Disorders of the Liver and Gallbladder in Cats
The liver performs numerous functions. It has a large storage capacity and functional reserve and is capable of regenerating. These properties provide some protection against permanent damage. However, the liver is also susceptible to injury because of its role in metabolizing, detoxifying, and storing various toxic compounds.
Signs that a cat has liver disease can vary and include loss of appetite, vomiting, stomach ulceration, diarrhea, fever, blood clotting problems, jaundice, abdominal swelling, excessive urination and thirst, changes in liver size, weight loss, and occasionally gastrointestinal bleeding.
A variety of blood tests can help detect and diagnose liver disease. X-rays and ultrasonography can help your veterinarian determine liver size and find irregularities, gallstones, and diseases of the gallbladder. Aspiration or biopsy procedures can be used to obtain samples for bacterial culture, cell and tissue analysis, and, when appropriate, toxicologic analysis. Other, less common tests, such as nuclear scintigraphy, may be used in some cases to identify portosystemic shunts and other blood vessel abnormalities.
Early treatment is critical for cats with sudden liver failure. Your veterinarian will prescribe specific treatment if an underlying cause can be identified. In cases of longterm or end-stage liver disease, and in cases of sudden liver disease when no underlying cause has been identified, supportive treatment is directed at slowing progression of disease, minimizing complications, and allowing time for the liver to regenerate and compensate. Supportive treatment may include the administration of fluids, medications to protect the liver, and dietary support.
The diet usually recommended for cats with liver disease is typically easy to digest and high in calories. Some liver disorders require modifications of fat or protein or supplementation with certain vitamins. Follow the specific advice provided by your veterinarian. It may be best to feed small, frequent meals. Cats that refuse to eat may require tube feeding.
Vitamin deficiencies can occur with liver disease. Prescribed vitamin and mineral supplements may include zinc, B vitamins, vitamin K, and vitamin E. Follow your veterinarian's recommendations on vitamin supplementation because overdoses of some vitamins can be harmful.
Hepatic encephalopathy is a neurologic syndrome caused by liver dysfunction and is seen in a number of liver diseases. Signs suggestive of hepatic encephalopathy include dullness, circling, head pressing, aimless wandering, weakness, poor coordination, blindness, excessive drooling, behavior changes (aggression for example), dementia, collapse, seizures, and coma. Treatment of hepatic encephalopathy includes supportive care and rapid reduction of the poisons being produced by the digestive tract. Severely affected cats can be comatose or semicomatose and should not be fed until their status improves. Treatment is likely to include intravenous fluids to correct dehydration and electrolyte (salt) imbalances. Enemas may be used to cleanse the intestines of ammonia and other poisons and to introduce nutrients that help decrease poison production. Medications to affect the bacterial populations in the gut may also be used to reduce the absorption of toxic products. Once the cat has been stabilized, treatment helps prevent recurrence. A protein-modified restricted diet may be prescribed. The signs of hepatic encephalopathy can be worsened by intestinal bleeding, infections, certain drugs (such as corticosteroids and sedatives), cancer, low blood sugar, fever, kidney disease, dehydration, and constipation. Your veterinarian may prescribe additional treatments to address these concerns.
Ascites is a condition in which fluid collects in the abdomen. In patients with liver disease, ascites is caused by a combination of high blood pressure in the liver and an imbalance in salt and water metabolism. The swelling may be controlled by prescribing a diuretic (a medication to increase the amount of water excreted into the urine), reducing sodium intake, extracting the excess fluid with a needle, or a combination of these steps.
Clotting defects occur in cats with liver disease because the liver produces many of the proteins responsible for the clotting process. In addition, there can be decreased absorption of vitamins that aid in clotting from the digestive tract. Clotting problems can be treated using transfusions of blood or plasma to provide the necessary clotting factors. Heparin and vitamin K can also be administered to decrease or increase clotting ability. Your veterinarian will prescribe the treatment most appropriate for your pet.
Cats with sudden liver failure and long-standing liver disease are susceptible to bacterial infections. Your veterinarian will be alert to this possibility because signs of the liver disease itself (for example, fever or low blood sugar) can be similar to those of infection. One or more antibiotics may be necessary to adequately treat the types of bacteria associated with the infection.
Fibrosis, the formation of fibrous scar tissue in the liver, can eventually lead to liver cirrhosis. Cirrhosis is a serious disease that disrupts liver function. However, fibrosis can sometimes be reversed or reduced by the use of appropriate medications. Your veterinarian can determine which, if any, of the available medications would be beneficial for your pet.
