Involuntary Muscle Trembling in Dogs

Involuntary muscle trembling is any repetitive muscle movement that is impossible for the animal to control. It can affect a single, isolated limb, or be a generalized movement that includes the entire body. It can happen when your dog is at rest or in the process of carrying out an intended movement. Movements can be intermittent and unpredictable, or they may regularly occur at a certain time or during a certain task. The trembling may be only a few seconds in duration, or it may last for an extended period. Very severe tremors can make it difficult for a dog to eat or stand and may result in serious complications if not treated immediately.

Involuntary muscle trembling is a type of involuntary movement that manifests as tremors, twitches or continuous shaking. This is usually a result of chemical and neurological imbalance rather than weakness in the muscles. There can be many contributing factors including hereditary, environmental, and age-related issues. As well as being distressing to the dog, this may interfere with normal motor functions, and in very severe cases can be life-threatening.

• You notice a tremor in one or several limbs which your dog is at rest
• You notice your dog is weak and trembling when he attempts to move
• You notice your dog has a persistent twitch or tic that persists during sleep
• Your dog has severe bouts of shaking which may involve the entire body
• Your dog appears to have seizures.
• You see behavioral changes in your dog, especially increased anxiety in relation to tasks which involve movement.
• Your dog is incapable or has difficulty completing normal tasks, such jumping onto the couch or climbing stairs.

Types

• Resting Tremor - a back and forth movement in part or all of the body while the muscles are at rest and supported by gravity.
• Action Tremor - a tremor that occurs when a muscle is contracted in a voluntary action. The contraction could just be to maintain a standing position, called a postural tremor, or it could be in order to move a limb called a kinetic tremor. Kinetic tremors are some of the most common in dogs.
• Twitch - a twitch is a movement located in small bands of muscle fibers that can cause a rippling movement under the skin. Unlike tremors they can continue while the animal is asleep.
• Generalized Tremors - a tremor which involves the entire body and seems to be without cause.
• Cerebellar related tremor - a kinetic tremor which is caused by some kind of disease or abnormality in the cerebellum. These often start with the head and can result in balance issues. They do not persist during sleep or under anesthesia.
• Myoclonus - a type of seizure which involves quick involuntary shaking, usually of short duration, with no loss of consciousness.

Similar looking muscle tremors can often have very different causes, so it’s important to examine all the possibilities. Most tremors are the result of a chemical or neurological imbalance in the brain.

• Hereditary - many types of hereditary conditions can cause tremors. One of the most well-known is Generalized Tremor Syndrome which is the result of a congenital condition most common in small breeds like White Terriers and Maltese, although it can occur in any breed. It isn’t always apparent at birth but often appears between the first and second years of a dog’s life. Orthostatic Tremor (OT) is a postural tremor that only affects the dog while standing still. It is found sometimes in breeds of large dogs such as Great Danes and Deerhounds.
• Drugs and Toxins - many drugs and toxins can cause tremors in dogs, including some which are safe for humans such as caffeine. Some drugs prescribed to dogs can also cause tremors as a side effect, so check the medications your dog is taking.
• Injury to the Brain - tremors are often caused by abnormal brain activity. All types of brain injuries including trauma, stroke and brain tumors can cause this.
• Canine Distemper - cerebellar related tremors and myoclonic seizure both occur as part of canine distemper, although this is an unlikely cause if your dog has shots.
• Age - Dogs can sometimes develop tremors as they age, called Physiologic and Essential Tremor Syndrome. These age-related tumors often involve the pelvis, and they can worsen with anxiety or intense emotions. The tremors can be very slight at first, but over time they may progressively worsen and cause balance and coordination problems.
• Seizure - Seizures can look very different on different dogs, so don’t rule them out even if your dog’s signs don’t fit the traditional Grand Mal Seizure. Periods of pronounced shaking in can often be preceded by an initial anxiety period, and a post seizure period of disorientation, confusion, and weakness (see seizure section.)

The veterinarian will perform all regular tests such as blood and urine tests to see if there is any abnormality. He will go over your dog’s family history and medications as well as possible exposure to toxins or contagious diseases. Brain imaging tests such a CT and MRI can determine abnormal brain activity or injury to the brain.

Close observation will help to determine the frequency and duration of your dog’s trembling and if there is a pattern of the cause. This is invaluable information for the veterinarian since involuntary muscle trembling which occurs intermittently or unpredictably can be difficult to diagnose. Sometimes videotaping your dog can help show the veterinarian what an attack looks like if it’s impossible to demonstrate during an office visit. Additional signs such as behavior and appetite changes can also be helpful.

If the veterinarian decides an MRI or CT is necessary this will require another office visit and probably an anesthetic to avoid distress and ensure the test can be carried out.

The method of treatment will depend largely on the cause of the tremors. Many sources of involuntary muscle trembling cannot be cured, but it is possible to treat the signs and help your dog compensate for the disability.

• Severe trembling attacks that will not stop should be treated as an emergency. Medications such as diazepam can help to stop the tremors and the veterinarian will also be able to treat the dehydration and hypothermia that result from such a prolonged attack.
• If the cause is determined to be one of the medications your dog is currently taking, a different medication can be prescribed.
• If the cause is exposure to a toxin, removing the toxin may be an effective treatment.
• Some hereditary conditions can be treated or ameliorated with medication, but there is often not a cure for this type of condition. Taking medication for a lifelong condition can also have further complications.
• Medication can help tremors that are a result of brain injury, but it will depend on the severity. Some tumors can be removed with surgery, but this is risky and may involve further complications.
• Age-related tremors are difficult to treat. Your dog may be able to take medication to help with the symptoms, depending on the advice of your veterinarian.

Depending on the cause, some dogs with involuntary muscle trembling can be treated and make a full recovery. Others may be able to lead fulfilling lives with tremors that cause only mild problems. Your veterinarian may recommend specific exercises to practice or movements to avoid. Trembling may prevent your dog from engaging in strenuous exercise, but mild exercise will help with overall health. Try to avoid weight gain as this will further complicate mobility. If this is a problem, discuss an appropriate diet with your veterinarian.

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