Kittens shake for reasons that range from completely harmless to genuinely urgent. The two most common causes are simple and benign: muscle twitching during sleep (a normal part of neurological development) and shivering from cold (because young kittens cannot regulate their body temperature well). Beyond those everyday explanations, though, shaking can signal toxin exposure, infections, congenital brain abnormalities, nutritional deficiencies, or liver problems. The difference between “nothing to worry about” and “get to a vet now” usually comes down to when the shaking happens, what it looks like, and whether other symptoms are present.
Sleep Twitches Are Normal and Actually Important
If your kitten shakes, jerks, or paddles its little legs while sleeping, you’re almost certainly watching a healthy brain at work. Those twitches happen during REM sleep, the phase when mammals dream, and research indicates they play a real role in wiring the nervous system. Spontaneous muscle twitching during REM sleep helps young animals build sensorimotor maps and improve the organization of spinal circuits by activating skeletal muscle repeatedly as the brain develops.1Theoretical and Natural Science. Muscle twitching during REM sleep contributes to the development of the body In plain terms, each little jerk is the brain rehearsing how to control the body. Kittens spend a large portion of their day asleep, and a large share of that sleep is REM, so you’ll see these twitches often.
Sleep twitches typically look like quick, rhythmic flicks of the paws, tail, ears, or whiskers. The kitten stays limp and relaxed between twitches and wakes up normally if disturbed. If your kitten is only shaking while asleep and seems perfectly fine when awake, there is no reason to worry.
Cold and the Kitten Thermoregulation Problem
Very young kittens are bad at staying warm. Their small bodies lose heat quickly, and the biological machinery for generating warmth through shivering doesn’t fully mature until they’re several weeks old. Research on kitten thermoregulation found that shivering as a cold-defense response, along with piloerection (fur standing on end), doesn’t appear reliably until after about 45 days of age.2Physiology & Behavior. Development of thermoregulation in the kitten Before that point, kittens depend almost entirely on external heat sources: their mother, littermates, blankets, or a heating pad you provide.
This means that if you have a kitten younger than about six weeks and it’s shaking or trembling while awake, cold is the first thing to rule out. The fix is straightforward: warm the kitten’s environment. A well-insulated nest kept around 85–90°F (29–32°C) for neonates, gradually decreasing as they age, usually stops the shaking. If warming the kitten up resolves the trembling within a reasonable time, cold was the answer. If it doesn’t, something else is going on.
Permethrin and Other Toxin Exposures
This is one of the scariest and most preventable causes of shaking in kittens: accidental exposure to permethrin, a common insecticide found in many flea treatments designed for dogs. Cats lack the liver enzyme needed to break down permethrin efficiently, so even a small dose can cause severe poisoning. The most common scenario is a well-meaning owner applying a dog flea product to a cat, or a kitten grooming a dog that was recently treated.
A retrospective review of 42 cases of feline permethrin toxicity found that tremors or muscle fasciculations occurred in about 86% of affected cats, with additional signs including twitching, extreme sensitivity to touch, seizures, fever, drooling, uncoordinated movement, and dilated pupils.3PubMed Central. Feline permethrin toxicity: retrospective study of 42 cases A separate study of 20 cases similarly identified seizures, muscle fasciculations, and tremors as the hallmark clinical signs of permethrin poisoning in cats.4PubMed. Permethrin toxicity in cats: a retrospective study of 20 cases
The tremors from permethrin poisoning tend to be full-body, continuous, and severe. They usually begin within hours of exposure and can escalate to seizures. If your kitten has been around any flea product, household insecticide spray, or a recently treated dog, and starts shaking, treat it as an emergency. Prompt veterinary treatment with intravenous fluids and muscle-relaxant medication can be lifesaving, but delay makes outcomes worse.
Permethrin isn’t the only toxic culprit. Kittens are curious chewers, and household items like certain houseplants (lilies are notoriously dangerous for cats), antifreeze, rodent bait, and even some essential oils can cause neurological signs including tremors. The general rule: if shaking starts suddenly in a previously normal kitten, especially with drooling, vomiting, or behavior changes, suspect poisoning and call your vet or an animal poison control hotline immediately.
Cerebellar Hypoplasia From Panleukopenia
Some kittens are born shaking, and the tremors never go away. The most common cause of this is cerebellar hypoplasia, a condition where the cerebellum (the part of the brain that coordinates movement) doesn’t develop to its full size. In cats, this almost always happens because the mother was infected with feline panleukopenia virus (also called feline parvovirus) during pregnancy. The virus targets rapidly dividing cells, and in a developing fetus, the cerebellum is particularly vulnerable.
Cerebellar hypoplasia is recognized as the principal cerebellar disease in cats and is caused by in utero infection with the panleukopenia virus.5Problems in veterinary medicine. Ataxia, dysmetria, tremor. Cerebellar diseases Research has confirmed that parvoviral proteins can be detected in the Purkinje cells of the cerebellum in kittens with this condition, both in experimental infections and in naturally occurring cases.6PubMed. Identification of feline panleukopenia virus proteins expressed in Purkinje cell nuclei of cats with cerebellar hypoplasia
Kittens with cerebellar hypoplasia show what veterinarians call “intention tremors,” meaning the shaking gets worse when the kitten is trying to do something deliberate like eat, walk, or bat at a toy. They may bob their heads, overshoot when reaching for food, sway when walking, and fall over frequently. The degree of impairment varies widely: some kittens wobble slightly, while others can barely stand.
