Most dog shaking is harmless: cold, excitement, fear, wet fur, or the fine tremor many dogs develop in old age. But shaking is also one of the ways poisoning announces itself, and a dog that suddenly trembles all over, wobbles, drools, or acts disoriented needs a veterinarian now, not a wait-and-see. The fastest way to sort the two apart is to ask what changed in the last few hours, whether the shaking stops when your dog is asleep or distracted, and whether anything else is wrong.
If you suspect your dog ate something, call your vet, the ASPCA Animal Poison Control Center at 888-426-4435, or Pet Poison Helpline at 855-764-7661. Do not induce vomiting unless a veterinary professional tells you to — with a tremoring or drowsy dog it can cause aspiration pneumonia.
What the referral data actually shows
Almost every article on this topic offers the same list of causes in roughly the same order. There is better information available. A 2025 retrospective study from the Royal Veterinary College reviewed 198 dogs presented with generalized tremors between 2003 and 2023 and reported which diagnoses actually came back (Liatis, Bhatti & De Decker, Journal of Veterinary Internal Medicine, 2025).
| Diagnosis | Dogs | Share |
|---|---|---|
| Intoxication (any agent) | 91 | 46% |
| Idiopathic generalized tremor syndrome (IGTS, "shaker dog") | 49 | 24.7% |
| Low blood calcium (hypocalcemia) | 13 | 6.6% |
| Meningoencephalitis of unknown origin | 9 | 4.5% |
| Low blood sugar (hypoglycemia) | 6 | 3% |
| High blood calcium (hypercalcemia) | 5 | 2.5% |
| Degenerative brain disease | 5 | 2.5% |
| Tetanus | 4 | 2% |
| Other (portosystemic shunt, Addison's, tumors, orthostatic tremor, etc.) | 16 | ~8% |
Two things stand out. First, poisoning was the single largest group. Second, within those 91 poisoning cases the agent was never identified in 33 of them — and where it was identified, the most common culprit was mold toxins (29 of 91 intoxications, 31.9%), ahead of slug bait (metaldehyde, 11), avermectin dewormers (6), and cannabis (4).
Read that carefully, because it is the practical takeaway competitors miss: the leading identified cause of dramatic full-body tremors in this hospital population was a dog eating moldy food, garbage, or compost. Not chocolate. Not rat bait. Compost.
One caveat on interpretation: this was a single referral hospital, so the mix is skewed toward dogs sick enough to be referred to specialists. It tells you what serious generalized tremor usually turns out to be. It does not tell you how often a shaking dog is simply cold — that is far more common in the real world and rarely reaches a neurologist.
Triage table: benign shivering vs. red-flag tremor
| Pattern | What it usually looks like | What to do |
|---|---|---|
| Cold | Shivering outdoors or after a bath; hunched posture; stops within minutes of warming up. Small, thin, short-coated, very young and very old dogs shiver soonest. | Warm and dry your dog. If shivering continues indoors once warm, it is not the cold. |
| Excitement or anticipation | Whole-body quiver at the door, before food, before a walk. Tail up, ears forward, dog otherwise normal and eager. | No action needed. |
| Fear, stress, noise phobia | Trembling with tucked tail, flattened ears, panting, lip-licking, hiding, pacing. Tied to fireworks, storms, the vet, strangers. | Provide a quiet, dark retreat. Recurrent noise phobia is treatable — discuss it with your vet before the next fireworks season. |
| Senior tremor | Fine trembling of the hind legs in an older dog, worse when standing still, unchanged for months. | Not an emergency, but have it examined: it can also reflect arthritis pain or weakness. |
| Pain | Trembling with a tense abdomen, a "praying" stretch, reluctance to jump or be touched, panting at rest. | Same-day veterinary appointment. Never give human painkillers. |
| Suspected toxin 🚩 | Sudden onset over minutes to a couple of hours, whole body, symmetric, often with vomiting, drooling, wide pupils, unsteadiness, jumpiness to touch or sound. | Emergency. Call a vet or a poison line immediately. Take the packaging or a photo of what was eaten. |
| Generalized tremor syndrome 🚩 | Young adult dog, often small and often female, developing fine whole-body tremor over days; may wobble, tilt the head, or have flicking eyes. Worse with excitement. | Prompt veterinary referral. It typically responds to prescription corticosteroids and needs diagnosis first. |
| Low blood sugar 🚩 | Puppies, toy breeds, diabetic dogs on insulin, or dogs after xylitol ingestion: shaking in episodes, weakness, glassy stare, collapse. | Emergency. If the dog is conscious and swallowing, rub a little honey or syrup on the gums en route — but go. |
| Addisonian crisis 🚩 | Weeks of vague illness — off food, vomiting, lethargy, waxing and waning — then sudden collapse, weakness, shaking. | Emergency. Mention the history of on-and-off illness; it is a diagnostic clue. |
| Seizure activity 🚩 | Collapse, stiffening or paddling, loss of awareness, often urination or defecation, then a confused recovery period. | Emergency if it is a first seizure, lasts over 5 minutes, or repeats. |
Shaking vs. seizure: how to tell in 30 seconds
This is the distinction that changes what you do next, and it comes down to one question: is your dog still there? For a closer look at signs and observations relevant to changes in movement or awareness, see Seizures in Dogs.
