Although Growlithe remains the "signature Pokémon" of many Officer Jennys, they will sometimes use different Pokémon. The Officer Jenny in Mutiny in the Bounty! used Growlithe's evolved form, Arcanine. In some parts of the Pokémon world, police forces will have special Pokémon teams, such as Spinarak in Spinarak Attack.
The Officer Jennys of Unova and Kalos do not use Growlithe, as they are not generally found in those regions. In Kalos, the most common Pokémon Officer Jennys use Manectric.