A scent preservation kit prepared by an elderly woman with dementia in 2015 was used to locate her after she went missing earlier this week. (Photos: Courtesy of the Citrus County Sheriff's Office)

A woman with dementia who went missing in Florida was found by a police dog in a matter of minutes, having bottled her scent in advance.

Citrus County Sheriff's Office said the anonymous woman had used a specialist scent preservation kit.

It can hold a person's scent for up to seven years.

In a Facebook post police said she stored the scent two-and-a-half years ago, and a picture of the jar showed it was dated January 2015.

Scent preservation kits involve rubbing a pad on a person's underarm, then sealing it in a sterile jar so police dogs have a reliable scent to smell before looking for a missing person.

Manufacturers say they work better and more quickly than articles of clothing, because they are not contaminated by other people's smells or smells from the environment.

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