Evaluation of granulocyte transfusion in healthy neonatal pony foals.

The research examined the effects of granulocyte transfusions (GTs) on healthy neonatal pony foals. After the transfusion, findings were that the foals had a significantly higher neutrophil count, showing that GTs may help increase neutrophil levels in young ponies, and some side effects were observed.

Study Method and Participants

• The study was conducted on seven healthy neonate pony foals aged between two and seven days. Granulocyte transfusions were performed on these foals, delivering nearly 1×10⁹ neutrophils for every kg of body weight.
• There was a group of healthy adult horses used as blood donors to assist in the GT. They were given hydrocortisone sodium succinate, which was used to increase the number of neutrophils in the blood.
• The leukocyte concentrates necessary for the GTs were then extracted from the adult horses’ blood through a process known as continuous-flow centrifugation leukapheresis.

Study Findings and Observations

• The neutrophil count in the foals’ blood significantly increased (p<0.05) one hour after the GT - from a base of approximately 4830 to 8870 neutrophils per microliter. However, 15 to 18 hours after the GT, the neutrophil count returned to levels similar to the base.
• In vitro testing showed that neutrophils from the leukocyte concentrates had a significantly reduced stimulated migration to zymosan-activated serum as compared to that of the donors’ peripheral blood neutrophils. However, the phagocytic and bactericidal capacities of the neutrophils were not significantly altered.
• Minor side effects such as mild depression and temporary diarrhea in one foal were reported following the GT. The foal developed these symptoms approximately 30 minutes after the start of the transfusion.
• Two adult horses – including the one who was the donor for the foal that showed side effects – showed signs of depression, piloerection, and muscle tremors during the leukapheresis procedure. This indicated the activation of the complement system, part of the immune response. However, the issues were resolved by using new disposable plastic materials for each procedure.

Conclusion and Implications

• The study provides insights into the effects and potential benefits of granulocyte transfusions in neonatal ponies. It showed a significant temporary increase in neutrophil levels but a return to normal levels after some hours, suggesting that this might be a viable method for boosting the immune function of young foals momentarily during times of weakness.
• However, the side effects noticed during and after the transfusion need to be taken into account. It calls for further investigation and strategies for minimising these side effects to ensure the welfare of the animals involved.