Ron Hines DVM PhD
The blood test results most indicative of a potential liver problem in your pet are elevations in its ALT, AST, GGT , and ALP enzyme levels. Its not that unusual for one or more of these tests to be a bit high but for your dog or cat to appears healthy. Those moderate elevations of one or two enzymes are often picked up in “wellness” checkups or yearly health checkups your veterinarian suggests.
The first thing you need to understand is that although we associate these enzymes with your dog and cat’s liver, there are many non-liver health issues that will also cause these enzyme levels to rise above normal. Things like pancreatitis in your dog or in your cat, infections like leptospirosis, gall bladder disease, portosystemic shunts, intestinal disease or a failing heart. Medications (such as corticosteroids), anti-seizure medications such as phenobarbital ( read here ) or NSAIDs, such as Rimadyl® , that your pet might be taking can also be responsible. So can herbal supplements. ( read here ) Transient unidentified processes not associated with organ disease can cause moderate, temporary elevations in these tests as well. So my approach is to retest these pets in 4-6 weeks. Many times, the second round of tests will be normal.
If your dog or cat’s liver tests are still elevated, a bile acids test and ultrasound examination are probably in order. If the bile acids test is high, your veterinarian might place your pet on a trial course of antibiotics and probably throw in some “liver support” products like Denamarin® or Denosyl®. They might even suggest a prescription diet such as l/d® Liver Care with the suggestion to repeat the blood test in 4-7 weeks. There is certainly no harm in giving all those unproven products a try.
When none of those options solved your pet’s problem, your veterinarian will want to determine if your dog or cat’s underlying issue is indeed in the liver or somewhere else. Symptoms like jaundice (icterus or yellowish skin), fluid buildup in the tummy (ascites), a mass or lump felt in the liver or seen on x-rays or any changes in the pet’s mental state (ie hepatic encephalopathy) make a primary liver problem likely. I believe that at that point most veterinarians would suggest that a fine, long needle be entered, under anesthesia, through your pet’s body wall. While guided the needle into the liver using ultrasound or a laparascope, a tiny plug or snippet of liver tissue (abiopsy specimen ) would be collected. That tissue would be sent to a veterinary pathologist to determine what abnormalities were present in the liver at a cellular level. An alternative when an abnormal liver mass (lump) is detected might be a fine needle aspirate. Cats with lymphoma involving the liver can often be diagnosed by identifying the cells in a fine needle aspirate. see here