Dog owners in Herefordshire, Worcestershire and Shropshire are being asked to donate suitable pets to the police force.
West Mercia's dog section is appealing for dogs up to 18 months old which can be trained for a career on the beat.
German shepherds are the easiest to train but other large dogs are wanted.
A spokesman said most of the dogs were donated but the force was in need of recruits as several handlers were retiring along with their dogs.
Searching for people
Insp Tony Fisher, head of the dog section, said: "We need dogs which are playful, inquisitive and in good health.
"Dogs which require plenty of stimulation are particularly suited to police work, and a dog with character will also fit in well.
"Ideally they need to have a sense of fun, love to bark, and be forward and assertive.
"Often the dogs which make the best police dogs have more energy than most owners can cope with, and may be destructive because they are not getting enough stimulation."
West Mercia has 35 general purpose dogs, mainly German shepherds or crosses, as well as 20 dogs of varying breeds which have been trained to search for drugs, explosives or cash.
The dogs, which live at home with their handlers, are used for incidents such as searching for people or abandoned property, and dealing with violent or armed offenders.