Liver Shunts and Vascular Anomalies


Congenital Portosystemic Shunts and possible link to cryptorchidism (retained testes)

Question: Dr. Richards:

over the last several months I've written a few times about my greyhound puppy Aniken Fiver who was struggling with a single intrahepatic PSS. He died Sep. 25 in a third surgery to try and save him, a radical and aggressive approach that failed utterly. I've been grieving his death intensely. last week Ani's breeder called to tell me that a colleague of hers has a greyhound puppy 5 months old who was the male pick of the litter for show who has a testicle that won't stay descended, which is ruining their plans for his show debut next month and they wanted to know if I was interested in providing a pet home for him. I talked to my vet about this and she did some research and said that cryptorchidism is associated with PSS. Can you verify this? this was the only time I've ever heard her state strongly an opinion against a possible adoption I've considered, but after all we've been through with Ani's liver shunt I don't blame her for being very careful about giving an opinion about whom I bring to her at this point. she has seen my greyhound rescue with idiopathic glomerulonephritis and my old greyhound with mitral valve insufficiency, renal insufficiency, back problems, and irritable bowel syndrome... in the 3 years I've worked with her I have not yet had a healthy dog. I know she's being wary. so I wonder about the association between cryptorchidism and PSS... any info would be much appreciated. I have already decided not to adopt this dog, but would still like to know for future reference.

also, if male puppy's testicle(s) have not descended by 5 months of age is it unreasonable to think they ever will? just curious... I've never had an intact dog and never plan to, but I do like to pass on credible information as much as possible when I get involved in cases like this.

Thanks again. Tina

Answer: Tina-

I have not found any information linking portosystemic shunts and cryptorchidism in textbooks but there is one article from the AVMA Journal that might suggest a link (summary below).

The article "Congenital Portosystemic Shunts in Dogs: 46 Cases" was authored by Dr. Johnson and colleaques from Michigan State University. It was published in the Dec 1, 1987 issue of the Journal of the American Veterinary Medical Association. (If you search the PubMed web site using the search term "Johnson CA", you can find the article summary). In the report, half of the male dogs with portosystemic shunts (PSS) were cryptorchid. I can't tell for sure how strong the correlation is between cryptorchidism and PSS is based on this, though. It may still be that only 1 in 10,000 cryptorchid dogs have PSS. If this were the case then you would have to be very suspicious of the possiblity of cryptorchidism when a PSS was found, but not very suspicious of PSS when a dog is cryptorchid. I tend to think that is the most likely possibility, because the books I have don't suggest looking for a liver shunt when contemplating surgical removal of retained testicles and if there were a whole lot of dogs with retained testicles who had PSS, I think they would, and because our practice experience doesn't suggest a strong link, either.

It is supposed to be highly unlikely that testicles will descend if they can not be found outside the body wall by around four months of age.

Despite the possibility that there wasn't a strong link between PSS and cryptorchidism, I can understand your vet's reluctance to take any chances since you had just been through such an ordeal.

Mike Richards, DVM 12/4/2001

Ameroid constrictor used to repair portosystemic shunt in greyhound puppy


I just saw your website after doing a search on portosystemic shunts. I adopted a little greyhound puppy that has this condition (single intrahepatic), and I had it surgically repaired at the CSU vet teaching hospital in Fort Collins, Colorado. After reading the many questions posted about portosystemic shunts I wondered if Dr. Mike or others who answered questions for subscribers about this condition knew about the new surgery for this (it was done on my dog): surgical ligation of the shunt with a cellophane band to slowly close the shunt over a 2-month period. It reduces the chance of a blood clot forming. My puppy is doing extremely well 3 weeks post-op, and I just wanted to share this information, so please pass it along it you think it is of interest to your vets or subscribers. It can be verified by Doctors Monet and Pelsue at CSU Veterinary Teaching Hospital in Fort Collins, CO (and probably others!).

Regards, Tina

Answer: Tina-

Thank you for writing with your experience. These devices are covered on the web site under their name, ameroid constrictors. I am glad that your puppy is doing well!

