Methocarbamol (Robaxin®) for Dogs, Cats, and Horses: Uses and Side Effects

Methocarbamol (Robaxin®) is a muscle relaxant veterinarians prescribe to help treat muscle spasms in dogs, cats, and horses. 

It is commonly used for conditions such as intervertebral disc disease (IVDD), muscle strains, toxin exposures, and certain neurologic disorders.

Here’s how methocarbamol works, when it’s prescribed, possible side effects, dosing guidance, and important safety information.

What Is Methocarbamol?

Methocarbamol is a muscle relaxant prescribed to help treat muscle spasms in dogs, cats, and horses.

Common uses in dogs and cats: Methocarbamol is commonly prescribed to treat muscle spasms associated with:

• Intervertebral disc disease (IVDD)
• Traumatic muscle strains
• Toxin exposures, including strychnine (rat poison), metaldehyde (snail bait), and permethrin toxicity in cats
• Infections that cause muscle spasms, such as tetanus

Methocarbamol is often prescribed alongside other medications used to manage IVDD and traumatic injuries, including nonsteroidal anti-inflammatory drugs (NSAIDs), gabapentin, and other pain medications.

Use in horses: Injectable methocarbamol is commonly used to treat muscle spasms, muscle strains, and exertional rhabdomyolysis ("tying-up") in horses. 

Oral methocarbamol for exertional rhabdomyolysis is an extra-label (off-label) use, meaning it is not included on the FDA-approved label but may be prescribed by a veterinarian when appropriate.

Compounded methocarbamol: In some cases, your veterinarian may recommend a compounded formulation when:

• Your pet has difficulty taking the commercially available formulation.
• The required dosage strength is not commercially available.
• Your pet is allergic to an ingredient in the FDA-approved medication.

Compounded medications are not FDA-approved. They are prepared by a veterinarian or licensed pharmacist to meet an individual patient's specific needs.

How Methocarbamol Works

Methocarbamol works through the central nervous system to reduce muscle spasms without acting directly on the muscles themselves.

It interrupts abnormal nerve signals traveling to skeletal muscles—the muscles responsible for voluntary movement, such as the biceps and triceps—allowing them to relax. Methocarbamol does not reduce the muscles' ability to contract or function normally.

Unlike skeletal muscle, smooth muscle (such as the muscles in the intestinal tract) is not affected by methocarbamol.

How To Give Methocarbamol

Give methocarbamol exactly as directed by your veterinarian.

Methocarbamol is typically given two to three times daily, but the exact dose and dosing schedule depend on why it has been prescribed and the severity of your pet's condition. 

Always follow the directions on the prescription label or those provided by your veterinarian.

Missed a Dose?

If you miss a dose of methocarbamol, give it as soon as you remember. 

However, if it is almost time for your pet's next scheduled dose, skip the missed dose and resume the normal dosing schedule.

Do not give extra or double doses.

Methocarbamol Side Effects

Methocarbamol is generally well tolerated, but side effects can occur in dogs, cats, and horses.

Common side effects in dogs and cats include:

• Sedation
• Salivation or excessive drooling
• Vomiting
• Low energy (lethargy)
• Weakness, especially hind limb weakness in geriatric pets
• Lack of coordination (ataxia)

In horses, side effects may include:

• Sedation
• Ataxia (lack of muscle control leading to uncoordinated movements)
• More profound sedation when methocarbamol is used with other sedating medications

Human Side Effects

Although methocarbamol is also prescribed for people, human and veterinary doses differ.

If you accidentally ingest this medication, contact your physician or your local Poison Control Center.

Monitoring Your Pet

No specific monitoring is required while your pet is taking methocarbamol. However, your veterinarian may recommend routine testing based on your pet's health, other medications, or the condition being treated.

When To Call Your Veterinarian

Contact your veterinarian if:

• Your pet develops severe side effects.
• You suspect your pet has received an overdose.
• You have additional questions or concerns about using methocarbamol.

Methocarbamol Overdose

A methocarbamol overdose can cause serious central nervous system depression and requires immediate veterinary attention.

Signs of an overdose may include:

• Excessive sedation
• Staggering
• Depressed reflexes
• Inability to stand
• Vomiting
• Excessive salivation
• Weakness
• Difficulty walking

Do not induce vomiting at home. Pets with an altered level of consciousness are at increased risk of aspirating (breathing in) vomit, which can lead to serious complications.

If you suspect your pet has received an overdose, contact your veterinarian immediately or an animal poison control center. Consultation fees may apply.

• Pet Poison Helpline: (855) 764-7661
• ASPCA Animal Poison Control: (888) 426-4435

How To Store Methocarbamol

Store methocarbamol according to the product label to help maintain its safety and effectiveness.

Storage instructions:

• Store methocarbamol at controlled room temperatures between 68 F and 77 F (20 C–25 C).
• Always confirm storage instructions by reading the product label.
• Keep out of reach of children and pets.