DOES MY DOG’S LIVER HAVE BAD PLUMBING (CIRCULATION)?

I spent the Fourth of July Holiday week end in the Mountains of North Carolina with a dear friend. In the process, we visited the Boone Farmer’s Market. I especially loved the truck bed loaded with chickens for sale.

On the way home we passed the Independence Day Puppet Parade in the small river town of Todd, NC. http://www.examiner.com/article/fourth-of-july-nc-liberty-parade-todd

Otherwise it was a weekend of hikes alone on the creek beds that cross property surrounding the cabin.

With the dogs, Kate, Lola, and Duke, we crossed streams, chased tennis balls, and collected wild flowers. 

For Bear, the 12 yr. old Chesapeake Bay retriever, all is not as it seems. He is missing his right eye as a complication to glaucoma, is arthritic, and has some changes in his liver. 

For his age, infirmities are anticipated and treated accordingly to support a good quality of life.

As a child, I would be forced to eat liver (flavored with bacon) that I found extremely foul and a form of punishment. Upon entering college and learning the filtration function the liver serves, my theory of its nastiness as a meal was confirmed. The packaged version at the meat counter confirmed my distaste.

 However, I am intrigued by the many hepatic(liver) functions.

In younger dogs, abnormal liver bloodwork values can be an unexpected surprise. To help explain one common liver (hepatic) disease, I will focus on a condition called microvascular dysplasia. 

I KNOW MY DOG HAS A LIVER, BUT WHAT DOES IT DO?

The liver performs an amazing list of duties. It acts as a sewer treatment plant, works to help store sugar, and manufactureskey proteins. To accomplish these tasks, most of the blood that is carried to the liver for these processes arrives via the portal vein from the intestines.

OKAY, BORE ME WITH AN ANATOMY LESSON OF BLOOD FLOW TO THE LIVER. 

The MAIN TRANSPORT BLOOD VESSEL TO THE LIVER ( portal vein ) drains the intestines, stomach, pancreas, and spleen. Within the liver, the portal vein branches into many smaller vessels so that the blood can filter throughout the tissues to each liver cell.

WHAT IS MICROVASCULAR DYSPLASIA (MVD) OF THE LIVER? 

When these mini vessels are abnormal on liver biopsy, the condition is called "hepatic microvascular dysplasia (HMD or MVD)" or "portal atresia". This means the microscopic vessels within the liver are underdeveloped or absent; subsequently, the liver becomes smaller and stops processing toxins, sugars, and proteins normally. It is also called PORTAL VEIN HYPOPLASIA. 

 When larger vessels outside or inside the liver are involved it is called a portosystemic shunt.

WHAT ARE THE CLASSICAL SIGNS OF THIS LIVER SHUNTING DISORDER I SHOULD LOOK FOR WHEN SELECTING A PUPPY FROM A BREED AT RISK?
A young dog less than 1 year of age that is a “poor doer” or not as big or as strong as litter mates are common denominators.  Some would call these puppies the “runt of the litter “with a “sensitive stomach”. Others will have difficulty in housebreaking with an increase in thirst and urination. They may lay around a lot or seem tired due to toxins not being eliminated by the liver and subsequently accumulate and insult the brain. In more advanced cases, seizures and distended “pot bellies” will be noted.   Unfortunately, in some cases, especially Schnauzers, the disease may not manifest until five to seven years of age.  It should be noted that many dogs with the condition show no signs. 

ARE CERTAIN BREEDS MORE COMMONLY AT RISK?
Some breeds are more commonly affected: Yorkshire Terriers, Cairn Terriers, Maltese, West Highland Terriers, Dachshunds, Pugs, Schnauzers, Poodles, Shih Tzu, Lhasa Apso, Havanese, and Cocker Spaniels. It has rarely been reported in Irish wolfhounds, Golden Retrievers, and Labrador Retrievers,  although any breed may be afflicted. 

THE BLOODWORK AND URINE SAMPLES ARE OFTEN ABNORMAL. CAN YOU BE MORE SPECIFIC?  Added tests needed?
Reported findings when the liver is not doing its job include normal to elevated liver enzyme ALT (biomarker generated by abnormal liver cells), low protein ALBUMIN, and low BUN (a break down product of protein metabolism). In severe cases, when URATE bladder stones form with high ammonia levels when the liver is not detoxifying the breakdown of protein properly, and a liver function test may be recommended as well. Added testing includes a combination of radiographs, ultrasound, and liver biopsy.

ONCED IT IS DIAGNOSED, HOW IS THIS HEPATIC DISEASE TREATED? 

-lower protein diets specifically recommended for patients with this condition

-probiotics such as Proviable

-neutriceuticals (holistic type supplements) to help improve liver function such as Denamarin

THE PROGNOSIS IS often GOOD FOR DOGS WITHOUT SIGNS OF THE LARGER PORTOSYSTEMIC SHUNTS. 

Betsy T. Sigmon DVM, Diplomate ABVP, Canine and Feline Practice
Creature Comforts Animal Hospital
Cary, NC