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January 31, 2012 at 6:00 AM

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Veterinary Q&A: Liver disease

danabrooks.jpgDr. Dana Brooks, an internist at Seattle Veterinary Specialists in Kirkland, answers this week's questions.

Question: What role does the liver play in a dog or cat's body?

Answer: The liver has many functions. The main functions are detoxification (takes drugs or toxins out) of the blood stream, regulation of blood-sugar levels, maintenance of blood protein and cholesterol levels, production of bile that helps to metabolize fats and production and maintenance of normal blood-clotting factors.

Question: What can go wrong with a liver?

Answer: The basic disease processes are divided into infection; inflammation; toxicity; cancer; metabolic disease; congenital diseases; and trauma.
Most people think hepatitis (inflammation of the liver) is a viral disease, because this is common in people. But viral hepatitis is very uncommon in dogs. Cats can develop hepatitis as part of the viral disease feline infectious peritonitis.

Infectious causes of hepatitis in dogs and cats are more commonly caused by bacteria, and less commonly by fungal, parasitic or protozoal diseases, such as fungal (blastomycosis), parasitic (roundworm migration in puppies and kittens), protozoal (toxoplasmosis).

Hepatitis can also occur when the body's immune system attacks itself. This is one of the more common causes of liver problems in dogs and cats.

The cause of the immune-system disturbance is not always apparent. In cats, it is often associated with inflammatory bowel disease (usually associated with food allergies).

Some breeds of dogs can be predisposed to developing hepatitis, such as the Doberman, Labrador and cocker spaniel.

Chronic hepatitis can lead to cirrhosis, which is an irreversible condition in which healthy liver tissue has been replaced by nonfunctioning scar tissue.

Liver toxicities can occur from ingesting certain poisonous mushrooms (Amanita); blue green algae; xylitol (found in sugar-free items such as chewing gum); acetaminophen (Tylenol); and abnormal reactions to some therapeutic medications (arthritis medications, immunosuppressant medications, anticonvulsants, and some antibiotics).

Many different types of tumors can affect the liver, some benign, some malignant. The cancer can start in the liver or it can spread to the liver from another site (metastasis).

Some metabolic diseases like diabetes mellitus, hyperthyroidism and hyperadrenocorticism (Cushing's) can cause elevations of liver enzymes.

The most common congenital disease to affect the liver is a portosystemic shunt. This occurs when an abnormal blood vessel allows blood to bypass the liver, which is responsible for removing toxins. There are also some rare storage diseases that can affect the liver in certain breeds (bedlington terriers, West Highland white terriers, Doberman pinschers.)

Question: When the vet orders a complete blood chemistry to determine the health of my pet, what kinds of liver-related issues might he/she be looking for?

Answer: The main tests that give us information about liver health are the enzymes ALT, ALP, GGT, AST and bilirubin. Increases in these numbers indicate that something is wrong with the liver, but not the specific disease process.

An ultrasound, aspirare or, preferably, a biopsy is usually needed to reach a definitive diagnosis. Other values such as BUN, albumin and cholesterol can be helpful as well. Decreases in these numbers indicate decreased liver function.

Another test that might be recommended when liver disease is found is bile acids, which looks at liver function more specifically. These are very elevated with shunts and liver failure.
Question: What are the physical symptoms of liver problems?

Answer: Some dogs and cats will have no symptoms of liver disease, and it is discovered on routine blood work. Symptoms in ill dogs and cats can include vomiting, decreased appetite, weight loss, seizures or disorientation (with shunts or end-stage liver failure), or a yellowish discoloration of the skin (jaundice or icterus).

Question: Is liver disease treatable or reversible? How quickly can liver cells rejuvenate?

Answer: Infectious hepatitis can be treated with antibiotics and should be reversible with the exception of viral disease. Immune-mediated hepatitis isn't cured, but it is managed with medications that suppress the immune system.

Metabolic disease is treated by treating the underlying disease process.

Toxicities are usually treated with supportive care and the damage is often reversible.

Cancer of the liver may be treated with surgery or chemotherapy based on the type.

Liver shunts are treated with surgery to close the abnormal blood vessel.

The exact amount of time for liver regeneration is not known and depends on many factors, such as how much damage occurred and how healthy the remaining liver tissue is. In general, weeks to months is most likely.

Question: Are any liver problems age-related?

Answer: Liver tumors tend to be more common in older dogs and cats, although liver cancer could potentially occur at any age.

