Determination of the lifespan of erythrocytes from greyhounds, using an in vitro biotinylation technique.

OBJECTIVE

To determine the RBC lifespan of Greyhounds, using an in vitro labeling technique.

DESIGN

RBC from dogs were labeled with NHS-biotin and their disappearance measured over time to determine RBC lifespan.

SAMPLE POPULATION: 5 Greyhounds that had been vaccinated against distemper, adenovirus 1 and 2 infections, parainfluenza, leptospirosis, parvovirus, and coronavirus infections, Bordetella bronchiseptica infection, and rabies the previous year; 3 sexually intact 14-month-old Beagles served as controls.

PROCEDURE: After venipuncture for CBC, catheters were inserted in the cephalic vein of each dog. Butorphanol was then administered to achieve mild sedation and analgesia, and glycopyrrolate was administered to ensure maintenance of adequate heart rate during phlebotomy. Dogs were positioned in lateral recumbency; blood was removed via jugular venipuncture, using a standard laboratory donor blood bag containing citrate-phosphate-dextrose solution. Blood was transferred aseptically into sterile polystyrene containers and NHS-biotin was added. After incubation, the labeled RBC were reinfused into the dogs and the blood was allowed to recirculate for 1 hour before the first postinfusion sample was taken. At frequent intervals, blood to be analyzed was taken by jugular venipuncture, and the percentage of labeled cells was determined by flow cytometry.

RESULTS

The mean RBC lifespan of non-Greyhounds was significantly longer than that of Greyhounds (104.3 +/- 2.2 days vs 53.6 +/- 6.5 days; P = 0.001). A negative linear correlation was also found between age of the Greyhounds and their RBC lifespan (P = 0.01, R2 = 0.91).

CONCLUSIONS

The shorter RBC lifespan of the Greyhounds may explain the finding of macrocytosis reported in earlier work. The reason for the shorter RBC lifespan in Greyhounds may be caused by differences in Greyhound RBC membrane structure or accelerated RBC removal from the circulation.