Why Is My Old Dog Shaking? Causes Ranked by Urgency

Why is my old dog shaking?

An old dog shakes for causes that run from harmless (cold, excitement, a dream) to emergencies (poisoning, seizures), so the useful question is how urgent it is.

The table below ranks shaking by urgency, from “go now” to “keep an eye on it”. Rows with a link rest on that source; the rest are our triage.

Tier	What you see	Likely group of causes	Act
1. Emergency now	Dog cannot be roused, or a seizure passes 5 minutes, or seizures repeat without recovery in between	Status epilepticus (ACVIM, 2023)	Emergency vet now
1. Emergency now	More than two short seizures that each stop on their own within 24 hours	Cluster seizures, as ACVIM defines them (ACVIM, 2023)	Emergency vet now
1. Emergency now	Shaking with breathing that takes obvious effort	Heart, lung or airway trouble (Animal Trust)	Emergency vet now
1. Emergency now	Sudden whole-body tremor with drooling, dilated pupils, odd behavior or sensitivity to touch, or any chance your dog ate a poison	Intoxication, the top cause in the 198-dog study (Liatis, 2025)	Emergency vet or poison line now
2. Same day	A first seizure that has ended and your dog is recovering	New-onset epilepsy, or a brain, metabolic or toxic cause	Call your vet today
2. Same day	Shaking plus vomiting, collapse, weakness or not eating	Metabolic, toxic, pain or infectious illness	Call your vet today
3. Within a day or two	Trembling that is new, keeps returning or stays when your dog is warm, calm and resting	Pain, weakness, nerve or brain disease	Book a visit; film it
4. Watch	Short shaking in cold or after excitement, then your dog acts normal	Cold or excitement (AKC)	Note how often it happens

A dog that looks well between episodes still needs a call if the shaking is new.

How can I tell shaking from shivering and a seizure?

The clearest line is awareness: a dog in a convulsive seizure usually loses consciousness, while a dog that is trembling still knows you are there.

The International Veterinary Epilepsy Task Force (IVETF) wrote in 2015 that “as a rule the animal will lose consciousness during convulsive epileptic seizures” (BMC Vet Res). Myoclonic seizures are the exception, and awareness cannot be judged reliably during focal seizures. Use the table as a set of questions to answer on film for your vet.

Question	Shivering or trembling	Seizure (convulsive)
Does your dog respond to its name or your touch?	Usually yes, though it may be dull	Typically not in convulsive seizures; consciousness is lost
Can you interrupt it?	May ease once your dog is warm and calm; that points to cold, not away from disease	Does not stop on request
What does the body do?	Fine movement of the legs or whole body, with the dog still aware	Convulsive movements
Other signs to note	Drooling, odd behavior and dilated pupils were more common with poisoning in the 198-dog study	Note drooling, loss of bladder control and how your dog acts after
How long?	Time it	Most are brief; past 5 minutes is an emergency
Afterward	Note whether your dog acts like itself once warm and calm	Call your vet even if your dog recovers

Focal seizures, which show in one area, can blur this table. If you cannot rouse your dog during an episode, treat it as an emergency.

What are the emergency causes of shaking in an old dog?

The emergency causes are seizures that last over 5 minutes or repeat without recovery, and poisoning.

The ACVIM consensus statement of 2023 says that once a seizure lasts more than 5 minutes it is most likely to be prolonged and not self-limiting. The IVETF also counts two or more seizures without full recovery in between as status epilepticus. ACVIM treats more than two self-limiting seizures within 24 hours as cluster seizures, also an emergency. Cornell’s seizure guide says the same for a seizure past five minutes: go to the clinic immediately. Do not wait to see if it stops on its own. Our guide to elderly dog seizures covers what to do next.

Poisoning needs the same speed. The ASPCA lists the first signs of xylitol poisoning as vomiting, lethargy and loss of coordination, which can progress to seizures. It says xylitol can cause low blood sugar, and that liver damage can occur within 12 to 24 hours. Xylitol is a sweetener in some gum, candy and baked goods. In the US, the ASPCA Animal Poison Control number on that page is (888) 426-4435. Elsewhere, call your local emergency vet or poison service. Take the packet with you.