Acute liver failure results in sudden loss of liver function, which is often associated with hepatic encephalopathy and clotting abnormalities. It can occur due to a sudden injury of a previously healthy liver or due to an additional insult to an already diseased liver. It is important to seek immediate veterinary treatment to support the liver until it can regenerate and compensate for the insult. Any underlying causes of the liver failure need to be identified and treated, if present. Make sure to tell your veterinarian about any medications your pet receives or any access your pet may have to poisons. Treatment may include intravenous fluids, vitamin supplementation, diet changes, antibiotics, and certain liver medications. Another goal of therapy is to prevent or treat hepatic encephalopathy.
Hepatic lipidosis is the most common cause of liver disease in cats. Excessive accumulation of fat (triglycerides) within the liver leads to liver failure. The cause is unknown, but the disease is associated with a period of poor appetite (a few days to several weeks), especially in obese cats. Factors that may trigger loss of appetite include a change of diet (to initiate weight loss or to a food that the cat does not like) or other stressful events (such as moving, boarding, introduction of a new pet, getting lost, or death of other pets or owners). Hepatic lipidosis can also be associated with a metabolic disease (such as diabetes mellitus) or digestive system disease that causes loss of appetite.
Signs of hepatic lipidosis vary but can include dramatic weight loss (more than 25% of body weight) due to loss of appetite, vomiting, lethargy, and diarrhea. Jaundice or pale mucous membranes, excessive drooling, enlarged liver, inability to hold up the head, decreased activity of the intestines, and decreased body condition with retention of abdominal fat are commonly seen. Abnormal bleeding can develop, but signs of hepatic encephalopathy are not typically seen.
Veterinarians diagnose hepatic lipidosis based on a cat's history, physical examination findings, blood tests, and abdominal ultrasonography. The diagnosis is confirmed by analyzing a sample of the liver taken with an ultrasound-guided needle. To diagnose some causes of hepatic lipidosis, a larger biopsy must be taken during surgery.
Treatment is primarily supportive unless the underlying cause can be found. Fluid treatment is used to correct dehydration. Vitamin, mineral, and electrolyte deficiencies are common, and supplementation is often necessary. Additional liver medications may also be necessary.
Nutritional support is essential. Occasionally, a prescribed appetite stimulant will help if started early in the disease process. However, most of the time appetite stimulants are not effective, and placement of a feeding tube is necessary. Your veterinarian will recommend an appropriate food, usually a high-protein, calorie-dense, balanced diet. Initially, feedings are small and given frequently. The outlook is good if the diagnosis is made early, treatment is started promptly, and the underlying disease, if any, can be treated. Cats with concurrent pancreatitis tend to do more poorly. Recurrence of hepatic lipidosis is rare in cats who recover.
Inflammatory liver disease is the second most common liver disease reported in cats. The 2 types of inflammatory liver disease in cats are cholangitis/cholangiohepatitis syndrome and lymphocytic portal hepatitis.
Cholangitis is an inflammation of the bile ducts (small tubes within the liver that carry bile to the gallbladder and the small intestine). Cholangiohepatitis is an inflammation of the biliary tract that extends into the surrounding liver tissue. The differentiation between cholangitis and cholangiohepatitis depends on the location of inflammation within the liver. Cats with cholangitis or cholangiohepatitis may have other inflammatory disorders as well, such as inflammatory bowel disease, pancreatitis, and kidney disease (chronic interstitial nephritis). The combination of inflammatory bowel disease, pancreatitis, and cholangiohepatitis is often called triaditis. Other conditions associated with the cholangitis/cholangiohepatitis syndrome include bacterial infections, blood poisoning (septicemia), inflammation of the gallbladder, gallstones, liver flukes, tumors, and malformations or obstructions of the bile ducts. The diagnosis may involve bloodwork and ultrasonography, but the definitive diagnosis requires biopsies taken from several parts of the liver.
Suppurative (acute) cholangitis/cholangiohepatitis usually causes obvious and sudden illness in cats. Signs include fever, enlarged liver, abdominal pain, jaundice, lethargy, vomiting, poor appetite, and weight loss. The syndrome is typically seen in young or middle-aged adults. Affected cats have an increased risk for infections from the digestive tract. Treatment consists of fluids to correct dehydration and longterm (2 to 3 months) antibiotics to treat bacterial infections. Medications to protect the liver, vitamin supplementation, and nutritional support are often necessary. If there is an obstruction between the liver and the gallbladder, surgery is required to restore normal function.
