Liver disease is a relatively common problem in dogs and occasionally seen in cats. In recent years, great advances have been made in understanding the causes of liver problems and improving the management of diagnosed cases.
Understanding the Liver
The liver is the most important organ of metabolism in the body and current estimates suggest that it has at least 1500 functions.
The liver plays a central role in the metabolism of proteins, fats carbohydrates as well as certain vitamins and minerals. Therefore, liver disease can lead to problems with the metabolism and storage of these nutrients and the breakdown of their potentially harmful by-products (detoxification).
The most important of these toxins is ammonia, which is produced by the bacteria in the large intestine from the breakdown of protein and absorbed into the bloodstream. Ammonia is also produced by the cells of the body when the body tissues are broken down to meet the animal’s needs i.e. if the animal cannot obtain all the nutrients that they require from their diet.
In cases of severe liver disease, these toxins enter the blood circulating around the brain and cause the nervous signs associated with the disorder known as hepatic encephalopathy. These nervous signs include fits, tremors, excess salivation and head pressing.
Nutritional management is the cornerstone for the treatment of dogs with liver disease and will reduce the need for some of the more costly and potentially hazardous medical therapies.
As the liver receives over half of its blood supply from the vessels which drain the intestinal tract, dietary modifications can have a great effect on the number of nutrients and toxins to which the liver cells (hepatocytes) are exposed.
The diet that you feed your pet should provide sufficient energy and nutrients to meet your pet’s needs, provide for the repair of the damaged liver cells, reduce toxin production and limit the absorption of these toxins from the bowel.
The key nutritional considerations include:
The protein level of your pet’s diet needs to be carefully controlled and balanced to your pet’s needs.
If the protein level is too high, the body will produce too much ammonia, and if the protein level is too low your pet will begin to break down their own body tissues.
The cells of the liver also need protein for repair. High-quality proteins are recommended, as they are digested and absorbed before they reach the bacteria in the large intestine and therefore less likely to result in the production of ammonia.
Carbohydrate and fat
The levels of carbohydrate and fats in the diet need to be carefully controlled to supply highly digestible sources of energy. Liver disease reduces carbohydrate metabolism and many patients are unable to efficiently use glucose.
Glucose utilisation can be improved by slowing down the delivery of glucose from the intestines to the liver by incorporating complex carbohydrates, such as starch and fibre into the diet.
Dietary fibre has a number of benefits for patients with liver disease. It assists in the removal of ammonia and other toxins in the faeces and inhibits ammonia production by the bacteria in the colon.
Vitamins and Minerals
Diets for patients with liver disease need to be supplemented with water-soluble vitamins (B complex and C) to compensate for impaired synthesis, increase demand and increased losses. Zinc is involved in the detoxification of ammonia and a deficiency is commonly seen in patients with liver disease.
Supplementation of the diet with zinc helps to reduce hepatic encephalopathy and protects the liver from excessive levels of copper accumulating in the liver causing further hepatocyte damage.
Sodium intake should also be moderated as an excessive intake will exacerbate ascites (fluid accumulation in the abdomen) which can occur with some forms of liver disease.
Feeding Dogs with Liver Disease
As the balance of nutrients in your pet’s diet is key to their management your veterinary surgeon may recommend a special diet. These will provide the ideal balance of nutrients for pets with liver disease.
It is often highly palatable, energy-dense and contains highly digestible nutrients with a moderated level of protein.
Complex carbohydrates are often used to allow slow delivery of glucose the balance of soluble and insoluble fibre present helps to reduce ammonia absorption. The diet is also supplemented with water-soluble vitamins and zinc and has moderated levels of sodium and copper.
Your veterinary surgeon understands that liver disease often causes a lack of interest in food. Because of this, a special diet must not only benefit health but must taste good, too.
Clinical signs of liver disease
- Weight loss
- Loss of appetite
- Enlarged abdomen
- Nervous signs
Diagnosis of liver disease in pets
- Blood test
Feline Liver Disease
Liver disease in the cat is less commonly seen. Cats tend to show fewer problems associated with protein intolerance and hepatic encephalopathy than dogs.
Cats are obligate carnivores and have a higher basic dietary protein requirement than dogs and cannot adapt to very low levels of protein, which can make catering to their dietary needs difficult.
Your veterinary surgeon may prescribe a special Veterinary Diet to aid the management of your cat’s condition. These diets are highly palatable to support cats who may have poor appetites.