Portosystemic Shunt

[Kirstymellon]

I have some bad news to share. We had to take our three month old pup into the vet today and we were told that the little guy suffers from a ?portosystemic shunt?. I am not really certain about all of the technical aspects of it, but essentially there is a blood vessel that is putting the toxins from his liver back into his blood stream. The toxins then go to his brain and cause him to have seizures. He is still at the vet right now and they are keeping him under observation, doing some more tests and trying to clean out his system.

 

We had no idea that there was something wrong with him until this morning when he woke us up at 6 am screaming at the top of his lungs. When we went to get him from his crate, he seemed like he had turned into a zombie. He could not see, he was unresponsive, his mouth was open and he was drooling everywhere. When my husband set him down, Cisco started walking into things and then began walking around the perimeter of the room. It was like he was not aware of anything. He could not see, he could not hear, but he kept walking in circles around the room. It was like he was no longer operating his body. It was scary.

 

We had him at the vet as soon as it opened at 8 am. When the vet examined him, he began to scream and she told us that he was having a seizure and that dogs tend to vocalize when they are having seizures. It was the most frightening and heart breaking thing I have seen. She gave him some valium to relax his muscles and gave him a shot to end the seizure. She then did some blood work on him and that is how we found out the cause of the seizures.

 

The vet called a little while ago and said that he has not had a seizure since we left (he had two while we were there), but there has been no change in his vision. She is hoping that his eyesight will come back as she flushes all of the ammonia and other toxins out of his system, but assures me that blind dogs can still lead normal lives ? they just need a Seeing Eye Person. The office is going to call us and let us know if we have to take him to the emergency animal hospital so that he can have medical attention tonight, should he need it. Apparently the practice is split into two; one is open at night and the other during the day.

 

We are not really sure what is going to happen. The vet is hoping that an enema with flush his system of toxins and hopefully we can control his seizures with a low protein food. Apparently protein contributes to these toxins, so controlling the amount of protein he consumes should control the amount of toxins in his system. If that does not work, then he will have to have surgery. We are hoping that he will not need surgery because there are a lot of risks that go with it.

 

Has anyone had experience with this condition in the past? It is a fairly common problem in border collies? What are our chances for recovery?

 

Thank you in advance!

[AK dog doc]

Hi Denny

I'm sorry to hear about your news. However, this isn't completely hopeless. Not all of these dogs do well, but some do; it depends on several factors, however, only some of which you have any control over.

 

To begin with, it seems as if you didn't get a completely clear picture of what a portosystemic shunt (PSS) is or how it works, so let me back up and go over that so that what I say later will (hopefully) make more sense. Sorry if I'm repeating things you already know.

 

In normal animals, the nutrients that are absorbed from the intestines cross over into the blood stream and are taken to the liver for processing via what's called the portal circulation. This means that the blood in the portal circulation has very high levels of certain substances which are NOT intended to hit the main circulation "raw" - those things are supposed to be metabolised by the liver into "user-friendly" nutrients that the organs and tissues can handle, and toxins are supposed to be filtered out. The brain is pretty sensitive to some of these substances, notably the nitrogen-containing compounds, and over-exposure to them causes seizures. This means that siezures from a PSS tend to occur in a certain time frame after eating, particularly after eating a high-protein meal, since protein is high in the nitrogen-rich compounds.

 

There are a couple of ways a shunt can form. One is that a pup can be born with abnormal vessels which go from the intestines, bypass the liver, and dump into the main circulation. Another is that a pup can have a failure of closure of normal portal-bypass circulation. In embryonic life, the pup isn't eating for itself; it gets its nourishment from the mother's circulation. This means that there's no need to pass the blood from the intestines through the liver first, since there are no foodstuffs being absorbed from the intestines. Hence there is a handy shunt that bypasses the liver (and another one that bypasses the lungs, since the pup isn't breathing for itself, either, but that's another story). At birth, when the baby starts the breathe for itself, the increased oxygen tension in the blood is supposed to make the shunts constrict down and close completely. Sometimes this doesn't happen, and then you have unmetabolised nutrients (and also toxic byproducts of intestinal bacteria) being dumped into the main circulation, which causes siezures. The last way to have a PSS, which is the worst, is to have an acquired shunt as a result of cirrhosis. In this scenario (which is the least likely one for your puppy), there is scarring to the liver - usually due to toxin ingestion, infection or certain rare metabolic disorders. This scarring makes it so hard to get blood through the liver that the body starts developing collateral circulation to go around it.

 

So, what to do? Medical care is about reducing absorption of toxins (hence the enema, as well as a higher-fiber diet and/or lactulose, both of which decrease the absorption of some substances from the gut), and decreasing the amount of brain-troubling substances in the diet (hence the protein restriction, which decreases the nitrogen-bearing compounds available to be absorbed in the first place). Some dogs do very well on this regimen for quite a while, maybe for life. This depends partly on the size of the shunt and partly on some other factors such as the owner's diligence and compliance, the dog's innate seizure threshold, its other general health, and so on.