Nonsuppurative (chronic) cholangitis/cholangiohepatitis usually affects middle-aged or older cats. Affected cats are typically ill for months or even years before diagnosis. Signs include intermittent vomiting and diarrhea, fluctuations in appetite, hiding behaviors, and jaundice that comes and goes. Progression to cirrhosis (end-stage liver disease) is possible but not common. Supportive fluid treatment, antibiotics, vitamin supplementation, and other appropriate drugs may be prescribed. Treatment with a corticosteroid is often recommended because of the suspected immune-mediated aspect of this disease. Additional types of medications may help cats that do not respond to initial therapy. Some types of medications may be needed longterm.
Lymphocytic portal hepatitis is an inflammatory disease of the liver that does not involve the biliary tract.. The cause is uncertain, but it may be related a reaction to organisms, debris, or immune cells that arrive in the liver from the digestive tract. Your veterinarian will be able to provide a treatment program based on the most current information.
Because the liver is the main organ that metabolizes drugs, some drugs can cause liver dysfunction in cats. The specific signs and effects depend on the drug and dosage. In many cases your veterinarian will be aware of the potential for liver disease when prescribing these drugs and will monitor your cat for any signs of decreased or altered function. It is also very important not to give your cat any human medications without consulting your veterinarian. Acetaminophen (Tylenol®), for example, is extremely toxic to cats.
Other substances that are toxic to the liver include heavy metals, certain herbicides, fungicides, insecticides, rodent poisons, aflatoxins (produced by mold), amanita mushrooms, cycad plants (Sago palm ornamental plants for the yard and home and bonsai plants), and blue-green algae.
If your pet has had an accidental overdose of a medication, has had an adverse reaction to a medication (even at the prescribed dosage), or has eaten a poison, a veterinarian should be consulted immediately. If necessary, the veterinarian can take steps to minimize absorption of the drug or poison. Depending on the situation, the veterinarian may induce vomiting, administer activated charcoal, pump the animal’s stomach, or administer an appropriate antitoxin. Any information you can provide regarding the toxin can help your veterinarian provide more rapid treatment.
Also see Introduction to Poisoning.
Portosystemic shunts have already been described as a congenital (inborn) liver defect. However, in some cases they can develop as a part of illness that causes high blood pressure in the portal vein (the vein that carries blood to the liver from the digestive tract). In these instances they are called acquired shunts. Signs include excessive thirst, vomiting, and diarrhea. Fluid accumulation in the abdomen (ascites) and intermittent neurologic signs (hepatic encephalopathy, see above) are common. Medical treatment of these signs and the underlying disease can lead to a favorable response in some cats. Cats with acquired shunts can live several years without any signs, and some can live a normal life with treatment.
Several types of infections may cause liver disease, including viral, bacterial, fungal, and parasitic disease.
Feline infectious peritonitis is caused by a virus. Infection leads to widespread inflammation, especially in the abdomen (including the liver), and inflammation of the blood vessels (vasculitis). Jaundice, fluid accumulation in the abdomen, vomiting, diarrhea, and fever are common signs.
Virulent systemic calicivirus is an aggressive form of a common upper respiratory virus of cats (called feline calicivirus). Outbreaks of the virus usually occur in shelters and catteries, resulting in the death of 33–60% of affected cats. Adult cats are most severely affected. Signs include fever, loss of appetite, swelling of the limbs and face, jaundice, hair loss, and sores on the nose, lips, ears, and feet.
The bacteria Mycobacterium avium can cause liver infections in young Abyssinian and Somali cats that are born with immune deficiencies. Affected cats often have vague signs, including weight loss despite eating large amounts of food. The lungs can also be affected. Your veterinarian can prescribe antibiotics to treat the condition. Relapses can occur and may be due to immune system dysfunction.
Other types of bacterial infections, such as those caused by Clostridium piliforme (Tyzzer Disease), can cause liver damage. Infections in other parts of the body can transfer to liver tissue and cause damage or dysfunction. Because the liver can help protect the body from bacterial infections, cats with liver failure or with longterm liver disease are more susceptible to bacterial infections in other parts of the body.
The most common fungal infections associated with liver dysfunction are coccidioidomycosis and histoplasmosis. If the liver is involved, signs may include abdominal swelling, jaundice, and liver enlargement. Coccidioidomycosis can be treated with longterm (6 to 12 months) use of antifungal medications. However, relapses sometimes occur. Histoplasmosis is often treated using prescription antifungal medications. Depending on the level of illness, the outlook for recovery may be poor. Lifelong antifungal treatment is necessary for some cats with these diseases.
