What does the liver do?
The liver is a complex organ that is responsible for many vital functions. The liver is sometimes called the "factory of the body," since it is a metabolic organ that performs or controls many of the chemical processes necessary for normal bodily function.
For example, the liver manufactures many essential substances such as proteins, bile and blood-clotting factors. It also plays a role in controlling the metabolism and use of food substances such as fats, carbohydrates, and proteins. In addition, it detoxifies or removes many waste substances and potentially damaging drugs or chemicals. Because of the liver's many functions, disease processes can affect the liver in many ways.
What are the signs of liver disease in cats?
Some signs are strongly suggestive of liver disease, most notably jaundice, which appears as yellow discoloration of the skin, eyes and mucous membranes (like the gums), and ascites (a swelling of the abdomen due to build-up of fluid).
These conditions are often accompanied by less specific signs that can be variable, including lethargy, appetite changes, excessive thirst and urination, weight loss, bleeding disorders, vomiting, and diarrhea. These may be the only signs noted in some early or mild cases of liver disease. Unfortunately, jaundice and ascites can be signs of diseases involving other body systems.
How is liver disease diagnosed?
In mild or early cases of liver disease, the signs are often non-specific and further diagnostic testing is necessary. Since the liver is responsible for such a wide range of metabolic functions, there is a wide range of blood and urine laboratory tests that may be useful to assess liver disease and function. Radiographs (X-rays) and ultrasonography will demonstrate any changes in the size or appearance of the liver.
Will my cat need a liver biopsy?
A wide range of disorders may affect the liver, resulting in abnormal liver tests. One of the chief limitations of blood and urine tests and non-invasive imaging techniques is that, while they may indicate the presence of liver damage or dysfunction, they cannot indicate the cause of the problem or the potential response to therapy.
In some cases, a liver biopsy will provide a specific diagnosis, which helps your veterinarian determine the most appropriate treatment and an accurate prognosis. A small sample of liver tissue may be obtained by introducing a biopsy needle through the skin, directly into the liver (via fine needle aspiration) or by means of exploratory surgery. Your veterinarian will consider several factors to determine which method is appropriate for your cat, including the most likely disease process and whether exploratory surgery may provide the opportunity for treatment as well as diagnosis.
Your cat will require heavy sedation or general anesthesia so the biopsy sample can be safely obtained. There are some risks associated with anesthesia, sedation, and biopsy, and the risks may be slightly increased with some forms of liver disease. Fortunately, in most cats, the risks are relatively low and the technique can be performed safely and without any significant complications.
How is liver disease treated?
Treatment for liver disease depends on the diagnosis. However, certain basic and simple supportive measures are useful and strongly recommended. Changing the diet is often helpful and may delay the progression of disease. Since the liver is involved in digestion and metabolism of all the major food groups, the traditional recommendations are to provide a diet that "reduces the workload" of the liver. However, the most appropriate way of doing this in cats is less clear than in other species.
Although a reduction of protein intake can be beneficial for some liver problems, the cat is an obligate carnivore, meaning that they require high levels of good-quality meat protein in their diet. In most animal species with liver disease, including people, dietary fats are restricted. In cats, dietary restriction of fats is of questionable benefit, since cats also have high dietary fat requirements.
It is appropriate to minimize dietary carbohydrate levels in cats with liver disease. However, the overriding priority is that the cat continues to eat. Therefore, palatability is a crucial consideration in determining the most appropriate diet for a cat with liver disease, especially if the cat has a poor appetite. In some cases, a feeding tube may need to be placed so your cat can continue to get adequate nutrition. Special prescription diets have been formulated to meet the needs of cats with liver disease and your veterinarian may recommend feeding your cat one of these scientifically formulated diets.
