Non-invasive evaluation of the haemodynamic effects of high-dose medetomidine in healthy cats for semen collection.

Objectives: This study aimed to assess non-invasively the cardiovascular effects of high-dose medetomidine on healthy male cats undergoing semen collection.

Methods: Haemodynamic evaluations were assessed on the basis of clinical examination, systolic arterial pressure (SAP) and transthoracic echocardiographic examination. Eight client owned, male domestic shorthair cats were sedated with a bolus of medetomidine intramuscularly (IM; 0.13 mg/kg), and semen collection was performed. A second transthoracic echocardiographic examination and SAP measurement were carried out 15 mins after sedation. At the end of the examination, the patients received a bolus of atipamezole (0.3 mg/kg) IM.

Results: The cats were deeply sedated, relaxed and laterally recumbent during the entire procedure. No rhythm abnormalities were observed during the examinations and no significant increase in SAP was recorded. Heart rate dropped from 200 ± 33 to 92 ± 13.1 beats per min after sedation. There was a significant increase in left ventricular dimensions and the left atrial area. The parameters of left ventricular systolic function were reduced, as were systemic and pulmonary cardiac outputs. Peak diastolic wave velocities were significantly reduced, while isovolumic contraction and relaxation time of the left ventricle were prolonged. Aortic valve insufficiency was recorded for all cats, while mitral valve insufficiency was noted in five cats. None of the subjects developed systolic anterior motion of the mitral valve.

Conclusions And Relevance: The protocol allowed us to collect good semen samples in healthy cats. However, high-dose medetomidine induces significant haemodynamic effects on the feline heart, mainly due to a reduced heart rate, an increased cardiac preload and impaired systolic function. The animals recovered from the anaesthesia, after antagonist administration, without showing any clinically relevant consequences.