A generalized seizure involves sudden loss of consciousness, along with stiff or paddling limbs, dilated pupils, vocalization, and frequently loss of bladder or bowel control (Merck Veterinary Manual, Epilepsy in Small Animals). A tremoring dog, by contrast, is awake. It can look at you, respond to its name, and usually stay standing.
| Check | Tremor / shivering | Generalized seizure |
|---|---|---|
| Say the dog's name | Responds, tracks you | No response, unaware |
| Posture | Usually standing or sitting | Usually collapsed on its side |
| Limb movement | Rhythmic fine trembling, movement small | Rigid extension or paddling, movement large |
| Urination / defecation | Uncommon | Common |
| Duration | Minutes to hours, can be continuous | Usually seconds to a couple of minutes |
| Afterwards | Normal behavior between episodes | Disoriented, blind, pacing, ravenous for minutes to hours |
| During sleep | Usually stops | Not applicable — dog is unconscious during the event |
That last line has support: in the RVC series, tremors were assessed during sleep in 17 dogs and were absent in 13 of them. Tremor that vanishes in deep sleep and returns on waking is a genuine tremor, not a seizure.
Two honest limits. Dreaming twitches during sleep are normal and are neither. And some poisonings produce jerky, irregular whole-body contractions in a conscious dog (myoclonus) that look like a mix of both — the RVC authors say plainly that separating tremor from generalized myoclonus is difficult even for veterinarians. If you cannot tell, treat it as the more serious option and get help.
Poisons that make dogs shake
Tremor is a core sign for a specific set of toxins. Any of these justifies an immediate call.
Moldy food, garbage, and compost (tremorgenic mycotoxins)
The most under-covered cause on this list and, in the RVC data, the most frequently identified poison. Penicillium molds growing on walnuts, peanuts, dairy products, pasta, silage, and compost produce tremorgens such as penitrem A. Signs can start within one to two hours: vomiting, salivation, unsteadiness, jumpiness to touch and sound, muscle twitching, tremors, and seizures (Merck Veterinary Manual, Tremorgenic Neuromycotoxicosis in Dogs). Most dogs recover with treatment, though Merck notes recovery can take days to weeks, and a small number of dogs have remained unsteady for months.
Practical consequence: a securely lidded compost bin and a closed trash can prevent more tremor emergencies than any supplement on the market.
Xylitol (birch sugar)
In dogs — and dogs alone among domestic species — xylitol triggers a rapid, dose-dependent insulin release that can cause profound hypoglycemia, with vomiting, weakness, unsteadiness, seizures, and coma; liver injury can follow (Merck Veterinary Manual, Xylitol Toxicosis in Dogs; Cornell Riney Canine Health Center). It hides in sugar-free gum, mints, peanut butter, chewable vitamins, toothpaste, and some medications. Check the label of every "sugar-free" item in your house.
Chocolate and caffeine
Methylxanthines cause restlessness, a racing heart, tremors, and seizures at higher doses. Dark chocolate, baking chocolate, and cocoa powder carry far more theobromine per gram than milk chocolate (Merck Veterinary Manual, Chocolate Toxicosis in Animals). Weigh what was eaten and what type before you call; it changes the risk assessment completely. If you want to explore the related questions about food choices and feeding, start with How Much Chocolate Can Kill a Dog? Vet-Verified Toxic Doses.
Cannabis and edibles
Dogs make up the overwhelming majority of reported marijuana exposures, and typical signs are depression, wobbliness, dribbling urine, startle sensitivity, and a slow heart rate rather than pure tremor (ASPCApro, Marijuana Toxicosis in Animals). The real danger is often the vehicle: a THC brownie is also a chocolate exposure, and a THC gummy may also contain xylitol. Tell the vet exactly what the product was. Veterinarians are treating the dog, not reporting the owner.
Permethrin and other pyrethroids
Concentrated permethrin spot-ons are the classic cause of tremors and seizures in cats, but overdose, ingestion of a tube, or a small dog wearing a large dog's product can produce salivation, hyperexcitability, tremors, and seizures too (Merck Veterinary Manual, Plant-Derived Insecticide Toxicosis in Animals). Never apply a dog product to a cat, and dose strictly by weight.
Slug and snail bait (metaldehyde)
Eleven of the 91 poisoning cases in the RVC series. Metaldehyde produces severe, rapid-onset tremors and seizures and carries a high mortality rate without fast treatment. Common in gardens in spring and autumn.
