Is Your Pet’s Liver in Trouble?
“Increased liver enzymes” – these words can trigger worry and confusion. But understanding what they mean and what can be done is crucial for your pet’s health. This blog post will guide you through the essentials of liver enzymes, their significance, and the steps you can take if your furry friend is affected.
What are Liver Enzymes?
Think of liver enzymes as tiny workers inside your pet’s liver cells. They’re involved in all sorts of essential processes, from breaking down food to detoxifying harmful substances. When the liver is healthy, these enzymes mostly stay within the liver cells. But when something goes wrong, they can leak out into the bloodstream, showing up as “elevated liver enzymes” on a blood test.
The Alphabet Soup of Liver Enzymes: ALT, AST, ALP, and GGT
When your veterinarian runs a liver panel, they’re typically looking at four key enzymes:
- ALT (Alanine Aminotransferase): This is the most liver-specific enzyme, particularly in dogs and cats. It’s mainly found in the liver, with smaller amounts in the heart, kidneys, and muscles. A rise in ALT often indicates damage to liver cells.
- AST (Aspartate Aminotransferase): While also found in the liver, AST is present in many other tissues, including the heart, muscles, and brain. An increase in AST can suggest liver problems, but it could also point to issues elsewhere, like muscle injury.
- ALP (Alkaline Phosphatase): ALP is found in the liver, bones, intestines, and other tissues. Elevated ALP can be a sign of liver disease, especially in cats. In dogs, certain medications can also cause ALP levels to rise.
- GGT (Gamma-Glutamyltransferase): GGT is found in the liver, kidneys, and pancreas. It’s often used in conjunction with ALP to assess liver and biliary health. In cats, GGT can be a particularly useful indicator of liver issues.
Many factors can cause liver enzyme elevations
Why Do Liver Enzymes Go Up?
Many factors can cause liver enzyme elevations:
- Liver Cell Damage: Infections like viral hepatitis and feline infectious peritonitis (FIP), toxins including certain medications such as acetaminophen, the artificial sweetener xylitol, and ingestion of Sago palm or Amanita mushrooms, metabolic diseases such as copper storage disease, cancer and decreased or abnormal blood flow to the liver for example from a portosystemic shunt (PSS) all can damage liver cells, causing enzyme leakage.
- Bile Duct Obstruction: Blockages in the bile ducts (the tubes that carry bile from the liver) can lead to a backup of bile, injuring liver cells and increasing enzyme levels. Causes of bile duct obstruction include gallstones, inflammation, pancreatitis and tumors.
- Medications: Certain drugs, particularly in dogs, can induce the liver to produce more enzymes. This doesn’t always indicate liver damage, but it can complicate test interpretation. Corticosteroids (like prednisone) and anticonvulsants (phenobarbital) are common culprits.
- Other Health Issues: Because some liver enzymes are also found in other tissues, increases can sometimes be due to problems elsewhere in the body, such as muscle injury (affecting AST) or bone disease (affecting ALP).
- Specific Diseases: In dogs, these include conditions like vacuolar hepatopathy (often associated with steroids), metabolic and endocrine diseases (Cushing’s disease, diabetes mellitus, hepatocutaneous syndrome), infectious diseases such as Leptospirosis, and liver tumors. In cats, common causes include cholangitis (inflammation of the bile ducts), hyperthyroidism, hepatic lipidosis, and certain infections such as feline infectious peritonitis (FIP) and feline leukemia virus (FeLV).
- End-Stage Liver Disease: In patients with end-stage liver disease where the majority of their liver has been replaced by cirrhosis (scar tissue), liver enzymes can actually be lower than expected, or in some instances even normal. This is because there no longer remains enough liver cells to produce and release enzymes. This can be a deceptive finding, as normal liver enzymes in these patients do not indicate a healthy liver but rather a severely compromised one.
Dogs vs. Cats: Key Differences
While the same liver enzymes are measured in both dogs and cats, there are important differences in how they’re interpreted:
- ALP Sensitivity: ALP is a tricky enzyme. In dogs, it’s very sensitive, meaning it often goes up even with minor liver issues. However, it’s not very specific – a high ALP doesn’t always mean liver disease. In cats, ALP is less sensitive (so it might not catch minor issues as readily), but it’s more specific, meaning if it’s high, there’s a stronger chance of actual liver disease. This means a high ALP in a cat is often more concerning than in a dog.
- Glucocorticoid-Induced ALP: Dogs have a unique ALP isoenzyme that’s increased by glucocorticoids (prednisone, aka steroids). This can complicate interpretation, as elevated ALP might be due to steroid medication rather than primary liver disease. Cats do not have this isoenzyme and any increase in ALP in a cat needs further attention.
What Should I Do if My Pet’s Liver Enzymes are High?
First, don’t panic! Elevated liver enzymes aren’t always a sign of serious disease. Your vet will likely recommend further testing to determine the underlying cause. This might include:
- A thorough physical exam and history: Your vet will look for signs of liver disease, such as jaundice (yellowing of the skin and eyes), an enlarged liver, or other abnormalities. You should tell your vet about all medications (including over the counter medications and supplements) you are giving and any possible exposure to plants (Sago palms, mushrooms), household chemicals or environmental hazards (free-standing water).
- Additional blood tests: These can provide a more complete picture of your pet’s overall health and liver function. Some blood tests that can be useful include a chemistry profile especially looking at your pet’s cholesterol, glucose, albumin. Additional liver-related tests that can be helpful include bile acids and a protein-c level.
- Ultrasound imaging: This can help visualize the liver and bile ducts to look for blockages, tumors, or other abnormalities.
- Liver biopsy: In some cases, a small tissue sample from the liver may be needed for a definitive diagnosis.
Treatment Strategies
Treatment will depend on the underlying cause of the liver enzyme elevation and may include:
Medications:
- Antibiotics: For bacterial infections.
- Antivirals: For viral infections, for example feline infectious peritonitis (FIP).
- Liver Protectants: Medications like SAMe (S-adenosylmethionine), vitamin E, milk thistle, N-acetylcysteine (NAC) and ursodeoxycholic acid (UDCA) can help support liver function and regeneration.
- Anti-inflammatories: To reduce inflammation in the liver.
- Specific Medications: Diseases such as Cushing’s disease (hyperadrenocorticism), copper storage disease and hepatocutaneous syndrome (SND) can be benefited by specific medications.
Dietary Changes: Special diets formulated for liver health can be crucial. These diets are typically lower in protein and may contain increased levels of antioxidants and easily digestible ingredients. Low-copper diets can be helpful for patients with copper storage disease.
Surgery: In some cases, surgery might be necessary, such as to remove a bile duct obstruction or a liver tumor, or to correct a portosystemic shunt (PSS). Sometimes surgery for a liver biopsy can be helpful in obtaining a diagnosis.
Supportive Care: This may include intravenous fluids to maintain hydration, medications to control vomiting or nausea, and nutritional support.
Low-copper diets can be helpful for patients with copper storage disease.
Prognosis
The prognosis for pets with elevated liver enzymes varies greatly depending on the underlying cause, the severity of the condition, and the individual pet’s response to treatment. Some liver diseases are reversible with appropriate management, while others may require lifelong care.
Contact Us
If your pet has elevated liver enzymes, we understand it can be concerning, but early detection and appropriate management are key to ensuring the best possible outcome. We encourage you to contact us so we can discuss the next steps in diagnosis and treatment. We will guide you through the process, explain the available options, and help you make informed decisions about your pet’s care. We are here to support you and your pet every step of the way.
Author:
James Woods DVM, MS, DACVIM (SAIM)
Ph: (912) 721-6410
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