Haematological responses of repeated large volume blood collection in the horse

The haematological response of regular, repeated blood harvesting was inves tigated in 40 Thoroughbred and non-Thoroughbred horses that donate 8 litres of blood every 3 weeks for the purposes of commercial blood production. Wh en this volume of blood was removed on five occasions over 12 weeks, no adv erse effect on packed cell volume (pcv), haemoglobin (HB), and red blood ce ll count (RCC) was observed Although PCV, RCC and Hb Values decreased durin g the first week after brood collection, followed by a gradual increase in values until the next harvest time, all values remained within published re ference ranges. Derived red cell indices [mean corpuscular volume (MCV), me an corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentr ation (MCHC)] also remained within reference range. We conclude that the re moval of approximately 8 litres of blood (approximately 16 mi kg(-1) or 20 per cent of blood volume for a 500 kg horse) from blood donor horses every 3 weeks allows time for adequate recovery of haematological variables and d oes not result in adverse haematological changes.