Variation in biochemistry test results between annual wellness visits in apparently healthy Golden Retrievers

Annual wellness testing is widely recommended for apparently healthy dogs, but there is little data to assist with distinguishing normal variation from clinically important changes.

To define variability in biochemistry analytes between annual wellness tests in healthy Golden Retrievers.

Four hundred thirty-four Golden Retrievers undergoing annual health assessments by their primary care veterinarians as part of a prospective cohort study.

Changes in 23 biochemistry analytes were calculated between year 1 and year 2 health checks for 196 dogs classified as healthy for ≥3 consecutive years. Using a direct nonparametric method, annual change intervals were constructed to define normal variability. A validation cohort of 238 dogs without a diagnosis of systemic disease for ≥3 consecutive years were compared with the reference and annual change intervals, and the proportions of dogs outside annual change intervals and a population-based reference interval were compared by using a McNemar test.

Annual change intervals were calculated based on 190 dogs after outlier removal. For all 23 analytes, >90% of dogs in the validation cohort were within the annual change interval. There were no significant differences in the classification by reference versus annual change intervals.

The annual change intervals met performance requirements for classification of dogs that did not develop systemic disease in the year following wellness testing as normal.