A tremor is an involuntary, rhythmic twitching of opposing muscles. They usually are visible to the naked eye and sometimes can even be felt when touching affected areas. Tremors are caused by the synchronous contraction of muscles that are antagonistic to one another, which means that they normally pull in opposite directions. When they pull in the same direction at the same time, it causes a to-and-fro movement in the affected area of the body. Sometimes, they involve genetic or developmental abnormalities but can also be caused by trauma, spinal cord lesions, inflammation, exposure to toxins, heart disease, and immune system disorders.
Symptoms and Types
Involuntary tremors involving any body part may be seen in an affected dog. The tremors may be localized or generalized. Localized cases usually affect the head or hind limbs.
Causes of Tremors in Dogs
Tremors are caused by the synchronous contraction of reciprocally innervated, antagonistic muscles, leading to a regular to-and-fro movement in all or part of an affected dog’s body. The underlying cause of tremors is often unknown (idiopathic). Tremors generally can be related to genetic or developmental conditions, trauma, compressive lesions of the spinal cord, inflammation, exposure to any of a number of tremorgenic toxins, poor blood perfusion to pelvic muscles due to cardiac disease, immune-mediated diseases, metabolic diseases and degenerative diseases of the nervous system.
The therapeutic goal is to identify and treat the underlying cause of canine tremors. Many causes of tremors are treatable, although in very young dogs tremors can reflect genetic or developmental abnormalities that cannot be treated or well managed. Tremors are not a disease but rather are a clinical sign of some other underlying disorder. Most veterinarians will begin with a thorough physical examination, comprehensive blood tests and urine analysis. If these tests do not reveal the cause of the tremors, more advanced diagnostics may be necessary, including radiographs, ultrasound, CT scans, MRI and/or spinal taps. While the results of these tests are being evaluated, dogs suffering from tremors typically are treated symptomatically with pain relievers, muscle relaxants, corticosteroids or sedatives.
Your veterinarian will perform a complete physical exam on your dog after taking a complete medical history, including a background history of the symptoms and the time of onset, and possible incidents that might have led to this condition. If brain disease is the primary cause of the tremors, the laboratory tests are usually found to be normal. Other diagnostic tests will include X-rays, computed tomography (CT-Scan), and magnetic resonance imaging (MRI), especially in cases where the pelvic limbs are affected.