Investigation of the relationship between ionised and total calcium in dogs with ionised hypercalcaemia.

OBJECTIVES: To investigate the relationship between total and ionised calcium concentrations in dogs with ionised hypercalcaemia and to evaluate how albumin influences this relationship. METHODS: Initially, a reference interval for ionised and total calcium was established using a large population of healthy adult dogs. Our teaching hospital clinical database was searched to identify adult dogs with ionised hypercalcaemia between 2012 and 2017, a time frame when the same sample handling and analysis protocols were in place as for the healthy reference interval population. The relationship between ionised and total calcium concentrations was then examined in the ionised hypercalcaemia population. RESULTS: Based on biochemical analysis of 351 healthy adult dogs, a reference interval of 1.18 to 1.53 mmol/L for ionised calcium and 2.24 to 2.85 mmol/L for total calcium was established. Using these reference intervals, 63 dogs with ionised hypercalcaemia were identified, of which 23 did not have total hypercalcaemia. Only seven of the 23 dogs with ionised hypercalcaemia and total calcium below the upper limit of the reference interval had hypoalbuminemia. The majority of dogs with ionised hypercalcemia and normal total calcium had a modest increase in ionised calcium. CLINICAL SIGNIFICANCE: If relying on total calcium alone, more than one third of dogs with ionised hypercalcaemia will be classified as normocalcaemic and the majority of these dogs had normal serum albumin.

Sensitivity and specificity of microRNA-122 for liver disease in dogs.

BACKGROUND: Current tests for diagnosing liver disease in dogs are sub-optimal. MicroRNA-122 (miR-122) is a sensitive and specific biomarker of liver injury in humans and rodents. Circulating miR-122 could have utility in identifying dogs with liver disease. OBJECTIVE: Establish the reference interval for miR-122 in healthy dogs and determine performance in a range of dog breeds with liver disease and control animals with non-liver disease. ANIMALS: Stored serum from 120 healthy dogs, 100 dogs with non-liver diseases, and 30 dogs with histologically confirmed liver disease was analyzed. METHODS: Retrospective study. Medical records of dogs with liver disease, non-liver disease and healthy dogs were reviewed. Serum miR-122 concentrations were measured by PCR and compared with the characteristics of the dogs and their conventional clinical measurements. RESULTS: In healthy dogs the 2.5th, 50th, and 97.5th quartiles of miR-122 were 110 (90% CI 80-114), 594 (505-682), and 3312 (2925-5144) copies/µL, respectively. There was no difference between healthy dogs and dogs with non-liver disease (median ± IQR: healthy dogs 609 [327-1014] copies/µL; non-liver disease 607 [300-1351] copies/µL). miR-122 was higher in dogs with liver disease (11 332 [4418-20 520] copies/µL, P < .001 compared to healthy dogs). miR-122 identified dogs with liver disease with high accuracy (receiver operating characteristic area under curve for comparison with healthy dogs: 0.93 [95% CI 0.86-0.99]). The upper limit of normal for healthy dogs (3312 copies/µL) had a sensitivity of 77% and specificity of 97% for identifying liver disease. CONCLUSION AND CLINICAL IMPORTANCE: Liver disease can be sensitively and specifically diagnosed in dogs by measurement of miR-122.