Most of you canine lovers have probably had some blood work done on your dog:
- For a wellness check
- For a pre-anesthetic profile
- Or when your dog is feeling under the weather
Just about every basic canine blood panel we run includes liver enzymes.
Elevated liver enzymes are one of the most common laboratory abnormalities in dogs. It’s sometimes difficult to determine if the dog truly has a primary liver condition or if the elevated liver enzymes are secondary to liver (hepatic) disease.
A liver biopsy, an actual piece of liver tissue, is needed for a diagnosis.
A liver biopsy in dogs is usually never the first step when the dog has increased liver enzyme activity. If an actual liver mass is detected on radiographs or other imaging, a biopsy may be indicated sooner than later.
The vast majority of dogs with high liver values do not have a tumor, however, and there are many decisions to be made concerning these abnormal liver lab values.
Abnormal Liver Enzymes in a Dog
If they are called liver enzymes and they’re abnormal, that means there must be something wrong with the liver, right?
The liver is a complicated organ, known as a clearing house for many drugs and toxins, both in and out of the body. The liver can clear away an infection from another part of the body, or it can be turned into overdrive, clearing out a drug or other toxin.
Any of these processes can elevate the liver enzymes in the blood. Figuring out what’s actually going on inside this fabulously complicated organ cannot be determined by elevated liver enzymes alone.
As a veterinarian, when I get blood results back with abnormal liver values, I have to consider more than just that number on a lab sheet, particularly if those abnormal values are for a presumably normal or healthy dog.
Say I have a happy, healthy 5-year-old dog who needs a lump removal and a dental procedure, and the liver values come back double than normal. The dog is not losing weight, not drinking more water, no vomiting or diarrhea, no lethargy, etc.
In other words, the pup has no symptoms of liver disease.
What to do?
Although the treatment plan may vary from vet to vet, most vets don’t get terribly excited about these values, particularly in a “healthy” dog, and we recheck those enzymes in 2–4 weeks.
To consider the dog healthy, however, we need to view the high liver enzymes as part of a bigger health picture:
- Is the dog on any drugs that may cause elevation, such as anti-seizure meds?
- Is the dog a breed prone to liver disease?
- Is this a young dog or small-breed dog who might have been born with a congenital anomaly (liver shunt)?
- Is the dog suffering from other diseases, such as diabetes, endocrine disease, etc.?
- Is there any history of toxin exposure?
The Next Step
To rule out all these possibilities to the best of our ability, we repeat the blood work, urinalysis, get radiographs or other imaging and perform more specific liver blood tests, like for bile acids.
If all these seem normal, we can monitor these liver enzymes for some period of time, possibly a few months.
If they are rising, however, or if they were very elevated and stay elevated, a biopsy of the liver is often the next step.
Liver Biopsy in Dogs
A liver biopsy requires a small piece of liver tissue to be obtained. Then that tissue is submitted to a pathologist for histologic interpretation and — with any luck — a diagnosis.
The most noninvasive way to obtain this piece of liver tissue is to do an ultrasound-guided biopsy with a tru-cut biopsy needle. This is called a percutaneous liver biopsy. In many ways, it’s similar to a breast biopsy in women.
Think of a tru-cut needle as a large, long outer needle with an internal needle inside of it:
- The needle apparatus is inserted through the skin, into the abdomen and into the liver.
- Then the internal needle is pushed into the liver tissue, captures a tiny piece and is drawn back into the larger needle, and the entire tru-cut needle is removed from the body.
- The small piece of liver tissue is now ready to be sent to a pathologist to be examined.
The pathologist looks at the liver cells and renders an interpretation.
No blood tests or imaging can give us this information — you need an actual piece of liver for a diagnosis.
Advantages of a Percutaneous Liver Biopsy in Dogs
The main advantage of a percutaneous liver biopsy in dogs is that it requires short-acting anesthesia and virtually no recovery time.
The dog is in the hospital for no more than a few hours and goes home wide-awake.
The second advantage is the low risk involved for the patient and no recovery time. The low risk includes hitting a vessel causing some post-biopsy bleeding, but this is usually minor.
Blood tests to check for clotting factors are done before the biopsy to make sure the dog can form a good blood clot. The liver is the source of many clotting factors, so this clotting profile is essential before any liver biopsy.
Prior to ultrasound, this procedure was much trickier, when hitting another organ or perforating the diaphragm was more likely.
Thanks to advanced imaging, the risk of these complications is minimized.
Disadvantages of a Percutaneous Liver Biopsy in Dogs
The largest disadvantage of this procedure is the small size of the tissue sample obtained.
Pathologists would much prefer an actual piece of liver (a wedge biopsy) that can be obtained only through a laparoscopic or actual open abdominal surgery. Obviously, recovery time from an abdominal surgery is longer, with more possible complications (death).
A second disadvantage is the cost.
Any biopsy procedure in a dog carries with it the expense of:
- A work-up
- Sedation or anesthesia
- The actual procedure
- Supportive care
- The pathologist’s lab fee
If the percutaneous liver biopsy does not render a diagnosis — or if the dog needs a wedge biopsy or exploratory as a next step — the client must be ready for another hefty bill.
This is one economical reason why high liver enzymes can be frustrating to the vet and the client.
When a Liver Biopsy Is Indicated
- If liver enzymes, specifically the ALT, stay persistently elevated or continue to rise for more than a month, a liver biopsy is probably indicated.
- If the dog is symptomatic of liver disease and the ALT is high, a biopsy is definitely indicated — sooner than later.
Getting an actual diagnosis of the liver disease dictates the proper treatment.
Some dogs have benign processes going on in the liver (hepatic nodular hyperplasia), which means the enzymes will probably remain high in this patient, but no treatment is necessary. This condition will not affect the dog’s life.
Other progressive liver diseases, like chronic hepatitis, can be life-threatening and require specific treatment. A biopsy is the only way to truly diagnosis this serious disease in dogs.
This vet is preparing to take a biopsy of his own dog:
Let Good News Be Good News
When you have a biopsy taken on yourself and you get good news, you are ecstatic, right?
Oddly, some people are pretty funny about that scenario when it comes to their pets.
I’ve had a few of these frustrating high liver enzyme cases where we decide to do a biopsy — and guess what? The news is good! The dog only has some “benign changes” going on in an aging liver.
But what have some of these clients said to me?
Here’s a gem: “Then why’d you have to put him through that biopsy?”
Well, I had to “put him through” that in order to get an answer!
I know the money situation in veterinary medicine is tough and things are only getting more expensive, but if you decide to do diagnostics on your pet and you get good news back, pat yourself on the back for doing the right thing.
It’s much better to do something like a liver biopsy and get an answer than to let a serious disease like chronic hepatitis go lurking in your dog’s liver, slowly destroying this vital organ.