Erythrogram and red cell distribution width of Equidae with experimentally induced anemia

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.(ABSTRACT TRUNCATED AT 250 WORDS)