Tuesday, January 7, 2014

Hepatic Lipidosis (Fatty Liver Disease) by Dr. Dana Lewis


Lipidosis (abnormal fat metabolism) is a cause or contributing cause of liver failure when a cat that was once overweight loses weight too quickly. (While it is more common to occur in an overweight cat, it can happen in any cat who loses a considerable amount of weight suddenly). Cat owners don’t realize the danger with this rapid weight loss, and are pleased to see the chunky cat becoming “healthier” weighted. The good news is that there is a good recovery rate for this condition provided it has not progressed too far, but this will require aggressive support to reverse the disease process, and also if the underlying reason for the problem is not serious in itself.  If a cat has gone missing and returns feeling unwell or without an appetite, have it evaluated immediately.

Fatty Liver (Hepatic Lipidosis)

Approximately 2 weeks of eating 1/2 - 3/4 the normal amount of food is needed to develop a fatty liver.  Cats evolved as predators of small birds and rodents, eating multiple small meals throughout the day. As carnivores in the wild, cats would be lean and never develop extensive fat stores.

This changed when cats became domestic. The modern housecat has the opportunity to become overweight and should the cat get sick or lost, and stop eating, a very big problem occurs since the cat liver was never intended to handle huge amounts of mobilized fat. The liver becomes infiltrated with fat and fails. Complicating matters are the high dietary protein requirement that is unique to cats; protein malnutrition develops fast when cats do not eat.

But My Cat Loves to Eat!  Why Did the Feeding Frenzy Stop?

Initially there was an underlying cause of the decrease in food intake that started the cat down the slippery slope to lipidosis. Keep in mind that hepatic lipidosis rarely happens for no apparent reason. If there is an underlying cause, it must also be addressed.  If you’re lucky, the underlying cause has resolved (such as the cat was lost/starved and has now been found).

Cornell University looked at 157 cats with lipidosis and looked at what conditions occurred first. Here is a summary of what they found:
  • 28% had inflammatory bowel disease
  • 20% had a second type of liver disease (usually cholangiohepatitis)
  • 14% had cancer
  • 11% had pancreatitis
  • 5% had social problems (new cat, new home, threatening other pet or person at home)
  • 4% had some kind of respiratory disease
  • 2% were diabetic
Liver Disease vs. Liver Failure

About 70% of cats in liver failure are jaundiced (yellow); they are also frequently nauseated, will not eat, and are obviously ill. The jaundice (also known as icterus) is often not noted by the pet owner but can often be seen by carefully examining the whites of the eyes, the gums, or in the ear flaps. Sometimes the yellow color is not evident to the naked eye but is picked up as a blood test elevation in bilirubin, a yellow pigment normally processed by the liver.  The average cat with lipidosis is middle-aged, has lost at least 25% of its original body weight, and 38% will have vomiting, diarrhea or constipation.

Liver disease may be picked up as an elevation in a blood test enzyme called alkaline phosphatase, or ALP. This enzyme should never be elevated in a cat. There are several forms of this enzyme in the body, not just the liver version, so an elevation is suggestive of liver disease and usually requires follow up testing of actual liver function.  Other liver enzymes on routine blood panels are alanine aminotransferase (ALT) and aspartate aminotransferase (AST).   We also look at other blood values that the liver has a role in processing or producing, such as BUN and albumin.  A lab test that might be helpful in determining underlying cause is the GGT (gamma-glutamyl transpeptidase) level. It is usually not elevated in lipidosis but would be elevated if there is an underlying additional liver disease or in the event of pancreatitis.

It is important to distinguish tests of liver damage, like enzymes, versus tests of liver function, like bile acids. The enzymes ALT and AST are normally held inside liver cells; when their presence is detected free in the bloodstream, this is an indicator of liver cell death. A liver can have damage without any decrease in its overall function, so elevations don’t equal liver failure.  Also, liver enzymes can be really low in end-stage failure due to so few living cells producing these enzymes anymore, so normal enzymes do not equal a healthy, functioning liver.

A liver function test is different. In a liver function test, the liver is actually asked to do something and we measure whether it does the job sufficiently or not.  In this way, we can see if the liver is actually in need of support.  The one frequently used is called a Bile Acids Test.  Testing bile acids is not necessary if bilirubin is already elevated.

Tissue sampling such as biopsy or needle aspirate is crucial to the diagnosis of liver disease. Without a tissue sample, all we can tell is whether or not the liver is in failure and specific therapy for a specific type of liver disease is not possible (though general support of the failing liver may still be possible.) A needle aspirate or tissue biopsy shows hepatic lipidosis +/- other forms of liver disease.

