Determination of the effects of intramuscular and intranasal medetomidine on heart size, sedation level and vital parameters in cats

Medetomidine, an alpha-2 adrenergic agonist, is widely used in cats due to its well-established sedative and analgesic effects. However, a thorough literature search revealed no studies to date investigating the effects of medetomidine delivered via IN and IM routes on cardiac size in cats. Therefore, the aim of this study is to assess and compare the effects of IN and IM administration of medetomidine on cardiac size in cats. 14 male cats were included in the study. Medetomidine (IN medetomidine or IM medetomidine) was administered to both groups at a dose of 0.08 mg/kg.The parameters HR, RR, RT, SpO2, SAP, and DAP data and sedation parameters were recorded. Radiographic images were taken at (Tb), (T0), 5 (T5), 15 (T15), 30 (T30), 45 (T45), and 60 (T60) minutes, in four views (right lateral, left lateral, ventro-dorsal, and dorso-ventral). Vertebral Heart Score (VHS) was evaluated using R-VHS, L-VHS, VD-VHS, DV-VHS, T4-R-VHS and T4-L-VHS measurements, and Cardiothoracic Ratio (KTO) was evaluated using VD-KTO, DV-KTO, VD T6-10, DV-T6-10 and R T5-7 measurements. In conclusion, both administration routes resulted in significant increases in VD-KTO values compared to baseline, with no significant differences between the two groups for this parameter. The cats tolerated both IN and IM medetomidine administration well, and no significant differences were observed in most clinical parameters, suggesting that both methods were equally effective and safe in inducing sedation. While the IM route led to a faster onset of sedation and lateral recumbency, there were no significant differences in recovery times or overall clinical outcomes between the groups.