Non-toxic medical causes worth knowing
Idiopathic generalized tremor syndrome (shaker dog syndrome)
The second most common diagnosis in the RVC series and one many owners have never heard of. It causes acute, fine, whole-body tremor in young adult dogs — median age at onset 2 years in that cohort — and is believed to be immune-mediated, which is why it typically responds to corticosteroids (VCA Animal Hospitals, Shaker Syndrome in Dogs). Originally described in small white dogs like Maltese and West Highland White Terriers, it is now recognized in any coat color and in larger breeds. In the RVC data, affected dogs were significantly more often female, and their tremor did not improve in the first 48 hours without steroids — a useful contrast with poisoning, where improvement within 48 hours occurred without corticosteroids.
Low blood calcium and low blood sugar
Hypocalcemia was the third most common diagnosis (13 dogs). It classically appears in small-breed nursing mothers in the weeks after whelping and causes panting, restlessness, stiffness, and tremors that escalate quickly. Hypoglycemia, meanwhile, tends to produce episodic shaking: in the RVC series, 5 of the 6 hypoglycemic dogs had episodic rather than continuous tremors. Both are emergencies.
Addison's disease
Hypoadrenocorticism causes nonspecific lethargy, poor appetite, and weight loss before it produces an acute crisis (Merck Veterinary Manual, Addison Disease in Animals). Its reputation as "the great pretender" is earned. A young-to-middle-aged dog with a months-long history of coming and going illness who suddenly becomes weak and shaky deserves specific mention of that history at the clinic.
Distemper myoclonus
In unvaccinated or incompletely vaccinated dogs, canine distemper virus can leave a rhythmic, involuntary twitch of a muscle group — classically the jaw, producing "chewing-gum fits" — that persists after the dog otherwise recovers (Merck Veterinary Manual, Canine Distemper). It is rhythmic, localized, present at rest, and often continues during sleep — which distinguishes it from most other tremors. Rare where vaccination coverage is high; still seen in shelter and imported dogs.
What to record for your vet
Shaking is intermittent, and it almost never performs in the exam room. A 20-second phone video is one of the most useful diagnostic contributions an owner can make — the RVC authors themselves list the absence of video documentation as a limitation of their study.
- Film the whole dog, head to tail, in landscape, for at least 20 seconds. Cropped clips of one leg are far less useful.
- Say your dog's name on camera and film the reaction. This records consciousness, the single most important variable.
- Film both at rest and walking. Some tremors stop during movement; others appear only on standing.
- Capture one calm moment and one excited moment if it is safe. Tremor that worsens with excitement points in a different direction than tremor that does not.
- Note the exact time it started and what happened in the preceding six hours: walk route, off-lead time, bins raided, visitors, new medication, new flea treatment.
- Photograph any packaging — front, ingredient list, and weight — and bring it with you. Bring the vomit if there is any, in a sealed bag.
- Take your dog's temperature rectally only if it is safe and you already know how. Sustained tremor generates heat, and hyperthermia matters clinically.
- Log the episodes if this is recurring: date, time, duration, what your dog was doing, how long recovery took.
Mistakes owners make with a shaking dog
- Inducing vomiting at home. In a tremoring, sedated, or unsteady dog this risks aspiration pneumonia — a complication Merck specifically flags in tremorgenic poisoning. Only ever on veterinary instruction.
- Waiting to see if it passes. For toxins, decontamination is most effective early. Hours matter.
- Withholding information. Nobody is judged for a dog that got into the trash, the edibles, or the medication drawer.
- Giving human medication. Ibuprofen, acetaminophen, and human sedatives are dangerous to dogs and can obscure the diagnosis.
- Assuming an old dog's hind-leg tremor is "just age." It often is, but pain and weakness look identical from across the room.
- Confusing repeated head shaking with body tremor. Persistent shaking of the head alone is usually an ear problem, not a neurological one — see our guide to dog shaking head for that specific pattern.
Myth vs. fact
| Common belief | What the evidence supports |
|---|---|
| "Only small dogs shiver." | Small, thin, and short-coated dogs lose heat faster and shiver sooner — but in the RVC tremor series the median body weight was 10.9 kg, with a range up to 53 kg, and Labrador Retrievers were the second most common breed. |
| "Shaking always means pain." | Pain is one cause among many. In referral cases, poisoning and immune-mediated tremor syndrome dominated. |
| "White dogs get shaker syndrome; other dogs don't." | It was first described in small white breeds, hence "little white shaker," but is recognized in dogs of any coat color and in larger breeds. |
| "Tremors mean a seizure is coming." | Not reliably. Tremor and seizure are distinct events, though some poisons can cause both. |
| "A dog with a wagging tail can't be seriously ill." | In the RVC series, roughly four in ten poisoned dogs had tremor as their only neurological sign on examination (reported as 38.5% in the study table and 45% in the text). Otherwise-normal behavior does not exclude poisoning. |
| "Vomiting means the danger has passed." | Vomiting can reduce absorption, but it does not clear the stomach reliably, and it raises aspiration risk in an unsteady dog. |
Frequently asked questions
Why is my dog shaking but acting normal?
