High ALP in Cats: What the Blood Test Means

Name: High ALP in Cats: What the Blood Test Means
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

A high ALP on your cat's bloodwork usually means something is irritating the liver or bile ducts, though it can also come from other tissues or steroid use. Alkaline phosphatase, or ALP, is one of several liver enzymes your veterinarian measures on a routine chemistry panel. The number alone does not diagnose a disease, but it tells your vet where to look next.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

ALP is an enzyme found mainly in the liver and bile ducts, and smaller amounts come from bone, intestine, and other tissues.
Cats normally have much lower ALP values than dogs, so even a mild rise in a cat deserves attention.
Common causes include cholangitis (bile duct inflammation), hepatic lipidosis (fatty liver), bile duct blockage, and sometimes medications like steroids.
A single high ALP is a clue, not a diagnosis. Your vet will usually pair it with other liver values, a physical exam, and often an ultrasound.
Mild isolated increases sometimes turn out to be harmless, but only your veterinarian can decide that after looking at the whole picture.

What a High ALP Looks Like and What Is Normal

Most cats with a high ALP show no obvious signs at all. The value is often found by accident during routine bloodwork before surgery or a wellness visit. When signs do appear, they tend to be vague: poor appetite, weight loss, vomiting, lethargy, or a yellow tint to the gums and skin (jaundice).

The liver sits in the front of the abdomen and handles bile production, fat metabolism, and carbohydrate metabolism [1]. Because it does so many jobs, changes in its size or structure often show up as changes in blood values [1]. That is why vets treat liver enzymes as a screening tool, not a final answer.

Normal ALP ranges vary by laboratory, so always compare your cat's result to the reference range printed on your report. In general, cats run lower than dogs. A value that would be unremarkable in a dog can be meaningful in a cat.

Main Causes of a High ALP in Cats

Several conditions raise ALP in cats. The table below groups the most common ones and what usually tips your vet toward each.

Cause	Typical clues	How urgent
Cholangitis (bile duct inflammation)	Jaundice, vomiting, fever, other liver enzymes also up	Urgent, needs treatment
Hepatic lipidosis (fatty liver)	Overweight cat that stopped eating, weight loss, jaundice	Emergency, can be life threatening
Bile duct obstruction	Jaundice, pale stools, marked ALP and bilirubin rise	Emergency
Liver parasites (such as Platynosomum fastosum)	Jaundice, apathy, dehydration, vomiting, constipation	Urgent, needs diagnosis
Liver cancer	Weight loss, enlarged liver on exam, abnormal ultrasound	Urgent
Steroid use or steroid-related disease	Recent steroid medication, otherwise mild signs	Routine to urgent depending on cause
Portosystemic shunt (abnormal blood vessel bypassing the liver)	Young cat, small body, neurologic signs, low albumin	Urgent

Cholangitis and Bile Duct Disease

Cholangitis is one of the more common liver problems in cats. In a study of 93 cats with liver and biliary disease, cats with cholangitis, hepatic lipidosis, liver cancer, and portosystemic shunts all had significantly higher liver enzyme activity, higher bilirubin, and lower albumin than healthy cats [2]. That study also found the difference faded when cats were compared with age-matched controls, which is a reminder that age matters when reading these numbers [2].

Hepatic Lipidosis

Hepatic lipidosis happens when a cat stops eating and the liver fills with fat. It is a life-threatening disease, and it is often triggered by anorexia and negative energy balance [3]. In a study of 50 cats, the 30 with naturally occurring hepatic lipidosis had significantly higher liver enzymes and total bilirubin than the 20 healthy controls [3]. If your cat has not eaten for a couple of days and looks yellow or dull, that is a same-day problem.

Liver Parasites

Some liver flukes and parasites can inflame the bile ducts. In six cats diagnosed with Platynosomum fastosum infection, common signs included jaundice, apathy, dehydration, vomiting, and constipation, and their liver enzyme levels were significantly elevated [4]. This parasite is more common in warm, humid regions, but it is worth mentioning to your vet if your cat hunts lizards or frogs.

Steroids and Other Non-Liver Causes

Cats given steroid medications, or cats with certain hormonal conditions, can have a higher ALP without true liver damage. ALP also comes from bone and other tissues, so a rise does not always mean the liver is the source. Your vet uses the pattern of all the liver values together to sort this out. For a deeper look at how vets read these patterns, see Liver Enzyme Interpretation in Dogs and Cats: Beyond the Numbers.

Red Flags That Make It an Emergency

Call your veterinarian right away, or go to an emergency clinic, if you see any of these:

Yellow gums, skin, or whites of the eyes
Your cat has not eaten for 24 to 48 hours, especially if it is overweight
Repeated vomiting or vomiting that will not stop
Collapse, weakness, or trouble walking
Confusion, head pressing, or seizures
A swollen or painful belly
Dark urine, pale stools, or bleeding that will not stop

Jaundice plus a cat that has stopped eating is the classic emergency combination. Hepatic lipidosis can move fast, and early treatment makes a real difference [3].

Safe Things You Can Do at Home While Waiting

You cannot lower ALP at home, and you should not try. What you can do is keep your cat stable and give your vet good information.

