Elevated blood calcium (hypercalcemia) in cats has multiple causes including idiopathic hypercalcemia and lymphoma. Diagnosis and management are essential to prevent organ damage and chronic welfare harms.
Hypercalcemia causes chronic discomfort and progressive organ damage if untreated, but is often not immediately obvious because clinical signs are non-specific and develop gradually. The welfare priority is identifying hypercalcemia through routine blood screening before significant organ damage occurs, then determining the cause because treatment differs dramatically based on underlying disease. A cat with idiopathic hypercalcemia managed with dietary modification can have excellent quality of life for years. A cat with lymphoma-driven hypercalcemia needs appropriate cancer treatment for the hypercalcemia to be managed. Chronic untreated hypercalcemia causes progressive renal damage that reduces the cat's quality of life and lifespan. The welfare case for investigation and treatment is clear and the outcomes are often good when diagnosis occurs before severe renal compromise.