Use of an indirect sampling method to produce reference intervals for hematologic and biochemical analyses in...

As with other animal species, comprehensive reference intervals (RI) for psittaciform species are rare and plagued by common issues, including sparse information regarding methods used to analyze specimens, low sample sizes, and improper statistical analyses. The purpose of this study was to examine the use of an indirect sampling method of RI generation from several years of data collected from specimens of multiple psittaciform species submitted to a veterinary diagnostic laboratory. These data were unselected for health status. A previously published method for indirect RI generation was applied to data collected for routine hematologic and biochemical analyses. Seven species groups were examined, and sample size ranged from 346 to 2358. Results showed that RI varied by species and appeared to represent a broader range than expected compared with other RI and traditional clinical expectations for core health assessments, such as total white blood cell count and white blood cell differential results. Some biochemical results reflected more narrow ranges, and a few were consistent with other published ranges. The intervals were likely influenced by changes related to stress and underlying disease. The results of the current study reflect the imprecision of this method related to data obtained from the population served by this laboratory. Overall, this method is not suitable for the production of comprehensive RI, although it may provide rough estimates for some limited analyses until traditional RI can be generated.