How Does Your Dog Liver Enzymes Work? | What Does A Liver Enzyme Test Mean?

How Does Your Dog Liver Enzymes Work? | What Does A Liver Enzyme Test Mean?

Have you ever been confused by the results of your dog’s blood work?

The numbers you get from your dog‘s blood tests can be confusing, and sometimes veterinarians don’t do a good job of explaining them.

It can be difficult to understand a test about the body‘s immune system. The letters that appear on your dog’s test results are likely to include the alphabet soup.

If your dog’s had his labs checked recently and those tests show elevated liver enzymes, you need to understand what this means. What to do about it is another topic, but let’s take a look at the information we get from those elevated liver enzyme results.

What is the role of this vital organ in your dog’s body?

What The Liver Does

One of the largest and most important organs in your dog’s body is the liver, which performs about 500 daily tasks.

Some of the key activities of the liver are listed here.

1. Detox

First, the liver clears potentially toxic chemicals from both inside and outside the body, including drugs, vaccines, environmental toxins and even intestinal microbes. In order to detox, the liver needs critical antioxidant nutrients and enzymes such as glutathione (an important antioxidant molecule that helps prevent aging and chronic disease). The liver detoxifies harmful substances by a complex series of chemical reactions. The role of these various enzyme activities in the liver is to convert fat-soluble toxins to water-soluble substances. Once these substances are bio-transformed and no longer toxic, they then exit the body via urine or bile.

2. Storage

The blood sugar levels are regulated by the liver, a storage unit that stores sugar. Iron, copper, vitamins B-12, A, D, E and K are all stored in the liver.

3. Production And Regulation

The production of the liver is all that is important.

  • The production of bile helps with the digestion of fats.
  • The making of red blood cells are dependent on the production of blood proteins, clotting factors and substances. Red blood cells are recycled in the body’s tissues.

Free radicals produced during oxidation with vitamins C and E, as well as glutathione, can be mitigated by the liver.

4. Nutrient Breakdown and Absorption

The liver not only breaks down nutrients from the diet, it also helps the body use those nutrients in the buildup of tissues. There is hardly a more important organ in the body and so when the AST, ALT, ALP and GGT all start to elevate, what does this mean?

Graphic of dog liver

Liver Enzymes

There are other liver measurements you’ll see in your dog’s blood panel, but I want to focus on the liver enzymes and what they mean.

  • AST – Aspartate transaminase (formerly SGOT or serum glutamic oxaloacetic transaminase). If your dog’s AST is elevated, it may come from the liver but this enzyme is also found in red blood cells, heart, muscle, pancreas and bile. So if your dog’s AST isn’t normal, your vet should find out what’s causing the elevation. AST is normally low in serum so should be measured along with ALT as part of a liver panel to see what’s going on.
  • ALT – Alanine aminotransferase (previously called SGPT or serum glutamic pyruvic transaminase). If it’s elevated, ALT can signify liver or hepatic alert as to liver cell death … but this enzyme also comes from the kidney as well as the intestines, so liver problems aren’t necessarily the only cause of elevated ALT, and further analysis is warranted.
  • ALP – Alkaline phosphatase is found in bone, kidney, bowel (intestines) and the placenta (if pregnant), as well as the liver. The levels of this enzyme are highest in the bone and the liver. Basic phosphatase is a homodimeric enzyme that is high in young fast growing animals, so it’s not unusual to see elevated ALP in young dogs. But whatever your dog’s age, if ALP is elevated, ask your vet to investigate the reason.
  • The GGT is a glutamyl transferase. It’s useful for detecting and monitoring disease of the bile duct. The most sensitive indicator of liver disease is the GGT. If you are concerned about your dog’s health, make sure that your vet includes GGT as a part of the panel.

I would like to emphasize the need for a GGT test. It is important that you ask for it, because not all veterinarians measure this.

Why GGT Is Important

GGT can help confirm or rule out liver problems, as well as other diseases. Liver And Bile (Hepatobiliary) Disease

  • GGT is the key liver enzyme linking lab reports to liver disease. This enzyme increases in post-hepatic biliary obstruction and can reach 5 to 30 times normal.
  • If ALP is elevated but not GGT then skeletal disease is more likely the problem, and not hepatobiliary disease.
  • Increased GGT and increased ALP often indicates hepatobiliary disease … but in rare cases there can be gammopathies (abnormal gamma gobulin levels) present that could lead to unreliable GGT results.
  • GGT is less useful than transaminase in detecting infectious hepatitis, as it rises only modestly.

Other Liver Problems

  • In detecting cholangitis and cholecystitis, GGT is highly effective. The rise of GGT happens earlier and stays higher than other measures.


  • Huge elevations of GGT are also seen in the serum of both primary and secondary neoplasms (cancers) so it’s essential to know if those levels are high. This study has more information on Gamma-glutamyl transferase: risk and prognosis of cancer.

RELATED: Top Foods For Preventing Cancer In Dogs. Fight back by reading this post.

Environmental Toxins

  • GGT is elevated with exposure to chemicals and persistent organic pollutants (POPs) so it’s a sensitive marker for environmental toxicity.
  • Elevated GGT can also indicate exposure to fungus and molds. These may be environmental or in your dog’s kibble, where mold found in corn and other grains comes in the form of dangerous mycotoxins in the food. These mycotoxins can cause liver failure and can precede cancer of the liver so it’s important to know if your dog’s been exposed.

The GGT can help rule out other diseases.

  • Patients withrenal failure and muscular diseases have normal GGT levels.

This is an example of a healthy dog showing all of their enzymes, including GGT, well within normal ranges.

Table with healthy dog's Liver Enzyme Results

Some of the things that might affect your dog’s body are listed here.

What Affects The Liver

There are many outside influences that can affect your dog’s levels of cholesterol.


Drugs like phenytoin and phenobarbital prescribed for seizures, as well as any other drug, including heartworm medication, can result in abnormal liver enzymes, so if your dog is on any medication your vet should always consider whether that may be the cause.

Vaccine Adjuvants

Viral infections can affect liver enzyme tests and so can the vaccines for viral diseases. In humans, the Hepatitis B vaccine induces liver damage primarily when it contains the toxic vaccine adjuvant aluminum hydroxide, the common aluminum salt adjuvant in vaccines – and found in all veterinary vaccines. The aluminum hydroxide adjuvant also triggers the motor neuron autoimmunity issues seen in Gulf War Syndrome sufferers. This syndrome has been found to be indistinguishable from the autoimmune disease ALS or Amyotrophic Lateral Sclerosis (Lou Gehrig’s disease).  This is essentially what happens in MS or multiple sclerosis, another neurodegenerative disease, and I have seen cases of this type of disease in dogs following vaccination.

Aluminum hydroxide also caused a loss of mitochondria and cell death in mouse livers exposed to low doses of the Hepatitis B vaccine. 144 genes in the mouse livers were altered in their expression only a day following vaccination. In 2002, Hepatogastroenterology reported that the Hepatitis B vaccine was associated with high risk for hepatitis, gastrointestinal disease and other liver function tests.

Chemicals that affect thecrine system.

There are chemicals in the environment that can affect the body’s hormones. There are pesticides and hormones in our water and food supply. The most important internal organ is the liver, which is open 24/7. It is important to protect liver health because it is involved in every bodily process. The vital organ that helps detoxify the body from our increasingly toxic world can be compromised if your dog follows a natural lifestyle.

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