The important things to know: cerebellar hypoplasia isn’t painful, isn’t progressive (it doesn’t get worse over time), and isn’t contagious. Many “CH cats” live long, happy lives with minor accommodations like low-sided litter boxes and non-slip flooring. It’s not curable, but it doesn’t need to be “treated” in the traditional sense. If you adopt a wobbly kitten from a shelter, this is often what’s going on.
Nutritional Deficiencies, Especially Thiamine
Kittens that are fed an unbalanced diet, or adult cats switched to a new food, can develop deficiencies that cause neurological problems including tremors. Thiamine (vitamin B1) deficiency is the classic example. Cats have relatively high thiamine requirements, and certain diets can fall short, particularly raw fish diets (some raw fish contains an enzyme that destroys thiamine), improperly formulated homemade diets, or commercial foods that have been overprocessed or improperly stored.
Clinical reports document cats presenting with vestibular signs (loss of balance, head tilt, circling) and seizures that were ultimately diagnosed as thiamine deficiency triggered by a diet change.7PubMed Central. Clinical signs, MRI features, and outcomes of two cats with thiamine deficiency secondary to diet change The good news is that thiamine deficiency, caught early, responds well to supplementation. The bad news is that if it goes unrecognized, it can cause permanent brain damage.
If your kitten is on an unusual or homemade diet and starts trembling, losing coordination, or tilting its head, mention the diet to your vet. Switching to a nutritionally complete commercial kitten food and administering thiamine injections usually resolves the problem if the deficiency hasn’t been present for too long.
Infections That Affect the Brain
Several infectious diseases can cause tremors in kittens by inflaming the brain or the membranes around it.
Feline infectious peritonitis (FIP) is one of the most feared. FIP is caused by a mutated form of feline coronavirus, and when it affects the central nervous system, it can cause tremors, seizures, personality changes, and progressive neurological decline. Diagnosing CNS involvement with FIP has historically been difficult, though newer diagnostic tools are improving accuracy. One study evaluating cerebrospinal fluid testing found that the method had a sensitivity of 85% and specificity of about 83% for detecting FIP in cats with neurological signs.8PubMed Central. Diagnostic utility of cerebrospinal fluid immunocytochemistry for diagnosis of feline infectious peritonitis manifesting in the central nervous system The recent development of effective antiviral treatments for FIP has dramatically changed the prognosis, but early detection and aggressive treatment remain critical.
Toxoplasmosis, caused by the parasite Toxoplasma gondii, is another infection that can involve the nervous system in cats. General clinical signs include fever, appetite loss, and difficulty breathing, but the disease can also produce neurological symptoms when it reaches the brain.9Frontiers in Veterinary Science (via Europe PMC). Clinical Toxoplasmosis in Dogs and Cats: An Update While toxoplasmosis is more commonly a concern in immunocompromised cats, kittens with immature immune systems can also be vulnerable.
Inner ear infections (vestibular disease) are worth mentioning here too, because they produce dramatic symptoms that owners sometimes describe as “shaking.” A kitten with a vestibular problem typically holds its head at an angle, falls toward one side, and may have rapid involuntary eye movements. It can look alarming, but many cases of peripheral vestibular disease in cats are treatable and resolve with appropriate care.
Liver Shunts and Hepatic Encephalopathy
A less common but important cause of tremors in young cats is a congenital portosystemic shunt, sometimes called a liver shunt. In this condition, a kitten is born with an abnormal blood vessel that routes blood around the liver instead of through it. Because the liver is responsible for filtering toxins from the blood, a shunt means those toxins, particularly ammonia, build up and affect the brain. The result is hepatic encephalopathy, which can manifest as tremors, disorientation, circling, head pressing, drooling, or even seizures.
Tremors have been specifically documented as a neurological sign in cats with hepatic encephalopathy caused by congenital portosystemic shunts.10PubMed Central. Tremors in cats with hepatic encephalopathy‐congenital portosystemic shunts or postattenuation neurological syndrome Kittens with liver shunts often also show stunted growth, poor appetite, and episodes that seem to come and go, sometimes worsening after meals when the ammonia load spikes. If your kitten is small for its age, a poor eater, and has intermittent neurological episodes, a liver shunt is something your vet should investigate. Depending on the anatomy of the shunt, surgical correction is sometimes possible and can dramatically improve quality of life.
