not fully understood but involves general CNS depression rather than direct action on neuromuscular junctions.

Primary Uses in Dogs

Muscle spasm associated with trauma, intervertebral disc disease (IVDD), tetanus toxin-associated muscle rigidity (tetanus antitoxin adjunct), strychnine or permethrin toxicity-associated muscle tremors, and post-surgical muscle pain.

Dosing Quick Reference

Indication Dose Frequency
Muscle spasm (mild) 44 mg/kg q8h PO
Tetanus/toxicosis 44–220 mg/kg IV slow over 3 min
Maximum daily dose 330 mg/kg/day divided doses

Common Side Effects

  • Sedation and drowsiness (expected, dose-related)
  • Ataxia and wobbliness
  • Muscle weakness
  • Hypersalivation
  • Nausea or vomiting
  • Urine discolouration (dark brown/green — harmless)

Monitoring

Monitor respiratory rate and sedation level during IV use. Ensure adequate hydration. For toxin cases, monitor muscle rigidity score every 2–4 hours.

⚠️ Methocarbamol causes significant sedation — do not let dogs climb stairs, jump, or be unsupervised near water. Reduce dose in renal impairment. IV administration must be slow (do not exceed 2 mL/min) to prevent cardiovascular effects. The urine colour change is harmless.

What Is Methocarbamol?

Methocarbamol (Robaxin-V) is a central-acting skeletal muscle relaxant that works by depressing polysynaptic reflexes in the spinal cord and brain stem. It does not have direct action on the neuromuscular junction or on skeletal muscle fibres. In veterinary medicine, it is FDA-approved for use in dogs and cats for the relief of muscle spasm associated with acute inflammatory musculoskeletal conditions, disc disease, trauma, tetanus, and toxin-induced hypertonicity (e.g., strychnine, metaldehyde, tremorgenic mycotoxins).

Indications and Dose Ranges

  • Musculoskeletal spasm (oral): 44 mg/kg q8h × 3 days, then 22–44 mg/kg q8–12h
  • Severe spasm / tetanus (IV): 55–220 mg/kg IV slowly (max rate 2 mL/min)
  • Toxin-induced hypertonicity: 55–220 mg/kg IV titrated to effect
  • Maintenance oral: 20–45 mg/kg PO q8–12h

How to Use This Calculator

  1. Enter your dog’s body weight in kg or lbs
  2. Select the indication and route
  3. Choose the tablet or injectable strength
  4. Click Calculate to see dose range and frequency
  5. For IV doses, always administer slowly — rate matters

🧮 Methocarbamol Dose Calculator

Methocarbamol Dosing Result

References

  1. Plumb DC. Plumb’s Veterinary Drug Handbook, 9th ed. Wiley-Blackwell; 2018.
  2. Robaxin-V (methocarbamol) Prescribing Information. Pfizer Animal Health; 2020.
  3. Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed. Elsevier; 2016.
  4. Gfeller RW, Messonnier SP. Handbook of Small Animal Toxicology and Poisonings. Mosby; 2004.