Hematological and morphometric differences of blood cells from rheas, Rhea americana (Struthioniformes: Rheidae) on two conservation farms

Abstract Today, blood tests are an indispensable tool in avian medicine. This study aimed to describe and compare hematological and morphometric data of erythrocytes, leukocytes and thrombocytes of rhea, Rhea americana. To do so, 58 rheas of both sexes on two farms, one in Cachoeiro do Itapemirim, Espírito Santo (ES), and the other in São Carlos, São Paulo (SP), were selected. Blood samples were taken and their RBC counts, PCV and Hb levels were determined and used in hematimetric index calculations. The total and differentiated leukocyte counts and the TPP and fibrinogen serum levels were also obtained. The results from the two farms analyzed were compared by means of the t test. There were differences in the parameters of the erythrocyte series between the two flocks because of a process of hypochromic macrocytic anemia observed among the rheas in ES. The values for the erythrocyte series and indexes were: RBC, 2.81 ± 0.15 x106/μl; PCV, 44.20 ± 2.86%; Hb, 12.12 ± 0.74 g/dL; MCV, 15.75 ± 0.89 fL; MCH, 43.18 ± 1.82 pg; and MCHC, 27.44 ± 0.80 g/dL. The values for the leukocyte series were: WBC, 12,072 ± 4116 /μL; heterophils, 64.10 ± 9.90%; eosinophils, 2.05 ± 2.06%; monocytes, 6.40 ± 2.99%; lymphocytes, 26.93 ± 9.62%; and basophils, 0.52 ± 1.27%. These can all be suggested as references for rheas reared in Brazil. Statistical differences were observed in erythrocyte length measurements, which were higher in the rheas in SP than in those in ES. Regarding width, the heterophils, lymphocytes and monocytes of the birds in ES were statistically greater than those of the birds in SP. It was concluded that rheas may exhibit morphometric alterations to blood cells and differences in blood elements according to the type of management to which they are subjected