 

Surgical care is about closing the shunt. This has two potential problems. One is that the shunt can be what's called "extra-hepatic" - meaning the vessels that bypass the liver are outside the meat of the liver itself - or it can be "intra-hepatic", which means that the abnormal vessels are buried within the tissue of the liver and cannot be accessed to close them down. If the PSS is intra-hepatic it's non-surgical, then you're pretty much stuck with medical management, and as I said, some dogs seem to do fine on this. If the PSS is extra-hepatic, then surgery is an option (this is all assuming the liver is otherwise healthy, and does not have cirrhosis or a metaboic disorder). What complicates surgery is that you can't just tie off the shunt vessel all at once and be done. That usually causes immediate trouble, because it increases the blood pressure to the liver too suddenly and causes all sorts of problems, both for the liver and for the intestines. So, you have to shut it down gradually. There are several different devices that are used to gradually shut down the shunt so that the liver and gut have time to adjust to the change; these are applied to the shunt vessel and gradually the shunt narrows down over a period of weeks after the surgery and (in theory) closes off completely. This doesn't always work as planned; there can be complications of surgery even several weeks out. However, when it does work, you may end up with a completely normal dog.

 

As far as percentages - how often it works and how often it doesn't - I'd have to leave that up to the surgeons doing the procedure (this is something we would punt to the boarded surgeons down in Anchorage.) As for the odds of the shunt being fixable by surgery - well, I'm not usre. Extra-hepatic shunts tend to be more common in small breed dogs and intra-hepatic ones more common in large breed dogs - but BCs are sort of medium, so I'm not sure what to tell you there.

 

The first thing is to stabilize the puppy and get him through the initial crisis. I usually run a bile acids test to confirm the shunt (your vet will know what this test is), and get the pup on a medical and dietary regimen to keep him as stable as possible. After that you can try to locate the shunt via ultrasound or another technique (like exploratory surgery +/- a venoportogram), and based on the results decide if surgery is an option.

 

I hope that made enough sense to be worth wading through it all. Good luck with this; I hope it turns out well for you and your pup.

[Kirstymellon]

Thank you for your post. Our vet actually explained it close to that. We received our bile acids tests results form the Univ of Illinois with a 121. We were told that the normal is 0-7.5. I see 121 and flipped being that far of a departure from specification. For an update, our little guy is coming home now (he has been at the vet all day and on seizure watch for most of the night. The night vet called and said that the best thing would be for him to be home and comfortable. His eyesight has returned to normal, motor skills are returning, and basically seems to have recovered from the seizure. We are taking him in tomorrow to see what the next step is: we were told (as of 8:30am today) that diet is first, then a nuclear medicine test to see where exactly the shunt is (internal/external of the liver) if the dieting fails, then surgery using the slow closure procedure that you described earlier in your post. Off to get our baby!

 

Thanks again for your insight!

Denny

[Oreo's mom]

Praying for you and your little pup. Please keep us posted.

[ArmyDoc]

Wow, what a story. Please let us know the outcome. Very interesting; I don't see any of this sort of thing in the world of adult human medicine (cirrhotics and surgical shunts yes, but not of the congenital variety - they're either fixed in childhood, or died therein).

 

I'll be thinking good thoughts for you and your dog.

 

-kevin-

[ArmyDoc]

Wow, what a story. Please let us know the outcome. Very interesting; I don't see any of this sort of thing in the world of adult human medicine (cirrhotics and surgical shunts yes, but not of the congenital variety - they're either fixed in childhood, or died therein).

 

I'll be thinking good thoughts for you and your dog.

 

-kevin-

[ArmyDoc]

Wow, what a story. Please let us know the outcome. Very interesting; I don't see any of this sort of thing in the world of adult human medicine (cirrhotics and surgical shunts yes, but not of the congenital variety - they're either fixed in childhood, or died therein).

 

I'll be thinking good thoughts for you and your dog.

 

-kevin-

[ArmyDoc]

Oops, sorry. Don't know what happened there.

 

-kevin-

[INU]

Thanks for sharing your knowledge as usual DogDoc.

Does this happen to puppies usally?

When you say "high protein food", what kind of food are you talking about? I give Jazzy a sausage-the kind comes 6 in a little can(to get her used to clickers) everyday and some salmon for her dry skin.

 

Denny,

Glad to hear that the pup's vision came back to normal! Hopefully it will be under control with food

[Kirstymellon]

we are giving him prescription diet l/d (liver disease). it is a low protein, low salt diet that reduces the amount of ammonia in his system. less ammonia, less chance of seizures. He is doing great now. He is a happy Border Baby now. He has probably gained 3 lbs since thursday. He has tons of energy, is not moody, and is just all out puppy.

 

Here he is now, all sad because he has to wear the "Elizabethan" Collar

 

 

Poor Baby

[AK dog doc]

Hi INU

This isn't very common, actually. I think I've seen maybe 4 in 10 years (out of the hundreds of puppies and dogs I see every year, that makes for pretty small numbers). Both foods you mention are high protein foods, but a normal puppy should be able to handle that without any trouble, so I wouldn't worry about giving those foods to your dog.

 

Denny, glad to hear your pup is feling better! Cute photo (but how do you stand the guilt? E-collaring such a darling puppy! how COULD you?)

 

Gotta run, just coming off call and on my way to work...