AST, ALT, GGTP And Alkaline Phosphatase In Dogs’ And Cats’ Livers

“ALT” stands for alanine transaminase, an enzyme present in the cells of mammalian livers. While the enzyme may also be found in a few other organs, the quantities are low enough to make ALT reasonably liver-specific. The same enzyme is also known by an older name, SGPT, which stands for serum glutamic pyruvic transaminase. Normal serum level of ALT in dogs should be between 12 and 118.

Some canine liver problems can be diagnosed by blood and urine tests.
Some canine liver problems can be diagnosed by blood and urine tests.

ALT is known as a “leakage enzyme,” meaning the cells that contain it must die in order for it to be released. Therefore, if serum ALT levels are up, some death of liver cells has occurred. However, it is important to recognize that there is not a direct correlation among the elevation of the enzyme, the amount of liver damage and the prognosis for the patient. However, trends may be followed that give an indication of improvement or worsening of liver disease.

Many diseases may affect ALT, as well as non-liver conditions. For example, congestive heart failure (CHF) may result in poor blood circulation, causing stagnation of liver blood flow and poor liver function. Some medications, most notably phenobarbital used for seizure control.

“AST” stands for aspartate transaminase, which is also an enzyme. The older name is “SGOT,” which stands for serum glutamic oxaloacetic transaminase. AST is also present in the liver and several other organs including skeletal muscle, heart muscle and red blood cells. Interpretation of the enzyme is similar to ALT, while recognizing that it is much less liver-specific. Normal level in dogs is 15-66.

Alkaline phosphatase is also present in the liver, as well as bone, placenta and other locations. From the liver, it normally moves into the intestinal tract along with bile through the bile ducts. However, if bile flow is obstructed, levels within the liver may rise sufficiently to ‘back up” into the bloodstream. Patients with rapidly growing bones, puppies and kittens, as well as pregnant animals, may have elevated alkaline phosphatase levels.

Bile ducts may become obstructed at the microscopic level, inside the liver, or the macroscopic level, in the large ducts that leave the gall bladder, pass through the pancreas and enter the intestinal tract, where bile aids in the digestion of fats.

GGTP or gamma glutamyl transpeptidase, also becomes elevated in biliary obstruction, and is much more specific than alkaline phosphatase. It is also a much newer test.

It is important to realize that these are not measurements of liver function, rather they are measurements of liver damage. Now, that won’t keep physicians or veterinarians from calling them liver function tests. It’s not that we don’t know better, it’s just the term used as an inappropriate shortcut. To assess the function of the liver, we will discuss bile acids in this series.

See you tomorrow, Dr. Randolph.

80 Comments

  1. My dogs name is Bheem. He is a 5 yrs old Lab his level of SGPT is 1000u/I SGOT is 127 u/I and ALP-PS is 390 u/I. He is very active, eating and sleeping well. No problem at all but the levels have shooted up when compared to the test we have done a month ago. Even then the liver enzyme levels like SGPT was 600 and SGOT is 40 and ALP-PS is 600 what could be the problem. What’s the best treatment option

    • With levels increasing in the face of proper symptomatic treatment, you will need to be more aggressive, including abdominal ultrasound and liver biopsy, with the full panel of tests on the liver biopsy specimen. This sounds like runaway liver disease that will not be controlled with conservative symptomatic treatment. Thanks for reading, Dr. Randolph.

  2. Hi Dr. Randolph –

    We have a 5+year-old mutt (no one uses that term anymore!) who has been the best dog I’ve ever lived with. Nugget is a hound/retriever mix (I think). She’s affectionate, playful, and protective (sometimes a bit too much, but nodoggy’s perfect). She has had no health problems in her time with us. Normally, she spends her time at home in the same room as my wife and me, but in December, she started spending a lot of time upstairs in our bedroom (where she sleeps at night) – something she had never done before. That self-isolation continued and increased – which led to an after-hours visit to the vet on January 3.

    The vet started Nugget on doxycycline as a precautionary measure, but on January 4, we learned that that her ALT levels were high – 331. We stopped giving Nugget the doxycycline (her labs for other problems were all negative), and on Jan 6, we started her on a 14-day course of Denamarin (225 mg 1x/day…Nugget weighs about 30lbs). The vet also performed an ultrasound. Thankfully, that was negative.

    Unfortunately, Nugget’s lethargy seems to be worsening. Yesterday, she spent 22 hours in our bedroom. (It would have been 23 if I’d left the bedroom door open all day.) Today is not much better. She has had almost no appetite yesterday and today and is not drinking water. She’s been willing to play a bit with me when she’s been downstairs, but she certainly doesn’t want to play as long as she would when she was healthy.

    I have a blood test scheduled for Jan 23, but I don’t think I should wait that long to have someone see her. I hope to get to see her regular vet tomorrow (at our local VCA). I don’t know if they have a board-certified internist on staff, but from reading your comments, it sounds like I should insist on seeing one – and seeing one as soon as possible. Anything else that you’d recommend?

    Thank you!

  3. Thank you so much for this informative article. My dog was diagnosed with Stage B1 Mitral heart disease last year. No symptoms and medications needed. I noticed in the past few months his ALT increased from 109 to 165iu/L.
    And his urine specific gravity is now 1.010. We are scheduled for a retest. Any other recommendations for testing and what are your suspicions?

    • If liver-protective medications can’t get the ALT back to or near normal, diagnostics and treatment definitely need to be more aggressive, along with finding a reason (if it isn’t known yet) for the fixed urine specific gravity. Thanks for reading, Dr. Randolph.

  4. My dog head her head. I was concerned about concussion. My 16 year old has some dementia but she was extra confused. My vet give me the test. Alt 1562 u/land Alkp is 3154 u/l. Vet said palliative care or Euthanized. I am trying to help her but I’m a hurting her. Anyway of lowering it or let her go now before she is in to much pain. Need help Jennifer & Rubie

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