Animal selection during animal experiments

In order to obtain the desired experimental results, appropriate observation objects must be selected according to the purpose of the experiment. When selecting animals, the following factors should be considered:  
Species selection

The degree of response of different species of animals to the cause of the same disease can vary greatly. When selecting experimental animals, try to choose species that are more sensitive to stimuli and close to humans. For example, when performing fever experiments, rabbits should be preferred: guinea pigs should be preferred for allergic reactions and allergic reactions; mice should be used for observation of half-lethal doses.

Gender choice  
Because of the significant changes in the sexual cycle of the metabolism of adult females, these changes affect the response of the test animals to certain experimental factors. Therefore, when selecting experimental animals, male animals are generally used, but male mice or rats should not be used in hot plate analgesia experiments, and the half-lethal dose should be determined by male and female.

Week age or weight choice  
Generally, adult animals are selected. The mice weigh 18-22 g, the rats weigh 200-250 g, the guinea pigs weigh 350-450 g, the rabbits weigh 2.5-3.5 kg, and the beagle dogs weigh 8-20 kg. However, some experiments have special requirements on animal body weight or age. For example, the anti-inflammatory test of rat foot swelling method should use 120-150kg rat, which is sensitive to inflammatory agents. When making a permanent hypoperfusion model of the rat brain, rats of 13 weeks or older should be used, which can greatly reduce the mortality.

State selection  
The degree of expression of the experimental animal on human diseases and the response to the applied factors are not only related to the physiological characteristics of the animal itself, but also affected by the state of the animal, such as whether it is hunger, whether the sleep is sufficient, whether it has other diseases or the like. Therefore, animals with health, responsiveness, and other conditions that are as consistent as possible should be selected as observation targets.  

Selection of experimental conditions  
Because environmental factors have a strong interference effect on experimental results, such as light and dark (ie, photoperiod) have an important impact on metabolism in the body. In the experiment, the experimental environment should be selected as much as possible consistent with the natural life of the test animal or artificially controlled to the extent of the condition.