Background: The veterinary antibacterial florfenicol, an alternative to chloramphenicol that is prohibited for use in food-producing animals due to its hematotoxicity .But some references indicate that florfenicol also induces hematotoxicity. Objective: The aim of the study was to use suckling pups of rats as a model to detect the hematotoxicity of florfenicol. Methods: Fifteen lactating female rats (8 pups per mother) were divided into three groups C (control), F1 and F2 were treated with florfenicol (0, 50 and 100 mg/kg, intramuscularly (i.m) during the first five days after parturition,  respectively. Blood smears were prepared from newborns at 3, 7,14 and 21 postnatal day (PND) and stained with May-Grunwald Giemsa to study changes in the erythrocyte morphology.
Results:  Treatment of lactating female rats with a florfenicol(100 mg/kg) in the group (F2) led to severe hematotoxicity represented by appearance of the anulocyte cell as an indication of  hypochromia in a state similar to thalassemia and accompanied by the appearance of stomatocytes and target cells at (3 and7 PND) ,but fragmentation of erythrocytes were observed on the 14 PND, which persisted until the 21 PND. Whereas,  blood smear from newborns in group (F1) at 3 (PND)  showed  cells with finger-like projections which are an indicator of hemoglobinopathy, which was followed by the fragmentation of RBC which continued until 7,14 (PND) accompanied by a late appearance of anulocyte and target cells on day 21 
Conclusion: We conclude from our current study the success of the newborn model in detecting the hematotoxicity of  florfenicol.