Does your dog shake? Most dogs do, but have you asked yourself whether it is normal or not? There are many reasons your dog might quiver, tremble twitch or shake, and today we will discuss some of them. 

Behavioural Shaking 

Many dogs will shake for normal behavioural reasons, just like humans and other animals do. Usually this is nothing to be worried about. This often happens when a dog is excited, scared, stressed or anxious. It occurs when adrenaline and other hormones are released into the bloodstream. Adrenaline is a ‘fight-or-flight’ hormone that increases blood flow to the muscles, increases the heart rate and increases blood sugar, in preparation for rapid action (i.e. fighting or running away!). This stimulation can sometimes cause involuntary trembling or shaking. Certain dog breeds may be more well-known for this (greyhounds, whippets and lurchers are commonly mentioned by owners) but it can occur in any breed of dog. 

Similarly, as in people, dogs can shake when they are cold. By involuntarily shaking the body, heat is generated through muscle movement to help keep core temperature at a safe level. Of course, prolonged periods in the cold can increase the risk of hypothermia (low core body temperature), which can be dangerous, so if your dog is shivering due to cold, they should be wrapped up in coats or blankets, and ideally moved to a warm environment. 

General Illness 

Some dogs may shake due to non-specific illnesses. Although there will likely be other symptoms, the shaking should not be ignored as it may indicate more severe disease than is apparent. 

Nausea often causes shaking, particularly just before or after vomiting. Dogs can be nauseated due to eating food they are intolerant of or if is toxic, gastrointestinal inflammation or infection, neurological disease causing balance issues, certain medications, or more serious diseases such as kidney, liver or cancer. Similarly, pain of any kind may cause shaking and should be addressed. 

Finally, just like humans, a fever (pyrexia) or overheating (hyperthermia) can also lead to shaking as well. A fever can be a dangerous condition caused by infection, heat stroke, toxins and immune-mediated diseases. If prolonged, it can start to damage cells and can even be fatal. If your dog is shaking and feels hot, they should be seen by a vet immediately.  

Metabolic Disease 

Shaking can be caused by some metabolic disorders. Two of the more common are hypoglycaemia and abnormal calcium levels. 

Hypoglycaemia (low blood sugar) can lead to shaking through the release of adrenaline (released to increase blood sugar), which acts on the muscles as explained above. Shaking may also occur due to physical lethargy and feeling faint. With severe hypoglycaemia, partial or full seizures may occur – an extreme form of shaking caused by misfiring brain cells (more on seizures later). Hypoglycaemia in dogs can be caused by starvation, infectious diseases, during pregnancy or lactation, due to liver disease, through toxicities, certain cancers, or via insulin overdose. A dog suspected of having hypoglycaemia should have some honey or sugar solution rubbed across their gums, and veterinary attention immediately.  

The body tries to maintain calcium at a normal level (calcium homeostasis), but disease can lead to hypo- or hypercalcaemia (low- or high blood calcium), which can both cause forms of shaking. Hypocalcaemia can be caused by loss of calcium in milk during lactation, disease of the parathyroid glands in the neck, lack of calcium absorption from diet, kidney disease, sepsis, and certain toxicities. Calcium helps regulate nerve contraction, and hypocalcaemia can lead to random firing of nerves that causes twitches and spasms. Extreme hypocalcaemia can cause seizures too. Similarly, hypercalcaemia can lead to overstimulation of nerves and twitching, spasms and seizures. It can be caused by parathyroid disease, bone damage, cancer, kidney disease, toxicities and underactive adrenal glands (Addison’s disease). 

Other metabolic disturbances, such as alterations in potassium, magnesium or blood acidity may also cause forms of shaking. All of these require diagnosis by a vet, usually via blood sample, and treatment of the underlying disease. Some cases may require supplementation of the deficient chemical, or drugs to bind to the excess. 

Toxicities 

There are certain toxins that, if ingested, may cause tremors, shivering, shaking or seizures. The mechanism of action causing shaking varies, and can be due to causing hypoglycaemia, altering calcium, or direct action on the neurological system. The following list is not exhaustive but includes some of the most common. 

Various veterinary drugs can cause tremors if given inappropriately. These include anti-parasitic drugs containing permethrin, ivermectin and moxidectin, anxiety-relieving drugs like sertraline, or bronchodilators such as salbutamol. Always follow the dosing guidelines given by your vet and never give a dog medication without a vet’s instructions.  

