What Liver Values May Change With Cancer?

The liver values on your dog's chemistry panel fall into two groups, and knowing which is which explains most of the confusion around them.

The first group is enzymes. ALT, ALP, AST and GGT are proteins that normally sit inside liver cells or line the bile ducts. When those cells are damaged, irritated, or stimulated, the enzymes leak into the blood and the numbers go up. That tells you something is going on. It doesn't tell you the liver is failing.

The second group actually measures how well the liver is working. Bilirubin, albumin, glucose, cholesterol, urea and bile acids reflect jobs the liver does. When these drift in the wrong direction, function is genuinely affected, and that matters more.

In a dog with cancer, liver values change for several reasons. A tumor in the liver, or cancer that has spread there, is one. But two others are far more common: prednisone, which reliably pushes ALP up and can send it very high indeed, and chemotherapy, particularly lomustine, which raises liver enzymes in the large majority of dogs who receive it.

Here's the thing most owners need to hear. Raised liver enzymes are extremely common in older dogs and usually have nothing to do with cancer or cancer spread. What your veterinarian is watching is the pattern, the trend over time, and whether your dog is actually unwell.

Key points

• Liver enzymes measure leakage and stimulation. They don't measure how well the liver is working.
• ALP is the value most often raised and the least specific. On its own it rarely means much.
• Prednisone reliably raises ALP, sometimes above 5,000 U/L, starting within a couple of days of the first dose.
• Lomustine raises liver enzymes in up to 86% of dogs who receive it, which is why ALT is checked before every dose.
• Bilirubin, albumin and bile acids are the values that indicate genuine liver dysfunction.
• Raised ALP before treatment for bone cancer carries prognostic weight, though it comes from bone rather than liver.
• One mildly elevated value in a well dog usually means nothing. A rising trend means more.
• Ask for copies of results so you can see the direction of travel yourself.

Detailed explanation

The enzymes

ALT, alanine aminotransferase. This one lives inside liver cells and is reasonably specific to the liver in dogs. When liver cells are damaged, ALT leaks out. It's the value oncologists watch most closely during chemotherapy, because it's the earliest reliable signal that a drug is causing trouble.

ALP, alkaline phosphatase. ALP is the value most likely to be flagged on your dog's results and the one least likely to mean what owners think it means. It comes from several places: the lining of the bile ducts, bone, and, in dogs specifically, a form induced by steroids. Older dogs frequently have mildly raised ALP with no identifiable cause and no consequences.

AST, aspartate aminotransferase. Similar to ALT but less liver-specific, since it also comes from muscle. It's usually interpreted alongside ALT rather than on its own.

GGT, gamma-glutamyl transferase. Associated with the bile ducts. Often rises alongside ALP, and helps sort out whether a raised ALP is coming from the liver or from bone.

The values that show whether the liver is working

Bilirubin. A pigment the liver processes and excretes. When it builds up, you get jaundice, the yellow tinge visible first in the whites of the eyes and the gums. Raised bilirubin is a more serious finding than raised enzymes.

Albumin. A protein the liver makes. A falling albumin can mean the liver isn't producing enough, though it also drops with protein loss through the gut or kidneys and with inflammation. It needs interpreting alongside everything else.

Globulin. Not strictly a liver function marker, but worth mentioning because a markedly raised globulin can point toward multiple myeloma, a cancer of plasma cells.

Glucose, cholesterol and urea. All can shift with significant liver dysfunction. Low blood glucose has another cancer connection too, since insulinoma drives it down.

Bile acids. This is the test that answers the question enzymes can't. Measuring bile acids before and after a meal shows how effectively the liver is clearing them from circulation. If your dog has persistently raised enzymes and nobody is sure whether it matters, this is often the next step.

When cancer is the cause

Primary liver tumors. Hepatocellular carcinoma is the most common, and it often produces markedly raised ALT along with ALP. Bile duct carcinoma and hepatic hemangiosarcoma also occur. Certain breeds carry higher risk, including Scottish Terriers, Miniature Schnauzers, Shih Tzus, Welsh Corgis and Beagles.

