The clinical signs of liver disease (medically referred to as “hepatobiliary disease”) can be extremely variable due to the liver’s extensive interaction with other organs and its independent regenerative capacity. More than half (and maybe up to 70 or 80 percent) of functional liver tissue must be destroyed before actual liver failure occurs. Often, there are no clinical manifestations of liver disease, or the condition may present with only vague and nonspecific signs. Once symptoms do develop, liver disease is usually quite advanced, although the severity of any given clinical signs does not necessarily correlate with the extent of liver damage or the cat’s prognosis. Additionally, because the liver is intimately involved in so many bodily functions, what appear to be symptoms of liver disease might actually be caused by an abnormality in another organ or organ system. Keeping this in mind, there are a number of signs that, taken together, can be suggestive of liver dysfunction, which can be mild or severe and can present acutely or develop slowly.
Symptoms of Liver Disease in Cats
Among its many other functions, the liver is responsible for filtering toxins out of the blood and regulating the metabolism of food. Symptoms of liver disease are associated with a build-up of these toxins. When toxins accumulate in the blood stream because the liver is unable to remove them, the affected cat will become increasingly thirsty as its body attempts to flush toxins out in the urine. Cats with liver disease tend to drink more and urinate more than usual. They also tend to lose their appetite and, over time, lose weight and muscle mass as well. Other common signs include depression, lethargy, weakness, weight loss, bad breath, poor or unkempt hair coat, nausea, vomiting, diarrhea and dehydration. Another common sign is abdominal enlargement, which may be the first sign noticed by owners or may be discovered during a routine physical examination by a veterinarian. The distended abdomen is caused by an enlarged liver or spleen (“organomegaly,” which means an enlarged organ), excess fluid in the space between abdominal organs (called “effusion”), or poor abdominal muscle tone (called “muscular hypotonia”). Each of these causes may or may not be associated with primary liver disease.
Some other clinical signs of liver disease are jaundice, bilirubinuria, acholic feces and behavioral and neurological changes. Jaundice is the yellow staining of the serum or tissues, including skin and mucous membranes, caused by an excess of the bile pigment, bilirubin. Jaundice, also referred to as “icterus,” can turn a cat’s urine a bright, yellowish-orange color (“bilirubinuria”). Acholic feces – or changes in fecal color – are caused by an absence of bile pigments in the intestinal tract, making the cat’s stools pale, gray and putty-colored. This normally indicates complete bile duct obstruction associated with primary liver disease.
Behavioral and neurological changes reported in cats suffering from liver disorders include aggression, restlessness, agitation, dementia, disorientation, depression, trembling, circling, incoordination, staggering, aimless wandering or pacing, head-pressing, blindness, excess salivation, tremors, generalized seizures and even comas. The general term for this condition is “hepatic encephalopathy.” “Hepatic” means emanating from or pertaining to the liver. These signs can develop in cats with liver disease because the cerebral cortex of the brain is exposed to circulating toxins that normally are removed by a healthy liver, but escape hepatic detoxification in cases of liver disease. Most gastrointestinal toxins are derived from bacterial metabolism, or digestion, of proteins and their by-products. Ammonia is one of the most common gastrointestinal toxins contributing to the clinical signs of liver disease, which can wax and wane over time. Hepatic encephalopathy is a chronic condition which cannot be cured but usually can be controlled.
Companion animals with liver disease often have problems with coagulation, or clotting, of their blood, because of the integral role of the healthy liver in this process. In cats, the upper gastrointestinal tract – usually the stomach and duodenum, which is the first part of the small intestine - is most commonly affected by coagulation disorders associated with liver disease. This can cause gastrointestinal bleeding/hemorrhage, which owners may detect by seeing fresh blood in their cats’ litter box. Affected cats may also vomit blood.
Finally, increased volume of urination and drinking of water typically accompany serious liver dysfunction. Your veterinarian may refer to these symptoms as “polyuria” and “polydipsia.”
If your cat exhibits any of the symptoms discussed, and especially if you notice a number of them occurring at the same time, please see your veterinarian immediately. Only a veterinarian can run the crucial tests needed to confirm a diagnosis of liver disease.