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Tizanidine and dogs: Why this drug is unsafe for pets

Tizanidine is not safe for dogs. Learn about safer alternatives.
By and | Updated on Dec. 30, 2024 Medically reviewed by Emma Ryan, DVM
Sick or sleeping dog: Is tizanidine safe for dogs

Key takeaways

  • Do not give tizanidine to a dog.

  • There is no standard tizanidine dosage for dogs.

  • If a dog should accidentally ingest tizanidine or show signs of tizanidine poisoning, call an animal poison control center or take the dog to a veterinary emergency hospital.

  • The most common signs of tizanidine toxicity in dogs are lethargy, sleepiness, slow heart rate, and low blood pressure.

In this article:

Veterinarians do not use the skeletal muscle relaxant tizanidine in dogs. There are no veterinary studies on the effects or safety of tizanidine in companion animals and no published dosages. If a dog is given or accidentally eats tizanidine, that’s a potential veterinary emergency requiring inducing vomiting or monitoring the dog in a veterinary clinic. 

What is tizanidine used for in dogs?

Veterinarians do not use tizanidine, a drug more commonly recognized as brand-name Zanaflex. Some online pharmacies may sell single tablets as a veterinary drug, but these are similar to human versions in dosage strength. There are no published tizanidine dosages for dogs, so veterinarians do not know what dose is safe and effective to give to dogs.

Doctors primarily use tizanidine to treat muscle spasticity due to multiple sclerosis, muscle injury, spinal cord injury, stroke, or amyotrophic lateral sclerosis (ALS) in people, but they sometimes prescribe it off-label to treat back pain, neck pain, or muscle pain. A veterinarian can prescribe tizanidine for problems such as a slipped or herniated disc, but it is uncommon for veterinarians to prescribe tizanidine for dogs because there are no standardized dosages, veterinary research, or safety data to support the prescription.

Is tizanidine safe for dogs?

Do not give dogs tizanidine unless prescribed by a veterinarian. If tizanidine is prescribed, which is uncommon, ask the veterinarian if there are safer alternatives. There is no safety data regarding the use or ingestion of tizanidine in dogs.

Veterinarians generally regard tizanidine ingestion as a veterinary emergency if the dose cannot be vomited up. If a dog ingests any amount of tizanidine, immediately call a veterinarian or the ASPCA Animal Poison Control at 888-426-4435. If the capsule cannot be vomited up, they may suggest taking the dog to an emergency veterinary hospital for observation. 

Tizanidine belongs to a class of drugs called alpha-2-adrenergic agonists. These include drugs like clonidine and romifidine, but these drugs have very specialized uses in veterinary medicine.

Side effects of tizanidine in dogs

Veterinarians do not use tizanidine in dogs. They only experience tizanidine side effects when animals accidentally eat tizanidine meant for people.

The most common signs of tizanidine poisoning in dogs are:

  • Lethargy
  • Sedation
  • Vomiting
  • Loss of coordination
  • Slow heart rate
  • Low blood pressure

Common side effects of tizanidine in people include:

  • Dry mouth
  • Sleepiness
  • Weakness
  • Dizziness

The most serious side effects in dogs include:

  • Low blood pressure
  • Slow heart rate
  • Slowed breathing
  • Respiratory depression (inability to breathe)
  • Coma

Interactions of tizanidine with other pet meds

Although tizanidine is not safe for dogs, the effects of tizanidine poisoning, such as heart or breathing problems, can be worsened if the dog is taking other medications that have similar effects. These include:

CBD also slows down the nervous system and might cause sleepiness and slowed breathing, further contributing to problems that can occur if a dog ingests tizanidine.

Can dogs overdose on tizanidine?

Veterinarians do not generally know if there’s a safe and effective dose of tizanidine for dogs. For this reason, they usually consider any ingestion of tizanidine to be an emergency in a dog. 

Caregivers should call the ASPCA Animal Poison Control Center or a veterinarian if a dog takes any amount of tizanidine. 

If tizanidine ingestion is recent, the veterinarian will advise that the caregiver induce vomiting in the dog and watch for the capsule or tablet. If the dog then manages to vomit up the tablet, the veterinarian will probably advise the caregiver to watch the dog for symptoms over the next few hours. If tizanidine ingestion is not recent or the dog does not vomit up the tablet, the advice may be to take the dog to an emergency clinic for observation or to watch for symptoms.

Signs of tizanidine poisoning in a dog include:

  • Listlessness
  • Sleepiness
  • Drowsiness
  • Vomiting
  • Confusion
  • Slow heart rate (bradycardia)
  • Weak pulse
  • Low blood pressure (hypotension)
  • Coma

Tizanidine alternatives for dogs

Tizanidine is a centrally-acting muscle relaxant. It reduces muscle tightness and muscle spasms by slowing down nerves in the spinal cord. 

In people, tizanidine is primarily used as an antispastic muscle relaxant. Spasticity is when muscles tighten quickly and all at once and is characterized by “tight” or “stiff” muscles. Spasticity is usually due to nervous system disorders such as multiple sclerosis, ALS, brain injury, spinal injury, or spinal disc problems. 

Tizanidine is also an antispasmodic muscle relaxant. These drugs relieve muscle pain and are commonly used in people to treat back pain or neck pain. Other antispasmodic muscle relaxants used in dogs include methocarbamol. The only other muscle relaxant that has both antispastic (tight muscles) and antispasmodic (painful muscles) effects is diazepam.

Dogs suffer muscle spasticity when muscles are damaged, nerves are damaged, muscles or ligaments are sprained or strained, or when spinal discs slip. Tetanus infections also cause muscle spasticity, though tetanus is not common in dogs. Veterinarians use a variety of treatments and medications to treat these problems, including:

Muscle relaxants aren’t always the first treatment of choice. When they are used, veterinary literature recommends methocarbamol or diazepam. 

Other veterinary skeletal muscle relaxants are used for specific problems in dogs such as:

Summary

Do not give tizanidine to a dog. Veterinarians do not know how safe it is in dogs or the appropriate dosages. They have other effective and safer treatment options that can help dogs with muscle spasticity feel better.

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