Erythrogram and red cell distribution width of Equidae with experimentally induced anemia
Easley, J.R.
American Journal of Veterinary Research 46(11): 2378-2384
1985
ISSN/ISBN: 0002-9645 PMID: 3000231 Document Number: 250524
The erythrogram (erythrocyte histogram) and red cell distribution width (RDW) were evaluated in 5 purebred horses and 1 pony of mixed breeding with experimentally induced anemia. Four horses were studied for 6 weeks after 20% of their estimated blood volume was removed on each of 2 consecutive days (40% total blood loss; acute blood-loss group). Two horses were given acetylphenyl hydrazine IV daily, until acute Heinz body hemolytic anemia was induced; the 2 horses were then evaluated for 6 weeks. One horse and the pony had 20% of their estimated blood volume removed via phlebotomy once each week for 8 weeks to induce iron-deficiency anemia (chronic blood-loss group); the horse had been partially depleted of iron before the study began. Weekly blood samples were examined for changes in the erythrogram, RDW, mean cell volume (MCV), and erythrocyte glucose-6-phosphate dehydrogenase activity. Fourteen days after acute blood loss, mild increases were seen in the MCV, which persisted to day 42. The RDW was increased at day 14 and remained increased until day 42; however, the percentage increase was double that of the MCV at days 14, 21, and 28. Erythrograms had mild extensions of the right slope at days 14 to 28. Mean erythrocyte glucose-6-phosphate dehydrogenase activity increased in all 3 groups, but individual concentrations were erratic. In the 2 horses with acute hemolytic anemia, modest increases of similar magnitude were seen in RDW and MCV. The RDW returned to pretreatment values by day 28, but MCV remained increased through day 42. The erythrogram had an extension of the right slope at days 14 and 21, and a mild shift to the right of the entire histogram was seen at day 21 in 1 horse and at day 28 in the other horse. This shift to the right persisted through day 42. In the chronic blood loss study, the horse that had been partially depleted of iron had no apparent increase in erythroid response; the RDW essentially did not change; and the MCV progressively decreased from day 21 to the end of the study (day 56); the erythrogram had a slight shift to the left from day 35 to day 56. The pony, which did not have prior iron depletion, had increased RDW and MCV at day 7; although these values were decreasing by day 56, the values continued to be higher than pretreatment values. The percentage increase of RDW was 2 to 5 times greater than that of the MCV from day 7 to day 35. Changes in the shape and position of the erythrogram were seen from day 14 to day 56. The erythrogram and RDW were useful in evaluating equine erythrocyte responses to different types of anemia.