Haematological responses of repeated large volume blood collection in the horse.

This study evaluates the impact of regular, large volume blood draw on the wellbeing of thoroughbred and non-thoroughbred horses, finding that taking approximately 8 litres of blood every three weeks does not result in any negative changes to the horses’ blood health.

Study Aim and Methodology

• The main aim of this study was to assess the haematological response (or changes in blood components) in horses that are subjected to a cycle of large volume (8 litres) blood harvesting every three weeks.
• This investigation was conducted on 40 Thoroughbred and non-Thoroughbred horses, chosen for their role in commercial blood production.
• The focus was to monitor the potential impact on certain blood parameters including the packed cell volume (PCV), haemoglobin (Hb), red blood cell count (RCC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC).
• Blood was drawn in this schedule five separate times over the course of 12 weeks.

Findings of the Study

• Upon examination of the horses’ blood after each collection period, researchers noticed that there was no negative impact on their PCV, Hb, RCC levels.
• It was noted that while the levels of PCV, RCC and Hb dipped during the first week following blood collection, they gradually bounced back and increased until the next collection time. Importantly, all these values remained within the acceptable and healthy range for the horses.
• The derived red cell indices, including MCV, MCH, and MCHC, which provide information about the size and haemoglobin concentration in red blood cells, also remained within the reference ranges, indicating no adverse changes.

Conclusions

• The study concluded that drawing approximately 8 litres of blood from horses (equivalent to approximately 16 ml kg(-1)or 20 per cent of blood volume for a 500 kg horse) every three weeks allows time for adequate recovery of these blood cell variables and does not result in any adverse haematological changes.
• In simpler terms, the horses’ bodies were able to compensate for the blood loss and renew their blood components within the three-week time frame between blood collections.