Scottsdale-based Petsense LLC soon will launch an online store. The national pet-food retailer that targets smaller markets will open its e-commerce store Monday, reports The Arizona Republic. Petsenseonline.com will work much like other retail websites. It will feature more than 3,000 items and allow customers to check inventories at local stores. The launch is part of the company's aggressive expansion plan to operate stores in 700 markets over the coming decade. Petsense is on track to open…