What did the 198-dog tremor study find?

A 2025 study of 198 dogs with generalized tremors found intoxication in 46% of cases.

Liatis, Bhatti and De Decker reviewed dogs seen at one referral center between January 2003 and December 2023 (J Vet Intern Med). Here is the arithmetic from the abstract:

Final or presumed diagnosis	Dogs	Share of 198
Intoxication	91	46%
Idiopathic generalized tremor syndrome (IGTS)	49	24.7%
Hypocalcemia	13	6.6%
Meningoencephalitis of unknown origin	9	4.5%
Hypoglycemia	6	3%
Hypercalcemia	5	2.5%
Degenerative encephalopathies	5	2.5%
Total itemized	178	89.9%

The 20 remaining dogs (10.1%) are not itemized in the abstract. Three findings help owners:

• Dogs with intoxication had a hyperacute, symmetric onset. Dogs with IGTS had an acute, progressive onset that favored one side.
• Behavior change, drooling, abnormal mentation, dilated pupils and sensitivity to touch were common with intoxication. Poor appetite and balance signs were common with IGTS.
• Improvement within 48 hours without corticosteroids happened only in dogs with intoxication.

What it did not show: how common each cause is in a typical old dog at home. These were dogs with generalized tremors seen at a single referral center. The dogs with IGTS were younger than those with intoxication.

What if the shaking is a first seizure in an older dog?

A first seizure in an older dog needs a vet visit the same day, because later-life seizures are more often linked to a structural brain cause.

In a 2025 analysis of 254 epileptic dogs from clinics in Finland and Lithuania, dogs with structural epilepsy were older, with a median age of 108 months (9 years) (Jankauskas et al., Animals). Among them, 35.5% developed status epilepticus. The study is retrospective and cannot tell you the odds for your dog. It does support asking for a full workup after any first seizure. Report confusion or night-time pacing to your vet along with when any seizure happened, and see our guide to dog dementia signs for what those signs can mean.

Why are my old dog’s back legs trembling?

Trembling in an old dog’s back legs can come from weakness or pain in the hindquarters, or from a nerve or spine problem.

What comes with the trembling tells your vet where to look, so write it down: whether it shows after a walk or when your dog stands still, and whether your dog drags a paw, slips or collapses. Dragging, slipping or collapse needs a same-day call. Collapse also has heart causes: Cornell notes that cardiac arrhythmia can cause weakness and collapse that gets mistaken for a seizure, and a video helps your vet tell them apart. Joint pain is a common driver in seniors, so see signs of dog arthritis too. Our page on back legs giving out sorts sudden collapse from slow weakness, and gives a home checklist for slippery floors.

Film the legs while your dog stands on a non-slip surface. Note whether the trembling stops when your dog lies down.

Is it normal for an old dog to shake?

Short shaking from cold or excitement is normal. The AKC describes an old dog whose body could no longer regulate temperature after a swim, and blankets stopped the shaking. Shaking that is new, frequent or paired with another sign is not something to put down to age.

Use your own dog as the baseline. A dog that has always shivered after a bath is different from a dog that never shook and now does every evening. If the shaking comes with heavy breathing at night, read our guide to old dog panting at night for a breathing-rate check.

What should I film and note for the vet?

Film one clear 30 to 60 second clip of the shaking, plus a written note of the time, the setting and what happened before.

Your vet cannot see an episode that ended in the car. Tonight’s checklist:

1. Start the clip wide, so the whole body is in frame, then move closer to the legs and face.
2. Say your dog’s name once in a normal voice and film whether it looks at you.
3. Note the clock time the shaking started and stopped. Count 5 minutes from the start.
4. Write what came before: a meal, a walk, a new treat, a new medicine, time in the yard or garage, chewed items such as gum or packets.
5. Note whether your dog could stand and walk during and after.
6. Note eating, drinking, vomiting and urination for the past day.
7. List all medicines and supplements, with the product names.
8. Bring the clip, the note and any packaging.

If it turns out to be a seizure, the same note helps your vet judge how many seizures there have been and how far apart.