Protein-Losing Nephropathy in Dogs: Welfare Guide
Disease Overview
Protein-losing nephropathy (PLN) involves excessive loss of protein through damaged glomeruli (filtering units) in the kidneys, causing hypoproteinaemia, oedema, ascites, and progressive renal failure. Common causes in dogs: immune-mediated glomerulonephritis (often associated with chronic infections, neoplasia, or immune disease); familial nephropathy (Bernese Mountain Dogs, Soft-Coated Wheaten Terriers, English Cocker Spaniels predisposed); amyloidosis (Shar Peis, Beagles); and less commonly, other glomerulopathies.
Welfare Consequences
PLN causes multiple welfare harms: hypoproteinaemia (low albumin) causes peripheral oedema and ascites — visible swelling and abdominal distension causing discomfort; thromboembolic disease (pulmonary embolism, aortic thromboembolism) — a potentially fatal complication causing acute severe welfare compromise; hypertension — causing ocular and neurological damage; and progressive CKD with associated uraemic signs. The multisystem nature of PLN creates significant cumulative welfare burden.
Diagnosis
Urine protein:creatinine ratio (UPC) >2.0 on two consecutive tests (ruling out UTI) indicates significant proteinuria warranting investigation. Serum albumin (hypoalbuminaemia), cholesterol (hypercholesterolaemia — compensatory increase), blood pressure, and complete blood count provide essential staging information. Renal biopsy (histopathology, immunofluorescence, electron microscopy) provides definitive diagnosis of the glomerulopathy type, guiding specific treatment.
Treatment
Treatment depends on underlying cause: immunosuppressive therapy (prednisolone, mycophenolate, ciclosporin) for immune-mediated glomerulonephritis; treating concurrent infections, neoplasia, or inflammatory disease removes triggers. Anti-proteinuric drugs: ACE inhibitors (enalapril, benazepril) or ARBs (telmisartan) reduce glomerular hypertension and proteinuria. Thromboprophylaxis (clopidogrel, aspirin) is critical given the high thromboembolic risk. Diet: renal diet reduces phosphorus and provides omega-3 fatty acids.
Monitoring and Prognosis
Regular monitoring is essential: UPC every 1-2 months (tracking proteinuria response to treatment); serum albumin, creatinine, SDMA, electrolytes; blood pressure; and body weight. Prognosis varies widely by aetiology and severity at presentation. Dogs with severe hypoalbuminaemia (<15g/L) and concurrent hypertension have poor prognosis. Early diagnosis and treatment initiation before significant renal damage occurs gives the best welfare outlook. Owner education about thromboembolic warning signs (respiratory distress, acute paralysis) allows rapid emergency response.