By Christie Long
I spend a lot of time trying to interpret lab work so I can diagnose diseases.
I often tell clients that submitting lab tests on their dog or cat might give us the exact answer as to what is wrong, or it might prompt more questions and subsequently more tests.
A great example of this is the interpretation of the lab values that tell us about how the liver is doing. The liver is an amazing organ that sits quietly in the abdomen, nestled cozily against the diaphragm, filtering the blood through its intricate plumbing, clearing it of toxins. In addition, it manufactures a host of critical compounds necessary for utilizing the nutrients we get from our food.
Labs measure the amount of several of these compounds in circulating blood. When damage is occurring in the liver, the amounts of these compounds increase, because that damage is destroying liver cells, and that is causing those compounds to spill into circulating blood at higher-than-normal levels. It’s wonderful that we can detect this, but most liver conditions cannot be specifically diagnosed with routine blood work. It can be frustrating when apparently healthy animals have abnormal liver values on routine wellness lab work, but this is often when it’s most critical to figure out exactly what’s going on.
It’s fairly common to find mild elevations in the liver values of healthy dogs and cats. Dental disease can cause mild elevations in one specific liver enzyme, so often a thorough dental cleaning and the extraction of diseased teeth will resolve the elevation. Other times, these are transient changes, and if there are no clinical signs of liver problems, such as vomiting, diarrhea or reduced appetite, it’s perfectly reasonable to plan to recheck those values in a month or so. If the elevation has resolved, that’s great, but if not — and especially if it’s even greater than before — further testing is warranted.
The next logical step to take depends on exactly which values are elevated, but I often recommend an abdominal ultrasound. A skilled radiologist can help us learn a lot about the liver and gall bladder with an ultrasound. We can typically see changes to those organs that help us figure out what’s going on.
Advanced blood testing also can help determine if the liver is functioning properly. A bile acids test involves drawing a blood sample after an overnight fast, feeding a meal and then drawing a second sample one hour later. A well-functioning liver can clear the bile acids, which are secreted into the small intestine to help digest fat, from the bloodstream in that timeframe; a poorly functioning one cannot.
Ultimately, an exact diagnosis may only come from a biopsy of the liver tissue itself. A biopsy can diagnose conditions as diverse as hepatitis, cancer and a deficiency in the way copper is stored. These conditions all require very different forms of treatment, and for this reason, it’s important to not ignore liver value elevations.
Christie Long is a veterinarian at the VCA Animal Hospital in Fort Collins, CO. Long left her job in software sales in 2000 to travel for 13 months. Along the way, she was touched by the plight of the animals she saw and somewhere in the Nepalese Himalayas she vowed to return to school to become a veterinarian. While she often finds end-of-life situations heart-wrenching, she considers herself blessed to be called upon as a trusted adviser to families during difficult times. Dr. Long’s family includes her husband and travel partner, Wiley, their son, Wiley IV, their dogs Pancake and Gizmo and cats Sneaky and Sidh.