PORTOSYSTEMIC (LIVER) SHUNT

In view of the good news on Papnet that a Pap bitch has had a successful operation for this condition, I thought it wouldn`t do any harm to repeat this summary of the problem.

WHAT IS PORTOSYSTEMIC SHUNT?
I can feel you cringe already! We`re still trying to cope with PRA! But this is another inherited problem we must take seriously.
Portosystemic shunt is an inherited abnormality in the blood vessels which should connect the dog`s intestines with his liver. The liver acts as a filter for all the unwanted toxins that come into the system when the dog eats.. In the case of a shunt, the blood vessels have not developed correctly in the growing puppy, and a duct that should have closed shortly after birth, hasn`t closed at all. As a result the toxins, mainly ammonia and bile acids, go directly into the bloodstream, poisoning the puppy each time he eats.

HOW WILL I KNOW?
A shunt isn`t like PRA. It shows up in young puppies. Sometimes as young as 8 weeks. And there are different levels of seriousness. You will be seeing poor body condition, poor growth, lack of energy and depression, and in acute conditions, fits, episodes of uncontrolled shaking and collapses, often after eating. The puppy is steadily being poisoned by his food, because his liver is not able to function properly. In less acute cases, you are looking at a nervy, irritable poor doer, who lacks energy and is "never quite right". Even in these cases, life expectancy is not good.

CAN MY VET DIAGNOSE THIS?
Yes! This problem can easily be tested for, and the answer is definite. The test involves taking two blood samples, one before food and one after and is not particularly distressing for the dog. The vet is looking for a high count of liver enzymes, and a raised amount of ammonia and bile acids. The ammonia levels are usually conclusive.

WHAT IS THE TREATMENT?
Less acute cases can be treated by diet. Usually it`s a special low protein prescription diet, with perhaps rice, or potatoes added. Lactulose is usually also given also. The diet is expensive, and you will be no stranger to your vet! Treatment is for life.
The other possibility is surgery. The operative technique to repair portosystemic shunt is well established. Ultrasound or a dye test can tell just where the problem is, and then it can be repaired., giving you a healthy dog, provided the problem lies in the part of the blood vessel outside the liver, and not inside it. But there is some risk, and, yes, you guessed it, it`s expensive!


IS IT INHERITED?
Yes it is, and even more deviously than PRA. We are dealing with a polygenic recessive, (established by Meyer et al. in 1996) which means that a lot of genes, (which wouldn`t cause any harm individually), have to come together in both parents before any of their offspring develop this fault. And it is very variable in severity: at one end of the spectrum you have the puppy which dies of it, and at the other the dog who simply lives his short life as a "very poor doer". It is VERY DIFFICULT to trace any inheritance patterns in this sort of situation; even more difficult than with PRA. But, unlike PRA, there is a test and the problem shows up early. You need not be in any doubt as to whether Fido has this problem. It would obviously be a very bad idea to breed from any dog with this condition, or a dog which had thrown puppies with this condition, or a dog related to an animal with this condition. If we are vigilant, we can avoid it.


IS THIS COMMON IN PAPILLONS?
We are trying to find out, by compiling a database of cases. Certainly it is NOT confined to Papillons. It is a serious problem in Wolfhounds, and in Maltese in America, and has been reported in several toy breeds.


I`M A BREEDER - WHAT SHOULD I DO?
At its simplest, don`t breed from any animal which has been diagnosed with portosystemic shunt, or has produced puppies with the disorder, or whose parents or siblings have been diagnosed with it. If you are in doubt, have a test done. This is NOT like PRA: it shows up early and there IS a test, and you don`t have to wonder or guess.

I`M A PET OWNER - WHAT SHOULD I DO?
If your puppy or young dog is thin and not gaining weight, and is ill, unsteady, shaking or having fits after meals, head for the vet and have him tested. Let`s face it, with these symptoms you should be visiting a vet in any case, especially if there are fits. The old idea that fits are normal in growing puppies is just not true: fits should always be investigated as they can be symptoms of other serious problems. I am disturbed to discover that some Scottish breeders are still repeating this old chestnut about "just puppy fits" to puppy buyers. With the modern view that the seller of a puppy is liable in law for subsequent health problems, this attitude is as dangerous for the seller as it is cruel to the puppy buyer.