Mike Richards, DVM 4/3/2001

Portosystemic shunts in Golden Retriever puppy

Question: Dear Dr. Richards,

My wife and I recently purchased a Golden Retriever puppy. After a few weeks we awoke to find her dragging her nose and was wandering around seemingly intoxicated. After several tests at our local vet (bial analysis, sonogram etc.), she was diagnosed with an intraheptic shunt. The vet prescribed a low protein diet together with a lactulose supplement and suggested we speak to a specialist as soon as possible.

I understand that the new diet will "slow" down the effects of the disease although the only long-term hope is surgery. My question to you is, how long can she be expected to live a healthy life before the onset of seizures, complications etc., and how successful is this surgery?

Finally, I understand that treatment for intraheptic shunts is fairly revolutionary. Do you know where I can go to find a surgeon that has treated this condition successfully? We live in the NY/NJ area, but are prepared to travel further afield if necessary.

Thanks in advance for your help.

Answer: John-

Some dogs with portosystemic shunts can be maintained long term with dietary therapy, combined with lactulose and an antibiotic such as neosporin or metronidazole. However, surgery is still considered to be the best option for most dogs with this problem.

There isn't a good way to predict how long dietary therapy will work to control the clinical signs associated with portosystemic shunts. This therapy doesn't really slow down the progression of the problem, it just controls the symptoms associated with it.

What happens with a portosystemic shunt is that blood returning through the venous circulation through the liver, where toxins are removed, simply by-passes the liver and is returned to the circulation unchanged. In addition, portions of the liver which are dependent on this circulation do not develop, so dogs with portosystemic shunts do not have normal liver development or liver function. By surgically tying off the shunt, the blood is forced back through the liver, as it should have been, and this allows it to be cleansed of toxins and for the liver to develop in areas it could not.

This is a high risk surgery. There are increased anesthetic risks, although these can be reduced by proper planning. There is an increased surgical risk due to the location of the shunt and the tendency for increased bleeding in patients with decreased liver function. Finally, when the surgery is otherwise successful, the increase in blood pressure in the liver can cause problems in some patients in some patients several hours to a day or so after surgery.

Despite the risks, surgery is still considered to be better than medical therapy by most specialists, since it does stop further deterioration of the liver, when it works. The mortality rate within the first month of surgery was 29% in a review of 160 cases (Wolschrijn, et al, Utrecht University, April 2000). If total ligation of a shunt is possible and the patient survives the surgery and immediate post-surgical period, the prognosis is very good for long term success. If only partial ligation of a shunt is possible, about 45% of dogs will have a recurrence of clinical signs within 4 or 5 years.

Intrahepatic shunts are more difficult to repair than extra-hepatic shunts and for both it is important to find a surgeon who has some experience in treating these shunts. I am not aware of a radical new surgery for this condition, I think it is just difficult enough that it is necessary to find a good surgeon. I do not know who the most experienced surgeon in your area is, but I suspect that there are good surgeons at the Animal Medical Center in Manhattan, at the University of Pennsylvania and at Cornell University. It is entirely possible that there is an equally competent surgical specialist closer to you. Your vet will have an idea of who the best surgeon in your area is, or may suggest one of the referral centers above.

I am sorry you are faced with this problem. Finding the right surgeon is important. It is worth making a long trip to find an experienced surgeon if that is necessary.

Mike Richards, DVM 8/25/2000

Portosystemic Shunt

Question: Dear Dr. Mike, I am writing you about my 9 month old Shis-Tzu. I have read your informatiion on your web site. This was helpful. I have additional questions that I would like to ask. I have some decesions to make and would appreciate your thoughts. My dog is a 9 month old Shis-Tzu. When she went to be spayed the lab work showd an ALT of 660. A repeat 2 weeks later was 750. She had her surgery uneventfully. Three weeks later the ALT was 950. This wek she had an asotope flow study that showd a 59% shunt. I am told most significant shunts show values of 80-90%. This raises the question of hepatic dysplas or a 2nd or different problem. The options are to 1] just watch until she becomes symptomatic, 2] exploratory looking for a shunt and do a liver bipsey at the sme time. She is a bit small, only 9.5 lbs. She eats well and is bright, alert and playful. Her stools are normal. PMHx: corneal laceration at 2 months that has been corrected with a conjunctival patch. 2nd surgery for suture removal. Cyclosporine eye drops for nearly 4 months. Spayed without complications. In the house is a 5 year old Great Dane, a 5 year old indoor cat and a box turtle [ 5 years in the house]. My thoughts are that if a extrahepatic shunt is not likely the I do not want to put her through another surgery. I have her on the Scienc/ liver diet now. Of course we will follow her enzymes, albumin and BUN. I am a pediatric neurologist but know very little about dogs. Thank you for your help.

