2. Similarity of time images or age states.
3. Similarity of population distribution Experimental animals with similar genes in natural populations are closed animals.
4. Similarity of ecological or health conditions The existing ordinary animals, clean animals, SPF animals, sterile and learned animals with different microbial quality levels represent different microecological models, have different characteristics and are suitable for different research purposes.
5. Similarity of disease characteristics
6. Similarity of anatomical features In surgical model or teaching, large animals are closer to humans than small animals in practice. The sympathetic nerve, vagus nerve and aortic decompression nerve in the neck of rabbits walk independently. If we want to observe the effect of decompression nerve on the heart, we must choose rabbits. Rabbits are very sensitive to temperature changes and are suitable for experimental studies such as fever, fever reduction and pyrogen examination.
(1) Age: It is appropriate to choose mature young and middle-aged animals. (2) Weight: There is a certain correlation between the weight of experimental animals and their age. Select experimental animals with normal development and weight meeting the requirements. (3) Gender: Different genders of the same species (strain) have different responses to many external stimuli. (4) Physiological conditions: Different physiological conditions have different responses to external stimuli.