A challenging case: Severe hypercalcemia in a puppy with hypoadrenocorticism
The point of interest in this case was not the disease, but the degree to which it caused an elevated calcium concentration.
Mar 01, 2009
Treatment had included intravenous lactated Ringer's solution (26 ml/kg every 12 hours as a bolus) and injections of aminopentamide hydrogen sulfate (0.03 mg/kg every 12 hours), enrofloxacin (0.59 mg/kg every 12 hours—note that enrofloxacin is contraindicated in small- and medium-breed dogs between 2 and 8 months of age), and penicillin G (19,480 U/kg every 12 hours). The puppy's clinical signs had improved slightly after 24 hours of hospitalization, at which time it had been discharged to the owner. The referring veterinarian had tentatively diagnosed renal failure due to a genetic or congenital problem. A therapeutic renal diet had been the only treatment prescribed.
PHYSICAL EXAMINATION AND DIAGNOSTIC TESTING
We suspected hypoadrenocorticism and performed a CBC, a urinalysis, a serum chemistry profile, and an ACTH stimulation test. The CBC results revealed no abnormalities. The lack of a stress leukogram in this critically ill animal supported our suspicion of hypoadrenocorticism. The urinalysis results were normal, including a urine specific gravity of 1.020 (adult dog reference range = 1.015 to 1.050). Puppies older than 4 weeks of age have urine specific gravity measurements similar to those of healthy adult dogs.1 However, urine specific gravity is expected to be increased in the face of hypovolemic shock, even in a puppy.
Serum chemistry profile results revealed mild azotemia and hyponatremia and severe hyperkalemia, hypercalcemia, and hyperphosphatemia (Table 1, day 7). The sodium:potassium ratio in this puppy was 16.6. A sodium:potassium ratio < 24 is highly correlated with hypoadrenocorticism.2 We also considered primary hyperparathyroidism and secondary hyperparathyroidism due to renal failure as differential diagnoses for the hypercalcemia. However, because of the owner's financial limitations and our strong suspicion of hypoadrenocorticism, we did not measure ionized calcium and parathyroid hormone concentrations. Furthermore, the dog had been receiving a high-quality commercial puppy food and had no known ingestion of toxins such as rodenticides, psoriasis drugs, or excess vitamin D or calcium.