Cancer that has spread to the liver. The liver is one of the most common sites for spread, particularly from lymphoma, hemangiosarcoma, mast cell tumors and various carcinomas. Enzyme changes here are variable and often unimpressive, which is why liver involvement is usually confirmed by ultrasound and sampling rather than bloodwork.

Bone cancer and ALP. This one is worth knowing because it catches people out. In dogs with osteosarcoma, a raised ALP before treatment is a recognised negative prognostic factor. The ALP in that case is coming from bone, not liver, so it isn't a sign that anything is wrong with the liver at all. If your dog has bone cancer and ALP is mentioned, this is probably why.

Multiple myeloma raises globulin, as above.

When the treatment is the cause, which is more often

Steroids. If your dog is on prednisone and the ALP has gone up, the steroid is almost certainly why.

Glucocorticoids induce a specific form of ALP found only in dogs, and they also cause liver cells to swell and accumulate glycogen. The effect is fast and it is large. ALP starts rising within about two days of the first dose and can climb past 5,000 U/L. It's less widely known that ALT, AST and GGT can rise too, usually at a similar rate but nowhere near the same magnitude.

This process is normally benign and reversible, resolving slowly over weeks once the steroid stops. It matters mainly because a big ALP in a dog with cancer looks alarming, and owners understandably assume the worst. Ask directly whether the steroid explains it.

Very high doses over long periods can cause more serious liver change, so it isn't something to ignore entirely. But context first.

Lomustine, also called CCNU. This is the chemotherapy drug most associated with liver injury in dogs, and the numbers are substantial. Increases in liver enzymes occur in up to 86% of dogs receiving it. In one randomised trial, 84% of dogs on lomustine alone developed raised enzymes.

Most of those dogs never develop liver problems that need treating. But lomustine can also cause a delayed, cumulative liver injury that is sometimes irreversible, which is why ALT is checked before every dose and why treatment gets delayed or stopped if it climbs too far.

Many oncologists prescribe Denamarin, a combination of SAMe and silybin, alongside lomustine. In the trial mentioned above, dogs receiving it had significantly smaller rises in ALT, AST, ALP and bilirubin, and were significantly more likely to complete their full course. Worth knowing when weighing that evidence: the study was funded in part by the company that makes Denamarin.

Toceranib can raise liver enzymes, which is one of the reasons for its monitoring schedule. Doxorubicin and several other agents can too.

Other medications. Anti-seizure drugs, some antibiotics, and various other medicines affect liver values. If your dog started something new shortly before the change, mention it.

What your veterinarian is actually looking at

Not the single number. Four things:

Which values moved together. ALT rising alone points somewhere different from ALP and GGT rising together, which suggests the bile ducts. ALP alone in a dog on prednisone points at the prednisone.

How much. A value at twice the top of the range means something different from one at twenty times. Though magnitude and seriousness aren't the same thing, and a modest rise in bilirubin worries a clinician more than a huge ALP in a dog on steroids.

The direction. A value that has climbed steadily across three visits matters more than a single flagged result. This is the strongest argument for keeping your own copies of results.

Whether your dog is sick. A dog eating well and behaving normally with slightly raised enzymes is in a very different position from a dog who is jaundiced, off food and losing weight.

What usually happens next

If liver values change and there's genuine concern, the next steps commonly include repeating the panel after an interval to see whether it's a blip, running a bile acids test to check function, imaging with abdominal ultrasound, and if something is found, sampling it with a needle aspirate or biopsy.

If a medication is the likely cause, the usual approach is to pause it, recheck in a couple of weeks, and see whether the values come back down.

What this doesn't tell you

A chemistry panel won't tell you whether cancer has spread to the liver. Enzyme changes are too unreliable in both directions. Dogs with substantial liver metastasis can have near-normal values, and dogs with dramatic values can have a liver that's structurally fine.

