Abstract
Background:
Diabetes insipidus (DI) is an uncommon canine endocrinopathy causing polyuria and polydipsia. It may be central, due to antidiuretic hormone (ADH) deficiency, or nephrogenic, from renal insensitivity to ADH. Differentiation between these forms is essential for appropriate treatment. Although the water deprivation test (WDT) is considered the gold standard for confirming the diagnosis, it carries significant risks.

Aim:
This study aimed to review the pathophysiology and diagnostic methods of DI in dogs, emphasizing the safety and applicability of water deprivation and desmopressin tests, as well as the potential of complementary biomarkers.

Methods:
The study methodology consisted of a qualitative narrative review using the Scopus, SciELO, Web of Science, and Google Scholar databases. Original articles, literature reviews, and case reports published in English between January 2015 and January 2025 were included. The terms “diabetes insipidus”, “canine”, “diagnosis” OR “water deprivation test” were established for searching and researching on the platforms.

Results:
The diagnosis of canine DI begins with the exclusion of other common causes of polyuria and polydipsia, with hyposthenuria as an early indicator. The WDT is considered the gold standard for definitive diagnosis, but it involves considerable risks of dehydration and hypernatremia for the patient. Therapeutic testing with desmopressin is a safe and viable alternative for differentiating between central and nephrogenic forms of the disease. Recent studies highlight copeptin as a promising biomarker for assessing vasopressin activity in the body, while advances in the molecular characterization of AVPR2 and AQP2 suggest a promising future for noninvasive biomarker-based diagnosis in veterinary medicine.

Conclusion:
The diagnosis of canine DI is complex and requires the combination and interpretation of clinical, laboratory, and therapeutic tests. Although the WDT is considered the gold standard, the desmopressin test offers a safer and more stable alternative. Advances in biomarker research may improve diagnostic accuracy and patient safety in the future.

Key words: Canine; Desmopressin; Endocrinopathy; Polydipsia; Polyuria.