Effect of Dexmedetomidine Low Doses with or without Midazolam in Cats: Clinical, Hemodynamic, Blood Gas Analysis, and Echocardiographic Effects

Marina Lopes Castro; Bruna Maia Cerqueira Câmara; Maira Souza Oliveira Barreto; Raphael Rocha Wenceslau; Andressa Karollini E Silva; Natália Fagundes; Renata Andrade Silva; Eutálio Luiz Mariani Pimenta; Suzane Lilian Beier

doi:10.1155/2022/9613721

Effect of Dexmedetomidine Low Doses with or without Midazolam in Cats: Clinical, Hemodynamic, Blood Gas Analysis, and Echocardiographic Effects

Anesthesiol Res Pract. 2022 Nov 24:2022:9613721. doi: 10.1155/2022/9613721. eCollection 2022.

Authors

Marina Lopes Castro¹, Bruna Maia Cerqueira Câmara¹, Maira Souza Oliveira Barreto², Raphael Rocha Wenceslau², Andressa Karollini E Silva¹, Natália Fagundes¹, Renata Andrade Silva¹, Eutálio Luiz Mariani Pimenta², Suzane Lilian Beier²

Affiliations

¹ Animal Science Post Graduation Program, Federal University of Minas Gerais, Departament of Veterinary Medicine and Surgery, Belo Horizon, Minas Gerais, Brazil.
² Veterinary Internal Medicine and Surgery Department, Federal University of Minas Gerais, Belo Horizon, Minas Gerais, Brazil.

Abstract

Objectives: The aim of the study is to compare the sedative, cardiorespiratory, echocardiographic, and blood gas effects of dexmedetomidine and methadone associated or not with midazolam for restraint chemistry in cats.

Methods: Eighteen healthy young cats (4.06 ± 0.48 kg) were randomly sedated with two protocols, through the intramuscular route: dexmedetomidine (5 µg.kg^-1), methadone (0.3 mg. kg^-1) and midazolam (0.3 mg. kg^-1) (DMTM, n = 9), or dexmedetomidine (7.5 µg.kg^-1) and methadone (0.3 mg. kg^-1) (DMT, n = 9). The cardiorespiratory parameters were measured at baseline, 5 and 10 minutes after pharmacological latency. The sedation, analgesia, and muscle relaxation scores were assessed before and 5 minutes after pharmacological latency, while arterial blood gas analysis and echocardiography were assessed before and after 10 or 15 minutes, respectively.

Results: There was no difference between the protocols regarding the cardiorespiratory, blood gas, and echocardiographic parameters used. The scores for sedation, analgesia, and muscle relaxation also did not differ between the protocols, with the degree of sedation, analgesia, and myorelaxation considered satisfactory in both groups. A significant decrease in heart rate (HR) was observed after administration of the sedative protocols, reaching a maximum reduction at T10 (46% and 53% reduction in the DMT and DMTM groups, respectively). The reduction in HR had an impact on echocardiographic parameters such as CO, which decreased 53% and 56% in the DMT and DMTM groups, respectively. There was a significant reduction in PaO₂, SaO₂, ejection fraction, and fractional shortening in both protocols. SpO₂ decreased significantly after 5 minutes of sedation in the DMT group, but with a minimum mean SpO₂ of 92% in T5. The respiratory rate decreased significantly at 5 and 10 minutes in the DMTM group, while PaCO₂ increased in both groups, indicating respiratory depression caused by the drugs. Conclusions and Relevance. The study pointed out that both sedative protocols can be recommended for clinical sedation of young and healthy cats in the doses used. However, both protocols resulted in cardiorespiratory depression in cats and also the particularities of the animals should be evaluated regarding reducing cardiac output by more than 50%.