Toxoplasmosis is a parasitic disease that can cause short-term liver failure due to liver cell death. The parasite is a protozoan, Toxoplasma gondii, that is found worldwide. Infection is more common in cats positive for feline immunodeficiency virus and feline leukemia virus. Jaundice, abdominal swelling, fever, lethargy, vomiting, and diarrhea are seen, in addition to signs of central nervous system, lung, or eye involvement. An antibiotic is used for treatment, and other drugs are sometimes necessary. Despite improvement after treatment, cats often have longterm infections and should be monitored for recurrent flares of the disease. The outlook depends on the severity of the illness. Toxoplasmosis can also infect humans and is most likely to cause signs in pregnant women and in people with an impaired immune system. Because the parasite is transmitted through feces, pregnant women and other people at increased risk of infection should avoid contact with cat litter boxes.
Several diseases involving endocrine glands can cause liver problems in cats. These diseases include diabetes mellitus and hyperthyroidism.
Cats with diabetes mellitus have an increased risk of developing hepatic lipidosis because diabetes mellitus increases the metabolism and mobilization of lipids. Lipids include any of a group of water-soluble fats and fat-like chemical substances that are sources of fuel for the body. However, when too many lipids are deposited in the liver, the function of the organ is impaired. Insulin replacement may or may not correct this storage problem. Diabetic cats also have an increased risk for inflammation of the pancreas (pancreatitis) and the bile duct (cholangitis) and for bacterial infections of the biliary tract.
Cats with hyperthyroidism have increased levels of certain chemicals (enzymes) in the liver and, in rare cases, an excessive amount of bilirubin (a yellow bile pigment). Cats with excess bilirubin may have jaundice. Despite the elevated liver enzymes, the function of the liver is usually normal. The liver enzyme levels almost always return to normal when the underlying causes are treated. However, a drug commonly used to treat hyperthyroidism (called methimazole) can, in rare instances, cause liver disease.
Hepatocutaneous syndrome is rare, longterm, progressive, and usually fatal. Diabetes mellitus is often present at the same time, but certain tumors, hormones, and drugs can also trigger the syndrome. Crusting and abnormalities on the footpads, ears, skin around the eyes, and pressure points are typical skin changes. Poor appetite, weight loss, excessive thirst and urination, and lethargy are also reported. Treatment may include antifungal drugs and antibiotics for skin infections, zinc and vitamin supplementation, administration of amino acids, high-protein diets, control of diabetes mellitus with insulin, and topical cleansing of affected skin. Unfortunately, treatment has little effect on the course of the disease, and the outlook is guarded to poor.
Liver cysts can be acquired (usually single nodules) or present at birth (usually multiple nodes called polycystic disease). Congenital polycystic disease of the liver has been reported in Persian cats. Cat with multiple cysts may also have cysts in the kidneys. The cysts often go undiagnosed but occasionally they enlarge and cause abdominal swelling and other signs such as lethargy, vomiting, and excessive thirst. Cats with multiple cysts throughout the liver can have signs of liver dysfunction. Your veterinarian may be able to feel nonpainful masses in the abdomen. Cysts may be identified with x-rays or ultrasonography, but a biopsy is needed for a definite diagnosis. Surgical removal of isolated cysts usually cures the condition but is not always necessary. Cats with multiple cysts that extend throughout the liver are treated with supportive medications and diet to reduce the signs of liver disease.
Tumors that originate in the liver (called primary tumors) are less common than those caused by spread from another part in the body (called metastatic tumors). Primary tumors are most often seen in cats more than 9 years old, and can be either malignant (cancerous) or benign. The most common types of primary tumors are biliary adenomas, biliary adenocarcinomas, lymphomas, and other blood cell tumors.
Metastatic (spreading) tumors of the liver are less common in cats than in dogs. Cancers that can spread to the liver include pancreatic, intestinal, and kidney cell carcinomas; mast cell tumors; and lymphoma. Metastatic tumors usually occur at multiple sites.
Cats with liver tumors may show no signs of disease, whereas others may be uninterested in food and lethargic. Seizures may develop because of hepatic encephalopathy, low blood sugar, or spread of cancer to the brain. An enlarged liver or an abdominal mass may be found during a physical examination. Animals may be pale (due to bleeding or anemia caused by longterm liver disease) or jaundiced. A biopsy is needed for a definitive diagnosis. If a single liver lobe is involved, surgical removal of the lobe is recommended. Chemotherapy may be effective for some other cancer types. The outlook is often poor for liver tumors that involve multiple lobes.
