Hi Becky,
I work with pet stores, groomers, vets, etc by having special photo day events. The store takes a percentage of the sales from the day. I also have pet day events for charity and donate some if not all proceeds.
I have also had contests, such as for Woofoween or Howloween, where the dogs are in costume, professionally photographed, and then the public votes on my website for a favorite. This is also a good charity fundraiser. Adding the charity causes the press to pick up on the story.
Making an effort to become friends with others in the pet industry gives you a tremendous advantage. You are highly recommended to all their customers and vice versa. I also take free photos of pet store and grooming shop owners and then make up big posters with my company name and number on them to put up in their store.
I got lots of ideas. Be as creative in your marketing as you are in your images. You will do great!
Debbie