Offer small amounts of a food your cat likes, warmed slightly to boost the smell. Do not force feed.
Keep fresh water available at all times. Dehydration makes liver problems worse.
Write down what you see: how much your cat eats, litter box changes, vomiting, energy level, and any yellow color.
Gather your medication list, including any steroids, supplements, or flea products.
Do not give human medications, pain relievers, or supplements without asking your vet first. Some are toxic to cats.
Keep your cat indoors and calm. Stress can reduce appetite further.

If your cat is not eating or is vomiting, skip the home care and call your vet. Those signs need same-day attention.

What Your Veterinarian Will Check and Test

Your vet will start with a full physical exam, including feeling the abdomen and checking the gums for jaundice. From there, expect some combination of the following.

Repeat Bloodwork

A single value can be misleading. Your vet may repeat the chemistry panel to see whether ALP is rising, falling, or holding steady. They will also look at ALT, GGT, bilirubin, and albumin alongside ALP, because the pattern of these values helps narrow down the cause [2].

Abdominal Ultrasound

Ultrasound is a safe, widely available tool for looking at liver shape and structure [1]. It can show an enlarged liver, dilated bile ducts, a mass, or changes in texture. Your vet may also measure the liver using standardized planes, which is a newer way to make those readings more consistent [1].

Additional Testing

Depending on what the exam and ultrasound show, your vet may recommend:

A bile acids test to check liver function
A fecal exam or specific testing if a liver parasite is suspected [4]
Thyroid testing, since hormone disease can affect metabolism and appetite. See Thyroid Testing in Cats: Diagnosing Hyperthyroidism and T4 Fluctuations.
A liver biopsy or fine needle sample, which is the most direct way to identify liver cancer or other tissue changes [2]
A urine test, which can also pick up blood or other abnormalities. See Cat Blood in Urine but Acting Normal: Causes and Next Steps.

If your cat is already on steroids or your vet is considering them, a blood test before starting is standard practice. See What to Expect When Your Cat Needs a Blood Test Before Starting Steroids.

Prevention and Monitoring

You cannot prevent every liver problem, but you can lower some risks and catch others early.

Keep your cat at a healthy weight. Obesity raises the risk and severity of hepatic lipidosis [3].
Never let an overweight cat go more than a day without eating. Call your vet if appetite drops.
Feed a complete, balanced diet and avoid sudden food changes.
Keep up with routine wellness bloodwork, especially as your cat ages. Trends over time are more useful than one snapshot.
Limit hunting if you live in an area with liver parasites, and ask your vet about screening [4].
Review all medications with your vet, since some can raise ALP.
If your cat has a known liver condition, follow the recheck schedule your vet sets. The timing depends on the diagnosis and your cat's response.

Limitations and When to Contact a Veterinarian

ALP is a screening clue, not a diagnosis. A high value can come from the liver, bile ducts, bone, medications, or other tissues, and the same number can mean different things in different cats. Age, weight, diet, and other lab values all change how your vet reads it [2]. Individual cases always need a veterinarian who can examine your cat and see the full lab report.

Use this timing guide:

Emergency now: jaundice, collapse, seizures, repeated vomiting, a cat that has not eaten for 24 to 48 hours, or a painful swollen belly.
Same day: vomiting, lethargy, poor appetite, or any new yellow color.
Routine visit: a mildly high ALP found on wellness bloodwork in a cat that is eating, playing, and acting normal.

Frequently Asked Questions

Does a high ALP always mean liver disease?

No. ALP comes from several tissues, and steroids or other conditions can raise it without true liver damage. Your vet looks at the full panel and your cat's exam to decide what the number means.

Can a cat have a high ALP and still be healthy?

Yes, sometimes. A mild isolated rise in a cat that is eating and acting normally may turn out to be harmless, but that is a judgment your veterinarian makes after checking other values and often repeating the test.

How long does it take for ALP to return to normal?

It depends on the cause. Some cats improve within days once the trigger is treated, while others take weeks. Your vet will set a recheck schedule based on your cat's diagnosis and response.

Is a high ALP in cats the same as in dogs?

No. Cats normally have much lower ALP than dogs, and the causes differ too. A value that would be minor in a dog can be more meaningful in a cat, so never compare the two.

Can I treat a high ALP at home?

No. There is no home remedy that lowers ALP, and some supplements and human medications are toxic to cats. The right move is to keep your cat eating and drinking and let your vet find the cause.

References

"Hepatometry in young and adult domestic cats using ultrasound". Topics in companion animal medicine, 2026.
Retrospective study of biochemical profile changes in 93 cats with different hepatobiliary diseases. Journal of feline medicine and surgery, 2025.
Evaluation of Serum Homocysteine and High-Sensitivity Cardiac Troponins in Cats with Hepatic Lipidosis: An Observational Clinical Study. Veterinary sciences, 2026.
Clinical, laboratory, and ultrasonographic insights into Platynosomum fastosum infection in domestic cats: Diagnostic challenges and hepatobiliary implications. Veterinary journal (London, England : 1997), 2025.