Cats shake for reasons ranging from completely harmless to genuinely urgent. The most common causes are cold, stress, pain, low blood sugar, and exposure to a toxic substance. A brief episode of twitching during sleep is almost always normal, while prolonged or full-body tremors paired with other symptoms like vomiting, drooling, or unresponsiveness point to something that needs veterinary attention fast.
Your Cat Might Just Be Cold
Cats regulate body temperature well, but they do shiver when they get too cold. A healthy cat’s body temperature sits between 98.1°F and 102.1°F (36.7–38.9°C), which is a narrower and slightly lower range than many veterinary textbooks used to cite. When that temperature drops below 95°F (35°C), a cat is in early danger. Below 90°F (32°C) is severe hypothermia and a veterinary emergency.
Mild hypothermia looks like subtle shivering, cold ears and paws, reduced appetite, and a cat curling up tightly or seeking warm spots. That’s the easy-to-fix version: bring your cat to a warm room, offer a blanket, and make sure they’re dry. If the shivering doesn’t stop within 20 to 30 minutes in a warm environment, or if your cat seems confused, uncoordinated, or hard to wake, something more serious is going on. Bluish gums, slow or shallow breathing, muscle stiffness, and dilated pupils all signal the body is losing the fight against cold and needs emergency help.
Wet cats, very young kittens, elderly cats, and thin or underweight cats lose heat fastest. If your cat got outside in cold weather or was recently bathed and is now shaking, temperature is the first thing to consider.
Sleep Twitching Is Normal
If your cat is shaking only while asleep, you’re probably watching normal dream activity. During REM sleep, cats experience rapid eye movements, small facial twitches, paw paddling, and brief muscle jerks. The key detail: during normal REM sleep, the body’s large muscle groups stay relaxed. A sleeping cat’s legs may twitch, but the rest of the body remains soft and still. You can usually wake them easily, and they’ll snap back to normal within seconds.
A seizure looks different. It involves rigid muscles, full-body convulsions, drooling, loss of bladder or bowel control, and vocalization. A cat having a seizure cannot be gently woken up. After a seizure ends, cats often seem disoriented, wobbly, or completely unresponsive for minutes to hours. If what you’re seeing matches that pattern rather than gentle twitching, it’s not a dream.
Stress and Fear
A frightened or stressed cat may tremble visibly. This is the same adrenaline-driven response you’d feel before public speaking: the nervous system floods the body with stress hormones, and muscles tense and shake. Common triggers include car rides, vet visits, new pets in the home, loud noises like fireworks, or a sudden change in environment.
Stress-related shaking is typically short-lived. Once the threat is gone or the cat feels safe again, the trembling stops. You’ll often see other fear signals at the same time: flattened ears, a puffed tail, hiding, or dilated pupils. If shaking happens only during identifiable stressful events and resolves quickly, it’s unpleasant for your cat but not medically dangerous on its own.
Low Blood Sugar
Hypoglycemia, when blood glucose drops to 60 mg/dL or lower, causes shaking that escalates in a predictable pattern. Early signs are subtle: unusual hunger, restlessness, and mild shivering. As blood sugar continues to fall, cats become uncoordinated and disoriented. Without intervention, this can progress to convulsions, seizures, and coma.
Kittens are especially vulnerable because they have tiny energy reserves and can become hypoglycemic simply from missing a meal or two. Adult cats on insulin for diabetes are also at risk if they receive too much medication or skip food after an injection. Some cats with hypoglycemia simply become very quiet and stop eating, which makes it easy to miss. If your cat is diabetic and begins shaking, offering a small amount of food is a reasonable first step while you contact your vet.
Pain and Injury
Cats in pain often shake or tremble, and they’re notoriously good at hiding discomfort. The shaking might be generalized or localized to one area. A cat with abdominal pain may tremble all over while hunching. A cat with a leg injury may shake that specific limb.
One condition worth knowing about is feline hyperesthesia syndrome, an extreme skin sensitivity almost always concentrated on the back near the base of the tail. Cats with this condition may have rippling skin, sudden aggression when touched, dilated pupils, and drooling. It can look alarming, almost like a seizure, but it’s a distinct condition. Diagnosing it requires ruling out other causes of pain in that area, including spinal arthritis, disc problems, parasites, allergies, and skin infections. If your cat’s back muscles seem to twitch or ripple on their own, especially near the tail, this is a possibility to discuss with your vet.
Poisoning and Toxic Exposure
Muscle tremors are one of the hallmark signs of poisoning in cats, and the most common culprit is permethrin, a flea-control chemical found in many dog flea treatments. Cats are extremely sensitive to permethrin. Even small amounts transferred from a treated dog to a cat through contact can cause toxicity. In one long-running UK study, over 1,300 cases of permethrin exposure in cats were reported to a veterinary poison service over an 18-year period.
In mild cases of permethrin poisoning, you’ll see paw flicking, ear twitching, and uncontrolled twitching of the skin along the back. Severe cases involve intense full-body tremors, seizures, and depression. Other signs reported include extreme sensitivity to touch, loss of coordination, dilated pupils, and temporary blindness. Tremors or muscle twitching appeared in 86% of affected cats in one study, with seizures in a third of cases.
Permethrin isn’t the only risk. Other common household toxins that can cause tremors in cats include certain essential oils, lilies, antifreeze, and some human medications. If your cat is shaking and you suspect any toxic exposure, time matters. Don’t wait to see if it gets better.
Fever
Just like people, cats can shiver when they have a fever. A rectal temperature above 102.1°F (38.9°C) is above the normal range for a healthy adult cat. Cats with fever often feel warm to the touch (especially on their ears), seem lethargic, lose their appetite, and may hide. Infections, inflammatory conditions, and immune reactions are the usual causes. A shaking cat that also feels unusually warm and is off their food may be fighting something off internally.
Red Flags That Need Immediate Attention
Some combinations of symptoms alongside shaking signal a true emergency:
- Seizure activity: whole-body convulsions, drooling, loss of bladder or bowel control, vocalization, or unresponsiveness
- Possible poisoning: shaking combined with paw flicking, skin twitching along the back, dilated pupils, or known exposure to a flea product, essential oil, or toxic plant
- Severe hypothermia: pale or bluish gums, slow breathing with long pauses between breaths, muscle stiffness, or inability to wake your cat
- Hypoglycemia progression: shaking that has moved past mild tremors into wobbliness, disorientation, or collapse, particularly in kittens or diabetic cats
Brief, isolated shaking that stops on its own, especially if there’s an obvious trigger like cold air or a stressful event, is usually not an emergency. Shaking that persists, worsens, repeats without explanation, or comes with any of the signs listed above warrants a vet visit, and in some cases an urgent one. Noting when the shaking started, how long it lasted, and what your cat was doing before and after gives your vet the clearest picture of what’s going on.