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.


  1. My 11 year old husky has been having some symptoms over drinking, less appetite, upset toileting habits and tired more. Took her to vet and they did a blood panel everything is fine except her Liver Enzymes which is over 1000 it was in the 300s in February and 200s in January. What exactly does this mean or what could it indicate? They have said she will need more tests.

    • “Liver Enzymes which is over 1000 it was in the 300s in February and 200s in January.” WHICH liver enzyme(s) were elevated? What did the doctor treating her say exactly it means? If he is saying she needs more tests, then you should pursue those. The liver is an incredibly complex organ with many parts and many functions. “More tests” might mean biopsy, culture and sensitivity and/or metal testing for her liver. Please send me answers to these questions. Thanks for reading, Dr. Randolph.

      • Hello

        Thank you for the reply. He did not say anything other than liver enzymes being in the 1000s. He has advised to do more bloods and a bile duct test and ultrasound. I am awaiting a call back to discuss further.

  2. My Pomsky got her liver panel done and her embark said she has one gene that shows she runs low in her ALT. Her lab showed her ALT was 166. What does this mean?

    • I will address “What does this mean?” because I don’t understand the part of your question before that. It means that IF YOUR ATTENDING VETERINARIAN AGREES (I’m not your dog’s doctor), you MIGHT be able to treat this mild elevation symptomatically or you MIGHT need to be more aggressive with liver biopsy, copper and heavy metal testing, histopathology, etc. Thanks for reading, Dr. Randolph.

  3. My dogs blood test results show everything is normal except ALKP is low at 15. My vet didn’t bring it up and I only noticed it when I was looking through it myself. Is this cause for concern?

    • I know of no significance of low alkaline phosphatase. I can imagine a scenario in which a small liver could make that happen. Liver size can be evaluated with ultrasound. Thanks for reading, Dr. Randolph.

  4. my dog (7 years old German pinscher) took the blood test because he has to be castrated, since he probably has a tumor on one of his testicles. He did an ultrasound and he has a lump inside of his right testicle, but luckily, the prostate and the regional lymph nodes are normal. And all the blood test results are normal except the ALT value which is a little increased (normal range in this Italian laboratory: 15 to 65 U/I):

    Total Protein : 7,1 mg/dl
    Albumin: 4,0 g/dl
    Globulin: 3,1 g/dl
    Alkaline phosphates: 73 mg/dl
    AST (GOT): 27 U/I
    ALT (GPT): 86 U/I
    GGT: 7 U/I
    Blood glucose: 102 mg/dl
    Creatinine: 1,07 mg/dl
    Azotaemia: 38 mg/dl

    The veterinarian told us that the alt value is not worrying and has set neutering for the next Tuesday. For the alt value he said that maybe after the surgery he will prescribe a supplement and after some time we can repeat the blood test. Do you think it is the best way to approach this? Does Metacam could affect the ALT result? Cause he took 4 days of Metacam a week before the test blood since he had backache. And he takes a supplement containing devil’s claw everyday to prevent these aches, could this affect it too? Thank you!!!

    • Absolutely Metacam, or any other NSAID can elevate ALT. If he can be off NSAIDs and steroids for a few weeks and the number comes down you’ll be happy! Meanwhile, I would recommend symptomatic treatment with a liver protectant. We use Denamarin by Nutramax (you can search for Denamarin and Nutramax on our site for more articles), but whatever your local doctor likes should be fine. Thanks for reading, Dr. Randolph.

  5. I’ve tried to leave another update twice yesterday but it’s not showing up so I’ll try 1 more time- if you are seeing it I apologize. Anyways I got Sammi’s results from the board certified Internist and CT scan – I was told it was the best case scenario with no liver shunts and all organs appearing normal so she is pretty confident in diagnosing hi with Microvascular displasia and saying he should live a normal lifespan and needs no treatment at this time other than a yearly urinalysis since his Rick of developing urinary stones is increased. I was told that there is no need to change his diet (especially since he is very fussy) and there’s no need to limit protein – she did say I could give him a hydrolyzed protein diet but it is necessary right now. I was quite happy after the phone call and email with all the info until I started doing research on this- everything I’m reading is saying to limit his protein to under 20% so I will contact the Internist with a few follow-up questions – I was told to be aware of any neurological symptoms-but that shouldn’t include seizures but that’s also not what I’m reading in my research…I am fairly relieved but still concerned because I’m being told he should live a normal lifespan BUT or unless he starts having other symptoms. . Any info you can give in my confusion would be appreciated but I will be contacting the Internist – I thank you so much for your prayers and all the time you take in helping all of us. Take care- Cathy & Sammi

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