My Cat Trembles in Its Sleep
Twitching during sleep is usually normal dreaming. Trembling while awake, or shaking that does not stop, is a different matter.
Is this an emergency?
If the trembling continues while your cat is awake, if it cannot be roused, or if there is vomiting, unsteadiness or confusion alongside it, come in the same day.
A cat twitching its paws, whiskers and tail while asleep is almost always in REM sleep. This is normal, occurs in kittens more than adults, and needs nothing done about it.
Normal sleep twitching
During REM sleep the brain is highly active while the body is largely paralysed, and small movements escape: paws paddling, whiskers moving, ears flicking, a soft chirrup. Kittens do this a great deal, partly because REM sleep plays a role in developing the nervous system.
The distinguishing features of normal sleep twitching are that it is small, irregular, involves the extremities rather than the whole body, and stops the moment the cat wakes.
When it is not normal
Wake the cat gently and watch.
If the trembling stops on waking, it was sleep activity.
If it continues while the cat is awake, that is not dreaming, and it needs looking at.
Also concerning: whole body rigidity rather than loose twitching; paddling with the head thrown back; drooling, urinating or defecating during the episode; a cat that cannot be roused; and an episode lasting more than a couple of minutes. Those describe a seizure, not a dream.
Trembling while awake
Causes include cold, particularly in kittens, thin cats and hairless breeds; pain anywhere in the body; low blood sugar, especially in kittens and diabetic cats; fever; poisoning; kidney disease; and neurological disease.
Poisoning deserves particular mention. Permethrin, found in dog flea spot ons, causes tremors and seizures in cats and is one of the most common serious poisonings we see. If your cat has been treated with a dog product, or has groomed a treated dog, this is an emergency.
What to do
If the cat is simply asleep and twitching, leave it. Waking a cat mid-dream startles it and achieves nothing.
If the trembling continues while awake: keep the cat warm and quiet, do not offer food if it is not fully alert, do not give any human medication, and note how long the episode lasts and what the cat looked like. Filming it is genuinely useful.
When to come in
Trembling that continues while awake. Any episode that looks like a seizure. Trembling with vomiting, unsteadiness, confusion or collapse. Trembling in a kitten, which can mean low blood sugar or low temperature and moves quickly. And any trembling after exposure to a flea product intended for dogs.