Feeding Pets with Liver Shunts

by Clinical Nutrition Team

Congenital portosystemic shunts (AKA liver shunts) are relatively common birth defects in pets where the blood vessels in the abdomen develop abnormally and instead of funneling blood from the intestines through the liver, the blood is able to bypass the liver and enters the systemic circulation. This abnormal blood flow prevents the liver from doing its job of processing the blood – eliminating medications, waste products, and toxins, breaking down nutrients from food, and regulating the body’s energy balance. Shunts are most common in small breeds of dogs, especially Yorkshire terriers, Maltese, and Cairn terriers. However, they can also be seen in larger dogs (such as Irish wolfhounds and retrievers) and less commonly in cats.

Pets with liver shunts can look and act completely normal and may only be diagnosed when bloodwork is done for another reason (shunts often cause changes in blood values that can be seen on routine blood panels) or may be the “runts” of their litters and may be quieter than normal for a young animal.  In severe cases, pets may stare at walls, act like they are drunk, or even have seizures (especially after meals) and experience urinary issues due to kidney or bladder stones caused by the buildup of compounds that would normally be removed by the liver.

Some shunts can be repaired with surgery or non-surgical interventional procedures but others either cannot be fixed or the treatment is too expensive for the pet owner. Typically, pets that are waiting to have their shunts fixed or those whose shunts cannot or will not be fixed are treated with a combination of medications and diet. Diet and medications do not fix the blood vessels in the liver, they simply reduce the symptoms so the pet can have a more normal life. Some pets can be well maintained with a good quality of life for years with diet and medications while others can develop uncontrollable symptoms and rarely liver failure.

Pets with shunts can have trouble with protein metabolism – they can’t get rid of the waste products after breaking down protein from the diet and it causes neurological signs, called “hepatic encephalopathy”, which including dullness, disorientation, difficulty walking, behavioral changes, and possibly even seizures. Not all pets with shunts develop obvious neurological signs, but those that do need to be treated with medications to increase protein tolerance. They are also typically fed diets that are lower in protein than typical commercial diets, but still have enough protein to meet their needs as too little protein could make them sicker. The amount of protein that is appropriate/tolerated will be different for each pet. Carefully considering the diet is especially important in a puppy or kitten because not all of the diets typically used to treat portosystemic shunts meet the nutritional needs of growing animals so alternatives or even nutrient supplementation may be necessary. Similarly, many therapeutic diets used to treat pets with shunts may not be good choices for healthy pets in the household.

Both the amount and the type of protein can be important. Egg, dairy, and soy protein are less likely to cause hepatic encephalopathy or shunt-associated bladder stones compared to muscle and organ meats. Therefore, carefully designed, good quality therapeutic diets typically use these proteins instead of meats, organ meats, or fish. Medications can help increase the amount of protein that pets with shunts will tolerate, so it is important to combine nutrition and medical treatments to maximize the pet’s nutrition while minimizing symptoms. Depending on how severe the symptoms are and whether the shunt can be surgically corrected, it may be possible to slowly increase the amount of protein over time, even to the levels in normal diets.

Your vet is likely to recommend one of several veterinary therapeutic diets for dogs with liver shunts that need lower protein diets. Lower protein home-cooked diets can also be designed for adult dogs but it is important that they be designed by a board-certified veterinary nutritionist with experience in managing dogs with shunts. Unfortunately, there are fewer commercial options available for puppies (even commercial therapeutic diet options are unlikely to meet the needs for large breed dogs with shunts) and home-cooked diet recipes carry high risk for growing animals. There are no therapeutic diets specifically designed for cats with liver shunts, so typically lower protein diets designed for other health conditions (such as kidney disease) are used in cats with shunts but they may need adjustment of other nutrients. Be sure to talk to your veterinarian about the most appropriate diet if your pet has a shunt and consider a consultation with a board-certified veterinary nutritionist if you need additional options or your pet is not doing well on the commercially available choices.

What about treats? Luckily, pets with shunts do not have to go entirely without treats. However, pets who have had hepatic encephalopathy should not be fed meats or high protein foods or treats (e.g. many biscuits, jerky, rawhides, bully sticks, pig ears) on top of the commercial diet or home-cooked diet recipe or they may develop signs again. Better treat options for dogs with shunts include meat-free dog biscuits, human snacks such as animal crackers and breakfast cereal, or non-toxic fruits and vegetables.

In summary, dietary changes can be very important to help manage pets with liver shunts. If your pet is diagnosed with a shunt, put together a thorough diet history of what you have been feeding your pet and talk to your veterinarian about what diet would be best suited to your pet.

Clinical Nutrition Team

Posts authored by the Clinical Nutrition Service team are by Dr. Lisa M. Freeman, DVM, PhD, DACVN, Dr. Deborah E. Linder, DVM, MS, DACVN, and Dr. Cailin R. Heinze, VMD, MS, DACVN

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