Why Should I Bile Acid Test My Papillon?
By Carlisle Peel
At the 2009 Papillon Club of America (PCA) National Dr. Sharon Center of Cornell University gave a talk on Liver Disorders in Papillons. This lecture focused mainly on Portosystemic Shunts (PSVA) and microvascular dysplasia (MVD). At that time PCA was participating in an AKC-CHF Research Study involving inherited Liver Disorders in Papillons. Dr. Center reported that at that time 50% of Papillons tested had elevated bile acids (a marker for MVD) leading her to believe that liver problems in Papillons may be more widespread than we realize. After this seminar many of us realized that we may personally have been dealing with one of these liver problems and became very interested in participating in the research. Papillon Association of Puget Sound (PAPS) organized two health clinics which in conjunction with Cornell allowed us to economically test our dogs. As Dr. Center anticipated, at least 50% of the dogs tested had abnormal bile acid levels leading to further discussions about what to do with this information.
What are Portosystemic shunts and Microvascular Dysplasia?
The liver filters out toxins, stores sugar, and makes proteins. Most of the blood that is carried to the liver for these processes arrives via the portal vein, which drains the intestines, stomach, pancreas, and spleen. This vein carries nutrients derived from food as well as toxic material collected from the intestines and colon. It is important that the liver cleanse this blood before it mixes with the systemic circulation.
In a Portosystemic shunt (PSVA) the blood bi-passes the liver entirely and the animal cannot process toxins or make proteins necessary for growth and normal function.
In Microvascular Dysplasia (MVD) some blood vessels within the liver are underdeveloped or absent. Depending on the severity, the functions of the liver can also be compromised.
Why test bile acids
- Bile acids are synthesized in the liver, are secreted into bile and are stored in the gallbladder between meals.
- As the stomach and intestines digest food, the gallbladder releases bile through a tube called the common bile duct. The duct connects the gallbladder and liver to the small intestine. The bile carries the bile acids that aid in the process of digestion.
- After digestion most of the bile acids are re-absorbed in the small intestines and put into the blood system through the portal vein. They are then taken directly to the liver where they are extracted back into the gallbladder.
- In animals with a Portosystemic shunt (PSVA) the circulation back through the liver is completely bypassed and high levels of Bile Acids are found in the blood stream. In Microvascular Dysplasia (MVD) the circulation is also interrupted to various degrees and higher than normal Bile Acids are found in the blood.
Signs of Portosystemic Shunts
Most affected dogs are considered the litter runt, often have small body stature, and appear unthrifty. Neuro behavioral sign may manifest during the first few weeks of life owing to hypoglycemia.
Clinical signs are often seen at a young age and may include poor growth, behavioral changes (circling, disorientation, unresponsiveness, staring into space, head pressing, blind staggers), seizures, and quiet demeanor. Many of the clinical signs may be confused with puppy hypoglycemia (low blood sugar). Other less common signs include diarrhea, vomiting, and excessive drinking or urinating. However, not all dogs with PSVA have symptoms or are ill; up to 20% of PSVA dogs may be asymptomatic which has resulted in some of these dogs being used for breeding. Some animals may not show clinical signs until they are anesthetized to be castrated or spayed. These animals may take days to recover from anesthesia, depending on what drugs were used. Other animals show no signs until they are older, when they develop bladder and kidney problems from excreting toxins and forming urine crystals and stones.
Signs of MVD
Research indicates that dogs with MVD usually do not manifest clinical signs, are not ill, and do not require medical or dietary treatments. Some breeders however report that a picky eater has been a primary indication of MVD. MVD dogs can live to an old age. If symptomatic they are likely unrecognized PSVA dogs.
Occasionally dogs with MVD can present with signs similar to dogs with congenital Portosystemic shunts. Often affected dogs are 3 to 4 years old before they have clinical signs. Some affected dogs are smaller than normal, with poor muscle development. They may seem less intelligent or quieter because of the toxins that depress their brains. They may have a loss of appetite or occasional bouts of vomiting and diarrhea. Some dogs may have a greater risk of infections or develop bladders stones. Severely affected dogs may be wobbly or act drunk or blind and can even seizure.
Why is Bile Acid testing Important? Summary of Information given by Dr. Center at the 2009 PCA National
- Possibly over 50% of Papillons have elevated bile acids. By addressing this we hope to avert major problems that may develop in this breed regarding inherited liver disorders.
- Several health conditions can contribute to abnormal bile acids such as lepto, hepatitis, and some medications, but the most common factor is MVD or PSVA.
- Elevated bile acids (over 25) in young dogs are usually exclusively related to MVD or PSVA. It is recommended that dogs with elevated bile acids have continued testing to determine if they are indicative of MVD or a Portosystemic shunt.
- Center recommended that breeders test their puppies while they are considered clinically healthy, ideally close to 6 months but can be done as early as 4 months. This provides information in the event that a bile acid test at a future time is above normal, and the veterinarian suggests costly and invasive testing. Knowledge that the dog had abnormal bile acids as a puppy would assist the Vet in determining whether further testing is necessary. Most MVD dogs require no treatment.
- Evidence indicates that PSVA and MVD are genetically related.
- Dr, Center suggested a balanced approach tomaking breeding decisions. Dogs with elevated bile acids should be bred judiciously. The recommendation is that breeders do not breed two dogs together that have elevated bile acids. Such a breeding can result in increased risk for liver shunts.
- There is evidence that bitches that reabsorb puppies during pregnancy may have a liver disorder. It a bitch continually reabsorbs puppies it would be prudent to run a bile acid test on her.
Bile Acid testing on our breeding dogs will allow us to make informed decisions on breeding. I have put together some information on the genetics of PSVA and MVD which helps in understanding the breeding decisions involved. If you are interested, please email me and I will send it to you. firstname.lastname@example.org Here also is a link to a brochure on liver disorders by Dr. Karen Tobias University of Tennessee College of Veterinary Medicine for those who want more extensive information.