Shih Tzus shake for many reasons, ranging from simply being cold or anxious to more serious issues like low blood sugar, pain, or toxin exposure. Most of the time, the cause is harmless and temporary. But because Shih Tzus are a small breed with specific health vulnerabilities, it’s worth understanding the full picture so you can tell the difference between a minor shiver and something that needs veterinary attention.
They’re Cold
This is the most straightforward explanation. Despite their long coats, Shih Tzus are a small, short-legged breed, and they lose body heat faster than larger dogs. The USDA classifies short-nosed breeds like the Shih Tzu as less heat tolerant, while their small body size also makes them less cold tolerant. Ambient temperatures below 50°F can cause cold stress in toy and small breeds, with shivering and muscle stiffness being the first visible signs.
If your Shih Tzu shakes after going outside in cool weather, during air-conditioned evenings, or on cold tile floors, temperature is the likely culprit. A light sweater or moving them to a warmer spot should stop the shivering within minutes.
Stress, Fear, and Anxiety
Emotional shaking is extremely common in Shih Tzus. When a dog feels stressed or frightened, their body releases adrenaline, which triggers visible trembling. Common triggers include thunderstorms, fireworks, car rides, vet visits, and separation anxiety when you leave the house.
The key to identifying anxiety-related shaking is context. If your Shih Tzu only trembles during specific situations and acts completely normal otherwise (eating well, moving freely, alert and responsive), the shaking is almost certainly behavioral. You can often reduce it by removing or reducing the trigger, creating a calm environment, or using desensitization techniques over time. Some dogs also respond well to calming aids like compression vests or background noise.
Low Blood Sugar
Hypoglycemia is a real concern for toy breeds, and Shih Tzus are no exception. Small dogs have limited energy reserves and can experience drops in blood sugar from missed meals, excessive exercise, or stress. While a lab reading below 60 mg/dL technically counts as low blood sugar, visible symptoms like muscle tremors, trembling, weakness, and lethargy usually don’t appear until levels drop below 40 to 50 mg/dL.
Puppies and very small adults are most at risk. If your Shih Tzu is shaking and seems weak, wobbly, or unusually lethargic, especially if they haven’t eaten recently, low blood sugar could be the cause. A small amount of honey rubbed on the gums can help in the short term, but this situation calls for a vet visit to rule out underlying conditions and prevent it from happening again.
Pain and Spinal Problems
Shih Tzus are one of the breeds predisposed to intervertebral disc disease (IVDD), a condition where the cushioning discs between the vertebrae in the spine bulge or rupture. This causes pain that can range from mild to severe, and one of the hallmark signs is shivering or panting that looks like anxiety but doesn’t match any obvious emotional trigger.
A dog shaking from pain often shows other subtle changes. They may be reluctant to jump on furniture, hesitate going up or down stairs, hunch their back, yelp when picked up, or seem stiff when walking. The shaking tends to be persistent rather than situational. If your Shih Tzu is trembling and you notice any change in how they move or carry themselves, spinal pain is worth investigating.
Generalized Tremor Syndrome
Originally called “white shaker dog syndrome” because it was first identified in small white-coated breeds, Generalized Tremor Syndrome (GTS) can affect Shih Tzus regardless of coat color. It typically shows up in young adults under two years old, causing tremors across the entire head and body. The tremors tend to get worse with exercise, stress, or excitement and improve or disappear completely during sleep.
GTS is diagnosed by ruling out other causes. Screening for infections usually comes back negative, and spinal fluid analysis may show mild inflammation or look completely normal. The good news is that dogs with GTS respond well to treatment, with tremors typically resolving within the first one to two weeks of starting anti-inflammatory medication prescribed by a vet.
Toxin Exposure
Sudden, unexplained shaking in a Shih Tzu can be a sign of poisoning. Because of their small body weight, even tiny amounts of certain substances can cause serious reactions. Xylitol, a sweetener found in sugar-free gum, candies, some peanut butters, baked goods, toothpaste, and even chewable vitamins, is one of the most dangerous. It causes a rapid drop in blood sugar that leads to vomiting, weakness, wobbliness, seizures, and potentially coma.
Chocolate, certain mushrooms, acetaminophen (Tylenol), and blue-green algae are other common household and environmental toxins that can trigger tremors or seizures. If your Shih Tzu suddenly starts shaking and you suspect they may have eaten something they shouldn’t have, this is an emergency. Don’t wait to see if it gets better on its own.
Ear Infections and Head Shaking
If your Shih Tzu is shaking their head specifically rather than trembling all over, the problem is likely in their ears. Shih Tzus have floppy ears with hair growth inside the ear canal, making them prone to ear infections. These infections cause itching, inflammation, and discharge, all of which trigger persistent head shaking.
Lift your dog’s ear flap and look for redness, swelling, brown or yellow discharge, or a strong odor. Head shaking from an ear infection looks different from a full-body tremor. It’s a deliberate, repetitive flapping of the head rather than an involuntary shiver. Ear infections won’t resolve on their own and need treatment to prevent the infection from spreading deeper.
Fever
Just like people, dogs can shake when they have a fever. A healthy dog’s body temperature runs between 100.0°F and 102.5°F. Temperatures above 104°F or below 99°F are considered emergencies. You can check your Shih Tzu’s temperature with a rectal thermometer designed for pets if you suspect a fever. Dogs with fevers often also seem lethargic, have warm ears, a dry nose, reduced appetite, or seem “off” in a way that’s hard to pinpoint.
Red Flags That Need Immediate Attention
Occasional, brief shaking that stops quickly and has an obvious cause (a loud noise, chilly weather, excitement) is usually nothing to worry about. But certain combinations of symptoms signal something more serious:
- Shaking with vomiting or diarrhea could indicate poisoning, infection, or organ problems.
- Shaking with wobbliness or difficulty walking suggests a neurological issue, low blood sugar, or toxin exposure.
- Shaking with limping or reluctance to move points to pain, possibly spinal.
- Sudden onset shaking with no clear trigger warrants a vet call, especially if your dog also seems lethargic or disoriented.
- Shaking that doesn’t stop after the suspected cause is removed (they’re warm, calm, and fed) needs professional evaluation.
If your Shih Tzu starts trembling out of nowhere and you can’t identify a reason, note any other symptoms you’re seeing. That information helps your vet narrow down the cause quickly.