Schillaci, T. T., Bishop, B. 2014. Effects of needle gauge on blood quality and potential for bruising with repeated blood collections in cynomolgus macaques. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 609-610. (Abstract #P226).

Obtaining quality blood samples while minimizing animal trauma related to venipuncture continues to be an important area of focus within the laboratory animal environment as it relates to both animal welfare and sample integrity. A review of the literature suggested that in humans, needle gauge can affect the quality of blood samples, and has implications for both the aversiveness of the sampling procedure acutely, as well as the number of samples which ultimately may need to be collected in a given experiment. Based on these basic principles, we hypothesized that there is a positive correlation between needle size and the magnitude of clinical bruising, but an inverse relationship between needle size and blood sample quality based on hemolysis and clotting incidence rates. Twenty-seven cynomolgus macaques (M. fascicularis) were divided into three groups (n = 9 per group) based on body weight (< 3 kg, 3 to 5 kg, and > 5 kg) and 3 animals in each group were bled using one of 3 size needles (21, 23, and 25 gauge). Animals in each group were bled at 6 time points over 24 h, mimicking a typical toxicokinetic study. Blood samples were evaluated for hemolysis, clotting, traditional hematology endpoints, and C-reactive protein (CRP), an acute phase inflammatory biomarker. Clinical measures included evaluation of injection sites for bruising. Results confirmed a positive correlation between needle size and the severity of bruising; however, no meaningful difference in sample quality, based on hemolysis and clotting incidence rates, hematology results, or CRP values were observed as a function of needle size. These results support the conclusions that increased needle size may cause increased clinical bruising, and hence an animal welfare concern, but does not impact overall blood sample quality.