Sincerly, Dr. C

Answer: Dr. C

I am hoping that you are referring to scintigraphy in your note, because I am not familiar with the term asotope flow study and am worried it is a testing procedure I am not familiar with.

However, if you are referring to scintigraphy, your understanding of the situation pretty much matches mine. For scintigraphy, Technetium pertechnelate is administered colonically. It is absorbed into the circulation that returns to the heart by way of the liver. If there is a shunt, the technetium is visible in the heart, to a gamma camera, prior to the time it appears in the liver. Measuring the fraction of the radioactivity that bypasses the liver allows an estimation of whether a shunt is present and how severe it is. When portosystemic shunts are present the fraction that bypasses the liver is normally between 65% and 90%, based on combining results from a couple of studies of this. Normally, less than 15% of the technetium bypasses the liver. Dogs with microvascular dysplasia are most commonly reported as having normal scintigraphy values. So, a value of 59% would certainly be highly suspicious for some sort of shunting.

Ultrasonagraphy often allows visualization of liver shunting, so this is another test to consider. It would also allow ultrasound guided liver biopsy, which would be useful in ruling out other liver conditions. Unfortunately, liver biopsy isn't helpful in the diagnosis of microvascular dysplasia unless there is new information on this that I am not aware of. Angiography may also show shunting but I don't think it is done all that often, anymore, due to the availability of ultrasound. I do think that some (perhaps many) veterinary surgeons feel completely justified in an exploratory surgery without prior ultrasound exam, especially in a patient with a known track record for tolerating anesthetic procedures. Sometimes, even after scintigraphy and ultrasound exam, surgery is the only way to find a shunt or to come as close as possible to ruling out the possibility that one is present.

However, even when shunts are present, some veterinarians prefer to treat medically, unless that approach doesn't work well. Using low protein diets (l/d would fit this need), administration of lactulose and if necessary, neomycin, it is often possible to control the symptoms associated with portosystemic shunts. Since your dog doesn't have any symptoms, I would tend to lean towards using the low protein diet and not doing anything else except periodic testing for liver enzymes and/or liver function (bile acid response testing). I tend to be a big believer in doing nothing, whenever possible. If your vet feels differently, his or her opinion has to be taken more seriously than mine, obviously. The presence of high ALT values is a little worrisome with this approach but if you are monitoring that situation, it still seems reasonable to me to do nothing, considering that your shih-tzu isn't showing much else in the way of obvious clinical signs.

For microvascular dysplasia, medical treatment is reported to work in the majority of cases. Which is fortunate, because there isn't a surgical approach for that problem.

I don't know if this was all that helpful. If there is something more specific that you want information on, please feel free to ask for more detail.

Mike Richards, DVM 3/6/2000

Ameroid constrictor devices

Q: I am planning to subscribe to your digest on the next business day, by phone, but I would like to know how quickly I can ask questions of Dr. Mike. Particularly regarding 'ameroid constrictor' tecnique with regard to the repair of extrahepatic shunts. I am planning to have this procedure done on my 5 year old Jack Russell and would like to know how common this procedure is. Thanks Maureen

A: Maureen-

At the present time it is my impression that closure of single extrahepatic shunts with ameroid constrictor devices is the preferred surgical technique. The success rate of the surgery appears to be about 75%, with some dogs dying during or shortly after surgery and some dogs developing multiple shunts as the single one previously present is closed down. If surgery is successful most dogs can live a pretty normal life, making surgery the preferred option among most veterinarians I know, at the present time.

