Methocarbamol is a muscle relaxant and active ingredient of Robaxin. It is FDA-approved for the treatment of muscle spasms and skeletal muscle conditions. How the drug works to prevent muscle spasms is not yet known, but it is similar in structure to guaifenesin (another muscle relaxant) and appears to be quite safe when used correctly.

Recommended Dosage

Note: Do not give methocarbamol to your dog unless you have permission from your vet. Always follow your vet’s instructions.

Methocarbamol is available as an injectable (to be injected intravenously) and in the form of tablets. Avoid freezing or refrigerating the injectable solution, keep it stored at room temperature instead.


If you are using the tablets, dogs require 60 mg/lb per day (divided into two or three daily doses). The dosage may be dropped to 30 mg/lb per day depending on your vet’s recommendation. If your dog’s symptoms have not improved after 5 days, stop using the medicine and speak to the vet about other treatment options.

You can use the chart and calculator below to find the typical dosage for your dog.

Chart of the canine methocarbamol dosage
Dog’s Weight In Pounds: Daily Dosage In Mg:

Take care and check the strength of the pills (this information can be found on the packaging) before giving them to your dog.

Injectable Solution

When using the injectable form of the drug, the dosage will depend on the cause of the dog’s symptoms. For most mild conditions, 10 – 20 mg/lb can be used. For other problems such as toxicosis, the usual dosage is 25 – 100 mg/lb. The exact amounts used will also vary depending on the vet – some prefer to use 70 mg/lb and then follow it up with doses of 35 mg/lb as required.

Do not exceed 150 mg/lb and avoid injecting at a rate of more than 2 mL/min.

Example: A 25 lb dog may be given 500 mg of methocarbamol in tablet form three times daily.


Is It Safe?

The medicine is safe for dogs when it is used correctly. Because the injectable solution contains polyethylene glycol 300, it may be unsuitable for dogs with kidney disease. Dogs with a known hypersensitivity to methocarbamol or guaifenesin may also be unsuitable for treatment.

Pregnancy/Nursing: Avoid use in pregnant or nursing animals if possible, although the AAP considers the medicine safe for breastfeeding mothers.

Safety Guidelines

We recommend following these guidelines to safely treat your dog with methocarbamol:

  • Do not use without veterinary approval, and tell the vet about any medical conditions affecting your dog (especially kidney disease), as well as any other medicines you are giving him.
  • Do not inject more than 2 mL per minute, and do not inject the solution subcutaneously.
  • Do not exceed a dosage of 150 mg/lb.
  • Store the injectable medicine at room temperature.


What Is It Used For?

Methocarbamol is commonly used to prevent muscle spasms and treat the symptoms of inflammatory/traumatic conditions affecting skeletal muscle. It is also often used in response to toxicosis.

Side Effects

The following side effects are possible:

  • Darkening of the urine.
  • Sedation.
  • Vomiting.
  • Weakness.
  • Loss of coordination.

Urine often becomes darker during treatment, and is considered to be normal.


Dr. Bailey
Plumb’s Veterinary Drug Handbook (sixth edition)