Photo from the personal archive of S.S. Podushkin

An important criterion for selecting dogs for drug detection training is the dog's type of higher nervous activity.

Dogs must have a pronounced degree of strength, balance and mobility of excitatory and inhibitory processes in the absence of elements of innate cowardice.
It's advisable to begin training drug detection dogs at 10-11 months of age. Training puppies starting at 5-6 months yields good results, as this is the period during which they develop the necessary reflexes and skills.

Detective dogs can also be used to search for drugs if they are not older than 6-7 years.