It appears to be important to be reasonably sure that the shunt is a single extra-hepatic shunt and not multiple shunts or microvascular dysplasia, a condition in which there is shunting occurs throughout the liver at the microvascular level.

Due to the age of your dog it is very important to consider the possibility of microvascular dysplasia since dogs with this condition often appear to grow normally and develop symptoms later in life while hepatic shunts are more likely to produce clinical signs early in life. I know of cases in which extra-vascular shunts were not discovered until very late in life, though. Even one case of a nine-year old dog that had been doing well until that age.

Portography (specialized X-rays designed to highlight the circulation in the liver) can be used to differentiate between single and multiple shunts. Liver biopsy is probably necessary to confirm microvascular dysplasia. Unfortunately these conditions can occur simultaneously in dogs and that makes the whole issue of diagnosis even more confusing. However, if a shunt can be visualized it is probably reasonable to assume that surgery should be considered. I am assuming this is the case since you seem pretty certain that an extra-hepatic shunt is present.

If surgery is not an option (as in microvascular dysplasia, multiple shunts, or for economic reasons) dietary therapy is reasonably successful at providing a comfortable life in many dogs. Using a high biologic value but low quantity protein diet (such as k/d by Hill's) is helpful in controlling many of the symptoms associated with hepatic shunts. This diet can be combined with lactulose and antibiotics to further decreased nitrogen production in the colon and lessen the production of ammonia even further. This is helpful since ammonia in the blood stream is the primary culprit in producing neurologic signs associated with liver failure.

I hope all goes well.

Mike Richards, DVM

Liver Shunt

Q: Dr. Richards Thank you so much for your immediate response to my questions regarding my JR.and her suspected liver shunt.

Yes, we have been trying to manage this situation for the past 4 months with K/D food and lactulose at a dose of 1/4 teaspoon twice daily. However, the mild seizure activity has begun to increase to a more severe level in the past 30 days. So, it seems that we will have to follow the surgical path. One of the doctors at the Univ. of Mo., Columbia, has suggested a rectal scintigraphy instead of a portagram to determine which type of shunt exists. But, I was unaware of the complications involved with microvascular shunts. This sheds some new light on the complication level, just when I was beginning to think in a more positive manner. I suspect this problem has been in existence for at least 2 years, but the type of behavior manifested up until recently gave no real hint of a liver problem. My 'Charlotte' was deaf at birth and we attributed lots of unusual behavior to that problem, not realizing until recent blood levels came back way out of the range of normal, that there was a liver problem. An ultrasound showed diminished liver size and possible kidney stones, but no real pat evidence of a shunt. So, now we will proceed with the rectal scintigraphy to get a more accurate picture. Again, thank you so much for your answers, and I will let you know the outcome of our situation. Maureen and 'Charlotte'

A: Maureen-

I have to admit first off that as a rural practitioner I have absolutely no experience first-hand with either contrast portography or scintigraphy. However, from reading about these procedures I am under the impression that scintigraphy is a very good way to diagnose whether a shunt exists and to quantify the amount of blood that by-passes the liver. Doing this before and after surgery allows a measurement of the success of surgery. I think that it would not identify microvascular dysplasia but would at least make it possible to tell if it is necessary to do liver biopsy to get a better idea of diagnosis. Per-rectal scintigraphy is supposed to be the least expensive really good way to diagnose liver circulatory shunts.

I think that this test provides the indication for surgery but that portography is still necessary to make certain that more than one shunt is not present and that it is usually done in conjunction with surgery. Again, this is my impression based on literature NOT first-hand experience. Still, you have to get to the point of knowing whether a shunt is present or not and it is less invasive and less expensive to do this with scintigraphy, so doing both tests seems justified.

I am sure that the veterinary school will do a good job and that the staff will be willing to explain the diagnostic process as carefully as you ask them to. The biggest mistake people make is not asking enough questions of specialists. Take a list of the things you want to know with you when you go to be sure you get the answers you want.

Good luck with this.

