What causes high liver enzymes in dogs?

Owning a dog means paying attention to small changes that can point to bigger health problems. Elevated liver enzymes are among the most common abnormal lab findings veterinarians see; they may suggest anything from a mild, reversible irritation to a serious liver disorder. I typically see enzyme elevations flagged after routine bloodwork, when a dog presents sick, or following known toxin exposure. Knowing why enzymes might be up and what to watch for helps owners act sooner, avoid unnecessary worry, and make better decisions with their vet.

Certain situations tend to prompt concern: a yearly check that shows an unexpected rise, an episode of vomiting or jaundice, or a known exposure to a toxic food or chemical. Some dogs are more likely to have liver issues—older dogs, breeds with genetic liver concerns, and any dog on long-term medicines such as anticonvulsants or certain anti-inflammatories. Most owners’ goals are straightforward: detect problems early, reduce harm, and choose treatments that fit the dog’s life. A blood test does not always mean the dog is severely ill, but it is a prompt to investigate.

Most likely reasons your dog’s liver enzymes are elevated

A short list helps frame the likely explanations if your dog’s liver enzymes come back high. These are not exhaustive, but they represent the causes seen most often in practice:

• Hepatocellular disease — inflammation of liver cells (hepatitis), fat accumulation (fatty liver), or long-term scarring (cirrhosis).
• Cholestatic conditions — problems with bile flow such as gallbladder disease, bile duct obstruction, or inflammatory changes in the biliary system.
• Drugs, toxins, and certain supplements — medications and substances the liver must process can raise enzymes when they injure cells or induce enzyme production.
• Systemic illnesses — endocrine disorders, immune-mediated disease, and infections that affect the liver secondarily.

How a dog’s liver works — the essentials every owner should know

The liver performs many jobs that keep a dog healthy: it filters and detoxifies substances absorbed from the gut, makes critical proteins such as clotting factors and albumin, stores certain vitamins and glycogen, and produces bile to help digest fats. Bloodwork measures enzymes that live inside liver cells or in the biliary system; these enzyme levels often rise when cells are stressed or damaged. The most commonly reported are ALT and AST (often linked to hepatocellular injury), and ALP and GGT (more tied to bile flow problems). Enzyme elevation signals that cells are reacting, but it is not the same as loss of liver function; a dog can have high liver enzymes and still have many of the liver’s functions preserved.

Inside the body: what drives enzyme increases

Liver enzymes increase for a few different biological reasons. When liver cells are injured by inflammation, infection, or toxic insult, they leak intracellular enzymes such as ALT and AST into the bloodstream; those enzyme rises often suggest hepatocellular damage. When bile ducts are inflamed, obstructed, or not functioning well, enzymes like ALP and GGT tend to climb because of cholestasis and altered bile handling. Some drugs and chemicals cause the liver to make more of certain enzymes without killing cells; that phenomenon, called enzyme induction, may raise values without immediate cell death. Acute inflammation often produces a sharp enzyme spike, whereas chronic scarring and long-term disease may cause moderate, persistent elevations and eventual loss of functional proteins made by the liver.

Common triggers that can cause sudden enzyme spikes in dogs

Practical triggers are what owners can realistically watch for. Many household items and foods can prompt a sudden rise: xylitol-containing gum or baked goods can cause severe liver injury in dogs; some wild mushrooms are hepatotoxic. Common medications and supplements can be culprits—NSAIDs, certain anticonvulsants, and herbal products sometimes damage the liver or interact with other drugs. Infectious agents such as leptospirosis or tick-borne illnesses can directly affect the liver, and systemic disorders like Cushing’s disease may alter liver enzyme patterns. Physical stressors also matter: heatstroke, prolonged seizures, or severe muscle injury can raise liver-associated enzymes, sometimes confusing the picture because muscle injury raises AST and other markers too.

