Hepatic Lipidosis (Fatty Liver) in Cats: A Diet Emergency

What hepatic lipidosis (fatty liver) is and how to recognize it in cats

Hepatic lipidosis, often called fatty liver disease, is a condition in which fat builds up inside the cells of a cat’s liver until the organ can no longer do its job. According to the Merck Veterinary Manual, it is the most common cause of liver disease in cats, and it is essentially a feline disease — this is one of the clearest places where cats differ from dogs, who do not develop fatty liver in the same way. The liver is a chemical factory that processes nutrients, filters toxins, and helps with digestion, so when it is choked with fat, a cat becomes progressively and dangerously ill. The reassuring part, which we will return to, is that this is one of the few life-threatening illnesses where the treatment is not a complex drug but food itself — getting the right calories back into the cat reverses the very process that caused the disease.

The signs tend to come on suddenly and get worse fast. The hallmark is a dramatic loss of appetite — the cat simply stops eating — followed by noticeable, rapid weight loss. The Merck Veterinary Manual notes that weight loss can exceed 25% of body weight. Owners also see lethargy and weakness, vomiting, and excessive drooling. The most alarming sign is jaundice: a yellow tinge to the whites of the eyes, the gums, and the skin inside the ears. Cornell Feline Health Center describes hepatic lipidosis as the most common cause of severe jaundice in cats. In serious cases, the liver’s failure can affect the brain, a complication called hepatic encephalopathy that can cause confusion, disorientation, or weakness. Because these signs can be subtle at first — a quiet cat hiding more than usual, or simply turning away from the food bowl — it is easy to lose precious days before realizing how sick the cat truly is.

What causes it in cats: the anorexia trigger and risk factors

The central trigger is simple but easy to underestimate: a cat that stops eating. When a cat goes without food, its body begins breaking down stored body fat for energy. As VCA Animal Hospitals explains, that fat is mobilized rapidly and sent to the liver, but the liver becomes overwhelmed and cannot process it fast enough. The fat accumulates inside liver cells and overwhelms them, and the liver starts to fail. This is why hepatic lipidosis is so closely tied to diet and to any event that makes a cat lose its appetite, even briefly. It is also why an otherwise minor problem — a few skipped meals — can spiral into a life-threatening crisis.

The single biggest risk factor is being overweight or obese, because a heavier cat simply has more fat to mobilize and flood the liver with. The stretch of not eating, known as anorexia, is often set off by something else: a stressful event like moving, boarding, or a new pet; an abrupt diet change or a food the cat dislikes; or an underlying illness. VCA notes that in more than 90% of cases there is an underlying or concurrent disease, such as pancreatitis, inflammatory bowel disease, diabetes, or cancer. The practical takeaway is blunt: a cat that stops eating for even a few days is in real danger, and an overweight cat is most at risk of all.

Diagnosis and when to see a vet

This is the most important section, so it deserves to be plain: any cat that has not eaten for roughly two to three days needs to see a veterinarian promptly. Hepatic lipidosis is urgent — effectively an emergency — because it can progress to liver failure and death without treatment, yet it is highly treatable when caught early. Do not try to “wait it out” or assume a finicky cat will start eating again on its own. If you notice jaundice (yellow gums, eyes, or ear skin), vomiting, drooling, or sudden weight loss in a cat that is off its food, treat that as a reason to be seen the same day rather than next week.

A veterinarian diagnoses fatty liver through a combination of findings rather than a single test. According to the Merck Veterinary Manual and Cornell Feline Health Center, this includes a physical exam (often revealing jaundice and an enlarged liver), blood work showing elevated liver enzymes and high bilirubin, and abdominal ultrasound, which typically shows an enlarged, abnormally bright (fatty) liver. The diagnosis is frequently confirmed with a fine-needle aspirate or biopsy of the liver, which reveals liver cells swollen with fat. Critically, the vet will also search for the underlying trigger — the illness or stressor that made the cat stop eating — because treating that root cause is part of the cure.

The diet connection: nutrition is the treatment

For most diseases, food is supportive. For hepatic lipidosis, food is the medicine. The cornerstone of treatment is aggressive, early nutritional support, and it is often life-saving. The disease was caused by a lack of calories, so reversing it means getting complete, balanced nutrition back into the cat. The Merck Veterinary Manual recommends a high-calorie, calorie-dense diet with balanced, appropriate protein for cats — and it specifically advises against restricting protein. This is a key difference from some other liver diseases, where protein is limited; here, protein restriction is generally avoided unless a cat shows specific signs of the brain complication called hepatic encephalopathy. If you are choosing what to feed during recovery, see our guide to the Best Cat Food for Hepatic Lipidosis Recovery.

The challenge is that a sick cat will not eat enough on its own, and appetite stimulants alone are usually not enough. For that reason, veterinarians very commonly place a feeding tube — often an esophagostomy tube that runs through the side of the neck into the esophagus — to deliver a measured, calorie-dense recovery diet several times a day. This sounds dramatic, but it is well tolerated, removes the daily stress of fighting a cat to eat, and is frequently what saves the cat’s life. Anti-nausea medication and appetite stimulants are used alongside tube feeding to support intake and keep food down. As the cat recovers and begins eating willingly again, the tube is removed.

Recovery, feeding tubes, and what to avoid

The prognosis is genuinely encouraging when the disease is caught and fed early. The Merck Veterinary Manual states the outlook is good if the diagnosis is made early, treatment is started promptly, and any underlying disease can be treated — and recurrence after recovery is rare. Left untreated, however, hepatic lipidosis is frequently fatal. Recovery is a marathon, not a sprint: VCA notes it commonly takes several weeks — on the order of six to seven weeks — of dedicated feeding. Many cats go home with the feeding tube still in place, and owners continue tube-feeding the prescribed diet for weeks until the cat’s appetite fully returns. Patience and consistency from the owner are among the strongest predictors of success.

A few things to avoid. First, never ignore a cat that has gone off its food — that delay is the main thing that turns a treatable problem into a fatal one. Second, do not attempt to crash-diet an overweight cat: forcing rapid weight loss can itself trigger hepatic lipidosis, so any weight-loss plan for a heavy cat should be gradual and vet-supervised. Third, avoid clumsy or stressful force-feeding at home without veterinary guidance; both Merck and the Clinician’s Brief caution that syringe force-feeding can backfire by causing food aversion, stress, and a risk of aspiration, which is part of why a feeding tube is preferred. When in doubt, the safest action is always the same: call your vet. Prevention follows the same logic as treatment — keep your cat at a healthy weight, make any diet transitions slowly, and never let a day or two of skipped meals slide without taking it seriously.

Frequently asked questions

For diet-side context, see Best Cat Food for Hepatic Lipidosis Recovery, Best Cat Food for Inappetence. To check whether your cat’s food matches the rubric criteria discussed above, paste the ingredient list into the KibbleIQ analyzer. For scoring methodology context, see our published methodology.

Related condition deep-dives: Pancreatitis in Cats · IBD in Cats.