Diabetes insipidus (DI) is persistent production of large volumes of dilute urine because the body either makes too little antidiuretic hormone (ADH, arginine vasopressin) or the kidneys cannot respond to it. It is rare in dogs, which is exactly why it matters on the exam: it is a diagnosis you reach only after excluding the common causes of polyuria and polydipsia (PU/PD), and the test traditionally used to prove it can kill the patient if it is done carelessly.
Key facts
Diabetes insipidus at a glance- Species / system: Dog; hypothalamus and posterior pituitary (central DI) or renal collecting duct (nephrogenic DI).
- Central DI (CDI): too little ADH. Causes include pituitary or hypothalamic tumours, head trauma, pituitary surgery, cysts and inflammation; many cases have no lesion found.
- Nephrogenic DI (NDI): normal ADH, but the collecting duct does not respond. Rarely congenital; much more often secondary to another disease.
- Classic presentation: an otherwise bright dog with profound PU/PD, nocturia or house soiling, and urine specific gravity (USG) persistently below 1.008, with a normal minimum database.
- Diagnosis of choice: exclude common PU/PD causes, then a desmopressin (DDAVP) trial.
- Treatment: desmopressin for CDI; treat the cause (and consider a thiazide) for NDI. Never restrict water.
- Not zoonotic or reportable (but leptospirosis, one cause of acquired NDI, is zoonotic).
What's inside
12 sections in the full guide- Key facts
- How the NAVLE tests this
- Cause and pathophysiology
- Clinical signs
- Diagnosis
- Differential diagnoses
- Treatment and management
- Prevention and client advice
- Prognosis
- Quick review
- Test yourself
- References
The full guide also has 5 tables, 3 figures, 3 self-test questions and 14 references, available to NAVLE members.
Read the full study guide
The full guide is part of every NAVLE plan, with diagnosis and treatment tables, figures, a quick review and self-test questions. Start a free trial to try the question bank, or log in if you are already a member.