Symptoms to watch for — red flags of potential liver disease

Bloodwork is only part of the story; clinical signs tell you how urgent the situation may be. Watch for jaundice (yellowing of gums, eyes, or skin), persistent vomiting, abdominal pain, severe lethargy, bleeding or bruising, and neurological signs such as disorientation, wobbliness, or collapsing. Dangerous lab patterns that suggest more than mild irritation include very high enzyme values combined with elevated bilirubin, low blood clotting capacity, or signs of dehydration and kidney involvement. Rapid deterioration—worsening mental status, ongoing bleeding, or inability to eat or stand—warrants immediate veterinary attention rather than watchful waiting.

If your dog’s results come back high, here’s what to do first

If you learn your dog has elevated liver enzymes, take a few clear steps. Stop giving any non-essential medications or supplements and remove suspected toxins from reach; if you suspect ingestion of a toxic item, call your veterinarian or a poison control service. Be prepared to give your vet a concise timeline: when the abnormality was first noted, any new medications, dietary changes, vomiting or diarrhea, and any known exposures. Expect the vet to recommend further tests to clarify the cause—these commonly include a complete blood count, a full chemistry panel, bile acids or bilirubin testing, urinalysis, and imaging such as an abdominal ultrasound. In some cases your vet may suggest more advanced diagnostics like specific infectious disease testing or a liver biopsy. Emergency treatments that may be needed depend on the situation but can include intravenous fluids, anti-nausea medications, attempts to remove or neutralize toxins, and medications to support liver function or control complications.

Daily care and prevention strategies to protect your dog’s liver

Many owners can reduce the risk of future problems through simple, practical steps. Store medications, human foods, and toxic household items out of reach and use pet-proof locks on cabinets if needed. Maintain a healthy weight for your dog—obesity and poor diet can promote fatty changes in the liver. Ask your vet for a medication review at regular intervals, especially for dogs on long-term drugs; monitoring bloodwork periodically may catch early changes before clinical disease develops. Keep vaccinations and parasite control up to date, since some infectious agents that affect the liver are preventable or manageable. If your dog has a chronic liver condition, follow your vet’s dietary and medication recommendations closely and schedule regular rechecks.

Practical gear and household items that reduce liver-related risks

A few items make prevention and quick response easier: secure cabinet locks and lidded trash containers can prevent accidental ingestion; a simple pill organizer and a phone app or written log help track medications and avoid accidental overdoses; a basic pet first-aid kit with gauze, bandage tape, and a rectal thermometer is useful in many emergencies. If you need to bring samples to the vet, a clean container with a small amount of vomit or a stool sample and a complete, written list of medications and supplements your dog receives are extremely helpful for diagnosis.

• Pet-proof cabinet locks and covered trash cans
• Pill organizer and a medication-tracking note or app
• Pet first-aid kit: thermometer, gauze, bandage tape, phone numbers
• Small clean containers for vomit/stool samples and a printed medication list

Which veterinarians and organizations to consult — trusted expert resources

When making decisions, rely on veterinary specialists, poison control services, and academic centers rather than general internet pages. Internal medicine textbooks and clinicians provide practical diagnostic and treatment approaches. Poison control centers and university teaching hospitals offer rapid, evidence-based guidance for toxins and complicated cases. Professional organizations and specialty colleges provide consensus guidance and can help you find a qualified specialist if your dog needs advanced care.

Cited studies, clinical guidelines, and suggested further reading

• Merck Veterinary Manual: Hepatobiliary disease in dogs and cats — detailed overview of causes and diagnostics.
• Nelson, R.W. & Couto, C.G., Small Animal Internal Medicine — chapters on hepatic disease and diagnostic approach.
• Plumb’s Veterinary Drug Handbook: Entries and reviews on drug-related hepatotoxicity.
• ASPCA Animal Poison Control Center: Xylitol toxicity and common household hazards for dogs.
• Cornell University College of Veterinary Medicine: Canine liver disease resources and client information sheets.