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.

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Dr. Randolph
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  1. My 3 year old ladadoodle just had his annual lab work done and i was very upset that the vet didnt mention his abnormal ALKP <10UL and ALT 126U/L . Is this cause for concern?

    • Conditions in which low alkaline phosphatase is a concern are extremely rare, and whether the ALT is a problem depends on what’s normal for that laboratory. If that’s within normal for that facility, it may be fine. However, if it’s elevated, I never ignore it. Search for “transaminase” and “Denosyl” and “Denamarin” to read more about treatment of liver conditions. Thanks for reading, Dr. Randolph.

  2. My 3 year old cat got her results back and it shows that s-ast is 211,3 (normal border is up to 30) and s-alt results are 81,7 (normal border is around 52).

    Can you let me know what this means, what is happening, what can i do etc? Please help

    • Have you not discussed this with the doctor treating your kitty? While these results are clearly on a different scale than we use (I’m assuming you’re in Europe or Asia), the ALT is a little less than twice the maximum of normal, which is not TERRIBLE, but it does mean that the liver is inflamed and that the enzyme is leaking from liver cells. WHY is the liver inflamed? At the very least, you’d need a liver biopsy to answer that question, and possibly other tests. However, many patients with mild elevations are treated symptomatically, and many of them get better on either Denamarin or its equivalent, with or without antibiotic therapy. What worries me the most is that your kitty is young to have liver disease, and finding the underlying cause with more aggressive diagnostics might make the difference between living three years and living eighteen years. Thanks for reading, Dr. Randolph.

    • While our boarded internists tell us we should not prognose our patients based on the LEVEL of ALT (formerly SGPT), the fact is we commonly do. That said, in our practice, the vast majority of well or not-too-ill patients with ALTs of 240 will respond to Denamarin and/or appropriate antibiotic therapy. Those who fail to respond will require liver biopsy. Thanks for reading, Dr. Randolph.

  3. Dear Dr. Randolph,

    First of all, thank you for the informative article.
    I came across this site meanwhile searching about elevated GPT levels in dogs.

    My 4.5 yrs old amstaff is asymptomatic but with the occasion of a routine blood work, at end of July 2019 its GPT level came to 104. He got liver protectors and change in diet (from Orijen 6 fish to a lower protein diet).
    One month later, in September, the GPT levels were 110 and now, end of December the GPT level is 135 (therefore gradually increasing).
    My vet still would like to go another 6 weeks with the same liver protector tablets and Royal Canine hepatic food.

    Should I worry ? Should I also seek the opinion of a second vet ?

    Thank you very much for your time.

    • It’s rarely a bad idea to get a second opinion. On the other hand, these numbers are quite low. In our practice, we would offer the client the opportunity to see an internist for a liver ultrasound and/or biopsy. Many veterinarians would say that’s too aggressive for numbers this low. Some would counter with, “Yes, but what if the internist finds something significant?” I can’t make any specific recommendations because I’m not your pet’s doctor, but a little more waiting time MIGHT be safe, and, if I were to proceed to a second opinion, I wouldn’t get another general practitioner’s opinion, I’d be asking my primary veterinarian to refer me to a specialist. Please write back later and let me know how he’s doing. Thanks for reading, Dr. Randolph.

      • Dear Dr. Randolph,

        Thank you very much for the prompt reply, its much appreciated.
        I’ll wait for the next appointment for blood work (till then will strictly adhere to the prescribed diet and liver protectors) and if the results wont get better I’ll ask my vet to refer us to the specialist (we live in Vienna, Austria, so that should be the Animal Hospital of Vienna University).

        I will keep you updated.
        Also I’d like to wish you pleasant holidays ! !

  4. my dog 2 years old female dashand has SGPT level of 30.43 IU/L and SGOT level 127.62 IU/L. Please instruct.

    • There is much more to treating a patient than knowing the results of two parameters pertaining to the liver. Your treating veterinarian will evaluate the entire patient and recommend a course of treatment. At the very least, I’m confident that he will recommend beginning a liver protectant, such as Denamarin. Thank you for reading and, please, update us on how your pet does going forward.

