Why Is My Dog Shaking?

Most trembling is cold, fear or excitement, and stops when the dog settles. The reason to read further is the smaller group of causes that look identical from across the room.

Tremor or seizure? One test

This is the distinction that matters most, because the causes and the urgency are completely different — and from a distance the two can look the same.

Try to get their attention. If your dog responds to you and is immediately normal, that is reassuring, and points to a tremor. If you cannot rouse them, or they come round confused and disoriented, treat it as a possible seizure and call your vet. A trembling dog is usually still aware of you. A seizing dog is not, and afterwards goes through a disoriented period that a trembling dog does not have. If that sounds like what you saw, seizures in dogs covers what to do.

The ordinary explanations

• • Cold. Small breeds, thin-coated dogs, puppies and seniors lose heat fast. If it stops when they warm up, that was it.
• • Fear, stress or anticipation. Fireworks, thunder, the vet car park. Trembling is one of the most common canine stress signals.
• • Excitement. Some dogs quiver when something good is about to happen. Harmless.
• • Old age. Hind-limb tremor at rest is common in senior dogs and is often unremarkable, though it is worth having pain ruled out rather than assumed.

The ones worth ruling out

• • Pain. Probably the most under-recognised cause. Dogs in pain tremble, hold themselves stiffly, and often go off their food before anything obvious appears.
• • Low blood sugar. Small-breed puppies, very active dogs and diabetic dogs on insulin can drop far enough to shake. This one is time-sensitive.
• • Mouldy food and compost. Mould on food waste, dairy, walnuts or peanuts produces tremorgenic mycotoxins. Small amounts cause fine tremors that can last hours to days; larger amounts cause seizures and can kill. Owners almost never volunteer “he was in the compost” unless asked.
• • Other toxins — including chocolate, nicotine, xylitol and some insecticides.
• • Nausea. Dogs often tremble when queasy, frequently with drooling and lip-licking.
• • Shaker syndrome. Also called white shaker dog syndrome, a steroid-responsive tremor condition classically seen in small white dogs but not limited to them.
• • Addison's disease — hypoadrenocorticism is a great imitator and trembling with lethargy is one of its faces.
• • Advanced kidney disease. Toxin build-up when kidney values rise can cause tremors.

What helps your vet

Film it. A short video is worth more than a description, particularly for distinguishing a tremor from a seizure. Note whether the shaking is whole-body or confined to the back legs or head, whether it stops during sleep — most tremors do, and that is a useful clue — and whether anything has changed: new medication, access to the bin, a warm room, a thunderstorm.