Chronic kidney disease (CKD) is one of the most common conditions affecting middle-aged and older dogs. Progressive and incurable, CKD requires long-term management to slow progression, manage clinical signs, and maintain quality of life. Understanding the disease and available interventions empowers owners to provide excellent welfare support.
Pathophysiology
CKD involves progressive loss of functional nephrons (kidney filtering units). The kidneys have substantial reserve — clinical signs typically emerge only when 75% or more of nephron function is lost. Common underlying causes include glomerulonephritis, chronic pyelonephritis, renal amyloidosis, polycystic kidney disease (inherited in some breeds), and renal hypoplasia. In many dogs, the original cause cannot be determined.
Clinical Signs by Stage
The IRIS (International Renal Interest Society) staging system grades CKD by creatinine and SDMA levels:
- Stage 1–2 (mild): Increased water intake, increased urination, mildly elevated kidney markers; often asymptomatic
- Stage 3 (moderate): Lethargy, poor appetite, weight loss, vomiting, pale mucous membranes from anaemia
- Stage 4 (severe): Profound depression, vomiting, oral ulcers, severe anaemia, seizures from uraemia; euthanasia often indicated
Dietary Management
Phosphorus restriction is the cornerstone of CKD dietary management — phosphorus retention accelerates nephron loss. Prescription renal diets provide controlled phosphorus, modified protein levels, omega-3 fatty acid supplementation, and alkalising agents. The transition to renal diet should be gradual. Dogs unwilling to eat renal diet may be given phosphate binders added to regular food as an alternative phosphorus management strategy.
Medical Management
- Phosphate binders (aluminium hydroxide, calcium carbonate, sevelamer) reduce intestinal phosphate absorption
- ACE inhibitors or amlodipine for management of proteinuria and hypertension
- Subcutaneous fluids administered at home to maintain hydration in more advanced cases
- Erythropoiesis-stimulating agents (e.g., darbepoetin) for non-regenerative anaemia
- Anti-nausea medications and appetite stimulants as needed
Quality of Life Monitoring
Regular assessment of quality of life is essential in CKD management. Owner-completed quality of life scales (e.g., HHHHHMM scale — Hurt, Hunger, Hydration, Hygiene, Happiness, Mobility, More good days than bad) help track welfare status and support decisions about end-of-life care. Vomiting, inappetence, severe anaemia, and weight loss are key welfare indicators requiring reassessment of management strategy.
Prognosis and Welfare Planning
Stage 1–2 CKD dogs can remain stable for years with appropriate management. Stage 3 dogs typically survive months to years. Stage 4 carries a poor prognosis measured in weeks. Early diagnosis through routine senior screening (annual blood and urine tests in dogs over 7 years) allows earlier intervention and better welfare outcomes.