Differences in hematologic variables in rats of the same strain but different origin

Area of Science:

• Veterinary Hematology
• Toxicology Research
• Animal Model Standardization

Background:

• Wistar rats are standard models in toxicologic studies.
• The influence of the animal source on hematologic reference intervals (RI) is not well-established.
• Variations in RI can impact the interpretation of toxicologic data.

Purpose of the Study:

• To compare hematologic data between Wistar rats from two distinct breeders.
• To establish preliminary reference intervals (RI) for the Sysmex XT-2000iV hematology analyzer.
• To highlight the importance of source-specific RI in preclinical safety studies.

Main Methods:

• Blood samples were collected from Wistar rats (n=135) from two breeders.
• Hematologic analysis was performed using a Sysmex XT-2000iV analyzer.
• Sex-specific 95% RI were calculated and statistically compared between groups.

Main Results:

• Significant breeder-specific differences were observed in multiple hematologic parameters, including white blood cell (WBC), red blood cell (RBC), and platelet counts.
• Differences were noted for mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean platelet volume (MPV), and plateletcrit.
• Hematocrit (HCT) and hemoglobin concentration showed significant differences in female rats between the two sources.

Conclusions:

• Hematologic RI in Wistar rats are significantly influenced by the animal supplier.
• Using historical or generic RI can lead to misinterpretation of compound-related effects in toxicologic studies.
• It is crucial to establish validated, source-specific RI for control animals in preclinical safety assessments.