Mike Richards, DVM

Suspected portosystemic shunt in Yorkie

Q: I have a six month old Yorkie. One night she wasn't acting normal, she was very tierd, not responsive she wasn't walking. I took her to the animal hospital and they couldn't find anything wrong with her. They kept her overnight and gave her intervenus. The next moring I took her to her regular vet and she performed a few tests she aslo kept her overnight with intervenus. When I picked her up the vet informed me that they suspected a systematic porto shunt. She is on prescription dog food a 2 medications. It has been over a week now and she is completely normal eating normal going to the bathroom normal playing as usual. The day that this happend to her I had given her chicken is there any way the chicken could of been bad and gave her this reaction and could that of been a reason for her blood wok coming up showing a liver shunt problem? Could it be the dog is acting so normal having this problem? Also, I wanted to know the difference in the life spand with and with out the corectted surgey that my vet recommends? Can it be possible that even though my vet says this is what she thinks it is, could she be wrong? should I have her retest her?


A: It is possible that your dog doesn't have a portosystemic shunt. It is also possible for her to react well enough to the medications and dietary changes to seem normal despite having a shunt. It may be necessary to do more testing to determine for certain if a portosystemic shunt is present. If your vet did bile acid response testing this can be a very good indication of the possibility of a shunt but it can't pinpoint the problem. There is some discussion of diagnosis of this problem on our website. Please use the search engine and the term "portosystemic" and I think you'll find it.

Mike Richards, DVM

Liver shunt in Sheltie

Q: Hi, I have a 2 1/2 year old female sheltie. She had a liver biopsy and it came back as her having a portocaval shunt inside her liver it was unable to be fixed in surgey. My question is whenever I try to do research on this all I find is portosystematic shunts. Is this the same thing and if not could you be so kind as to tell me the difference. I am completely out of money at this point and my dog is just a crazy little girl who is troubled with seizures and confusion. Please help us. I am more than willing to spend the money to make her better, because I love her with all my heart but unfortunately I cannot afford anymore trials.

Please help me I am at my last rope and really could use a break.


A: Dear Donna,

Shunts can occur inside the liver, in which case they are referred to as intravascular shunts and outside the liver, in which case they are extrahepatic shunts. All of the shunts are portosystemic shunts. This is the best term to use to describe an unknown type of liver shunt.

Extrahepatic shunts include porto-caval shunts which are one of the most common types of extrahepatic shunts. There are several ways that blood can by-pass the liver and empty directly into the systemic circulation, though. The advantage to the surgeon of an extra-hepatic shunt is that there is usually a place to surgically obstruct the shunt and re-route the blood flow to the liver which is where it belongs. Extra-hepatic shunts are easier to repair due to this.

Intrahepatic shunts are more difficult to repair because the shunt is hidden inside the liver where it is not easy for the surgeon to work. There are surgical procedures for fixing them, though. These are costly procedures and are probably done primarily at veterinary teaching hospitals associated with veterinary colleges. The success rate for surgery for intrahepatic shunts is less than for extrahepatic shunts.

If surgical repair is not an option due to the expense it is possible to manage many dogs with portosystemic liver shunts medically with reasonably good success. A low protein diet combined with administration of lactulose and/or neomycin can help to relieve the symptoms associated with liver shunts.

I hope that this helps you.

Mike Richards, DVM

Portosystemic Shunt or Liver Shunt

Q: Dr Mike What disease is normally diagnosed within one year of age and diverts blood flow past the liver resulting in poor weight gain and stunted growth? Some signs may include depression, circling, and head pressing.

Thanx Doc.

A: JD-

This condition is often referred to as a "liver shunt" but the current favored term appears to be portosystemic shunt. These have also been referred to by more exact terms since there are specific types of shunts that vary slightly. The broad categories are extrahepatic and intrahepatic shunts, depending on whether or not the shunt occurs in the liver or outside of it. Specific types of shunts are patent ductus venosus, portal-azygous, portocaval (portal-abdominal vena cava), atresia (lack of development) of the portal vein and acquired shunts that occur due to changes in blood pressure or circulation.

Hope this helps narrow your search for information.

