Tremors and Shaking

Tremors — involuntary, rhythmic muscle movements — in dogs and cats can indicate conditions ranging from simple cold or excitement to serious neurological disease or poisoning. Understanding the type, triggers, and accompanying symptoms helps determine whether tremors require emergency care or can be addressed at a regular veterinary visit.

## Types of Tremors

**Generalized tremors:** Whole-body shaking affecting all limbs and sometimes the head and trunk. May be continuous or intermittent.

**Localized tremors:** Shaking limited to one area, such as the head, one leg, or the hind quarters. Often indicate a more specific structural or neurological problem.

**Intention tremors:** Tremors that worsen when the pet tries to perform a specific action (like eating or reaching for a toy). These indicate cerebellar disease.

**Resting tremors:** Tremors present when the pet is relaxed but that stop with voluntary movement. Less common in pets than in humans.

## Common Causes

**Non-pathological (normal):** Cold or chilling, fear and anxiety (thunderstorms, fireworks, vet visits), excitement and anticipation, pain (trembling from discomfort), old age tremors (senile tremors), and breed-specific tremors (some small breeds tremble normally).

**Toxin exposure:** Chocolate, caffeine, marijuana, metaldehyde (slug/snail bait), mycotoxins (from moldy food or compost), organophosphate/carbamate insecticides, permethrin (cats — from dog flea products), macadamia nuts, xylitol, bromethalin (rat poison), and prescription medication overdose.

**Metabolic/Systemic:** Hypoglycemia (low blood sugar) — common in toy breed puppies and diabetic pets on insulin, kidney failure (uremic tremors), liver disease (hepatic encephalopathy), hypocalcemia (low calcium) — especially in nursing mothers (eclampsia), Addisons disease (hypoadrenocorticism), and electrolyte imbalances.

**Neurological:** Idiopathic generalized tremor syndrome ("White Shaker Dog Syndrome" — affects all breeds despite the name), cerebellar disease (congenital or acquired), inflammatory brain disease (meningoencephalitis), brain tumors, intervertebral disc disease, and degenerative myelopathy.

**Infectious:** Canine distemper (causes myoclonus — rhythmic muscle jerks), neosporosis, toxoplasmosis, and tick-borne diseases (ehrlichiosis, Rocky Mountain spotted fever).

## When Tremors Are an Emergency

Seek immediate veterinary care if tremors are accompanied by seizures, the pet recently ingested a toxin, the pet is a toy breed puppy that is lethargic and not eating (hypoglycemia), tremors are worsening rapidly, the pet has difficulty breathing, the pet is a nursing mother (eclampsia), there is loss of consciousness, the pet cannot walk or stand, or gums are pale, white, or blue.

## What to Do at Home

For mild tremors in an alert, responsive pet, keep the pet warm and calm, offer a small meal if hypoglycemia is possible, remove access to potential toxins, note when tremors started, what triggers or stops them, and any other symptoms, record a video of the tremors for your veterinarian, and do NOT give any medications without veterinary guidance.

## Diagnosis

Your veterinarian may recommend complete blood work (CBC, chemistry, electrolytes), blood glucose measurement, thyroid testing, toxicology screening if exposure is suspected, neurological examination, MRI or CT scan of the brain, cerebrospinal fluid (CSF) analysis, and infectious disease testing.

## Breed-Specific Considerations

Some breeds are predisposed to tremor-related conditions. Maltese, West Highland White Terriers, and Bichon Frise are predisposed to idiopathic generalized tremor syndrome. Cavalier King Charles Spaniels may develop episodic falling syndrome. English Springer Spaniels can have hereditary tremors. Dobermans may show "head bobbing" that is often benign.

## Diagnostic Workup for Tremors

Veterinary evaluation of tremors follows a systematic neurological approach: full neurological examination to localize the lesion (brain, spinal cord, peripheral nerves, or muscles), blood work including CBC, chemistry panel, and electrolytes (calcium, glucose, potassium), toxicology screening if exposure is suspected, thyroid testing, infectious disease panels (distemper, Neospora), MRI for suspected brain lesions, and CSF (cerebrospinal fluid) analysis for inflammatory or infectious CNS disease.

## Breed-Specific Tremor Syndromes

**White Shaker Syndrome (Generalized Tremor Syndrome):** Most common in small white-coated breeds (Maltese, West Highland White Terrier, Bichon Frise) but can affect any breed. Caused by CNS inflammation and responds well to corticosteroids. **Episodic Falling Syndrome** in Cavalier King Charles Spaniels causes exercise-induced muscle stiffness and collapse. **Scottie Cramp** causes episodic tremors and hypertonicity during excitement in Scottish Terriers.

## Emergency vs. Non-Emergency Tremors

Emergency tremors requiring immediate vet care: sudden onset with known toxin exposure, tremors progressing to seizures, tremors with altered consciousness, tremors with hyperthermia above 104°F, and tremors in a puppy or kitten (hypoglycemia risk). Non-emergency tremors to monitor: mild intermittent tremors in a senior dog that is otherwise eating and alert, exercise-induced tremors that resolve with rest, and cold-induced shivering in small or thin-coated breeds.

*Written by PetNurse Clinical Team · Sources: AVMA, ACVIM Neurology, Merck Veterinary Manual*