Shaker Syndrome in Dogs

What is shaker syndrome in dogs?

Shaker syndrome is a condition involving generalized head and body tremors in dogs. Other names for this condition include steroid responsive tremors or generalized tremor syndrome.

You may hear this described as 'Little White Shaker Syndrome', because the condition is seen most commonly in small-breed white dogs such as the Maltese, West Highland White Terrier, and Poodle. Although the condition is most common in dogs weighing less than 30 lbs., any color and size dog is susceptible to this condition.

What are the clinical 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 (for example, the head) or may involve the entire body. These tremors may vary in severity, from very mild to incapacitating (preventing eating, walking, etc.).

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 otherwise normal, except for the tremors. A small number of dogs may show other neurologic deficits during episodes of trembling, such as trouble with their vision or nystagmus (a rhythmic back-and-forth movement of the eyes), but this is very uncommon.

What causes shaker syndrome?

At this time, the cause of shaker syndrome is unknown. Several theories have been considered and tested, but none of these possible explanations have been confirmed through testing.

The condition is thought to be autoimmune in origin, given its response to steroids.

How is shaker syndrome diagnosed?

Shaker syndrome is a 'diagnosis of exclusion'. This 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 (such as liver disease, kidney disease, etc.) that may cause neurologic signs. Your veterinarian may also test for infectious diseases, such as canine distemper or other viruses/bacteria.

Depending on your dog’s condition, and the severity of his signs, your veterinarian may recommend referral to a neurologist for more advanced testing. This testing may include a CSF tap (in which a veterinarian removes a small amount of cerebrospinal fluid, the fluid surrounding the brain and spinal cord, under anesthesia for testing) and a MRI (magnetic resonance imaging, which allows visualization of the brain tissues). Not all dogs with presumed shaker syndrome require this extensive workup, but 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 will my veterinarian treat shaker syndrome?

Shaker syndrome is treated with prednisone. Prednisone is a steroid, which works by suppressing the dog’s immune system.

Typically, the tremors resolve within one to two weeks of beginning prednisone treatment. Once the tremors have resolved, your veterinarian will begin to gradually taper your dog's dose of prednisone. The goal is to maintain your dog on the lowest effective dose of prednisone, to maximize treatment efficacy while minimizing side effects.

Common side effects of prednisone include increased appetite, increased thirst, and increased urination. With long-term use, prednisone may also have effects on the skin, endocrine system (hormones), and immune system. Regular follow-up care with your veterinarian is essential to monitor for side effects, so that they can be promptly addressed if necessary. See handout "Steroid Treatment – Effects in Dogs" for more information.

If a dog cannot be adequately controlled on prednisone alone, or if side effects become problematic, other immunosuppressive drugs may be considered. These medications include mycophenolate, leflunomide, Cytosar, and others. Due to cost, however, these medications are not typically used as a first-line treatment for shaker syndrome.

What is the prognosis for shaker syndrome?

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