What are the Causes of Elevated Liver Enzymes in Canines?
Liver enzymes can be elevated for a large number of reasons, broadly these causes are broken up into two different categories hepatic and extrahepatic.
Below is a list of some of the possible causes of elevated liver enzymes in dogs.
Hepatic means inside the liver. The liver can become diseased from a large number of causes.
Extrahepatic means outside the liver, diseases in other organs can affect the liver causing elevated liver enzymes despite no actual liver disease.
What does a dog’s liver actually do?
First of all, let’s talk about what livers do. A lot of confusion surrounds this: we all know that livers are important, but many people find it hard to explain why. This is probably because they have a variety of different complicated jobs, mostly connected to metabolising food.
I like to think of them as the body’s boiler. Not because they literally generate heat, although they certainly do. But they are also a hotbed of metabolic reactions, releasing energy and other products from food, so that the body can use them. They also clear dead blood cells, toxins, poisons and waste products from the blood and make bile and some essential vitamins and minerals.
In short, our livers are vitally important and luckily, they are regenerative. That is, animals can grow new liver tissue when their livers are damaged. As the liver starts to struggle, lumps of extra tissue grow on the side. Sadly, the capacity of the new liver tissue is often limited. In severe, ongoing cases, the liver can become large with increasingly few useful cells and additional lumps on the side.
As an aside, this explains why it can be difficult to tell the difference between a cancerous liver and one that isn’t working but has tried to regenerate. A vet might tell you that a liver looks irregular or lumpy, but it may be regeneration or may be cancer, so biopsies are often needed.
The Typical Patterns of Clinicopathological Changes in Dogs With Liver Disease
In a dog with liver disease, the typical patterns seen will differ with where the disease lies, there will be differences depending on if the liver, bile duct, or both is affected. Once liver disease is suspected further tests may be performed to help confirm liver dysfunction and get a diagnosis to aid treatment.
It is important to note that there can be no clinicopathological changes in some dogs with liver disease due to the large reserve capacity that livers have, this means even with the disease the liver can continue to function normally and it may require more severe, widespread disease before it can be detected with testing.
Some common tests and their findings are listed below:
Biochemistry
Complete blood count
Urinalysis
Imaging
Other clinicopathologic tests include bile acid stimulation tests, cytology, histology, and checking clotting times.