The usual explanations are cold, excitement, mild anxiety, or an age-related tremor — especially if it starts and stops with a clear trigger and your dog eats, drinks, walks, and responds normally. That said, in the RVC referral series roughly four in ten poisoned dogs had tremor as their only neurological sign. If the shaking appeared suddenly today and your dog had any unsupervised access to food waste, medication, or a garden, call your vet rather than relying on normal behavior. For background that helps put behaviour and daily routines in context, read Why Dogs Sniff on Walks. To put those observations in context, see Why Do Dogs Circle Before Lying Down? Bedtime Behavior Explained for related questions about behaviour and daily routines.
Why is my dog shaking all of a sudden?
Sudden whole-body shaking with no obvious cold or fright trigger is the pattern most associated with poisoning. In the RVC data, 49% of tremor cases had a hyperacute onset of under 24 hours, and dogs with intoxication typically showed a hyperacute, symmetric, non-progressive presentation. Treat abrupt onset as urgent until a vet says otherwise.
Why is my dog shaking and panting?
Shaking plus panting at rest, without heat or exercise, suggests pain, stress, fever, or a toxin. In a nursing mother in the weeks after giving birth it also raises low blood calcium, which is an emergency. This combination warrants a same-day veterinary call. If you’re trying to describe what you’ve noticed, Why Do Dogs Pant? Cooling, Stress and Warning Signs explains what to look for.
Why is my old dog shaking?
Fine hind-leg trembling in senior dogs is common and often reflects normal aging, arthritis pain, or muscle loss. Age itself is not protective, though: in the RVC series 16.7% of tremor cases were dogs over nine, and hypercalcemia — which can accompany certain cancers — had a median onset age of 9.2 years. New or worsening tremor in an older dog deserves an exam. If you want to explore the related questions about age and life-stage needs, start with Grooming Tips for Older Dogs.
Is my dog shaking because he's cold?
Probably, if it happens outdoors or after a bath and settles within minutes of warming and drying. If the shivering carries on once your dog is warm indoors, look for another explanation.
Should I go to the emergency vet for a shaking dog?
Yes if the shaking came on suddenly, involves the whole body, or comes with vomiting, drooling, wobbliness, disorientation, collapse, dilated pupils, or possible access to a toxin. Yes for a first-ever seizure. Yes for a nursing mother, a diabetic dog, a toy-breed puppy, or a dog with known Addison's. Otherwise, book a routine appointment and bring your video.
Can anxiety alone make a dog shake?
Yes. Trembling is a recognized component of fear and stress in dogs, typically alongside tucked tail, flattened ears, panting, lip-licking, hiding, or pacing, and tied to an identifiable trigger such as fireworks, storms, or car travel. Recurrent, intense fear responses are worth addressing with your veterinarian rather than managing alone. If suitability is your main concern, read Melatonin for Dogs Travel & Car Anxiety before making a change. To check what to look for when choosing products for stress, sleep and settling, read Melatonin for Dogs With Car Anxiety and Best Time to Give a Dog Melatonin. Our guide to dog anxiety supplements summarises the available studies in dogs. To follow up on calming and behaviour, see Melatonin for Dogs with Separation Anxiety and Melatonin for Dog Anxiety UK.
What is shaker dog syndrome?
Idiopathic generalized tremor syndrome is an acute, fine, whole-body tremor of young adult dogs, thought to be immune-mediated and usually responsive to prescription corticosteroids. It made up 24.7% of the RVC tremor caseload, with a median onset age of 2 years. Diagnosis requires ruling out toxins and other causes, so it is not something to self-diagnose at home.
Veterinary disclaimer. This article is general educational information and is not a substitute for veterinary diagnosis or treatment. Shaking and tremors can indicate a medical emergency. If you are concerned about your dog, contact your veterinarian, an emergency veterinary hospital, the ASPCA Animal Poison Control Center (888-426-4435) or Pet Poison Helpline (855-764-7661). Both poison lines charge a consultation fee. Do not induce vomiting or administer any medication without veterinary instruction.
UK guidance
For UK-specific advice, read PDSA's guidance on PDSA Pet Health Hub, written for UK pets. If your dog's signs are new, persistent or worsening, speak with a vet; this article is general information, not a diagnosis.
If stress, separation, travel, grooming or noise sensitivity is part of your dog's routine, compare non-prescription options in our UK guide to the best over-the-counter anxiety medicines for dogs.