Mike Richards, DVM

Surgery for portosystemic shunt

Q: Dr Mike: First, I cannot tell you how much I enjoy reading your web page. I find it interesting and very informative. My wife and I recently adopted two labrador puppies, Maggie (yellow) & Izzy (chocolate). At 13 weeks, we discovered that Maggie had a portal systemic shunt. We took her to the Univ. of Penn Vet Hospital in Philadelphia where she subsequently had surgery. The vascular surgeon informed us that due to the possibility of portal hypertension, she was only able to close 75-80% of the shunt. As you know, if the shunt does not close the remaining 20% on its own, another surgery may be necessary. Although we have the financial resources to endure yet another $2,500.00 vet bill, I hate to see Maggie go through what appears to me to be experimental surgery. My sense is that the surgeons at this institution, albeit very skilled, will try anything to save this pup without regard to cost and quality of life. I basically have two questions.

1. In the event of yet another possible hospital stay and surgery, do you think that it is possible that after this second surgery Maggie will lead a normal life span? How would you advise your client with respect to putting Maggie to sleep?

2. Our two pups seem to love each other but seem to playfully fight all the time. Should we allow them to bite each other and knock each other around, or, should we break-up this little fights and attempt to keep them separated? Thank you so much for your help and opinions. Sincerely, David

A: David- I think that the surgery for portosystemic shunts has been in use long enough and successfully enough that it can't really be considered experimental anymore. That is a good thing but it doesn't change the situation too much. We have had several patients undergo this surgery and so far all have done well, even the ones in which the surgeons were hesitant immediately after surgery. So I think there is a good chance this will work out fine. As far as I know, we have only referred dogs with extrahepatic shunts (occurring outside the liver itself) and this surgery is easier to do than surgery in dogs with intrahepatic (inside the liver) shunts. In either case, I was under the impression that it was often necessary to only partially close the shunt since that was usually enough to change the circulatory pattern without causing abrupt changes in the systemic circulation that may be fatal. In some cases the degree the shunt can be or should be occluded is hard to judge and it is necessary to repeat the surgery. This may be more common with intrahepatic shunts. I am not sure of this, though. Labradors are supposed to be more likely to have intrahepatic shunts.

If another surgery is necessary I think I would tend to go ahead with it if the cost is reasonable for you to bear. The puppies from our practice really have done well, so far. I can't remember one of them dying postoperatively yet so I am assuming that they are doing well and enjoying reasonable lifespans.

I tend to think it is best not to interfere with the puppies too much when they are playing even if it appears to be fighting, as long as one of them isn't getting damaged in the interactions. Puppies need to play and they need to establish who is the dominant dog and this is sometimes done with a great deal of noise and "show" even though not much actual fighting occurs. Mike Richards, DVM

Liver shunt - yorkies

Q: Dr. Mike, I show and breed Yorkshire terriers. Up to this point, I haven't had anything with liver shunt. However, I know this is a problem in my breed and would like to know the symptoms and at what age it is most likely to occur. I get conflicting answers from the parent club and other breeders. I would also like to know if there is a definitive test for this. Thanks in advance. Charlotte

A: M- Yorkshire terriers are reported to have a higher than normal incidence of liver shunts. They are reported to be more likely to have extra-hepatic shunts which is good since they are easier to repair.

Most shunts cause recognizable clinical signs by the time a dog is a young adult but once in a while one is diagnosed at a later time in life. The oldest pet I have heard of a diagnosis of this condition that was previously undetected was eight years old. Since the severity of the condition can vary widely depending on how much blood flow is diverted past the liver it is possible for a lot of variation in clinical signs and time of onset of signs to occur. Often, this condition is recognized after a puppy fails to grow, making an early diagnosis pretty common, too.

Signs of portosystemic shunts include poor weight gain, sensitivity to sedatives (especially diazepam), depression, head pressing (pushing the head against a solid object), seizures, weakness, salivation, vomiting, poor appetite, increased drinking and urinating, balance problems and frequent urinary tract disease or early onset of bladder stones. If the signs of problems increase dramatically after eating this is a strong supportive sign of a portosystemic shunt.

