Vet-Approved Content
Does your dog shake or tremble?
I’m not talking about the dogs who shake themselves dry or flap their ears occasionally so much as the dog with a fine muscular tremor. The trembling may just affect one leg or the dog’s whole body.
If you don’t understand the reasons your dog trembles, this can be worrying.
Of course, sometimes the cause can be obvious, such as:
- A thin-furred dog in cold weather (they’re cold)
- Or an anxious dog at the vet (they’re frightened)
But other times, the reason the dog trembles is less clear.
Why Do Dogs Tremble?
So why do some dogs shake? Let’s look at 9 of the most common causes:
1. Fear
There’s a reason many dogs shake at the vet’s — fear!
Sadly, trembling at the vet clinic often goes with the territory (although many clinics are working hard to reverse this).
If your dog trembles when they’re relaxed at home, this is a different matter.
2. Cold
Trembling in a dog is caused by muscular activity, which generates heat. On a cold day — especially for dogs like Whippets or Greyhounds, who have thin skin and short hair — trembling in the dog is a way to generate heat and warm up.
For the geeks among you, shaking with cold has a special term: rigors.
3. Pain
Dogs shake when they’re in pain. There are 2 components to this:
- Pain is frightening and unexplainable to a dog, and this may make them anxious. Therefore, the dog trembles with fear.
- One theory is that shaking by the dog somehow “dulls” the sensation of pain by confusing the small radius pain receptors in the skin.
4. Partial or Focal Seizures
Some dogs have a bizarre form of erratic electrical activity in the brain that triggers a highly localized seizure.
Instead of affecting the whole body (with signs such as loss of consciousness, stiff legs, paddling movements, and loss of bladder and bowel control), the seizure is restricted to one piece of the anatomy.
Signs of this include the dog playing “air guitar” with one leg and not stopping, no matter how much you distract them.
Another form of focal seizures is the uncontrolled twitching or trembling of one part of their body, such as an ear, the whiskers or a leg.
If you think your dog may be having focal seizures, try to video record the event to show your vet. Witnessing the episode for themselves is helpful when vets are making a diagnosis.
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5. Shaker Syndrome
Calling all humans of white dogs like West Highland White Terriers and Malteses, as well as (confusingly) Beagles, Min Pins and Yorkshire Terriers.
All of these dogs can be smitten with a shaking condition that results in a strange gait and sometimes even collapse. We used to call this “white dog shaker syndrome,” but now just plain “shaker syndrome” is becoming the preferred term for it.
The condition starts suddenly, often when the dog is young (1–4 years old). The signs can gradually worsen over a few days and then stabilize.
Other signs include:
- Trembling and shaking
- Balance problems
- Head tilt
- Walking with a sway
- Seizures
It’s thought this condition is a form of immune-mediated disease. This means the immune system turns on the body and attacks its own tissue. In this case, the tissue is the brain, and the result is a mild form of encephalitis.
Shaker syndrome in dogs is treated with high doses of steroids. The idea is to reduce brain inflammation and switch off that self-harming immune reaction.
6. Low Blood Glucose
Have you ever gotten so hungry you started to shake?
Most likely, you were experiencing such a low blood sugar level (hypoglycemia) that you started to shake. This is most often a problem for 2 groups of dogs: those who are very small (the teacup breeds) and diabetics.
Those teeny-tiny toy dogs have low reserves of sugar, so if they skip a few meals, it can induce a condition similar to a diabetic who’s had too much insulin.
Which brings us to diabetics. If there’s a mismatch between the insulin given and the amount the dog eats, this can result in all the available blood sugar being used up and a hypoglycemic coma.
Shortly before this, you should see the classic shakes and tremors.
(Of course, this is a whole different scale to when we humans get over-hungry, so if you’re otherwise well, don’t worry about lapsing into a coma just because you skipped a meal.)
7. Low Blood Calcium Levels
This is a bit of a specialist tremor in dogs, most likely to happen only in specific, rare circumstances. Calcium is important for muscular contraction, and low levels can cause erratic muscular activity.
The first scenario is the nursing mother dog, when the puppies are 3–4 weeks old. At this age, they greedily take a lot of the mother’s nutrition from her body, including sucking down lots of calcium in her milk.
If the body struggles to make more calcium available from her bones, this results in low blood levels of calcium and some pretty dramatic twitching.
The second circumstance affects cats after thyroid surgery. The gland that controls blood calcium levels sits snug on top of the thyroid gland, and if its delicate blood supply is damaged, this can send calcium levels plummeting.
8. Addison’s Disease
Addison’s disease is caused by the body being unable to make enough of the stress hormone cortisol.
This results in lots of different vague symptoms such as sickness, diarrhea and general weakness. The signs often wax and wane but get progressively worse each time.
One of the less obvious clues is muscular weakness. This shows up as difficulty jumping up onto a favorite sofa and muscular twitches and tremors.
This condition most frequently affects young dogs but can also occur if dogs on steroids suddenly stop taking their medication.
In this video, vets are trying to figure out why this dog trembles:
9. Old Dog Tremors
Last but not least, old dog tremors.
The fancy term for these are “idiopathic,” but what this actually means is no one is sure why it happens.
One theory is that the protective layer around the nerves starts to thin with age (like the insulation perishing around electricity cables). This leads to misfiring of the nerves and those common muscular tics seen in senior pets.
Take a Video When Your Dog Trembles
Has your dog’s shaking taken on a new significance?
If you are worried, always get your pet checked by a veterinarian.
Film the shaking on your phone — seeing it firsthand is super helpful when the vet is making a diagnosis. Happily, most of the causes of the shakes have treatments, so it’s well worth pursuing the clues.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Sept. 21, 2018. 
