Liver shunts are fairly common in the smaller breeds and it is imperative that all breeding stock be checked for liver function and even in a pet havanese it may be wise to have a liver panel done. A liver shunt occurs when the blood is shunted around the liver rather than passing through it. A fetus needs its mother to clean the blood and that is achieved by allowing the veins surrounding the liver and, in some cases, interior to it to carry or shunt the blood away from the fetus liver. These veins should disappear by the age of three or four days. If they persist then varying degrees of sickness may result. There are very mild forms of liver shunts where only a necropsy may reveal the shunt. However in severe cases the puppy may begin at three or four months to act in a peculiar fashion, circling, falling down, throwing up and in general not to appear normal. In severe cases this can cause death. In the toy breeds the veins tend to be exterior to the liver and therefore operable. When the veins run through the liver only dietary management can help.
HEPATIC MICRO VASCULAR DYSPLASIA
is another type of liver disease that may not show up until five or six years of age. The dog may appear completely normal until that time and the only way to uncover this is by including a bile acid test in your yearly exams. The bile acid test is extremely sensitive to environmental factors and needs to be given separate to other blood work. The following is an article which I wrote on using this test as a diagnostic tool.
Bile Acid Tests Are Making Me Feel Bilious!
“Bile acid tests are too unreliable.”; “I can’t get my dog to eat for the test”; “What does all of it mean anyway?”; “I can’t be bothered, I’ll wait until there’s a genetic test.” These are a few of the comments that I have heard about bile acid testing, and believe me, I have felt the same at times. So what ARE the problems with the bile acid test, and can anything be done to improve their value to us as breeders? It is one thing to use the test on a very sick animal, after all, if the bile acid readings are 250 rather than 240 does it really matter; the animal is sick in either case. To suggest that an animal that tests at fifteen is well and one that tests at thirty is not requires more exactness in the testing and the testing procedure.
I have been corresponding with many other breeders who do regular bile acid testing and we have independently arrived at some of the following observations, questions and conclusions:
Dogs given excessive amounts of food during the testing return higher bile acid results than those fed smaller amounts. I went through this with my last round of testing. During the first testing session I took the dogs to the local park after their first blood draw, and fed them their usual home cooked meal. I allowed them to eat all they wanted. It was just one of those days when I wasn’t being particularly vigilant. I also returned to the vet office about fifteen minutes early for the second round of blood draws. The results were just over the normal range. This just didn’t jibe with the results from the first litter of this repeat breeding. Several weeks later I took the same dogs, plus an extra three year old, to the University of Guelph where the dogs were each given two tablespoons of Hill’s A/D (a soft dog food) and the timing between eating and the second blood draw was exactly two hours. None of the dogs was exposed to the smell of food, which is very important, since food smells can cause the gall bladder to contract and release bile. This time, all the dogs passed in the low normal range except for the three year old intact male who was exposed, by accident, just before going in for the blood draw, to his first female in heat. After we peeled him from the ceiling he tested at the higher end of normal. Was stress a factor in this normal but slightly higher reading?
The big difference between the first and second testing scenario is that I did NOT bring along my own food since the dogs would be able to smell it in the car; they were all fed the same food and the same amount of food; and, I also made sure that once my dogs were fed after the first blood draw, I took them out in the car and they did not have a chance to smell food of any kind.
It is believed by most people that it takes a dog longer to digest kibble (dry food), so it stands to reason that if a dog is fed kibble during the bile acid test, it will return higher bile acid counts because the transit time through the stomach and intestine will take longer.
Some veterinary offices are better at following the two-hour rule than others. What difference might this make.
Some breeders find that stress can cause the dog to return higher values.
Some labs claim that with their equipment, slight hemolysis (burst red blood cells which discolor the sample) is not a problem. This seems to contradict what we have been told in the past.
Breeders have found that certain drugs such as Flagyl will cause the bile acid results to be higher.
Some labs report in mg/dl (milligrams per deciliter) while most report bile acid readings as umol/l (moles/liter) so how do we convert this?
The normal range, for this particular test, in one lab may be different to the normal for another lab.
