Electrocardiographic Pattern of Agoutis (Dasyprocta prymnolopha) Chemically Contained by the Association of Ketamine and Xylazine

Abstract

Background: The agouti (Dasyprocta prymnolopha, Wagler, 1831) is an existing wild rodent in almost all of Brazil, used as a biological model in several scientific studies. Veterinary cardiology has showed great advances in the diagnostic area due to the possibility of cardiac evaluation by non-invasive methods. For the practice of scientific or handling procedures in wild animals, chemical containment is essential. Thus, it is important to know the effect of anesthetic protocols on the cardiovascular system, observed through complementary tests, such as the electrocardiogram. The objective of this study was to describe the computerized electrocardiographic tracing of agoutis chemically contained by the association of Ketamine and Xylazine.Materials, Methods & Results: Eighteen male and female clinically healthy animals, aged among 2 years, submitted to digital electrocardiographic examination, were used. The device used to obtain the tracing was the veterinary electrocardiograph (Electrocardiogram Acquisition Module for Computer) - Brazilian Electronic Technology (TEB). The analysis was always made from derivation II (DII). Chemical containment was performed by the combination of Ketamine and Xylazine, intramuscularly. The results showed that the heart rate for males was on average 113.25 bpm, while for females the value of 124.60 bpm was observed, and there was no significant difference between the genders (P > 0.05). The mean weight of males was 2.31 kg and for females 2.28 kg; there was no statistical difference for this variable (P > 0.05). For the QRS duration of 46.14 ± 5.05 ms (males) and 44.66 ± 5.94 ms (females) and PR interval of 79.94 ± 12.01ms (males) and 84.29 ± 12.37ms (females), there was no statistical difference (P > 0.05). The amplitude of the R wave of 0.42 ± 0.31 mV (males) and 0.36 ± 0.22 mV (females) showed no statistical difference (P > 0.05). The T wave showed itself both negative (10 animals) and positive (8 animals), with amplitude measured at 0.24 ± 0.16 mV for males and 0.25 ± 0.10 mV for females (P > 0.05). The anesthetic protocol was well tolerated by the animals of this experiment, and there were no episodes of arrhythmias during the time of their monitoring.Discussion: Wild animals, in general, need chemical containment, with a view to reducing stress during scientific and handling procedures. The protocols established in this work can be used in future experiments which require a longer handling time. The values found for heart rate (HR) of anesthetized agoutis were lower than those for non-anesthetized agoutis, proving the influence of the stress during retention and the depressant cardiovascular effect of the anesthetic drug used. The electrocardiographic parameters and the tracing morphology of the agoutis were like the results found for anesthetized small rodents. The QT interval was higher in males than in females, justifying the fact that it could be influenced by variations in HR, which also showed superior results for males. Taking into consideration the morphological similarity between different individuals, the QT interval in anesthetized agoutis did not present significant differences between the genders, a characteristic also found in ferrets. The animals of this experiment were submitted to food fasting, a fact that contributed to a better standardization of the experiment, preventing alterations in the morphology of the QRS complex, which could lead to changes in the measurements.