What is the most common cause of hypercalcemia in dogs?

The most common cause of hypercalcemia in dogs is lymphoma. Lymphoma is a type of cancer that affects the lymphatic system and is known to cause hypercalcemia due to the secretion of parathyroid hormone-related peptide (PTHrP) by the tumor cells. This peptide mimics the action of parathyroid hormone, leading to increased calcium release from bones and enhanced renal tubular reabsorption of calcium, resulting in elevated serum calcium levels.

Understanding the pathophysiology behind this condition is crucial for veterinary practice, as recognizing the signs of lymphoma can lead to earlier interventions and better outcomes for affected dogs. In contrast, while acute renal failure can cause some degree of hypercalcemia due to factors like dehydration and changes in calcium metabolism, it is not the most common cause. Similarly, chronic renal failure may lead to alterations in calcium and phosphorus balance, but phosphorus retention typically leads to hypocalcemia rather than hypercalcemia. Hypervitaminosis D can cause hypercalcemia but is not as frequently observed as lymphoma-related causes. Thus, lymphoma remains the leading cause of elevated calcium levels in dogs and is a critical consideration in the differential diagnosis of hypercalcemia in veterinary medicine.