Such rats are remarkably free from diseases of the respiratory and digestive tracts. Upon arrival in the laboratory, however, rats obtained from commercial suppliers should be placed in quarantine for a 7 day period. Viral or mycoplasmal infections may produce upper respiratory difficulties in rats, often indicated by a chattering or wheezing sound. Such infections are highly contagious. Another common disease observed in rats is labyrinthitis, a bacterial infection of the middle ear.
Infected rats display a marked twisting of the body when suspended by the tail.
If you are concerned about the health of animals in your care, you should alert your laboratory instructor. Rats that undergo surgical procedures must be rendered incapable of feeling pain via suitable anesthesia. Certainly, the same principle applies to animals that are to be sacrificed or euthanized at the end of a study. Methods of euthanasia should result in a rapid, painless, and humane death for an experimental subject. Such injections rapidly produce unconsciousness and then death.