  5. Hello Dr. Randolph, I am interested in knowing anything you have to offer in the form of information or advice about my 9 year old beloved Zoey, a dachshund mix. She has always struggled with her weight somewhat but is active and loves her walks and to play fetch. She has slowed down somewhat and loves to smell the flowers on the walks a little more in her golden years but otherwise, she is happy and healthy as she always has been. She is on Castor and Pollux Organix weight management food, takes a fish oil supplement and Glucosamine and Chondroitin with her breakfast every day. Her drinking and eating level seems the same. No diarrhea, vomiting, or lethargy. Her coat is still in great shape but in the last two years she’s begun to bite and itch a little more around her joints and belly. Her skin under her belly seems to me to look a little like “crocodile skin” in that it’s dry, but there’s no flaking or areas of redness, bumps, swelling, etc. Occasionally she bites at her feet as she’s trying to “scratch an itch”. The veterinarians she’s seen have all said she might have a slight allergy because of the area we live in (Virginia Beach, VA) and I now have a medicated shampoo to wash her with every other day on the affected areas along with my other dog who bites his feet quite often too.
    I noticed her randomly panting slightly more than normal about a month ago and with her being older, I took a look at a few sites to see if there was a reason for this. That’s when I came upon the possible idea that she could be starting to slowly show signs of Cushing’s. This past summer, she hurt her knee as she likes to “launch at things” that she thinks are dangerous…gotta’ love the dachshund spunk! I took her to the animal chiropractor in our area and he was able to stabilize the knee without surgery and she has shown no signs of pain or limping since. I have steps up to the couch and bed and make sure she doesn’t jump off anything. It seems her back legs might be a little weaker than when she was younger because she tries to “rev up” before she comes up on things, as if it’s a little tougher now.
    I took her to the veterinarian last week for vaccines and a wellness exam and asked for bloodwork. It showed she had elevated Alkaline Phosphate and GGTP levels in her blood. According to my searches, it seems quite possible that my intuition was correct about her having Cushing’s. The veterinarian said to put her on a daily dose of Denamarin (I am waiting for the pills to arrive in the mail so I have not started those yet). She also said to have her rechecked in six months. If the levels are not down or have increased, she will do the low dose dex test and/or ultrasound to check for Cushing’s or other liver abnormalities.
    My questions to you are:
    A.) what do you think these supplements can do for her if she truly does have a liver disease and can waiting six long months be harmful to her? Should I recheck her earlier than that to see if they have had an effect on her levels?
    B.) Also, since she’s almost 100% asymptomatic, is there another possibility for these high levels? Could it be another disease not related to the liver and if so what?
    As a side note, she has never been on medications that could increase these levels such as corticosteriods. She’s always been a VERY healthy young lady.
    She’s my dearest friend and I know you hear that all the time. But, we just have a special understanding and connection I’ve never felt with another dog. She’s a one of a kind and I need her in my life.
    I desperately want her to be ok and feel well, and I want to be a good friend and mom to her by doing all I can for her. Please advise. I would truly appreciate it.
    Thank you for your time, Alice

    • My questions to you are:
      A.) what do you think these supplements can do for her if she truly does have a liver disease and can waiting six long months be harmful to her? Should I recheck her earlier than that to see if they have had an effect on her levels?
      Denamarin is a cousin nutraceutical to Denosyl. You can read about Denosyl by clicking here. You can have similar expectations from Denamarin as from Denosyl.
      B.) Also, since she’s almost 100% asymptomatic, is there another possibility for these high levels? Could it be another disease not related to the liver and if so what? As noted in the post above, Alkaline Phosphatase is NOT specific for the liver, even though we first suspect the liver whenever the AlkPhos enzyme is elevated. That said, there are several other sources for alkaline phosphatase in the body. It is also not uncommon for a nine-year-old of any breed to have elevated alkaline phosphatase levels.
      An easy screening test for Cushing’s Disease is the urine cortisol:creatinine ratio. Obtain a urine sample, submit it to a laboratory, and in a few days or less you will have a result. IF the result is negative, the likelihood of Cushing’s Disease is near zero. Positive tests will require more testing, such as the ACTH stimulation test and/or low-dose dexamethasone suppression test.
      She’s my dearest friend and I know you hear that all the time.
      Yes, we do, but we never tire of it!

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