Amyloid is a protein that is not folded into the correct shape. The misfolded protein causes damage by displacing normal cells. Amyloidosis is an inherited disease of Abyssinian, Siamese, and Oriental short-hair cats. Although some cats may show no signs, others may have loss of appetite, excessive thirst and urination, weight loss, fever, enlarged lymph nodes, vomiting, jaundice, and an enlarged liver. Affected cats may collapse and have pale mucous membranes due to rupture of the liver and subsequent bleeding into the abdomen. Diagnosis is made by identifying amyloid deposits in liver biopsy samples. Amyloidosis is progressive, and the outlook for recovery is poor, especially if the diagnosis is made late in the disease.
The liver secretes bile, a substance that assists with digestion and absorption of fats and with elimination of certain waste products from the body. Bile is stored in the gallbladder and is released into the duodenum through the bile duct.
Jaundice (a yellow tinge noticeable in the skin, mucous membranes, and eyes) is often the main sign of diseases of the gallbladder and bile duct. An exception is cancer of the gallbladder, which may not cause jaundice.
Obstruction of the bile duct is associated with a number of conditions, including inflammation of the pancreas (pancreatitis), intestines, gallbladder, and bile duct; intestinal foreign objects; parasites; gallstones; and tumors. Tissue swelling, inflammation, or scarring can cause compression of the bile duct. A sudden, complete obstruction can lead to lethargy, fever, jaundice, vomiting, pale stools, and changes in appetite (either increased or decreased). Some cats develop abnormal bleeding within 1 week.
Diagnosis is based on laboratory tests, x-rays, and ultrasonography. Abdominal surgery is frequently necessary to diagnose and treat the obstruction. Cats with infections in the biliary tract are at risk for serious complications during surgery. Cats with pancreatitis can sometimes be treated with medication to relieve the obstruction, but if this is not successful, surgery may then be necessary. Gallstones rarely cause obstruction, but when this does occur, removal of the gallbladder is the preferred treatment in most cases. When cancer is present, surgery can provide temporary relief but is usually not a cure.
Inflammation of the gallbladder (cholecystitis) is usually caused by bacterial infections that start in the intestines and either travel up the bile duct or are spread through the blood. Other causes include body-wide diseases, tumors, abdominal trauma, and obstruction of the bile duct. Loss of appetite, abdominal pain, jaundice, fever, and vomiting are common signs. The cat may be in a state of shock due to abdominal inflammation.
The inflammation can also spread to the surrounding branches of the bile duct and the liver. Diagnosis is based on blood tests and ultrasonography and can be confirmed by biopsy for bacterial cultures and tissue analysis. Treatment usually consists of removal of the gallbladder and appropriate antibiotic medication to treat infection. The outlook is good if surgery and appropriate antibiotics are started early but is less favorable if diagnosis and treatment are delayed. After surgery, cats are at risk for recurrent bacterial infections of the biliary tract. Your veterinarian may instruct you to take your cat's temperature regularly so you can identify and treat these infections early on.
Gallstones rarely cause disease. In cats, gallstones are generally associated with bile duct inflammation. Most cats with gallstones show no signs or display discomfort only after eating. When seen, signs include vomiting, jaundice, loss of appetite, abdominal pain, and fever. Bacterial infections are often present. Treatment consists of appropriate antibiotics and liver medications. Surgery to remove the stones is necessary if gallbladder inflammation is present or if the stones are blocking the bile duct.
Infection with liver flukes is an uncommon cause of bile duct disease in cats. Platynosomum concinnum is the most common fluke to infect cats. It occurs in Malaysia, Hawaii, southeastern US, the Caribbean, South America, and western Africa. The fluke’s life cycle includes lizards and toads as intermediate hosts. Cats are infected when they catch and eat these animals. In areas where the fluke is common, 15–85% of cats with access to intermediate hosts are infected. The flukes do not cause any signs in most cats, but in others they obstruct the bile duct, which causes severe liver dysfunction. Signs vary depending on the number of flukes involved, but may include vomiting, diarrhea, fever, jaundice, depression, poor appetite, and an enlarged liver. The flukes can also damage the pancreas. Because most infected cats do not show any signs, diagnosis can be difficult. Fecal and blood tests and ultrasonography may be used. Antiparasitic drugs can be used to treat the infection. Additional medications are often necessary. The outlook is favorable for mild forms of the disease.
Rupture of the gallbladder or bile duct is most often due to gallstones, inflammation of the gallbladder, or blunt trauma. Rupture of the bile duct may also occur as a result of cancer or certain parasites. Rupture leads to leakage of bile into the abdomen, causing a serious condition called bile peritonitis, which may be fatal if the rupture is not repaired. Signs include decreased appetite, abdominal discomfort, abdominal distension, and jaundice. Treatment includes surgery, which consists of tying off the bile duct, removing the gallbladder, or connecting the gallbladder with the small intestine. Antibiotics and other medications are also typically used before and after surgery.