More often than not, dead rodents are located within walls or rafters. In this case, it is often necessary to endure the smell until it dissipates on its own. The length of time for the rodent to decompose depends on many factors, including size of the rodent, temperature, humidity and accessibility to decomposers like flies.
Unfortunately it may take three weeks or more to completely decompose. A professional may be contacted to break through and rebuild affected walls. This can be costly and not a viable option.
Even after elimination of the source of dead rodent smell, the unsettling scent may linger for up to two weeks. Natural ventilation is necessary to expedite the dissipation of the odor. Opening windows and using electric fans may prove helpful. Deodorizing air fresheners and disinfectants can also help to eliminate smells.
A professional exterminator can assist to make sure no more rodents gain access to your home or continue to take harborage by providing specialized rodent packets and boxes around and in the house. But sometimes the smell of an already dead rodent needs to take its time to decay."