Portosystemic shunt is a condition in which a dog or cat’s fresh blood supply bypasses the liver. Liver shunts that form before a pet is born are called congenital liver shunts, but cats and dogs prone to liver disease and high blood pressure within the liver can develop acquired liver shunts later in life. Read on to learn more about how liver shunts are diagnosed and treated in dogs and cats.
What Is a Liver Shunt?
A liver shunt is a blood vessel that bypasses fresh blood flow through the liver, and instead carries blood around this vital organ. Liver shunts that develop outside the liver are called extrahepatic. Intrahepatic liver shunts take place when a blood vessel inside the liver called the portal vein doesn’t seal properly at birth. Both cases result in the liver being unable to filter toxins before they are absorbed.
Diagnosing Liver Shunt in Pets
There are a number of tests that your vet will perform to diagnose your cat or dog with liver shunts. Symptoms of liver shunts include seizures, diarrhea, vomiting, disorientation, stupor, lethargy, and kidney stones. Young pets may appear underdeveloped, resist gaining weight, and have low muscle tone.
These symptoms are similar to many other pet disorders, so a combination of tests may be needed to narrow down the exact cause. After doing a thorough physical, your vet may perform blood work to measure bile acids. Other tests used to diagnose liver shunts include ultrasounds, CT scans, MRIs, portography, and exploratory surgery.
Cat and Dog Liver Shunt Treatment Options
Surgery is the most effective way to treat extrahepatic liver shunts. During this procedure, a device called the ameroid constrictor is used to close the shunt. Intrahepatic liver shunts are more difficult to correct surgically and often have more post-surgical complications than extrahepatic shunts.
When surgery is not an option, veterinarians can suggest a few treatment options that will help stabilize the condition, including a change in diet and administration of lactulose and antibiotics.
- Diet: Vets can help create a dietary plan for your pet that is easily digestible, rich in vitamins, and lower in protein since the damaged liver cannot process the toxins in animal meat as effectively. Protein content in this new diet will likely be restricted to 18% or less, and high-quality plant- and milk-based proteins can replace some animal proteins.
- Lactulose: This solution helps change the pH in the intestines to decrease toxin production. Its primary side effect is diarrhea.
- Antibiotics: Antibiotics can manage bacteria in the intestines and help reduce toxins.
Cat and Dog Liver Shunt Prevention
Congenital liver shunt develops in utero and cannot be prevented after a pet is born. It is unclear how pets inherit liver shunts, but veterinarians recommend that animals with congenital liver shunt not be bred. Acquired liver shunt occurs when there is high blood pressure in the liver, so early prevention is related to managing and correcting diseases like cirrhosis that cause those shunts to form.
What Causes Liver Shunt in Dogs and Cats?
Portosystemic shunt (PSS), more commonly known as liver shunt, is a condition in which the circulatory system bypasses the liver, denying fresh blood flow to this vital organ. Liver shunt is more often found in dogs, but cats are also susceptible to this condition. Read more about the causes and symptoms of liver shunt in dogs and cats.
What Is Liver Shunt?
Liver shunt occurs when there is an abnormal connection between the liver and the hepatic portal vein. The liver typically receives 75 percent of its blood supply from this blood vessel. The vessel’s primary function is to bring rich nutrients to the liver, which then processes them and rids them of toxins.
Causes of Liver Shunt in Dogs and Cats
Liver shunt is either present at birth (a congenital portosystemic shunt), or develops later in life (an acquired portosystemic shunt).
Acquired liver shunt most often develops due to liver disease, such as cirrhosis. In the case of cirrhosis, pets experience portal hypertension or high blood pressure in the hepatic portal vein.
Congenital liver shunt is a birth defect that forms in utero. The shunt appears either inside (intrahepatic) or outside the liver (extrahepatic).
- Intrahepatic Liver Shunt: During gestation, a puppy or kitten’s liver is not functional. Instead, all detoxification comes from the mother’s liver for the entire litter. Intrahepatic liver shunt occurs when the fetal shunt (called the ductus venosus) that carries blood from the fetal liver to the heart does not seal.