Ultrasound plus sampling answers that question. Bloodwork just tells you when to go looking.

When to contact a veterinarian

Seek emergency care immediately if your dog:

• Has yellow gums, yellow whites of the eyes, or yellow-tinged skin
• Is collapsed, very weak, or has pale gums
• Is disoriented, circling, unusually dull, or having a seizure
• Has a suddenly swollen or painful abdomen
• Is vomiting blood, or passing black tarry stool

Contact your veterinarian within a day if your dog:

• Has stopped eating, or is eating much less
• Is vomiting repeatedly
• Is drinking and urinating noticeably more
• Seems flat or tired, particularly while on lomustine or another oral chemotherapy drug
• Has orange or unusually dark urine
• Is due for a blood test before the next chemotherapy dose

Ask about liver values if:

• Your dog is on prednisone and you've been told the ALP is up, so you know whether it's the drug
• Your dog is on lomustine and you're unsure how often ALT should be checked
• Values have been flagged on more than one occasion and nobody has explained what the trend is doing

Questions to ask your veterinarian

• Which liver values are raised, and by how much?
• Are these enzymes, or values that show the liver isn't working properly?
• Could the prednisone explain this?
• Could any other medication my dog is on explain it?
• Have these values changed since last time, and which way are they going?
• Would a bile acids test tell us anything useful?
• Does my dog need an ultrasound, and would we sample anything found?
• If my dog is on lomustine, how often will ALT be checked, and at what point would you pause treatment?
• Should my dog be on a liver supplement alongside chemotherapy, and what's the evidence for it?
• Can I have copies of the results so I can track the trend?

Sources

American Animal Hospital Association. (2026). 2026 AAHA oncology guidelines for dogs and cats: Therapeutic modalities, chemotherapy. https://www.aaha.org/resources/2026-aaha-oncology-guidelines-for-dogs-and-cats/section-5-therapeutic-interventions/therapeutic-modalities-chemotherapy/

Christensen, J., Johnson, K., Ettinger, S., Garrett, L., Gordon, I., Ireifej, S., Love, A., & Wisecup, M. (2026). AAHA oncology guidelines for dogs and cats. Journal of the American Animal Hospital Association, 62(1), 1-37. https://doi.org/10.5326/JAAHA-MS-7549

dvm360. (n.d.). Practical matters: Several liver enzyme activities may increase in dogs receiving corticosteroids. https://www.dvm360.com/view/practical-matters-several-liver-enzyme-activities-may-increase-dogs-receiving-corticosteroids

Frontiers in Veterinary Science. (2022). Serum steroid profiling of hepatocellular carcinoma associated with hyperadrenocorticism in dogs: A preliminary study. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.1014792/full

Merck Veterinary Manual. (2024). Hepatotoxins in small animals. https://www.merckvetmanual.com/digestive-system/hepatic-diseases-of-small-animals/hepatotoxins-in-small-animals

Skorupski, K. A., Hammond, G. M., Irish, A. M., Kent, M. S., Guerrero, T. A., Rodriguez, C. O., & Griffin, D. W. (2011). Prospective randomized clinical trial assessing the efficacy of Denamarin for prevention of CCNU-induced hepatopathy in tumor-bearing dogs. Journal of Veterinary Internal Medicine, 25(4), 838-845. https://doi.org/10.1111/j.1939-1676.2011.0743.x

American Journal of Veterinary Research. (2020). Biochemical, functional, and histopathologic characterization of lomustine-induced liver injury in dogs. https://avmajournals.avma.org/view/journals/ajvr/81/10/ajvr.81.10.810.xml

This article is for educational purposes only and is not a substitute for veterinary care. Blood results should always be interpreted by your veterinarian alongside your dog's examination and history, and reference ranges vary between laboratories. Raised liver enzymes are common and usually do not indicate cancer. If your dog develops yellow gums or eyes, becomes collapsed or disoriented, or has a suddenly swollen or painful abdomen, seek emergency veterinary care immediately.