Muscle tremors in dogs are involuntary, repetitive, rhythmic muscle movements.
• Muscle tremors range in presentation from slow to rapid and from mild to debilitating
• Tremors can involve the whole body or can be localized to a specific region
• Causes include neurological disease, toxin exposure, metabolic disease, or infectious diseases
• Diagnosing the underlying cause involves physical examination, blood work, diagnostic imaging, and specialized testing for particular diseases
• Treatment varies depending on the underlying cause and may include muscle relaxants, pain medications, and sedatives
There are different types of tremors:
• Resting Tremor: occurs when the muscles are resting and are supported by gravity
• Action Tremor: occurs when the muscle contracts as part of a voluntary action
• Twitch: a rippling movement under the skin caused by the twitching of bands of muscle fibers
• Generalized Tremors: a tremor without an obvious cause and involves the whole body
• Brain-related tremor: a kinetic tremor, usually of the head, associated with the brain
If muscle tremors have been developing over time, notes of when, how strong, duration, and possible triggers, along with a video of the dog during a bout of muscle tremors, help guide diagnosis of the potential cause.
Many medical conditions can cause muscle tremors, depending on which muscle is affected and the health and age of the affected dog. Associated Conditions include:
• Neurological disease • Toxin exposure • Endocrine/metabolic disease • Infectious disease, including rabies
Note: While seizures are not muscle tremors, some types of seizure activity can look like muscle tremors. Specifically, an occurrence of myoclonus - a type of seizure of short duration, without loss of consciousness - appears similar to muscle tremors.
The exact prevalence of muscle tremors in dogs is unknown. A dog who suddenly develops muscle tremors needs EMERGENCY care, as sudden onset of muscle tremors may indicate serious blood sugar or calcium deficiencies. Sudden muscle tremors are also a sign of poisoning, especially if accompanied by diarrhea and/or vomiting.
Mild tremors rarely indicate serious disease or medical conditions. Violent or debilitating tremors usually indicate neuromuscular disease that require vet care.
The diagnostic approach for a dog with muscle tremors varies depending on the severity of the tremors. Typical tests, when warranted, include:
• Physical examination • Blood tests • Diagnostic imaging • Specialized testing for brain and muscular disorders
• Tests for specific infectious diseases like canine distemper or other viruses/bacteria
• Therapeutic trial with steroids for shaker syndrome: if the dog’s tremors respond to treatment, then the diagnosis is confirmed
If all known causes have been ruled out, the tremors are considered idiopathic, meaning the cause is unknown.
Treatment depends on underlying cause. While many causes of muscle tremors cannot be cured, vets prescribe pain medications, muscle relaxants, or sedatives to reduce occurrence and severity of muscle tremors themselves.
Muscle tremors are not to be confused with:
Trembling or shivering: can be caused by strong emotions, physical discomfort, or dreaming. Muscle tremors are not affected by emotions or discomfort. They continue once physical or emotional triggers have resolved.
Seizures: A dog who is having a seizure, while also having muscle tremors, may jerk, stiffen, collapse, lose consciousness, drool, or foam at the mouth. Dogs who have muscle tremors are alert and responsive and remain fully aware of their surroundings.
Hind Leg Weakness (Degenerative myelopathy): A dog with hind leg weakness struggles to get up and may have difficulty moving and seem unbalanced. They may also have muscle tremors related to this weakness, which are unrelated to typical causes of muscle tremors.
Muscle Fatigue: Older dogs can tremble when overworked. The muscle, when fatigued, uses trembling to help release stored glycogen/glucose which helps the muscle stay contracted. This trembling is different from muscle tremors as it resolves with rest.
Ataxia: A dog with ataxia has an abnormal gait, almost as if drunk, and is unsteady on its feet. The unsteadiness is different from the rhythmic repetitive contractions of muscle tremors.
Head Tilt: When muscle tremors affect the head, the head may shake or wobble. The wobble is different from the steady holding of the head to one side that characterizes head tilt.
Nystagmus: Nystagmus - or the involuntary and rhythmic movement of a dog’s eyes - is a symptom of vestibular disease and is not considered a muscle tremor.
If the dog also has difficulty moving and getting up, muscle tremors can be a sign of hind leg weakness (Degenerative myelopathy). If the dog also is jerking, stiffening, and losing consciousness, muscle tremors can be a sign of seizures. If accompanied by vomiting or diarrhea, muscle tremors can be a sign of poisoning and are considered an emergency.
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