Old Yeller Could Have Been A Cat Too!
Stephen Sheldon, D.V.M.
Of course, this article is about jaundice in cats. 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/her
bloodstream? First let's have a little science lesson. Hemoglobin, the component of red
blood cells that carries oxygen, is released when a red blood cell dies. Under normal
conditions a red blood cell lives 80-90 days. The hemoglobin is further broken down and
one of the components is bilrubin. Bilirubin is then taken to the liver where some of it is
modified (called 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 .....yata, yata, yata.
Now you can see how a cat could accumulate excess bilirubin; right? Either problems in
the liver metabolizing it occur; red blood cells die before they should and the liver gets
overwhelmed with it, or problems prevent it from leaving the gall bladder and everything
gets clogged up. These are called, in order, Hepatic, Prehepatic, or Posthepatic jaundice.
Prehepatic 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 anemia, 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/urinating a lot
(those 2 usually go together!) and stupor/dementia. In these cases the urine often appears
dark brown or orange; even the feces can take on this appearance. 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; 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 (which 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.
Posthepatic 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 ducts are completely blocked the stools may become gray colored. Complete
obstruction can also cause bleeding disorders as vitamin K absorption is decreased.
Besides pancreatitis and tumors, gallbladder stones can cause obstruction. One very
common cause is cholangiohepatitis, inflammation of the liver and gall bladder, the cause
for which is not known for sure. Liver flukes can also cause obstruction of the gall
bladder ducts.
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 (older cats), and abdominal radiographs (x-rays). If a hemolytic anemia is
suspected, tests for autoimmune diseases (coombs, ANA, RF) 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 immunosuppressive
drugs like cortisone, cyyclophosphamide 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. If GI ulceration occurs we use drugs like cimetidine, ranitidine, and
sucralfate. For cats with hepatic lipidosis it is critical to survival to begin getting food in
these cats immediately. This involves force feeding, nasoesophageal intubation (NE tube)
or a gastrotomy tube. Cats tolerate the NE tube fairly well and it's easy to maintain.
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% 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