Clinical chemistry reference intervals for health assessment in wild adult harbour seals

Reference intervals for clinical chemistry blood parameters are valuable for both individual diagnostics for animals in managed or veterinary care, and for evaluating wild population health. However, for marine mammals obtaining sufficient data from suitable groups or populations is logistically difficult. Here, we have assembled a large dataset of clinical chemistry results from free-living adult UK harbour seals (Phoca vitulina), analysed in the same commercial laboratory. We applied an open-source algorithm (available as the R package refineR, R version 4.5.2, refineR version 2.0.0) to produce robust reference intervals from these Real-World Data. This novel approach resulted in the generation of 95% reference intervals with 90% confidence bounds for 18 key chemistry parameters indicative of a range of physiological processes including, inflammation, nutritional status, kidney function and liver function. Reference intervals were also generated for triiodothyronine, the active thyroid hormone important in the regulation of metabolism. These intervals will provide critical baseline data for the assessment of harbour seal health as, to our knowledge, this is the largest dataset on which clinical chemistry reference intervals from wild-caught adult harbour seals have been based.