RESUMO
OBJECTIVE: To evaluate the onset and duration of hematological changes and the use of Doppler ultrasound (spleen) in dogs sedated with acepromazine or xylazine. STUDY DESIGN: Clinical study. ANIMALS: A total of 24 mixed breed dogs aged 1-4 years and weighing 15-25 kg. METHODS: Dogs were randomly distributed into two groups: acepromazine group (AG) which were administered acepromazine (0.05 mg kg-1) intramuscularly and xylazine group (XG) administered xylazine (0.5 mg kg-1) intramuscularly. Sonographic evaluations (morphologic and hemodynamic splenic vascularization) and hematologic tests were performed before drug administration (baseline) and 5, 15, 30, 60, 120, 240, 360, 480 and 720 minutes after drug administration. RESULTS: A significant reduction occurred in erythrogram variables in AG at 15-720 minutes corresponding with a significant enlargement of the spleen. In XG, a significant reduction was observed in the erythrogram variables at 30-60 minutes without a significant enlargement of the spleen. Hilar diameter did not change over time in either group. Flow alterations were found only in the splenic artery in AG, with a decreased final diastolic velocity observed at 60-120 minutes. CONCLUSIONS: Administration of acepromazine resulted in decreased red blood cell count, hemoglobin, packed cell volume and an increased diameter of the spleen. Xylazine administration resulted in similar hematologic changes but of smaller magnitude and duration and without splenic changes. The absence of significant changes in the Doppler flow parameters of the splenic artery and vein and the hilar diameter suggests that the splenomegaly that was observed in AG was not due to splenic vasodilation. No splenic sequestration occurred after xylazine administration. CLINICAL RELEVANCE: The results indicate that acepromazine decreases the erythrocyte concentrations by splenic erythrocyte sequestration and concomitant splenomegaly. Xylazine can cause slight hematologic changes, but without splenic changes.