These are all pretty nonspecific signs. This is frustrating since there is not a really easy test for this condition. You asked if there was a "definitive" test and there is almost one - special dyes injected into the liver circulation that show up on X-rays can outline the problem pretty clearly. Most of the time. But this is a pretty invasive test making it a poor choice for "screening" purposes. There are a number of possible abnormalities that might point towards a portosystemic shunt on routine labwork, including low BUN (blood urea nitrogen), low albumin, mild anemia, increases in ALT (serum alanine aminotransferase) or ALKP (serum alkaline phosphatase). If these hints are present, it would be a good idea to test the serum bile acid levels prior to eating and after eating. If this test is supportive of poor liver function THEN it may be a good idea to consider ultrasonagraphy and dye contrast X-rays. I have not seen a reference to this but perhaps ultrasound exam may be a reasonable screening test since it isn't too invasive and lack of hepatic circulation may be evident by ultrasound exam.

Hope this helps. Mike Richards, DVM

Neomycin use in microvascular shunting in the liver

Q: Dr. Mike, Just wanted to update you on our Charlotte. We returned from the Univ. of Columbia, Mo. yesterday, and thanks to Dr. Jimi Cook, resident surgeon, Charlotte has been diagnosed with microvascular shunting in the liver. A scintigraphy ruled out an extrahepatic shunt, so exploratory surgery was performed, and a biopsy was sent to the lab. (An ultrasound was also performed preoperatively to investigate kidneys, abdomen, liver and anything else she may have been hiding from us). During the surgery, Dr. Cook removed a rather large stone from her right ureter. Maybe that will keep her from having kidney problems down the road. The lab report confirmed microvascularization. So we will continue with K/D in small, frequent feedings, and switch from Lactulose to oral neomycin at .5 ml twice daily to try to keep the seizure symptoms at bay. I was wondering if you could explain the action of neomycin with relation to seizures. I don't quite understand this. And since Charlotte requires a lower protein diet, do you know if treats such as the 'pig ears' that dogs love so much would be safe for her?

Before signing off, thank you so much for our first issue of Vet Info Digest. What a fascinating article on heartworms! And I really love the story about the 'heavy metal poisoning'! Thanks again, M

A: M, Thank you for the update.

Neomycin is an antibiotic that is not absorbed from the digestive tract. It kills bacteria in the digestive tract that produce ammonia. There are mechanisms in the intestinal tract to absorb (or reabsorb) ammonia, which would normally be processed (or reprocessed) by the liver. Since Charlotte's liver isn't working properly, the extra ammonia is harmful to her and makes seizures from hepatic encephalopathy worse.

It is my understanding that lactulose and neomycin can be used at the same time, if necessary, to aid in controlling ammonia production in the digestive tract. If there is a future worsening of clinical signs it might be worthwhile to check into using these medications together.

I wish I could tell you if pig ears are an acceptable treat, but I can't. I have never seen a nutritional analysis of pig ears from a reliable source. The reason that k/d diet is recommended for dogs with liver disease is that it is low in protein and high in energy (k/d is a relatively high fat diet). In the case of liver diseases higher fat contents are OK. So if you find that pig ears are high fat but low protein they would be OK as a treat. I just don't know if that is the case.

I'm glad you liked the VetInfo Digest.

Mike Richards, DVM

Liver shunt

Q: I came across something on the web referring to "shunts" in pets, namely small dogs such as toy poodles. What are they?

A: Tom- Liver shunts are a congenital problem in some dogs. During gestation the placenta delivers blood with food and oxygen from the mother through the umbilical vein. This means that in the fetus, circulation is the reverse of circulation after birth, because the fetus' veins have the oxygenated blood and arteries return unoxygentated blood to the heart. In order to make this work, there is a shunt from the liver venous circulation to the arterial circulation. At birth, the pressure within the circulatory system changes as respiration occurs and this shuts the shunt, which eventually disappears. If this reverse in circulation doesn't happen for some reason, the liver is deprived of a blood supply and doesn't develop properly after birth. Many puppies can live with the small functioning portion of the liver for some time but eventually have problems and usually die if the situation is uncorrected. It is possible to surgically close the shunt and the surgery works well. I can remember hearing of one sheltie that was 6 years of age (or possibly older) before a congenital liver shunt was recognized, so some dogs can live a long time with this problem. It is very unlikely that your poodle is experiencing problems from a liver shunt.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...