Journal of Animal Science and Veterinary Medicine

Diagnostic ultrasound examinations are becoming longer and more frequent, yet the effect of scanning duration on circulating blood is poorly defined. This exploratory study examined how the duration of uninterrupted diagnostic brightness-mode scanning over the femoral region affects blood cell parameters in New Zealand White rabbits. Twelve male rabbits were allocated to four groups of three: a control group handled for 30 minutes with the scanner switched off, and groups scanned for 10, 20 or 30 minutes daily for five consecutive days. Blood was collected at baseline and immediately after each session, and red cell, platelet and white cell indices were analysed by repeated-measures analysis of variance with comparisons against the control. Packed cell volume, haemoglobin concentration and red blood cell count were lower after exposure, most clearly in the 30-minute group (packed cell volume 30.61 ± 3.45% versus 35.89 ± 0.70% in controls). Group differences were not significant, but the day and group-by-day effects were, and the 30-minute group fell significantly below its baseline from day 3 to day 5, with a less consistent decline at 20 minutes and no sustained change at 10 minutes. Monocyte counts were higher after 30 minutes than in controls (0.42 versus 0.10 × 10³/µl; p = 0.003). Platelet counts were lower in the 30-minute group than in controls (p = 0.030), but counts rose above baseline in every group and the difference reflected high control values. Lymphocyte and eosinophil differences occurred only at 20 minutes and were not graded. Other indices did not change meaningfully. Scanning for 30 minutes, beyond a routine examination, was therefore associated with progressive declines in red cell indices and higher monocyte counts. Restraint stress cannot be excluded as a contributor, and acoustic output was not measured, so larger controlled studies are needed.