Tremors in dogs have a wide range of causes, from harmless shivering due to cold or excitement to serious conditions like poisoning, metabolic imbalances, or neurological disease. The key to figuring out what’s behind your dog’s tremors is paying attention to when they happen, where on the body they occur, and what other symptoms come along with them.
Anxiety, Cold, and Other Non-Medical Causes
The most common reasons dogs tremble aren’t medical at all. Cold temperatures, excitement, fear, and anxiety can all produce visible shaking. Some dogs tremble every time their owner comes home, and many shake during thunderstorms, fireworks, vet visits, or periods of separation. These behavioral tremors tend to be situational and resolve once the trigger passes. Early signs of stress-related shaking often appear alongside other body language cues like yawning, lip licking, or ears pulled back.
If trembling only happens in predictable contexts and your dog is otherwise eating, drinking, and moving normally, it’s likely behavioral rather than pathological. That said, persistent or worsening anxiety-related tremors are still worth addressing since chronic stress affects a dog’s quality of life.
Poisoning and Toxic Exposure
Tremors are one of the hallmark signs of poisoning in dogs. A long list of substances can trigger them: chocolate, certain pesticides, rodent bait, antifreeze, strychnine, and illicit drugs, among others. Moldy food is a particularly underrecognized culprit. Molds that grow on old food, compost, or trash produce toxins that directly interfere with the brain’s ability to regulate nerve signals. These toxins block chemical messengers that normally keep nerve activity in check, essentially removing the brakes on muscle activation and causing uncontrollable trembling.
Poisoning-related tremors usually come on suddenly and are accompanied by other symptoms like weakness, disorientation, drooling, vomiting, diarrhea, or depression. If your dog develops tremors out of nowhere and you suspect they’ve eaten something they shouldn’t have, this is an emergency. Prolonged tremors from toxins can drive body temperature above 105°F, which is the threshold for heatstroke and organ damage.
Low Blood Sugar and Low Calcium
Metabolic imbalances are a common and sometimes urgent cause of tremors. Low blood sugar (hypoglycemia) can cause shaking, trembling, and in severe cases, seizures. Small breed puppies and toy breeds are particularly vulnerable because they have limited energy reserves. Dogs with diabetes or liver disease can also develop hypoglycemia.
Low blood calcium (hypocalcemia) is another trigger. Tremors, muscle twitching, and a tense or stiff body typically appear when calcium drops below 6 mg/dL. This is most often seen in nursing mothers whose calcium gets depleted by milk production, a condition sometimes called milk fever or eclampsia. Below 4 mg/dL, low calcium becomes life-threatening. Other signs of hypocalcemia include nervousness, a drunken-looking walk, excessive panting, disorientation, and fever.
Generalized Tremor Syndrome
Generalized tremor syndrome, originally called “little white shaker syndrome,” causes full-body tremors that can look alarming but respond well to treatment. It was first identified in Maltese, Poodles, and West Highland White Terriers, but dogs of any size, breed, or color can develop it. Most affected dogs show symptoms before age 5.
The condition is believed to involve immune-mediated inflammation in the cerebellum, the part of the brain that coordinates movement. Tremors tend to come in episodes and get worse with excitement, stress, or exercise. Dogs remain conscious and alert, which helps distinguish this from seizures. Treatment with immune-suppressing steroids usually produces noticeable improvement within days, and many dogs eventually discontinue medication, though some relapse and need additional courses.
Canine Distemper
Distemper is a serious viral infection that can cause a distinctive type of involuntary muscle twitching called myoclonus. These are rhythmic, repetitive jerks, often localized to a single muscle group, and they look different from the diffuse whole-body shaking seen with other causes. Distemper-related myoclonus can persist even after the dog recovers from the acute infection, becoming a permanent neurological aftereffect.
Distemper usually presents with other symptoms first: discharge from the eyes and nose, fever, coughing, and lethargy. Puppies and unvaccinated dogs are most at risk. Vaccination is highly effective at preventing it, which is why distemper is far less common than it once was.
Idiopathic Head Tremors
Some dogs develop a head-bobbing tremor with no identifiable cause. The head moves rhythmically either up and down or side to side, and the episodes tend to happen when the dog is resting or less active. Doberman Pinschers (especially those under a year old), Boxers, and Bulldogs are among the breeds most commonly affected, though it can occur in any breed.
The crucial distinction is that these dogs stay fully conscious, can walk, respond to commands, and can often stop the tremor themselves if distracted by a treat or a task. This is nearly the opposite of an intention tremor, where shaking gets worse when the dog tries to do something purposeful. A full diagnostic workup, including blood work, spinal fluid analysis, and brain imaging, comes back normal. The condition is generally considered benign.
Drug Sensitivity in Herding Breeds
Certain breeds carry a genetic mutation (called MDR1) that makes them unable to pump specific drugs out of their brain, leading to a toxic buildup that causes neurological symptoms including tremors, disorientation, and even seizures. Collies, Australian Shepherds, Shetland Sheepdogs, Old English Sheepdogs, German Shepherds, and their mixes have the highest rates of this mutation.
The antiparasitic drug ivermectin is the most well-known trigger. At the low doses used for heartworm prevention, it’s safe even in affected dogs. But at the much higher doses sometimes used to treat mange (50 to 100 times the heartworm dose), it causes neurological toxicity in dogs carrying the mutation. The common anti-diarrheal medication loperamide (Imodium) is another risk. At standard doses, it can cause neurological problems in dogs with MDR1 and should be avoided entirely in these breeds. A simple genetic test can identify whether your dog carries the mutation.
Structural Brain Problems
Dogs born with an underdeveloped cerebellum (cerebellar hypoplasia) can have lifelong coordination problems, including tremors that worsen when the dog tries to focus on a specific movement like eating or drinking. These are called intention tremors. Affected dogs may also show a wide-based stance, exaggerated leg movements, and general wobbliness. Brain imaging can reveal the structural abnormality, which varies in severity. Some dogs function well with mild cases, while others have significant daily limitations.
Aging and Muscle Fatigue
Trembling in older dogs, particularly in the hind legs, is extremely common and often reflects straightforward muscle weakness and fatigue rather than a serious neurological condition. As dogs age, they lose muscle mass, and the muscles that remain have to work harder to support the body. Arthritis-related pain can compound the problem, as the dog shifts weight and overloads certain muscle groups. You might notice the trembling is worst after walks or periods of standing and improves with rest.
Pain from any source, not just arthritis, can cause tremors. Dogs in pain often also show changes in appetite, reluctance to move, restlessness, or changes in posture. If your senior dog’s trembling is getting progressively worse or is accompanied by difficulty walking, dragging the feet, or loss of bladder control, these suggest something beyond normal aging.
Tremors vs. Seizures
One of the most important distinctions is whether what you’re seeing is a tremor or a seizure. During a seizure, dogs typically lose consciousness, fall to their side, stiffen, and may make paddling motions with their legs, drool heavily, or lose bladder control. They’re unresponsive during the episode and often confused or disoriented afterward.
During tremors, dogs remain conscious and aware of their surroundings. They can usually walk, respond to their name, and make eye contact. Some movement disorders called paroxysmal dyskinesias can look dramatic and seizure-like, but the dog stays mentally present throughout. Video is one of the most useful things you can provide to a veterinarian, since these episodes often don’t happen on cue during an exam. Recording the episode on your phone captures the details that help distinguish between these very different conditions.