- Extrahepatic Liver Shunt: In this type of liver shunt, the ductus venosus seals properly at birth, but a blood vessel outside the liver develops abnormally, compromising blood flow. While intrahepatic liver shunts are solitary, multiple extrahepatic liver shunts can appear.
Breeds Most Susceptible to Liver Shunt
Cats more often develop extrahepatic liver shunts, with mixed breeds, Persians, British Shorthairs, Siamese, and Himalayans being some of the most common breeds with this condition. Small dogs are also more prone to develop extrahepatic shunts. Those canine breeds include:
- Cairn Terriers
- Jack Russell Terriers
- Lhasa Apsos
- Shih Tzus
- Yorkshire Terriers
Large dogs are more likely to develop intrahepatic shunts. Common breeds include:
- Australian Cattle Dogs
- Australian Shepherds
- Labrador Retrievers
- Old English Sheepdogs
Symptoms of Liver Shunt in Dogs and Cats
Symptoms of congenital liver shunt may show up by the time your pet reaches six to twelve months of age.
Common signs of liver shunt in dogs and cats include:
If the liver shunt is congenital, then pet owners may notice symptoms manifesting in a puppy or kitten’s development, such as stunted growth, low muscle mass, or trouble gaining weight.
Treatment and Prevention of Liver Shunt
Treating liver shunt could mean surgery, diet change, antibiotics, or the administering of supplements like Denamarin. Learn more about prevention and treatment.
Frequently Asked Questions
How do you treat a shunt in a cat's liver?
The treatment of a liver shunt in cats depends on the type and severity of the shunt. In some cases, the shunt can be managed with dietary changes and medications, but in severe cases, surgical correction may be necessary. It is necessary to consult a veterinarian who can diagnose the shunt and recommend an appropriate course of treatment. The veterinarian may also refer the cat to a specialist for further evaluation and treatment.
What medication is given to a dog with a liver shunt?
Dogs with liver shunts may be treated with a combination of medications, including antibiotics to control infections, anti-inflammatory drugs to reduce swelling and pain, and medications to control seizures. The specific medications and dosages will depend on the individual case and should be determined by a veterinarian. Veterinarians often prescribe Lactulose which changes the microbial environment in the intestine. The medicine reduces bacterial growth in the intestines while acting as a laxative. That, in turn, reduces the time for stool presence in the gut and the absorption of toxins produced by bacteria. Additionally, a change in diet to a low-protein and low-ammonia diet may be recommended to reduce the workload on the liver. In severe cases, surgery may be required to correct the shunt.
What can I feed my cat with liver shunts?
Cats with liver shunts typically require a special diet to help manage their condition. This usually involves feeding a low-protein diet that is also low in certain amino acids that are metabolized by the liver. A prescription diet from a veterinarian may be recommended. Additionally, it may also be necessary to feed smaller, more frequent meals to reduce the workload on the liver. Dietary management is just one aspect of treatment for liver shunts, and it is important to follow the recommendations of a veterinarian to ensure the best possible outcome for the cat.
Can a liver shunt be treated without surgery?
In some cases, liver shunts can be managed medically without the need for surgery. This may involve dietary modifications, such as feeding a low-protein and low-ammonia diet, along with medications to control infections and reduce inflammation. However, the specific treatment plan will depend on the type and severity of the shunt, as well as the overall health of the animal. In some cases, surgery may still be necessary to correct the shunt, especially if the liver is not functioning properly. The best approach will be determined by a veterinarian based on a comprehensive evaluation of the individual case.
How much protein should a dog with a liver shunt eat?
The amount of protein that a dog with a liver shunt should eat will depend on the individual case and should be determined by a veterinarian. In general, dogs with liver shunts should not be given more than 18% of the protein in the diet to reduce the workload on the liver and prevent complications. This may involve reducing the overall amount of protein in the diet or limiting certain amino acids that are metabolized by the liver. The specific protein requirements will depend on the type and severity of the shunt, as well as the overall health of the dog.
More on Liver Disease
The Dog Symptom Checker
Food for Liver Disease in Dogs and Cats
Cat Symptom Checker: Match Your Cat's Symptoms to Health Conditions
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.