What causes elevated liver levels in dogs? Here’s the Answer

by

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.

  • Infectious hepatitis can be caused by viruses and bacteria.
  • Tumors in the liver can cause elevated liver enzymes as they begin to affect the organ’s function, some tumors can take a long time before changes are seen in bloods meaning the tumor can be quite large at diagnosis.
  • Toxins such as paracetamol, xylitol and some blue-green algae (cyanobacteria) and mushrooms.can cause elevated liver enzymes.
  • Trauma to the abdomen for example from being hit by a car can crush the liver and cause damage to the cells in the liver which can cause elevated liver enzymes.
  • Breed-specific diseases can cause elevated liver enzymes, for example, the Bedlington Terrier can have problems with storing copper, Doberman Pinchers can cause idiopathic chronic hepatitis, and Maltese Terriers can be more likely to develop congenital portosystemic shunts.
  • Nodular hyperplasia is a common benign change to the liver in elderly dogs, there is no treatment required but it can cause elevated liver enzymes.
  • Portosystemic shunts occur when a vein connects the blood supply from the intestines to the heart bypassing the liver (shunting). It can be congenital or acquired and causes liver dysfunction due to reduced blood supply, leading to elevated liver enzymes.

    • Extrahepatic means outside the liver, diseases in other organs can affect the liver causing elevated liver enzymes despite no actual liver disease.

  • Endocrine disease such as hyperadrenocorticism and hypothyroidism can cause elevated liver enzymes despite being diseases of the adrenal gland and thyroid gland respectively
  • Gastrointestinal disease such as pancreatitis and inflammatory bowel disease (IBD) can cause elevated liver enzymes due to inflammation in nearby organs (the pancreas and intestines)

    • 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

  • Severe elevations of AST and ALT with normal-mild elevations of ALP and GGT can show signs of hepatocellular disease.
  • Severe elevations of ALP and GGT with normal-mild elevations of AST and ALT can be a sign of cholestatic disease.
  • Elevations of bilirubin can show hepatobiliary disease.
  • Low levels of cholesterol and albumin (products of the liver) can show liver disease.

    • Complete blood count

  • Signs of inflammation can be a sign of hepatocellular disease.
  • Hemolysis can be detected with is a cause of an extrahepatic increase in liver enzymes.

    • Urinalysis

  • High levels of bilirubin can show hepatobiliary disease.
  • Urate crystals seen in the urine can be a sign of a portosystemic shunt (not specific).
  • A low concentration of urine can be seen in dogs with hepatic insufficiency and portosystemic shunts.

    • Imaging

  • Radiographs may show an enlarged liver or signs of masses on the liver.
  • Ultrasound is typically more sensitive to liver disease and may show diseases such as gallbladder stones or mucoceles, and portosystemic shunts. It is important to note that a diseased liver can look normal on ultrasound.
  • Computed tomography (CT) and Magnetic Resonance Imaging (MRI) can be useful for detecting liver changes associated with certain diseases.

    • Other clinicopathologic tests include bile acid stimulation tests, cytology, histology, and checking clotting times.

    Elevated Liver Enzyme in Dog