Acute haematological and ultrasonographic changes followiong 13% or 15% total blood volume donation in non-sedaded military working dogs

Background Veterinary transfusion medicine lacks standardized protocols governing the safe maximum volume of blood that may be collected from canine donors per procedure. Unlike human medicine, where a 13% total blood volume (TBV) threshold is well established, veterinary practice accepts a wide range of collection volumes, raising concerns about donor safety and post-donation homeostatic capacity. Objectives To evaluate and compare the haematological and ultrasonographic effects of withdrawing 13% versus 15% of TBV in non-sedated military working dogs, providing evidence to support the establishment of safety parameters for canine blood donation. Methods A prospective, randomized, controlled, parallel-group study with repeated measures was conducted in 11 clinically healthy military working dogs (German Shepherd Dog and Belgian Malinois breeds). Dogs were allocated to Group 1 (G1; n = 5; 13% TBV) or Group 2 (G2; n = 6; 15% TBV). Haematological parameters including packed cell volume (PCV), erythrocyte count, haemoglobin concentration, mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC), total plasma protein (TPP), platelet count, and leukocyte differential count were assessed at three time points: pre-collection (T0), immediately post-collection (T1), and 24 h post-collection (T2). Ultrasonographic measurements of the caudal vena cava (CVC) and abdominal aorta (Ao) diameters, and their ratio (CVC: Ao), were obtained pre-collection (T0) and immediately post-collection (T1) using M-mode ultrasonography. Results In G1, PCV decreased significantly between pre-collection (T0) and post-collection (T1) time points ( p = 0.03), while abdominal aorta diameter showed a statistically significant reduction after collection ( p = 0.01). No statistically significant differences were detected for any haematological or ultrasonographic parameter in G2. In both groups, all values remained within established species reference ranges throughout the observation period. Conclusions Both 13% and 15% TBV collection protocols were physiologically well-tolerated by non-sedated military working dogs, with haematological and ultrasonographic variables consistently maintained within reference intervals. The integrated approach combining haematological and ultrasonographic assessment provided complementary and clinically relevant information on acute volemic status changes after controlled blood collection.