By Dial A Vet Veterinary Team
A puppy who is smaller than its littermates, seems dull or wobbly after meals, or has an unusually bad reaction to sedation may have a liver shunt. A shunt is an abnormal blood vessel that lets blood from the gut bypass the liver, so toxins that should be filtered out reach the brain and the rest of the body. Many dogs with shunts do very well with treatment, especially when the problem is found early. This page explains the signs and the usual path from suspicion to treatment. For liver disease more broadly, see liver disease in dogs.
Key takeaways
- A portosystemic shunt is an abnormal vessel that carries blood around the liver instead of through it.
- Most shunts are congenital and show up in puppies or young dogs. Small breeds such as Yorkshire Terriers, Maltese, Shih Tzus, and Miniature Schnauzers are commonly affected; large breeds such as Irish Wolfhounds and Retrievers tend to have shunts inside the liver.
- Signs include poor growth, behaviour changes after eating, wobbliness, drooling, seizures, urinary stones, and slow recovery from anaesthesia.
- Diagnosis usually involves a bile acid test and imaging such as ultrasound or CT.
- Many single shunts can be treated surgically, and medical management helps control signs before and sometimes instead of surgery.
What a liver shunt is
Before birth, a puppy's blood bypasses the liver through a vessel that normally closes in the first days of life. If it stays open, or if another abnormal vessel is present, blood from the intestines goes straight into the general circulation. The liver does not receive the blood flow it needs to grow, and toxins such as ammonia build up. High ammonia affects the brain, a condition called hepatic encephalopathy.
Shunts outside the liver (extrahepatic) are more common in small breeds. Shunts inside the liver (intrahepatic) are more common in large breeds. Acquired shunts can also develop in older dogs with severe liver disease, and these are managed differently. More detail is available on our page about portosystemic shunts.
Signs of a liver shunt
- Stunted growth or being the runt of the litter
- Dullness, confusion, staring, or head pressing, often worse after a protein-rich meal
- Wobbliness, circling, or apparent blindness that comes and goes
- Excessive drooling
- Seizures
- Vomiting, diarrhoea, or poor appetite
- Drinking and urinating more
- Blood in the urine or straining, from ammonium urate bladder stones
- Prolonged recovery after sedation or anaesthesia
Signs can be mild and intermittent, so some dogs are not diagnosed until adulthood.
When it is an emergency
Go to an emergency veterinary hospital straight away if your dog:
- Has a seizure, or several seizures in a row
- Is severely disoriented, unresponsive, or cannot stand
- Is vomiting repeatedly or very weak
- Is straining to urinate and producing little or no urine
- Is a small puppy that is cold, limp, or not feeding (low blood sugar can be life-threatening, see hypoglycaemia in puppies)
How vets diagnose a shunt
Routine blood tests may show changes such as low albumin, low urea, low cholesterol, or small red blood cells. Urine may contain ammonium urate crystals. A bile acid test, taken before and after a meal, is a common screening test for abnormal liver blood flow. Blood ammonia may also be measured. Imaging confirms the shunt. Abdominal ultrasound can identify many shunts, and CT angiography gives a detailed map that helps a surgeon plan treatment. Some breeds, including Irish Wolfhounds, may be screened as puppies.
Treatment, in overview
Medical management aims to reduce the toxins absorbed from the gut and stabilise the dog. It usually involves a specific diet and medications chosen by your vet. Many dogs are managed medically for a period before surgery, and some older dogs or dogs with multiple or inoperable shunts are managed medically long term.
Surgery aims to gradually close the abnormal vessel so that blood is redirected through the liver. Gradual closure techniques, such as constrictor rings or bands, are commonly used to allow the liver to adapt. Intrahepatic shunts can be more complex and are sometimes treated by specialists using minimally invasive methods. Surgery is typically performed at a referral hospital, and dogs need close monitoring afterwards because complications such as seizures can occur in the first days.
Your vet or a specialist surgeon will discuss the likely outlook for your dog. Many dogs with a single extrahepatic shunt that is successfully closed go on to live normal lives.
Living with a liver shunt
- Feed only the diet your vet recommends, and avoid high-protein treats and scraps unless approved.
- Give medications exactly as prescribed.
- Keep a diary of behaviour changes, especially after meals.
- Attend follow-up bile acid tests and imaging after surgery.
- Tell any vet or groomer about the shunt before sedation or new medications.
FAQ
Can a liver shunt be cured?
Many single shunts outside the liver can be closed surgically with a good long-term outcome. Some dogs need ongoing diet and medication.
Is a liver shunt genetic?
Congenital shunts are more common in certain breeds and families. Affected dogs are generally not recommended for breeding.
My adult dog was just diagnosed. Is that unusual?
No. Some dogs with mild signs are not diagnosed until later. Your vet will check whether the shunt is congenital or acquired.
Talk with a vet
If your puppy or young dog has signs that worry you, or you want help understanding a shunt diagnosis, our vets can talk it through with you by video and help you plan the next steps. Book a consult at dialavet.com. If your dog is seizing, unresponsive, or very weak, go to an emergency vet hospital now.
References
- Merck Veterinary Manual. Portosystemic Shunts in Small Animals.
- American College of Veterinary Surgeons (ACVS). Liver Shunts.
- VCA Animal Hospitals. Portosystemic Shunts in Dogs.
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If your pet is having seizures or is seriously unwell, contact a veterinary hospital immediately.