Treatment of Fatty Liver Disease:


The cornerstone of treatment for lipidosis involves aggressive nutritional support. (In other words, a high protein diet must get into the cat to reverse the metabolic starvation state.) If this is done carefully, the recovery rate approaches 90%.  Cats that show a 50% drop in total bilirubin level within 7 to 10 days are statistically likely to survive.

Many people are reluctant to place or work with feeding tubes and want to try feeding the cat at home. There is no room for tentative treatment when it comes to this disease. Force-feeding at home can work but one must have a specific amount of food to feed and that amount must be successfully fed if the patient is to recover.  Generally, by the time a cat has gotten into trouble with hepatic lipidosis, most owners have already tried tempting cats with assorted favorite foods and gotten no results. At the point where lipidosis has developed, the cat CANNOT be given a choice about eating; there are several methods of providing food you can enlist.  Ask your veterinarian about diets that fit the high protein profile best for lipidosis cats, and if they have a feeding tube, use the diet recommended to reduce the likelihood of clogging issues.

For a few cats, force-feeding is non-stressful and easily performed. To provide nutrients, you have to understand how much of the food product should be fed daily and how much may be fed per meal. Food is generally canned and of a consistency like hamburger. Generally, food can be fed by syringe or meatball method.  Using a syringe can be stressful and you risk aspiration of the food into the lungs.  Canned food meatballs can be made of approximately a one-inch diameter and given to the cat in the same way you would give a pill. Be careful to give the cat enough time to fully swallow the first meatball before proceeding to the next one. An entire 3 oz can of cat food can be fed in this way. If struggling results or if the cat attempts to scratch or bite, this feeding method may be too stressful.  It is also quite messy.

Feeding Tubes:

Once the cat comes home, you can do this!  It might look intimidating, but the cat has to eat in order to recover.
(Jack from Chocolate and Crossants blog)
A nasogastric feeding tube can be passed by your veterinarian through the nose, into the stomach and sewn into place to allow feeding of a liquid diet. Placement of this kind of tube does not require anesthesia, and the tube is relatively easy to use. The tube can be dislodged by the cat, so an Elizabethan collar is necessary to protect the feeding tube. Only liquid diets can be fed through the tube due to its small diameter. The tube can also be pushed backward if the cat vomits, so that it opens towards the mouth instead of the stomach. All of these problems make the nasogastric tube the least popular of all the feeding tubes when it comes to long-term use; however, often this form of feeding is used for the first few days as this is when bleeding risk is highest and the patient is least stable for anesthesia. One of the other tubes can be placed when the patient is more stable.
(Eddie from esheley.wordpress.com)
Esophagostomy tubes are larger and stick out of a bandaged incision in the neck. Food must be blenderized but does not have to be fully liquid. The larger diameter of the tube makes feeding easier and the tube is more comfortable but the tube does require general anesthesia for placement.

Gastrostomy tubes can be placed via an endoscopy or a special applicator called an ELD gastrostomy applicator. This tube is placed under general anesthesia but thought to be the most comfortable to wear. A bandage around the belly protects the tube which enters directly into the stomach through the body wall, and which must stay in place a minimum of two weeks but can stay in place as long as a year (maybe longer, though the treatment of lipidosis requires generally 4 to 6 weeks or so of tube feeding).

When a patient has been in starvation mode for a while and then begins to eat, some serious metabolic problems may occur in the first few days as metabolism changes, such as low potassium or phosphate.  So expect the cat to be monitored in the hospital for the few days following initiation of nutritional support.

Some Feeding Tips:
  • Know how much of the food should be fed per day-size of meals and total amount per day gradually are increased over a couple days.  Follow your veterinarian’s guidelines.
  • Tube feeding should be expected to continue 4 to 6 weeks.
  • The feeding tube should be cleared with warm water prior to and again after food administration, or if it clogs during feeding.
  • Food must be warmed and administered slowly to avoid inducing vomiting.
  • Medication should not be administered through the feeding tube unless directed by your veterinarian. Many tubes are easily clogged this way.
Other Support
There are several medications that are supportive to the liver that might be used.  These might assist the body in excreting bile, supporting liver function, removing toxic bile acids, or replacing vitamins that are low.  Your veterinarian will let you know which ones are indicated for your kitty.

Written by Dr. Dana Lewis

Read more or contact Dr. Dana:
Dana Lewis, DVM
Lap of Love Veterinary Hospice
Raleigh, North Carolina
drdana@lapoflove.com  |  www.lapoflove.com

Dr. Dana assists families with Pet Hospice and Euthanasia in the Raleigh North Carolina area (Raleigh, Durham, Chapel Hill and the greater Triangle, as well as Wake, Durham, Orange, and Chatham counties. 

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