Tertiary hyperparathyroidism in a dog – Case report

Tertiary hyperparathyroidism (THPT) is rarely discussed in animals. This study aimed to report a case of tertiary renal hyperparathyroidism in a dog. A 16-year-old spayed female, Shih Tzu, previously diagnosed with stage 2 chronic kidney disease, presented increased levels of serum urea, creatinine, total calcium, ionized calcium, phosphorus and PTH, indicating THPT. Clinical treatment for the renal condition was initiated and cinacalcet hydrochloride (0.5 mg*kg-1, orally, once daily for 7 days, followed by 1 mg*kg-1, orally, once daily for 7 days) was administered to correct the hormonal disorders. PTH, total calcium and ionized concentrations decreased by 56%, 76% and 15%, respectively, in 14 days. However, exacerbation of the uremic crisis was observed, leading to death 26 days after the initiation of the medication. This report appears to be the first to comprehensively discuss THPT in veterinary medicine. The shorter life expectancy of these animals compared to that of humans may be a determining factor for the low prevalence of THPT in dogs. The tendency toward a reduction in PTH, total calcium and ionized calcium achieved after the initiation of cinacalcet hydrochloride use encourages the development of further clinical studies to investigate its application in animals.