What Are the Causes of Polydipsia & Elevated Liver Enzymes in Dogs?

Updated March 29, 2017

Polydipsia (excessive thirst) and elevated liver enzymes (ALT, ASP, ALP and GGT) can be caused by diabetes, liver damage, muscle injury, drugs, benign or malignant tumours, damage to other organs, bone diseases, gall bladder disease and hypothyroidism. Your veterinarian will need to run tests to discover the cause of your dog's polydipsia and elevated liver enzymes. Labrador retrievers, Dalmatians, Cocker Spaniels, Doberman Pinschers and Bedlington, Skye and West Highland white terriers are genetically predisposed to liver diseases and disorders.


Polydipsia, along with excessive urination and increased appetite, is a typical symptom of diabetes and hyperadrenocorticism (Cushing's disease). Additional symptoms of Cushing's disease include panting, high blood pressure, hair loss, drooping abdomen, thinning of the skin, hard lumps under the skin, skin infections, heart and muscle weakness and problems with the nervous system. Cushing's disease is usually caused by an adrenal or pituitary gland tumour. Blood tests and a dexamethasone suppression test can distinguish between diabetes and Cushing's disease.

Alanine Aminotransferase (ALT)

Increases in ALT levels indicate liver or muscle damage, gall bladder disease, gastrointestinal disorders, hypothyroidism, overuse of corticosteroid or phenobarbital medications or liver or bile duct cancer. A blood creatinine kinase determination can distinguish between liver and muscle damage. Discontinuing suspect medications and retesting ALT levels will determine if medication is the problem. Imaging studies can reveal tumours. An abdominal ultrasound can detect gastrointestinal problems. A liver biopsy might be necessary.

Aspartate Aminotransferase (AST)

Elevations in AST levels point to liver or muscle damage. Increased AST, along with increased ALT, is strongly suggestive of liver damage. Elevated AST, with no increase in ALT, indicates muscle damage. Gall bladder disease can cause mild increases in AST levels. Blood tests, ultrasound studies and possibly a liver biopsy are needed to provide a diagnosis.

Alkaline Phosphatase (ALP)

Increased ALP levels are associated with bone growth, hypothyroidism, bone cancer, bone infection, gall bladder disorder, liver cancer, hepatitis, chronic renal failure caused by elevated levels of parathyroid hormone, gastrointestinal disorders or corticosteroid or phenobarbital overuse. The greatest ALP increases usually indicate gall stones or liver or bile duct cancer. Blood tests, a serum chemistry profile, imaging studies and other diagnostics tests can distinguish between possibilities.

Gamma-glutamyltransferase (GGT)

Very high GGT results are indicative of gall bladder disease or bile duct obstruction. High GGT and high ALP point to liver disease. Moderate increases in GGT are associated with liver cancer. Blood tests, a serum chemistry profile, imaging studies and possibly a liver biopsy are necessary to distinguish between possibilities.

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About the Author

An organic chemist with a Master of Science from Case-Western Reserve University and a Master of Business Administration from Northwestern University, Ann Louise Truschel has been a freelance medical and business writer since 1982. Her client list includes big pharma, insurers, CME firms, medical journals, trade magazines, professional medical organizations, newspapers and The Department of Defense.