Young animals tend to be more prone to toxicities because they tend chew inappropriate things, and shunts are usually found in puppies or kittens if they are severe enough to cause clinical signs.

Question: Are there foods or diets that can improve the health of my pet's liver? Are there some we should definitely avoid?

Answer: Dogs and cats with significant liver dysfunction usually do better on a lower protein diet. The liver is responsible for detoxifying some of the bacterial byproducts of protein digestion, and by supplying a higher quality but lesser amount of protein, the liver is delivered less of a load of substances to remove.

There are some prescription diets designed for dogs with liver disease that are limited in copper (copper tends to get deposited in the liver cells when there is chronic inflammation and it can continue the damage), and supplemented in zinc (helps to decrease copper absorption and removal of copper from the liver), and vitamin E (for it's antioxidant effects).

Other than avoiding high protein in dogs and cats with liver disease, there are no other specific foods to stay away from. A high-fat died is usually not a problem with primary liver disease.

Question: If my dog is a breed that is prone to liver problems, or I know problems have cropped up in the breeder's line of dogs, should I have tests done more frequently or be on the lookout for certain symptoms that may appear? How can I be proactive?

Answer: Hepatitis is often asymptomatic, but yearly chemistry profiles are sufficient for most dogs and cats. Anytime a dog or cat becomes lethargic, is vomiting or has a decreased appetite, blood work is usually a good idea.

Question: Are liver transplants available for pets? Can partial livers be used in transplant as they can in humans?

Answer: To date liver transplants have not been routinely successful in dogs or cats. Much of the difficulty arising from liver transplantation is ethical (taking organs from a healthy dog not able to deny consent), and the availability of a compatible donor.

Dr. Dana Brooks

Brooks is a internal-medicine specialist at Seattle Veterinary Specialists in Kirkland. She graduated from Mississippi State University College of Veterinary Medicine in 1991 and completed her residency at Michigan State University Veterinary Teaching Hospital in 1995. She worked in the Northeast until 2007, when she joined SVS. Her special interests include hormonal and immune-mediated diseases as well as endoscopy. She lives with two black cats named Jasper and Logan.

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Read our past Q&As:
Veterinary Q&A: Human meds can be toxic for pets
Veterinary Q&A: Food allergies
Veterinary Q&A: Follow-up on toxins -- aloe vera
Veterinary Q&A: Common toxins for pets
Veterinary Q&A: Dogs with dry, itchy skin
Veterinary Q&A: Ways to stop stool eating
Veterinary Q&A: Holiday toxins that can hurt your pets
Veterinary Q&A: Itchy skin and hair loss in cats.
Veterinary Q&A: Pancreatitis
Veterinary Q&A: Dementia and senior dogs
Veterinary Q&A: More health issues facing aging dogs
Veterinary Q&A: Eye problems in aging dogs
Veterinary Q&A: Halloween treats and pets
Veterinary Q&A: Health issues facing aging dogs
Veterinary Q&A: Why blood work is necessary
Veterinary Q&A: Are prong collars safe for your dog?
Veterinary Q&A: Birth control for pets
Veterinary Q&A: How to find a good vet
Veterinary Q&A: Neutering your dog Part 2
Veterinary Q&A: Neutering your dog Part 1
Veterinary Q&A: Hyperthyroidism in cats
Veterinary Q&A: Incontinence in dogs
Veterinary Q&A: Hanging tongue syndrome
Veterinary Q&A: Bad breath in dogs
Veterinary Q&A: How much is too much exercise for my dog? Part 2
Veterinary Q&A: How much exercise does my dog need? Part I
Veterinary Q&A: A killer called bloat
Veterinary Q&A: Initial care for new puppies
Veterinary Q&A: Knee problems in dogs
Veterinary Q&A: Flea-control treatment
Veterinary Q&A: Bearded dragon lizards
Veterinary Q&A: Vaccinations for indoor cats
Veterinary Q&A: Lumps and bumps
Veterinary Q&A: More on aging dogs and arthritis
Veterinary Q&A: Aging dogs and arthritis
Veterinary Q&A: Puppy and geriatric exams
Veterinary QA: What dogs can safely chew
Veterinary QA: Why does it cost so much to clean a dog's teeth?
Veterinary QA follow-up: More on cleaning a dog's teeth
Veterinary QA: When to spay or neuter

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Do you have a question about pet health? Ask now! We'll pose some of your questions to a local vet in an upcoming post.

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