Monday, December 8, 2014

Did you just call my cat's liver "fat"? - Hepatic Lipidosis in cats




Hepatic Lipidosis, or Feline Fatty Liver Syndrome



What is the Fatty Liver Syndrome, and how does a cat get it?

The feline Fatty Liver Syndrome (FLS) is also known as feline hepatic lipidosis.  This disease is one of the most common liver diseases seen in cats. The liver is the organ in the body that makes proteins that help deliver nutrients to the body and aid in forming blood clots, among other important tasks. The liver also makes chemicals that aid digestion and detoxifying the body. The liver is a vital part of so many body functions that when it fails, the body cannot compensate.

Bilirubin in the blood and urine gives it this distinctive color brownish-orange to highlighter yellow
Often, a cat that has developed FLS has recently gone through a period of anorexia (not eating).  Sometimes, the period of not eating may seem very short, but in fact, the cat has only been eating tiny amounts, spending a long time at the food bowl, but only licking at the gravy or moving kibbles around, but not really ingesting any actual food. The chances of the FLS occurring are greater if the cat was overweight before the anorexia began.  Because the cat is not eating and taking in nutrients, the body begins to break down fat to supply energy. As fat is broken down to supply nutrients for the malnourished cat, the fat is deposited so rapidly in the liver that it cannot be processed. Cats are highly efficient predators that need a large supply of protein in their diet - they cannot process large amounts of fat. The liver stores the excess fat in and around the liver cells, resulting in liver enlargement and eventual liver failure.  The cat often becomes icteric or jaundiced as evidenced by a yellow color in the whites of the eyes or in the skin.  At this point, the disease will be fatal if not treated rapidly and aggressively.

Other conditions that may result in FLS include illness (such as upper respiratory infections or pancreatitis), periods of stress (moving to a new home, addition of a baby, addition of a new pet), changes in diet, diabetes, kidney disease, cancer, aggressive weight loss attempts by owners, and being lost (away from home and meals).

What are the symptoms?

  • Prolonged lack of appetite (anorexia) or poor appetite – often of several week duration
  • Rapid weight loss
  • Hiding in unusual places 
  • Vomiting
  • Diarrhea
  • Constipation or very small stools in the litterbox
  • Muscle wasting
  • Depression
  • Dehydration
  • Downward flexion of head and neck - more than the usual chin tuck when sleeping
  • Jaundice (e.g., yellowing of eyes or skin)
  • Drooling or nausea
  • Weakness, lethargy or eventual collapse
  • Severe cases may exhibit black tarry stool; bruising (abnormal clotting); abnormal behavior, seizures or coma (from buildup of toxins in the body)
  • Other symptoms will be related to concurrent, underlying disease
  • Eventual death, if untreated
 
How is it diagnosed?

Large fat deposits around liver cells

Diagnosis of the FLS is made from blood tests for liver function and from a liver biopsy or aspirate.  The latter involves inserting a very tiny needle through the skin and into the liver, removing a small number of liver cells, and examining those cells under the microscope.  The FLS cat will have a large amount of fat in and among the liver cells. 

Common tests that would indicate fatty liver would include liver-specific tests, such as ALT, AST, ALP which are liver enzymes. Additionally, a test for bilirubin would usually be elevated in the presence of this disease, because a functioning liver usually filters bilirubin out of the blood stream to eliminate it from the body. Buildup of bilirubin suggests that the liver cannot filter as it should. Similar tests would include checking cholesterol and ammonia levels. Additionally, cats with FLS are often dehydrated, have electrolyte imbalances, or may be anemic due to lack of nutrients and liver function, so testing to determine the scope of the problem in preparation for IV fluid therapy.

Additional diagnostics will likely be done to identify potential underlying causes of the poor appetite, so kidney function, a complete blood count, or other testing may be recommended. Ultrasound or x-rays may also be recommended. If the cause for anorexia is treatable or resolved, the prognosis is reasonably good.

Is this a treatable disease?

This disease is very treatable, but treatment of the FLS requires that the cat receive nutritional support until the appetite returns.  A consistently high quality diet will allow the liver to resume functioning so it may remove the fat.  This does not occur quickly; it takes an average of 6-8 weeks.  Therefore, a method of force feeding must be used to allow you to feed your cat at home. In most cases, we recommend the placement of a feeding tube in order to administer high-calorie feedings to your cat several times daily with minimal additional stress until the cat is eating well again on his own. Most cats tolerate an esophageal feeding tube very well. The liver has remarkable regenerative properties, so supporting the cat and treating underlying disease while the liver heals can be very effective, if intensive.

IV fluid therapy will help to correct dehydration. Anti-vomiting or anti-nausea medications will help the cat keep the food in his stomach. Appetite stimulants are generally not very helpful on their own in these cases because the cat is too ill to have any motivation to eat.
 

Approximately 2 weeks of eating 1/2 - 3/4 the normal amount of food is often all it takes to develop a fatty liver. If your cat seems to have poor appetite for more than a day or two, it is very important to have him examined by a veterinarian! If caught early, this condition has an 80-90% recovery rate, but if left untreated, death is the result in 90% of cases.

Additional resources:
Hepatic lipidosis information from Mar Vista Animal Medical Center