Breed-Related and Genetic Conditions
Certain genetic conditions are more common in specific cat breeds and can cause tremors that appear in kittenhood. A large case review of tremors in cats found that among degenerative brain diseases causing tremors, the most common were suspected cerebellar cortical degeneration and lysosomal storage diseases, each accounting for about half of the degenerative cases, and these conditions typically produced intention head tremors.11PubMed. Tremors in cats: 105 cases (2004-2023)
Lysosomal storage diseases are a group of inherited metabolic disorders in which the body can’t properly break down certain cellular waste products, leading to progressive damage in the brain and nervous system. Different storage diseases appear in different breeds: for example, certain forms have been identified in Siamese, Korat, and domestic shorthair lines. These conditions tend to show up in young kittens and worsen over time, which distinguishes them from cerebellar hypoplasia (which stays stable).
Hypomyelination is another rare congenital condition that has been reported in Siamese kittens, where the insulating coating around nerve fibers in the brain doesn’t develop properly. Affected kittens may tremble from a very early age. Some cases of hypomyelination improve as the kitten matures and myelination catches up, while others do not.
If your kitten is a purebred or from a known lineage and develops progressive tremors, your vet may recommend specialized testing to look for inherited metabolic or neurological disease.
How to Tell Normal Shaking From a Problem
With so many possible causes, it helps to have a mental checklist for sorting out what you’re seeing. Here are the questions to ask yourself:
- When does it happen? Shaking only during sleep is almost always normal. Shaking while awake warrants a closer look.
- How old is the kitten? Neonatal kittens (under four to six weeks) are prime candidates for cold-related trembling. Kittens that have been shaking since birth may have cerebellar hypoplasia or another congenital condition.
- Did it start suddenly? A kitten that was fine yesterday and is trembling today points toward toxin exposure, infection, or acute illness rather than a developmental condition.
- Is the kitten otherwise normal? Eating well, playful, alert? A shaking kitten that is otherwise thriving is less concerning than one that is also lethargic, refusing food, vomiting, or having diarrhea.
- Is there possible toxin access? Dog flea products in the house, houseplants within reach, open cleaning supplies, a recently treated dog the kitten may have cuddled with?
- Does the shaking get worse with intentional movement? Intention tremors that worsen when the kitten tries to eat or play point toward cerebellar problems.
None of these questions replaces a veterinary exam, but they help you gauge urgency. A kitten twitching in its sleep needs nothing. A kitten trembling after contact with a flea product needs an emergency vet visit within the hour.
Situations That Require Immediate Veterinary Attention
Some forms of kitten shaking are true emergencies. You should seek veterinary care immediately if any of the following apply:
- Seizures: Stiffening, falling over, paddling legs while awake, loss of consciousness, or unresponsiveness. Seizures look different from sleep twitches because the kitten is rigid, may vocalize, and doesn’t wake up normally.
- Known or suspected toxin exposure: Any shaking after contact with flea products, household chemicals, plants, or rodent bait.
- Continuous trembling that doesn’t stop: Persistent tremors that last for hours, especially if the kitten can’t rest or settle.
- Additional neurological signs: Head tilt, circling, inability to walk straight, blindness, or rapid eye movements alongside the tremors.
- Fever, lethargy, or refusal to eat: Tremors combined with signs of systemic illness suggest infection or metabolic crisis.
- Rapid worsening: Any tremor that’s getting progressively worse over hours or days, rather than staying the same.
When you do go to the vet, take note of details that will help with diagnosis: when the shaking started, whether it’s constant or intermittent, what the kitten has had access to, what it’s been eating, and whether the mother cat’s vaccination history is known. Video is genuinely useful here. Tremors that are dramatic at home have a way of stopping in the vet’s office, and a 30-second phone video gives your vet far more to work with than a verbal description.
Low Blood Sugar in Very Young Kittens
Hypoglycemia is an underappreciated cause of trembling in kittens under about eight weeks of age. Kittens have tiny energy reserves and fast metabolisms, which means their blood sugar can drop rapidly if they miss even a couple of meals. Orphaned kittens being bottle-fed, runts that struggle to compete with littermates at the nipple, and kittens recovering from illness are all at elevated risk.
The signs of hypoglycemia often include trembling, weakness, lethargy, and in severe cases, seizures or loss of consciousness. If you’re caring for a very young kitten and it starts trembling, offering a small meal or rubbing a dab of corn syrup on the gums while heading to the vet is a reasonable first step. Kittens that are eating well on a regular schedule rarely develop hypoglycemia, so it’s mostly a concern in neonatal rescue or fostering situations.
Anxiety and Overstimulation
Not every shake has a medical explanation. Kittens sometimes tremble from stress or fear, especially in new environments. A kitten just brought home from a shelter, riding in a car for the first time, or hearing loud noises may shake visibly. This kind of trembling tends to be context-specific: the kitten shakes in the stressful situation and stops once it feels safe again. It’s usually accompanied by other fear signals like crouching low, flattened ears, wide eyes, or hiding.
Stress-related shaking doesn’t require medical treatment, but it does tell you the kitten needs a calmer, more gradual introduction to its new world. A small, quiet room with hiding spots, consistent routine, and gentle handling usually resolves the problem within a few days as the kitten acclimates. If the shaking persists well beyond the adjustment period or shows up without any obvious stressor, it’s worth having a vet rule out other causes.