Polyuria & Polydipsia in Dogs & Cats

Diagnostic Tree Urology Peer Reviewed

increased water intake increased urine production (>80–100 mL/kg q24h) (>50 mL/kg q24h)

• Osmotic factors—increased plasma osmolality Assess signalment, history, examination findings, and MDB (CBC, serum biochemistry profile, • nonosmotic factors—hypotension, complete urinalysis, urine culture) hyperthermia, hypovolemia, pain, drugs

USG <1.025 (dogs) or <1.040 (cats) can suggest PUPD (see Urine Concentration Levels )

Yes No (most common) Abnormalities found? (least common)

Pursue appropriate diagnostics, including: Quantitate water consumption (if necessary) • Thoracic/abdominal/renal imaging • Thyroid/adrenal function testing • Bile acids • Leptospira titers Rule out otherwise silent Cushing’s disease • Hyperadrenocorticism/Cushing’s disease testing

Treat as necessary Yes No

Rule out CKD: stage 1 or Urine Concentration Levels* early stage 2 I Hyposthenuria = <1.008 I isosthenuria = 1.008–1.012 I Minimally concentrated = 1.012–1.029 (dogs), evaluate further 1.012–1.039 (cats) renal imaging, UP:C, I Hypersthenuria = ≥1.030 (dogs), ≥1.040 (cats) blood pressure, GFR

*Early-morning urine is best to assess concentrating ability

Yes No

62 cliniciansbrief.com • March 2013 Gregory F. Grauer, DVM, MS, DACVIM Kansas State University

includes: • Psychogenic/behavioral polydipsia Primary polydipsia • Portosystemic shunt/hepatic encephalopathy • Hyperthyroidism • Gi tract disease

Yes

evaluate response to exogenous ADH Hypersthenuric urine produced? No Primary polyuria while there is a stimulus to concentrate urine

Yes Hypersthenuric urine produced? Perform gradual water deprivation test cautiously** —cut water consumption by 5% –10% q48h until patient receives 80–90 mL/kg q24h Pituitary/central for 10 –14 days diabetes insipidus No

Attempt to differentiate primary nephrogenic diabetes insipidus For older patients, consider PUPD from secondary PUPD with • Primary (congenital—rare) acquired disease (eg, neoplasia, plasma osmolality • Secondary (acquired—common) inflammatory/infectious disease, head trauma)

Secondary/acquired causes include: • AKi/CKD/pyelonephritis • Hyperadrenocorticism • Hypoadrenocorticism **Test can be harmful to patient, as it must create a stimulus to concentrate • Pyometra Diagnosis urine (ie, mild dehydration). • Hypercalcemia/paraneoplastic syndrome Differential ADH = antidiuretic hormone, AKI = acute kidney injury, CKD = chronic kidney Diagnosis disease, GFR = glomerular filtration rate, MDB = minimum database, PUPD = • Hypokalemia/potassium depletion polyuria/polydipsia, UP:C = urine protein:creatinine ratio, USG = urine specific • Drugs (eg, diuretics, anticonvul- investigation gravity sants, corticosteroids) • Liver disease Treatment • Renal medullary solute washout • Diabetes mellitus Results • High-salt diet

March 2013 • clinician’s brief 63