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. I have a 17 month old maltese she has been a very healthy dog. Last Thursday evening something was wrong, she was not herself. She was not interested in playing and only wanted to rest. Since the weekend was coming and my vets office is not opened over the weekend because she was still acting not her normal active self I brought Zoey in to the vets office. Back on June I had them do a baseline blood panel during her vet visit. At that time her ALT was 131( slightly elevated but they were not concerned, her ALP 58. I am on a maltese Facebook group and have heard several people discuss liver shunts. So when I was at the vet on Friday I asked for another liver test that was 9/9/2022 the values then were ALT 234 and AST 72, I did not see a ALP reading. Because of the increase from June they suggested we do a bile acid test, that was done on 9/14 , the preprandial number was 78.9 and post prandial number was 52.16. My vet has now referred me to another vet office to have a lower body ultrasound. Here is my concern by Saturday 9/10 Zoey was back to her normal self, running around the house playing fetch and chasing the cats. Other than the day and a half of her not acting herself she seems fine. She did not vomit or have diarrhea when she was not herself on Thursday and Friday and she still managed to eat. Is the ultrasound being done prematurely since she is not exhibiting any of the clinical symptoms such as, head butting, vomiting and seizures, or is that something only exhibited much later in the progression of the disease. I just want to make sure we are not acting prematurely. I have been told to switch her to a low protein diet such as hills science diet I/D . I have also asked about a
    GGT (gamma-glutamyltransferase Enzyme test and was told that was a chemistry 17 panel, that sounded like a bigger blood panel, I thought it was just to test that particular enzyme. So I am not sure exactly what is the best course of action do I go ahead and have the ultrasound done knowing it may not be definitive, then what.
    Thank you so much!

    • You DEFINTELY don’t want to wait until you have dementia signs from liver disease before pursuing diagnostics. Is the practice to which you were referred a specialty practice, in other words, are you seeing a board-certified internist? If so, you are on the best possible track. If not, it’s something you might consider in the future. Please, do NOT turn your back on this condition just because she’s feeling better now. Thanks for reading, Dr. Randolph.

      • Not a internist it is just a clinic that does ultra sound in my area, my vet does not. Since she was only not herself for that day and a half could the high numbers be from possible exposure to a toxin, not sure what it could be but we did visit a burger joint that evening and I give her bits of the burger from the edge to avoid any condiments, maybe she got some catsup but I didn’t think so. I have withdrawn her normal treats and won’t be giving her any table scraps as I had been doing for the last month or so and thought I would postpone the ultra sound and have my vet simply run another liver enzymes test in early December, my thinking is if it was by chance just something she got into her liver would be clear of that, but if the high numbers persist then schedule the ultra sound. She is also taking Simparica, I have read that heartworm meds can increase liver enzymes. Does that accumulate in the liver over time, I ask because her numbers in June were slightly elevated and she was taking Simparica then also, it’s a monthly tablet.
        Is it possible she could have this liver shunt and have no symptoms now. I spoke with someone last night her 9 month old maltese started head butting then a seizure, that’s when they new something was wrong. But Zoey is acting like a normal healthy maltese, so you see why I am on the fence.

        • I would say that’s a completely reasonable, ultraconservative approach. Please keep in mind that Simparica is NOT heartworm preventive, it’s flea and tick control. I have seen NO reports of hepatic toxicosis from Simparica, however. That doesn’t mean she doesn’t have some kind of idiosyncratic response to it. Let’s see what happens with that next test. Thanks for the reply, Dr. Randolph.

  2. My dog was just admitted to er vet. Toy Poodle 8lbs. ALT is 333 GGT is 0 Hematocrit is 64.9 RBC 9.52 Globulin 4.7 They took an ultrasound of his gallbladder and liver and said the gallbladder has a lot of sludge in it and thick walls? Hoping he will be ok!!!

  3. My 12 year old Doxie has a very distended abdomen, is listless, but eating well. His labs are:
    ALT: 1
    AST: 210
    ALP: 2
    Creatine kinase: 515
    Total protein: 8.3
    Albumin: 4.1
    Globulin: 4.2
    Chloride: 105
    Platelets: 550
    MCH: 21.6
    MCHC: 32.5
    Reticulocyte hemoglobin: 24.3
    The vet prescribed a liver nutraceutical and will retest in three weeks. But, am worried.

    • There are many, many causes for distended abdomen, and all of them are serious. IF you feel your veterinarian is not doing enough, you have the right to request a referral to a board-certified internist. We’re saying a prayer for you and your Dachshund now. Thanks for reading, Dr. Randolph.

