The liver is the largest internal organ in the cat (and in humans, too!) and has many important functions. You can read all about what the liver does in cats and the related potential health problems in our articleArticle: Liver Disease In Cats. These health issues include things like liver cancer, inflammation of the gallbladder and even poisoning.
When something goes wrong with your cat's liver this can be a serious problem. So, if Kitty's blood tests show elevated liver enzymes, how alarmed should you be? We talked to veterinary expert Dr. Letrisa Miller - an award-winning veterinarian with more than twelve years’ experience as a feline-only practitioner - and have some answers for you!
What are liver enzymes anyway?First, a recap on what an enzyme is. In a nutshell, enzymes are proteins that can break apart specific large molecules into smaller ones. They can also create specific new compounds by putting together smaller molecules. Essentially, they are one of the body's tools to manage its biochemistry.
The liver itself is a wondrous biochemical factory where some molecules get torn apart into smaller more manageable pieces, while others get put together into larger structures used for storing energy or other purposes. It's no wonder that the liver uses many types of enzymes to manage this factory.
How can your veterinarian diagnose liver problems?There are many ways to check the liver, blood tests being just one of them. Other tests include -
Your vet will also take into consideration your cat's age and the overall condition of their health. He or she may ask you about what you feed your cat and inquire about changes in your cat's appetite and eating and drinking habits, as well as overall behavioral changes.
- Touching the cat's abdomen to feel the liver and its size.
- Looking at the cat's gums, the membranes under the eye and other tissues to look for jaundice.
- Using an ultrasound to look for changes in the liver's inner structure.
- Taking a biopsy and look at the liver cells under a microscope.
It's important to remember that the liver functions blood tests are just one tool. The results are usually not enough on their own.
What liver enzymes are usually tested in cats?Many "in-house" blood analyzers don't have all of these enzymes included in their profiles, but have the benefit of results in 10-15 minutes rather than 24 hours. Dr. Miller says that the following enzymes are usually covered in a liver functions blood test -
GGT (gamma-glutamyl transpeptidase)
GGT is often elevated in any liver disease, but it is markedly elevated in hepatic lipidosis.
ALT (alanine transferase)
ALT is very specific to leaking, damaged liver cells, but is otherwise pretty non-specific.
ALP (alkaline phosphatase)
ALP is fairly specific for biliary (bile ducts and gallbladder) damage in the cat, but it can come from the tiny bile ducts in the liver or the gallbladder and large ducts outside the liver.
AST (aspartate aminotransferase)
AST can be more sensitive in cats for some types of liver disease such as the granulomatous inflammation found in FIP, but is also produced by muscle damage.
Bilirubin is also included in the test. This is not an enzyme, but a product of hemoglobin breakdown that becomes part of the bile. A cat with high levels of bilirubin is jaundiced, but Dr. Miller warns against assuming that jaundiced cats necessarily have liver disease. There may be other reasons for jaundice, such as red blood cell disease.
Elevated liver enzymes in cats - what could they mean?According to Dr. Miller, the results can be indicative of many conditions. It's important to look not just at the separate figures, but at the ratios between them and the overall pattern they create.
The list of possible health conditions that cause liver enzyme counts to go up is very long. Here are the common ones -
Clearly, the source of the problem is not always the liver itself. In fact, sometimes the enzymes aren't coming from the liver, because other organs produce the same enzyme.
- Hepatic lipidosis
- Biliary obstruction
- Inflammatory bowel disease (triaditis)
- Endotoxin producing infections
- Hepatitis (there are different types of hepatitis)
- Biliary stasis
- E. coli enteritis
Could this be nothing?
Dr. Miller says that benign elevation of enzymes is rare in cats.The exception would be with elevated levels of ALP (Alkaline Phosphatase) in kittens. This can happen due to rapid bone growth, as osteoblasts - cells involved with bone formation - also produce ALP. In kittens, this can be a benign finding.
There are a few drugs that can elevate enzymes. If this happens, your vet may suggest that you stop the medication. Please note that you should never stop a course of medication without asking your vet first as in some situations, the benefit from the drug could still outweigh potential risks.
What's the prognosis?The prognosis - or expected outcome - depends on the actual diagnosis, which is based on your vet's overall assessment of the cat. Dr. Miller has encouraging words for you -
The diseased liver brings about loss of appetite, but without food, things will only get worse. That's why helping the liver to heal may include tube feeding, a procedure which scares many owners. Dr. Miller cautions against opting for force feeding instead of tube feeding, saying it could lead to long-term food aversion. "Feeding tubes are quickly and easily placed and allow all food and medications to be given without stress to the cat", she says.
What you should doElevated liver enzymes in cats are not the end of the world, but are an indication that something is wrong. The results of the blood tests require expertise and experience to decipher, as the overall pattern and ratio between the various enzymes need to be taken into account. You have to work with your veterinarian on getting a proper diagnosis. It may take further testing and some time, but it is the key to getting your cat better.
As always, if you don't feel comfortable with the medical care given to your cat, it's perfectly ok to seek a second opinion, preferably from a feline specialist.
You're not alone. Many cats have suffered - and recovered - from liver disease. Share your experience in our cat health forum to get the support of other cat lovers.
Dr. Letrisa Miller is a feline-only veterinarian who owns and operates the Connecticut Feline Medicine and Surgery, LLC at Manchester, CT.
Dr. Miller is a founding fellow of the International Association of Cat Doctors and has served as president in 2012 and 2013. She is also a member of the American Veterinary Medical Association, the Connecticut Veterinary Medical Association, the International Society of Feline Medicine, and the Veterinary Information Network.
From 2006 through 2011 Dr. Miller was a board member of the American Association of Feline Practitioners AAFP) and for several years she was the chair of the AAFP's research committee. In 2010 she represented the AAFP at the founding of the Cat Health Network, a collaboration among the American Veterinary Medical Foundation, Morris Animal Foundation, Winn Feline Foundation, and AAFP to fund and promote research in feline medicine.You can read more about Dr. Letrisa Miller on her website.