Old yellar could have been a cat, too
December 23, 2003
Of course, this article is about jaundice in cats, and please excuse the bad pun. Jaundice, or icterus, is a yellowish discoloration of the skin, eyes and mucus membranes caused by accumulation of excess bilirubin in the bloodstream.
So how and why would a cat accumulate excess amounts of bilirubin in his or her bloodstream? And what is Bilirubin anyway? First let’s have a little science lesson.
Hemoglobin, the stuff in red blood cells that carries oxygen, is released when a red blood cell dies. Under normal conditions a red blood cell lives 80 to 90 days. The hemoglobin is broken down for recycling and one of the components is bilrubin, also known as BR.
BR is then taken to the liver where some of it is modified – or, conjugated – and some is not; you don’t need to dwell on the difference. Your veterinarian does as it might aid our diagnosis. Regardless, most of it is made into bile and stored in the gall bladder where it aids digestion, gets reabsorbed and recirculated.
Now you can see how a cat could accumulate excess bilirubin, right? Either problems in the liver metabolising it occur; red blood cells die before they should and the liver gets overwhelmed; or problems prevent bilirubin from leaving the gall bladder and everything gets clogged up.
These are called, in order, hepatic, pre-hepatic or post-hepatic jaundice. Medicine’s not that hard.
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Pre-hepatic jaundice is often caused by or associated with hemolytic anemia. In this type of anemia the blood cells are burst open. or hemolyzed. Since the liver has a remarkable capacity to deal with excess bilirubin, the anemia is usually acute and severe.
The urine may appear red or port wine color. Some of the infectious causes are hemobartonella, babesia and cytauxzoonosis. Drugs like acetominophen (tylenol) can also cause hemolytic anemias as can transfusion reactions.
By far the most common cause of jaundice is liver disease or hepatic jaundice. In addition to jaundice, these pets usually show other signs of liver disease such as vomiting, diarrhea, ascities (fluid buildup in the abdomen), weakness, drinking and urinating a lot, stupor and dementia.
The urine and feces often appear dark brown or orange. Here’s a list of some of the causes: feline leukemia virus, feline immunodeficiency virus, feline infectious peritonitis, hepatitis, hepatic lipidosis, cholangiohepatitis (inflammation of the liver and/or bile ducts), toxoplasmosis, diabetes, drugs, toxins and cancer. That’s a pretty good list.
Hepatic lipidosis is worth a few minutes of discussion because it is peculiar only to our feline friends. Man and dogs can go days to weeks without food as their metabolism doesn’t cause them to go into liver failure. Cats on the other hand cannot go for more than a few days without food, especially if they are overweight – studies show almost half of them are.
Starvation and anorexia causes their liver to be infiltrated with fat and the cats go into liver failure. If your cat stops eating seek care very quickly.
Post-hepatic jaundice only has a few causes; most of them are related to compression of the gall bladder ducts. Pancreatitis or tumors of the pancreas can often cause this as the gall bladder ducts run near the pancreas on their way to emptying in the duodenum.
If the bile duct is completely blocked, say, with gall stones, the stools may become grey colored. Obstruction can also cause bleeding disorders as vitamin K absorption is decreased.
Diagnosis and treatment
To diagnose the cause of jaundice in your cat some lab tests are in order.
The minimum tests you should expect are: complete blood cell counts, serum biochemistries, urinalysis, thyroid tests (for older cats), and abdominal radiographs (X-rays).
If a hemolytic anemia is suspected, tests for autoimmune diseases will be run as will tests for blood parasites and viral infections.
Hepatic jaundice will require further testing in the area of the liver: bile acid tests and an abdominal ultrasound with or without liver biopsy are recommended. The same tests are indicated for post-hepatic jaundice in addition to checking blood amylase and lipase levels, which were probably ordered in the serum chemistries.
Once the cause is determined we can devise a treatment plan. Hemolytic anemias are treated by killing the blood-borne parasites or using heavy doses of immunosupressive drugs like cortisone, cyclophosphamide or azathioprine.
Hepatitis is treated by using supportive care such as intravenous fluids, antibiotics, and forced tube feedings. Hepatitis and cholangiohepatitis can be difficult to treat as there is no “magic bullet” for these diseases.
Deshydrocholic acid can be used to help improve bile flow through the gall bladder ducts. For cats with hepatic lipidosis it is critical to survival to begin getting food in these cats immediately. This involves force feeding, nasoesophageal intubation or a gastrotomy tube.
Diet is also important in treating jaundice. An ideal diet is Hill K/D. Diets for hepatic disease should be low in protein and have more of the calories coming from fat and carbohydrates. If your cat has a hemolyitc anemia a diet higher in protein is recommended as protein helps build red blood cells.
The prognosis depends on what caused the jaundice. Most cats are young cats about 4 years old. Some studies showed over 50 percent of cats with icterus died or were euthanized; these are not good numbers.
Early diagnosis and treatment most assuredly will help the odds if you cat becomes icteric.
Dr. Stephen Sheldon, owner of Valley Veterinary Services, practices by appointment at Alpine Meadows Veterinary Hospital in Edwards. He can be reached at 748-3062.