Shaker Syndrome in Dogs

What is shaker syndrome in dogs?

Shaker syndrome is a condition that involves generalized head and body tremors in dogs. Other names for this condition include steroid-responsive tremor syndrome (SRTS) or idiopathic generalized tremor syndrome (IGTS).

You may hear this condition described as “Little White Shaker Syndrome” because the condition is most common in small-breed white dogs, such as the Maltese, West Highland White Terrier, and Bichon Frise. 

Although the condition is most common in dogs weighing less than 30 lb (14 kg), any color and size of dog is susceptible to this condition.

What are the signs of shaker syndrome?

Affected dogs typically develop tremors during early adulthood, at one to two years of age. Tremors are rhythmic, repetitive, and involuntary muscle movements that look like shaking. Tremors may be localized to one area of the body (e.g., the head) or may involve the entire body. These tremors may vary in severity, from mild to incapacitating (e.g., preventing eating or walking).

In many dogs with shaker syndrome, the tremors worsen with excitement and exercise. Tremors may improve or completely resolve when the dog is resting or sleeping. Most dogs are normal except for the tremors. Some dogs may show other neurologic deficits during trembling episodes, such as trouble with their vision or nystagmus (a rhythmic back-and-forth movement of the eyes), but this is uncommon.

What causes shaker syndrome?

The exact cause of shaker syndrome is unknown. It is thought to be an immune-mediated condition, which means the immune system appears to play a role in the disease. This may result in mild inflammation of the cerebellum (the part of the brain responsible for coordination). This theory is supported by the fact that most dogs improve when treated with corticosteroids, which reduce inflammation.

How is shaker syndrome diagnosed?

Shaker syndrome is a diagnosis of exclusion, which means that your veterinarian will rule out, or exclude, all other medical causes for the tremors before arriving at a diagnosis of shaker syndrome.

In a dog with a new onset of muscle tremors, your veterinarian will first perform blood tests and urinalysis to rule out medical conditions that may cause neurologic signs, such as liver disease or kidney disease. Your veterinarian may also test for infectious diseases like canine distemper or other viruses and bacteria.

Depending on your dog’s condition and the severity of signs, your veterinarian may recommend a referral to a neurologist for more advanced testing, which may include:

• A cerebrospinal fluid (CSF) tap, also known as a lumbar puncture, in which a veterinarian removes a small amount of cerebrospinal fluid (the fluid surrounding the brain and spinal cord) under anesthesia.
• A magnetic resonance imaging (MRI) test to visualize the brain tissues.

Not all dogs with presumed shaker syndrome require this extensive workup. Your veterinarian will work with you to determine the most appropriate course of action for your pet. If the diagnostic tests are all negative, your veterinarian will begin presumptive treatment for shaker syndrome. Dogs with shaker syndrome typically improve within one to two weeks of starting treatment, which confirms the diagnosis.

How is shaker syndrome treated?

Shaker syndrome is treated with prednisone, a steroid that suppresses the immune system. Typically, the tremors resolve within one to two weeks of beginning prednisone treatment. Once the tremors have resolved, your veterinarian will gradually lower your dog's prednisone dose. The goal is to maintain your dog on the lowest effective dose of prednisone to maximize treatment efficacy and minimize side effects. Diazepam (a muscle relaxant) may also be used to help reduce the tremors, especially in the early phases of treatment.

Common side effects of prednisone include increased appetite, thirst, and urination. With long-term use, prednisone may also affect the skin, endocrine system (hormones), and immune system. Regular follow-up care with your veterinarian is essential to monitor for these effects so they can be promptly addressed if necessary.

If a dog cannot be adequately managed on prednisone alone or if side effects become problematic, other immunosuppressive drugs may be considered, such as cyclosporine or leflunomide.

What is the prognosis for shaker syndrome?

The prognosis for shaker syndrome is excellent. Most dogs' tremors are fully resolved within one to two weeks of beginning prednisone treatment and can be controlled with long-term use of low doses of prednisone.