Standard butt-shaking and tail wagging is a sign that your dog is a happy and healthy goofball. However, uncontrollable or uncomfortable shaking could have to do with an underlying disease, severe anxiety, or illness from something like poisoning or distemper.

This basic behavioral movement can be very indicative of dog health. It is important to be able to identify when a dog shake is just a shake, or when the shake is a worrisome tremor.

When Dog Shaking Is a Happy Dog's Shimmy

Dogs will do a body shake as a natural reflex.

Shakes caused by tail-wagging are normal behavioral signs of emotion.

Why Do Dogs Shake When Scared?

Dogs will sometimes shake out of response to both negative and positive emotions. When they are in the middle of a stressful situation like a thunderstorm or fireworks display, for instance, they will literally tremble with fear.

When a dog shakes with fear, they are trying to "shake off" that pent-up, nervous energy they are feeling. The shaking is often accompanied by anxiously panting, pinning back the ears, and tucking the tail between the legs.

Avoid situations that cause a large amount of stress for your dog, or consider talking to your veterinarian about anxiety medication. You may also want to consult a behavioral dog trainer about your dog's stress triggers.

When Dog Shaking Indicates Disease

Another common reason for dogs shaking is a disease. There are a number of medical conditions that relate to a dog’s excessive shaking. These include Addison's disease, generalized tremor syndrome (GTS), epilepsy, and kidney disease. Some dog breeds are more susceptible to these conditions than others.

Generalized Tremor Syndrome

Generalized tremor syndrome (also known as white dog shaker syndrome and responsive tremor syndrome) was first discovered in small dogs like Malteses and West Highland white terriers. Any dog can have GTS, however, no matter what size or breed they are.

The syndrome causes tremors in young dogs and can be treated by steroids like Prednisone. These reduce the inflammatory response in the body and suppress the dog's immune system.

In order to identify if your dog’s shaking is GTS-related, your veterinarian will perform blood or urine tests to rule out another medical condition like kidney disease. Most dogs recover from GTS within a couple of weeks of treatment with prednisone.

Addison's Disease

Just like human beings, dogs can get Addison's disease, a hormonal disorder that is caused by a deficient production of the adrenal gland hormones cortisol and aldosterone. Symptoms of Addison's disease include shaking, lethargy, weakness, poor appetite, and dehydration.

Addison's is not curable. If your dog has Addison's, your vet will prescribe a medication regimen that helps stabilize their hormone levels. It will take time to find the right dosage for your dog's Addison's disease. Annual blood work is required to make sure the replacement hormone medication is working properly.

Kidney Disease and Kidney Failure

Kidney disease is not entirely treatable, but it is manageable. In addition to shaking, kidney disease may cause your dog to urinate and drink water more frequently. It is most common in senior dogs, as this is a disease that develops over time and does not show until they have reached old age. It is estimated that more than one in 10 dogs will develop kidney disease over a lifetime.

Dogs who have kidney failure likely get it from decreased blood flow or from ingesting toxins like antifreeze, certain medications, or contaminated foods. Treatment includes medication, fluid therapy, dialysis, or diet change, depending on if your dog's kidney problems are acute or chronic.

Seizure Disorders and Epilepsy

Dogs can get epilepsy, a neurological disorder that causes episodes of seizures, which are temporary involuntary disturbances of normal brain function accompanied by uncontrollable muscle spasms.

According to VCA Hospitals, even though the seizure looks serious and will confuse or panic your dog, it is luckily not dangerous or painful. "The important thing is to keep the dog from falling or hurting itself by knocking objects onto itself," he writes. "As long as it is on the floor or ground, there is little chance of harm occurring."

Epilepsy and seizure disorders are treated with anticonvulsant medication, so make sure to consult your dog’s vet if your dog appears to have a seizure.

Why Do Dogs Shake Their Heads?

An ear infection is one of the most common reasons why dogs shake their heads. Check the inside of your dog's ears for inflammation, odor, and ear wax build-up, as these are signs that your dog has an infection such as ear mites. The ear wax will look like coffee grounds.

Mites are treatable with over-the-counter medication that involves regularly pouring an ear solution into your dog's ear canals. Make an appointment with your veterinarian if the mites and head-shaking persist.

Dogs shake their heads when getting up or wrapping up a stretch. The stretch-and-shake move is an instinctive dog behavior to ensure they are limber and ready to take on the day. Dogs will typically only shake their heads once or twice when stretching. In contrast, dogs who have an ear infection will shake their heads often throughout the day due to the irritation.

Dog Shivering

Dogs shiver because they might be too cold in the winter months, or the shivering could be a result of having ingested a poisonous substance. There are a number of toxins and poisons that cause shivering or muscle tremors in dogs.

Items that are toxic to dogs include poisonous plants, pesticides, onions, and xylitol, the sugar substitute found in many chewing gums and peanut butter. Remember to always read the ingredient list on any human food you are thinking of sharing with your dog.

If you think your dog has swallowed a potentially poisonous substance, call the Animal Poison Control Center as soon as possible at (888) 426-4435.

What to Do When Your Dog Is Shaking

If your dog's shaking looks more like the concerning kind than the happy kind, it is important that you make an appointment with your veterinarian to determine the exact cause. The vet will work out an appropriate treatment plan depending on your dog's condition.