Among eight horses who received transfusions with an incompatible blood type, seven developed mild signs of adverse reactions, including low fever, hives and increased heart rate.
were monitored for signs of reactions for five days. Among the eight who received transfusions with an incompatible blood type, seven developed mild signs of adverse reactions, including a low fever, increased heart rate and hives. None of the complications were life-threatening.
After any transfusion, a recipient’s body eventually destroys the donor’s blood and replaces with it with its own type. To determine how quickly this occurred in the study horses, the researchers drew blood from the recipient horses one hour after the transfusion and periodically for the next 35 days. They then tested each sample to determine how much donor blood was left.
“Horses can regenerate blood pretty quickly,” says NolenWalston. “Within a week they are already mounting a good regenerative response. If a horse is given incompatible blood, it’s possible that the blood would be destroyed so rapidly that the horse would develop dangerous anemia before the body had caught up and produced enough red blood cells to carry oxygen.”
The data showed that in incompatible pairs, the new blood was destroyed seven times faster than in pairs that were compatible, with half of the transferred red blood cells absent three to five days later. In horses given blood that was matched, the decline was gradual, suggesting a lifespan of around 70 days for the transfused cells.
This, Nolen-Walston says, indicates that matched blood types result in longer benefits and sheds light on the potential risks of incompatible matches. She notes that “other studies have described horses having fatal reactions to incompatible blood, so it is possible, though rare. In this study, most of the incompatibilities were horses receiving blood type ‘Ca,’ whereas the more lifethreatening reactions are more likely to be against type Aa and Qa blood.”
Reference: Journal of Veterinary Internal Medicine,