  4. I have a 23 months old mixed breed.
    He suddenly passed out this morning and sent to the vet. While in the vet, he vomited 3x. This stopped after vet gave maropilant and omipural injections.

    His lab results RBC 8.96X10; ALT result 1578; GGT of 14. We were advised to monitor, change diet to hepatic, and give liver supplements.

    Is my dog in critical condition?

    • That liver number is definitely of concern. Frequent monitoring will tell your pet’s doctor whether he’s responding to symptomatic treatment or whether he needs a liver biopsy. Thanks for reading, Dr. Randolph.

  5. I’m about to adopt a 7 yr terror mix from shelter. She was owner surrendered. Just had spay and 20 extractions for severe dental disease
    Her AST is 497, ALT 310, GGTP 4, CPK 6653

    I’m not sure if I should proceed w adoption as don’t know what’s ahead with her health

    • Only you can answer that question. However, it’s clear she’s going to need more work. More often than not, liver numbers such as these strongly imply more problems in the future. Are you up for that? if so, bless you. If not, no one can blame you for choosing to adopt some other pet with fewer or no problems. Thanks for reading, Dr. Randolph.

  6. My dog is 11 yrs old labrador he is facing issue of alt – 418.4 , creatine – 4.48. , Alkaline phosphatase – 542.3 , bun – 53.7 , urea – 115 and blood suger 116 please tell me what to do i am very much worried about him even he is not ready to eat renal food and not drinking too much water as he use to drink . Please suggest me something

    • He needs to be hospitalized where he can receive IV fluids, intensive care and constant monitoring. It’s the only way a patient with this set of parameters can be turned around, if at all. That may mean a referral facility with a board-certified internist in charge of his care, or an emergency clinic setting, unless your veterinarian can provide all of this. I’ll say a prayer for him. Thanks for reading, Dr. Randolph.

  7. My dogs ALT is at 288 and her ALKP is at 248 , both high the vet stated that they cannot tell if its her liver and wants to do an MRI, she is 11 yrs old. All my research has shown liver disease, She let out a yelp on Sunday and collapsed and after a few minutes she was up walking around and has been a fine, this morning the same thing happened. I am not sure what to do , I dont want to put her thru all this please help me

  8. I have a 10 year old Bichpoo. Two years ago my vet stated my dogs Alkaline Phosphatase level was high. When we went back for her 6 month appointment the levels were even higher. She gave me a script for Denamarin to be given on an empty stomach. My dogs have never been good at taking medication unless it it wrapped up in something very tasty. If I attempt to just pop the pill into her throat and massage it down she will throw it up about a half hour later. The vet said I could use a small amount of food to get her to take the pill. Six months after that her levels were still high around 800. My vet suggested an ultrasound which I scheduled. The ultrasound did not reveal anything but possibly a bout of pancreatitis in the past. Her urine sample was good. My dog is eating fine and drinking about the same (she never drank a lot of water). While she isn’t overly active at home, I can take her on a 2 mile walk with no problem. Unfortunately, I myself had a few surgeries earlier this year and could not always get out to get something I could put the pill into to get her to take it on a regular basis. In April I took her in for her semiannual checkup. Her Alkaline Phosphatase was up to 1490 and another liver enzyme was also elevated. My vet wanted me to make sure my dog had her Denamarin daily for the next 3 weeks and then retest her blood. I just had a call from the vet stating the Alkaline Phosphatase was at 1384 and the other liver enzyme was back in the normal range (high end). Her thoughts were that since I cannot get my dog to take Denamarin on an empty stomach that she is not getting the full benefit of the drug. She wants me to continue with the Denamarin but to also give my dog something called Ursodiol at night. Just wondering what your thoughts are on taking these two medications. Also my dog needs some dental work done, her breath is bad. Do the enzymes need to be back to normal before I consider having her have anesthesia?

    • I’d like to see your veterinarian refer you to a board-certified internist to get to the bottom of this. Please write back with that specialist’s report. Thanks for reading, Dr. Randolph.

    • I have 7 years old Dashchund. His name is Oreo. His liver values are not good.
      Alt – 402.4
      Ast – 68.8
      Alkaline phosphatase – 2358
      Globulin – 4.290
      Earlier vet prescribed Lysibin. What to do can you please suggest something. What we can look for diagnosis

      • Ultimately, diagnoses in liver patients come down to abdominal ultrasound and liver biopsy. That said, many clients who logistically or financially can’t go see a specialist for those procedures is able to keep the liver inflammation “to a low roar,” as my elementary teachers used to say, with symptomatic therapy. Monitor the chemistry profile regularly and throw the kitchen sink at that liver if you have to. Thanks for reading, Dr. Randolph.

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