Study of the respiratory function in laboratory animals is a frequent task in the study of drug toxicity, to assess pharmacological safety, the study of pharmacodynamics.
The associated question of normal values of respiratory motion frequency (respiratory rate, RR) in healthy animals. The purpose of this study was to assess the respiratory rate in the most frequently used in preclinical studies of laboratory animal species: mouse (n=10♀, n=10♂), rat (n=20♀, n=20♂), guinea pig (n=20♀, n=20♂), rabbit (n=20♀, n=20♂) and their comparison with the literature data.
All animals were first measured without general anesthesia, then the same animals were anesthetized and their measurements were repeated.
Also, the effect of accustoming rabbits to the measurement procedure (over a period of 2 weeks) in the additional group (n=5♀, n=5♂) was assessed, and the respiratory rate in young rabbits was assessed, also in the additional group of animals (n=5♀, n=5♂).
RR indicators in mice coincided with the literature and made 200-283 respiratory movements per minute. At the same time, the data obtained on non-anesthetized animals turned out to be statistically higher.
Respiratory rate indicators in rats with and without general anesthesia coincided with the literature and amounted to 91-106 breathing movements per minute. Female RR was statistically significantly lower in females than in males when using anesthesia.
In guinea-pigs, the values of RR fully coincided with the literature data and amounted to 89-120 respiratory movements per minute, while the use of anesthesia in both males and females of RR was reduced. Among the studied animal species, this species was most suitable for taking readings of RR without using anesthesia.
When analyzing the data obtained on rabbits, we drew attention to the extremely low value of RR in rabbits at rest, in the reference veterinary literature and a number of experimental works 30-80 breathing movements per minute. In other experimental works this indicator in intact females of rabbits was 120-200 movements per minute. We managed to register relatively low values of RR only in male rabbits in general anesthesia (79±9). In male rabbits without anesthesia, this indicator was 302±19 respiratory movements per minute, in females without anesthesia it was found that RR was 441±13, and in general anesthesia RR was reduced to 233±29 respiratory movements per minute.
We assumed that the rabbits, before the manipulation, need to be accustomed to the measurement procedure, and within 2 weeks they were accustomed to it. Also, the RR was measured in young rabbits.
It was shown that the adaptation of animals to the measurement procedure has a response to the reduction of RR in males of rabbits in consciousness to 224±17, in females to 163±9.
The use of younger animals at the age of 8-9 months in the registration of RR also had its effect on the RR index, it was 157±23 and 114±11 in males and females, respectively, and was lower than in older animals (12-14 weeks).
The research gave opportunity us to formulate some practical recommendations for measuring RR in laboratory animals.
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