Blood cell morphology and hematological parameters of rice field frog Hoplobatrachus rugulosus (Wiegmann, 1834)

Abstract

The rice field frog Hoplobatrachus rugulosus, a common anuran species found in wetlands throughout Thailand, is well known as an economically important farm animal. Hematological technique is a basic method to determine health of animals. Even though the data on hematology is crucial for manipulation and conservation of this frog, they are still very limited. Our research group tries to develop health assessment criteria based on hematological parameters of the frog. Therefore, hematological parameters including blood cell morphology and morphometry of wild caught H. rugulosus and hematological parameters with the normal reference values of farm raised H. rugulosus were examined in this study. The adult wild frogs were collected from natural habitat at Nan Province in wet season, 2014. The farm raised frogs including adult, juvenile and sicked frogs were collected from farm in Chiang Mai Province in 3 seasons during 2014. Blood samples were subjected for erythrocyte and leukocyte count by hemocytometer, packed cell volume (PCV) estimation, differential leukocyte count from Giemsa-stained blood smears and total protein quantification by Bradford assay. The results showed the morphological characteristics of wild H. rugulosus blood cells including erythrocytes, immature erythrocytes, thrombocytes, lymphocytes, monocytes, neutrophils, basophils and eosinophils. In wild caught frogs, the mean of PCV, number of lymphocytes and neutrophils showed significant sex-related difference. The hematological parameters of farm raised adult H. rugulosus that showed significant sex-related differences include erythrocyte count, PCV, plasma total protein, differential lymphocyte count, differential monocyte count, and differential eosinophil count. The hematological parameters of farm raised juvenile frogs that showed significant sex-related differences include PCV, plasma total protein, differential lymphocyte count, differential monocyte count, differential neutrophil count and differential eosinophil count. Most of hematological parameters of farm raised adult and juvenile frogs also showed seasonal variation except the differential basophil count. The normal reference values that have been established and validated to be sensitively used for monitoring of health status of adult farm raised H. rugulosus include erythrocyte count (for female in wet season), plasma total protein (for both sexes in cool dry season) and differential lymphocyte count (for both sexes in wet season). The hematological parameters and the normal reference values presented in this study could be regarded as the first report and a crucial baseline data for conservation and management of wild and farm raised H. rugulosus in Thailand.