Certain foods may cause tremors too. Some common ones include chocolate, coffee and other caffeine products, xylitol-sweetener (such as in chewing gum or peanut butter), blue cheese, macadamia nuts, and grapes and raisins. Rotten food can also be a big risk – when food rots, mould forms. These fungi release toxins that can cause tremors and seizures. Always clear up rotten food from the house and prevent your dog scavenging when outside.  

Other toxins that are known to cause tremors include certain pesticides and rodenticides, drugs like cannabis or methamphetamines, and some older types of slug bait. Keep these products sealed and away from dogs at all times.  

Neurological Disease 

Disorders of the neurological system commonly lead to more severe tremors or seizures in dogs. We’ve mentioned some already, so let’s continue the theme. 

Seizures have many causes. Many extra-cranial (outside the brain) causes we’ve mentioned, such as metabolic disorders, toxicities and nutritional imbalances. Others include hypoxia, hyperthermia or congenital liver or kidney disease. Intra-cranial disease (within the brain) can also cause seizures, including strokes and other vascular events, head trauma, cancer, congenital brain disease, or infections like feline infectious peritonitis, Toxoplasma and Neospora. Some dogs will have seizures with no obvious cause and may be considered idiopathic epileptic. All seizure activity can be dangerous and should be investigated by a vet – some dogs may require long-term treatment to control their seizures, depending on the cause. Not all seizures are tonic-clonic (full body loss of consciousness seizures), and partial twitching can be seen in some cases – this can make differentiating mild seizures from body tremors difficult.  

There is an immune-mediated condition called generalised tremor syndrome or steroid-responsive/idiopathic tremor syndrome (also termed Little White Shakers) which can cause full body tremors. As the nickname suggests, it is more frequently seen in small white dogs like West Highland white terriers, poodles and Bichon Frises, but can be seen in any dog. The cause is unknown but likely linked to the immune system, so immunosuppressive steroids can help improve the symptoms. Similarly, boxers, Dobermanns, bulldogs and other medium-breed dogs can be prone to idiopathic head tremors, where the head bobs in different directions for no apparent reason. There is no known treatment, but thankfully most dogs have a normal quality of life and may even stop bobbing as they get older.   

Dogs can also be born with a condition called cerebellar hypoplasia where the cerebellum (the part of the brain responsible for coordination and movement) is underdeveloped. This leads to wobbling when walking, tremors and high-stepping. Although there is no cure, many dogs can have a good quality of life with some assistance for mobility. Similarly, myelin disorders are a group of diseases where the nerves have a poor-quality or lack of insulating covering (myelin) which slows down the signals transmitted between nerves. Myelin disorders can be congenital diseases dogs are born with, or a disease developed due to infection, toxins or vitamin deficiencies. Of note, canine distemper, a viral disease, can cause a myelin disorder – this can be prevented via vaccination. Dogs with myelin disorders are often weak when walking, shake their limbs or whole body, and may struggle to walk. Treatment is also supportive.  

Musculoskeletal Disease 

Finally, musculoskeletal disease can cause shaking due to pain or physical weakness. Probably most common is osteoarthritis in elderly dogs. As a dog ages, the joints deteriorate and rub together, causing pain. This usually results in the dog moving less (often owners say the dog is less energetic or tired). Muscles not being used start to waste away, which reduces their strength. In extreme cases of muscle loss, this can lead to wobbling or shaking when your dog stands up, due to weak muscles struggling to maintain their stance (imagine standing on tiptoes for 10 minutes – your leg muscles are likely to shake). Although this muscle loss is difficult to reverse, pain relief, physiotherapy and gentle exercise like swimming can help slow the decline.  

Any other disease-causing muscle wasting can have similar effects, and many dogs that lose weight lose muscle mass too. Disorders like heart disease, kidney disease, cancer, adrenal disease and gastrointestinal disease can lead to wasting, and thus shaking. In extreme cases, the muscle of the heart can atrophy, leading to heart failure. Any unexpected weight loss should always be investigated.  

So, what do I do if my dog’s shaking? 

First, rule out the obvious – are they over-excited, or very cold? If not, then as you can see, there is a huge array of possible causes – and your vet should definitely be your next port of call!