The mentolabial approach is a novel, safe, and effective method of blood collection in rats (Rattus norvegicus) and Chinese hamsters (Cricetulus griseus).

Mentolabial blood collection is a safe, effective, and repeatable technique for blood sampling in rats and Chinese hamsters.

This prospective study evaluated the safety, efficacy, and repeatability of a novel mentolabial blood collection technique in rats (Rattus norvegicus), Chinese hamsters (Cricetulus griseus), and long-tailed chinchillas (Chinchilla lanigera). The technique involves inserting a needle through the skin below the inferior lip, targeting the gingival vein, with animals under chemical restraint. Success was defined as collection of ≥0.1 mL of blood. The mentolabial approach achieved a 100% success rate in both rats and Chinese hamsters (10/10 each) and 75% in long-tailed chinchillas (9/12). No clinical complications were observed in any species, and histopathology in rats and Chinese hamsters revealed no adverse tissue effects. Serial venipuncture was performed in a subset of Chinese hamsters (n=6) at days 0, 7, and 14; hematologic parameters remained within reference ranges with no statistically significant differences over time, supporting repeatability and safety. Anatomical characterization via dissection and histopathology was conducted to describe the relevant regional anatomy. The technique yielded clinically relevant blood volumes with precise control and minimal risk. The authors conclude that mentolabial blood collection may enable more routine hematologic monitoring in rodents in clinical practice and may support the 3Rs principles—refinement and reduction—in research settings by providing a less invasive, reproducible alternative to existing venipuncture methods.

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