It has been found and documented that blood from the same blood draw which is divided and then sent to two different labs can have results that vary by ten to twenty-five points. In both cases the normal ranges from each lab were set at zero to fifteen umols/dl. This next example is also documented. I was personally involved with one dog that tested in the 30+ range the first time he was tested. He was retested two days later, but the blood sent to a different lab and the results came back as low normal.
Are these valid assertions and if so what can we do to coordinate our testing and make it easier to share information. This becomes extremely important when looking at buying or breeding to a new dog that may live thousands of miles from your home.
I took some of these concerns to Dr. Shana Blois (Assistant Professor of Small Animal Internal Medicine and Diplomat of the American College of Veterinary Internal Medicine) at the University of Guelph. She commented as follows:
Different labs have different normal ranges because each machine varies to some degree in its measurements, even when the machines are from the same manufacturer. A lab will take a group of dogs known to have normal livers and bile acids and set the normal range based on the values returned by this set of dogs.
If a lab reports in mg/dl (milligrams/deciliter) the value can be multiplied by 2.547 to convert to ?mols/l (moles/liter). As an example, a reading of 10 mg/dl would yield a value of 25.47 umols/l. Moles are a molecular weight and the conversion factor is different for different substances such as cholesterol verses bile acids.
According to Dr. Blois, it is best to take the second blood sample as close to two hours after feeding as possible. While a few minutes may not make a difference, a thirty minute difference would impact the results of the test.
Asked Dr. Blois what food the University uses for testing and she said they always used two tablespoons of Hills A/D for dogs the size of the Havanese.
When I asked her about stress and even slight dehydration from a three-hour car ride, for example, which was the length of our trip to the university, she thought that it would not make a significant difference. She was dubious about stress making a difference but said there is no research on the subject.
When asked about certain drugs affecting the result she said that it was best to do the tests when the dogs were not on any kind of medication.
I also asked her about the dangers of doing a liver biopsy since the reaction of many breeders is that to perform this test is unnecessarily exposing a dog to extreme danger. Dr Blois thinks that the risk is about the same as any operation where an anesthesia is given, but the possibility of bleeding from the liver is minimal as long as the dog is otherwise healthy, and has normal blood clotting abilities (which can be checked with a blood test). A liver biopsy is definitely worth considering if there is any doubt at all about the health of a breeding dog’s liver after performing less invasive tests such as abdominal ultrasound. Additionally, some liver biopsies can be performed in a minimally-invasive manner such as via laparoscopy or ultrasound-guided biopsies.
Some machines, like the one used at the University of Guelph, for example, have a built in system to help reduce interference from hemolysis or lipidemia (fat cells). As a result, mild amounts of hemolysis or other mild interferences do not affect the measurements.
It is this author’s opinion, after doing bile acid tests for many years, that for breeders to be able to share the results and not be comparing apples and oranges, a very strict protocol must be followed. The history of the bile acid test has been to detect liver issues in very sick animals, to use it as a tool to detect very healthy dogs requires more consistency.
In the morning, when pottying the dog to be tested make sure that they do not have access to grass, poop, food or even the smell of food, therefore, no bacon and eggs at home or McDonalds on the way to the vet office.
Have available at all times.
After the first blood draw, feed the dog two tablespoons of Hills AD. This food is soft so any experienced breeder, veterinarian or assistant should be able to get a couple of tablespoons into a dog whether they are willing or not.
Make sure that once they are fed, they are not exposed to the smell of food during the next two hours.
Take the dog out in the car if you think that leaving him at the vets will raise the dog’s anxiety level. Again, no McDonalds or packed lunches while the dog is in the car.
Make sure that the second blood draw is as close to 120 minutes as is humanly possible.
Send your blood samples to the same lab as the rest of the breeders that you work with. An ideal solution would be for all breeders to use the same labs.
These procedures may help make the results of the bile acid tests more accurate, and more consistent between breeders. Is it worth it? Well, that’s for each breeder to decide, but even though the test is somewhat frustrating and not perfectly black and white, it is a good guide, especially when the results are paired over a period of time. I am now doing the tests for my breeding dogs when they are sixteen weeks, and then again, along with liver enzyme tests, before they are bred. If any of the results are inconsistent with the overall picture of that dog’s health or history, then I will do them again several months later. Not a perfect plan, but one that I feel protects my breeding plan and my dogs.