An evaluation of five commonly used anticoagulants, in relation to the accuracy of haematological tests for bovine, ovine, equine and canine blood

Summary

Haematological tests were performed at intervals over a 102-hour period on bovine, ovine, equine and canine blood samples collected into five commonly used anticoagulants — EDTA(K3) at two different concentrations, EDTA(Na₂), oxalates and heparin.

Haemoglobin estimations on blood from all animals in all anticoagulants gave acceptable results for the period studied.

PCV values were acceptable for the entire period with all samples from the bull and ram. All PCV values for the horse and dog proved unacceptable beyond 54 hours. The values from the horse were most consistent from anticoagulants, EDTA(Na_) and heparin, while the sample in heparin gave the most stable results for the dog.

Total and differential leucocyte counts were found to be most consistent with EDTA(K3)-2 at 1.02 mg/ml and EDTA(Na₂) at 1.5mg/ml. Samples were generally acceptable for 24–102 hours for the total counts and 3–12 hours for the differential counts with these anticoagulants. Heparin-treated blood from the bull and dog showed an initial increase in lymphocytes compared to counts from all other anticoagulants and on the basis of this trial cannot be recommended for this test in cattle and dogs.

Because of the rapid degeneration and autolysis of leucocytes it is emphasized that, for valid differential counts, the practitioner should submit well-made blood films prepared at the time of sample collection.

Of those anticoagulants studied, EDTA(K3)-2, and EDTA(Na2), can be recommended as the most suitable for general haematological use by veterinarians for cattle, sheep, dogs and horses as they had the least deleterious effect on the accuracy of haematological tests over the longest period of time.