A canine liver shunt (portosystemic shunt or PSS) is a blood vessel that bypasses the liver, carrying blood from the stomach, intestines, pancreas, and spleen to the heart before it has a chance to be filtered by the liver. The liver cleanses blood of things like protein, sugar, bacteria, and toxins. When a liver shunt is present, the liver doesn't get to do its job.
Shunts can be present at birth (congenital) or develop after birth (acquired).
Liver shunts are particularly common in certain breeds such as:
- Yorkshire Terriers
- Irish Wolfhounds
- Australian Shepherds
- Labrador Retrievers
- Toy Breeds
The true cause of this condition is not known.
Canine Liver Shunt Symptoms
Symptoms of liver shunts in dogs usually show up at an early age and usually impact the central nervous system or the gastrointestinal system.
- failure to grow at a normal rate
- behavioral changes (things like staring into space, circling, and disorientation)
- weakness or lethargy
- inability to gain weight
- too much weight gain
In some cases, signs of a canine liver shunt don't show up until a dog is older, when kidney and bladder problems such as stones develop.
Canine Liver Shunt Diagnosis
Symptoms of a liver shunt in dogs are similar to symptoms of some other illnesses, such as hypoglycemia (low blood sugar) and hydrocephalus (water on the brain). Tests must be done to rule these out.
Blood tests will then be done to check liver function. There are a number of blood tests that can be done to check for the possible presence of a shunt, including tests that check for protein, albumin, blood urea nitrogen, ammonia, and bile acid concentrations.
Abdominal x-rays will probably be taken to look at the liver. It will usually appear under-developed. A special x-ray with contrast called a portogram will show the actual shunt.
The shunt will also be visible by ultrasound, or by a nuclear scan called scintigraphy.
Canine Liver Shunt Treatment
Liver shunts in dogs can be treated medically or surgically. Most often they are treated medically until the dog is well enough to undergo surgery.
The dog is fed a diet low in protein, and medications such as lactulose and metronidazole or neomycin are given to prevent the manufacture and absorption of toxins such as ammonia. Some dogs do just fine with medical treatment only, but the majority do not. The liver continues to shrink and eventually fails.
In most cases, surgery is needed. Since the liver has not developed normally, the shunt cannot always be completely closed. Instead, the vet partially closes the shunt. In many cases, this is sufficient to relieve the symptoms of the disorder and the dog no longer needs the special diet and medications following the surgery. Success rates for surgical treatment are greater than 80%.
There is also a device called an ameroid constrictor. This device is a ring that is placed around the shunt. It slowly constricts over a period of four to five weeks, giving the liver time to adjust to the new blood supply.
Herbal remedies also show some promise in supporting liver function. A good source to research is PetAlive Liver-Aid Formula which is made specifically for this purpose. Discuss this and other options with your veterinarian.
Karen Tobias, DVM