By Arnold Plotnick, MS, DVM, ACVIM
Hepatic lipidosis (fatty liver disease) is a common disease of the feline liver in which abnormally large amounts of lipid (fat) accumulates within the cells of the liver. In other animals (humans, dogs, laboratory animals), lipid accumulation tends to be harmless, however, the cat’s unique pathways of protein and fat metabolism cause lipid accumulation in the liver to have severe consequences. Any breed of cat may be affected, and both sexes seem to be affected equally. Middle aged to older cats are more susceptible than young cats.
Most, but not all, affected cats have a history of being obese, as well as a history of a sudden loss of appetite, often precipitated by a stressful event, such as a move to a new home, separation from an owner, a new pet or family member in the household, or a sudden switch to an unpalatable food. Anorexia, depression, and intermittent vomiting are the first signs usually noted by the cat owner. As liver function worsens, cats may develop jaundice (a yellow discoloration to the whites of the eyes, gums, and skin), severe loss of muscle mass, drooling, and signs of mental dysfunction (severe depression, sudden blindness, seizures. Hepatic lipidosis can occur as a primary event, or it can occur secondary to other disease processes, such as diabetes. It is the most common liver disease encountered in cats.
Hepatic lipidosis can be a serious disease. Even with aggressive therapy, a few cats die from the condition.
The cause of hepatic lipidosis remains unknown. Obesity is thought to be a predisposing factor, as most (but not all) affected cats are obese at the time of disease onset. A period of anorexia (decreased appetite), occurring as a result of a stressful event (such as the addition of a new pet or family member, or a sudden change to a less palatable diet) can trigger the onset of hepatic lipidosis.
What To Watch For:
- Loss of muscle mass
- Jaundice (yellow tint to the whites of the eyes and possibly the skin inside the ears)
- Severe depression
- Possible seizures
The diagnostic tests needed to confirm the presence of hepatic lipidosis and exclude other liver disorders may include:
Complete medical history and physical exam. This includes examination of the gums, whites of the eyes, and other part of the body for jaundice (yellow discoloration). A history of obesity and sudden onset of anorexia after a stressful event is a classic finding in hepatic lipidosis. Physical exam usually reveals dehydration, severe weight loss, drooling and jaundice.
A complete blood count usually reveals mild anemia, and abnormally shaped red blood cells (known as poikilocytes), which are often an indicator of liver disease.
Blood tests that test organ function are especially important. Cats will usually have moderate to severe elevations of several liver parameters. A thyroid test is necessary to rule out a hyperactive thyroid as a cause of the liver enzyme elevations.
A bile acid test is a special blood test that may be necessary. It requires a blood sample after a 12 hour fast. The cat is then fed (force fed, if necessary), and another blood sample is taken two hours later. This simple test assesses the function of the liver.
Analysis of the urine may give information concerning the function of the liver.
X-rays of the abdomen allows assessment of the size and shape of the liver, and may help rule out a tumor as a cause of the liver problems..
Ultrasound of the abdomen allows limited assessment of the internal structure of the liver. It allows some assessment of the gall bladder and biliary system, and may rule out cancer as a cause of the liver disease. It may also help provide a method for obtaining a biopsy sample.
A fine-needle aspirate of the liver is a small sample of liver cells that are obtained by inserting a needle into the liver. This technique requires no or minimal sedation, and complications are extremely rare. Results must be interpreted cautiously, however, because concurrent liver diseases cannot be ruled out and may be missed.
A liver biopsy, in which a small sample of liver tissue is obtained, is the definitive test for diagnosing hepatic lipidosis. A biopsy specimen may be obtained surgically, or may be obtained using a special instrument that is inserted into the abdomen while being guided by the ultrasound probe. Surgical biopsies can be obtained by most veterinarians. Ultrasound-guided biopsies are often referral procedures.
Dietary therapy is the mainstay of treatment. Affected cats may need to be force fed, or fed through a tube in the nose (nasogastric tube) or esophagus (esophagostomy tube). Hospitalization is usually required for the first few days. Treatment for hepatic lipidosis may also include some or all of the following:
Vomiting is a frequent finding in cats with hepatic lipidosis. Many cats require a medication to help control vomiting, such as metoclopramide, maropitant, or ondansetron, especially during the initial 1 or 2 weeks of tube feeding.
Some cats with liver disease develop ulcers and subsequent gastrointestinal bleeding. Drugs that control gastric acidity, such as pepcid, omeprazole or pantoprazole, may be necessary to help control this. Sucralfate, a gastric protectant, may be used in conjunction with the antacids.
Antibiotics may be necessary in severe cases. They help kill off bacteria that produce harmful toxins that may lead to various mental manifestations of liver disease (drooling, depression, blindness, seizures).
Blood transfusions may be needed if the liver is so impaired that it cannot produce adequate clotting factors or cannot regulate the ability of the blood to clot properly.
Appetite stimulants (mirtazapine) may be helpful in cats that persistently refuse to eat.
Ursodeoxycholic acid, a drug that improves bile flow within the liver, may be helpful in selected cases.
Although the actual cause of the disorder is unknown, obesity and anorexia have been noted to be associated with the onset of disease. Therefore avoid overfeeding your cat to prevent obesity and avoid stressful situations that may cause a cat to suddenly stop eating, such as the addition of a new pet or family member, or suddenly changing your cat’s diet.