Reference intervals for hematological variables in wild Eastern grey squirrels (Sciurus carolinensis)

Abstract

The eastern gray squirrel (Sciurus carolinensis) is a North American tree squirrel species which has been introduced to several countries outside its native range. We made use of squirrels culled in Italy within control activities to establish hematological reference intervals for this invasive species, with the aim to broaden the current knowledge about its physiology. Blood from 104 individuals was analysed through a laser analyzer. Manual leukocyte differential counts on blood films were performed on a subset of 52 animals for validation of the automated counts, resulting in a good agreement between the two methods. Reference intervals and the 90% confidence interval of their limits were estimated for 19 hematological parameters, partitioning by sex when statistically significant differences were detected. For most variables, our results were comparable with the few data available on the grey squirrel and on related species. This study gathered valuable reference information for studies aimed at disclosing the mechanisms underlying grey squirrels' invasiveness and for future research on tree squirrels physiology.

Shifts in immune responses of an invasive alien species: A test of the evolution of increased competitive ability hypothesis using American Eastern gray squirrels in Italy

“…Regarding hematological analyses, a complete blood count (CBC) and a leukocyte differential count (LDC) were run on the full sample of 126 squirrels. Whole blood stored in EDTA was processed within 48 hours from sampling by using a Sysmex XT-2000iV hematology laser analyzer (Sysmex Corporation, Kobe, Japan), adequately validated for the species (Romeo et al, 2021).…”