Wednesday, July 22, 2009

liver shunts and proper diets

Congenital liver shunts are quite common in some breeds of dog - in the U.S., this is notably the yorkie. The proper terminology is "Portosystemic shunt" (PSS), and it denotes a situation where blood flow from the GI tract bypasses processing by the liver. This critical mistake means that protein particles absorbed from the GI tract are left untended by the gentle ministrations of the liver. The liver specializes in converting ammonia, a by-product of protein breakdown, into urea, which is less toxic and easily eliminated by the kidneys.

When ammonia accumulates in the blood, changes in neurotransmitters lead to brain dysfunction and the clinical manifestation ranges from simple lethargy to outright seizures. This condition is called hepatic encephalopathy or HE. For dogs with PSS, this is the limiting factor on quality of life and life expectancy, although the disease can be managed more or less with surgery or diet change (and often both).

It helps to restrict the protein in the diet, because that will lower overall ammonia levels. Some evidence also suggests that the *type* of protein influences the types of neurotransmitters orchestrating brain function. If aromatic amino acids predominate (more common in meat protein), the neurotransmitter balance will be tipped towards brain dysfunction.

This study compared the clinical results of feeding a low protein diet composed primarily of soy protein vs a low protein diet containing primarily poultry protein.
Dogs with PSS were fed first one of these diets, then the other, in blinded fashion so that neither the investigators nor the owners were aware of the diet being fed.

The study showed that both diets reduced signs of encephalopathy, which might be expected when reducing overall protein content. Interestingly, when dogs were eating the soy-based diet, ammonia levels were significantly reduced. In addition, these dogs had better blood coagulation capacity. [When the liver fails, the clotting factors normally produced are decreased, leading to possible bleeding episodes). This improved clotting capacity, along with an increase in another protein made by the liver, suggests that the soy-based diet actually enhances the liver's capacity to function.

The results of this study may be particularly important to owners considering shunt surgery for their dogs. Elevated ammonia levels (with the associated changes in brain neurotransmitter levels) mean that anesthesia is a bigger risk in these dogs than in normal dogs of the same age. And if clotting is immpaired, surgery could lead to uncontrolled bleeding.

So the study is *really* interesting because it suggests that feeding a low protein soy based diet BEFORE surgery could reduce the risk surgery presents. Nice.

Proot S, Biourge V, Teske E, Rothuizen J. Soy protein isolate vs meat-based low protein diet for dogs congenital portosystemic shunts. J Vet Intern Med 2009;23:794

6 comments:

  1. I have an interest in liver problems with dogs, as I have one with PSS and another with liver cancer. Can you recommend a soy protein food? Currently I am feeding them Organix, as we are an organic family (?) and using milk thistle to aid liver function, as prescribed by their doctor.

    I write 2 blogs with crossover interest to your subject matter: Organic Journey Online is all about living green and eating healthier (organic), and All Things Dog Blog focuses on creating happy dogs and happy families. I write about anything and everything that helps with this--health, activities, exercise, discipline, training, food, etc.

    I am enjoying your blog very much. I would like to subscribe via email, if you ever add this feature through Feedburner. You can let me know at LetsAdoptaDogPark@gmail.com. Keep up the good work.

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  2. I realize this is an older post, but am hoping this gets seen if anyone has an answer. I have a 5 1/2 mo old doberman puppy with multiple extrahepatic shunts. We have started a low protein diet, but am wondering if there are any recommendations for how much protein can be given to puppies that are still growing? I've read 18% based on dry matter for adults, but I've read on other boards to feed slightly more to pups who are growing. Just wondering how much is safe?

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  3. Hi Sara! I share your hopes that someone will see our posts. My 12 week old Peke puppy has just been diagnosed with a liver shunt. What a difficult decision to make! Do I pay for the surgery? What is his life expectancy? I read on other sites that it can be up to 11 years if medically managed but I've spoken to some vets this morning and they say they have not seen a dog live for longer than 12 months with this condition, even if corrected. My heart is broken!

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  4. This blog is monitored, however, it is impossible to give medical advice here. It is illegal for any veterinarian to give medical advice on a pet he or she has never seen, unless specifically consulted by that pet's own veterinarian as a professional courtesy. If you have a dog with a liver shunt, I would advise that you first ask your veterinarian for a referral to an internal medicine specialist (found in veterinary schools and private specialty practices). If you have nutrition questions, you can find veterinary nutritionists in the same types or practices. Nutritionists are harder to find than other specialists, so if there isn't one in your state, your veterinarian or internist can consult with one elsewhere, through the American College of Veterinary Nutrition (www.acvn.org).

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  5. My Yorkie was diagnosed with a liver shunt when he was 8 months old. We had the surgery and he seemed fine, for awhile. One day at the vets he had some blood work done and it showed that his enzymes were a bit elevated. The doctor prescribed lactulose. He seemed to do fine with that. Now he is 7 1/2 years old and I see too many of the symptoms that he had earlier (lethargy, weakness, drooling, head pressing, circling, pacing and recently tremors). He has a vet appointment this week to see what can be done, besides another surgery. I am trying the low protein diet but may ask the vet about the prescribed Hills L/D dog food. He is my special needs dog that besides the liver shunt, he was born deaf.

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    1. I have a 5 month old standard size golden doodle puppies female that was diagnoised with a large inopperable inhepatic liver shunt about a month ago-They tell me that her life expectancy is probably less than a year however she is doing remarkable. I make all of Bella's dog food . I make all of my dogs food I couldn't see putting her on a diet full of GMO"s as we are trying to get the toxins out of her body .She does get her share of dairy but I try to keep that type of protien lower- I suppliment her with lacelose and a liver support pill.Protiens for her are mostly veggie based-sprouted beans, ground chia ,flax,coconut quinio,She gets baked eggs shells -She also gets a fair amount of white fish,she does get the odd chicken leg or a piece of lean turkey with bone.I try to keep her protien between 15-18% per meal.She eats between 3-5 meals a day depending on the protien.I have always made my own dog food but I did consult a holistic vet to tweeck the type of protiens .Although She does tend to get a bit sleepy at times she goes on long walks and gets plenty of exercize(helps the blood move around).She is pretty much a normal puppy-

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