Retail as a Service
The biggest thing that sets you apart from your big box store counterparts is your relationship with your clients. Your clients view you as an expert since they trust you with their precious pet. It is a misconception that if the customer is able to purchase the products used during grooming they will forgo your service and do it at a time in the future. Generally those wanting to do in between grooming are going to do it regardless and purchase shampoo elsewhere.
Limited products that address specific problems (such as skin and ear irritation) could be viewed as a concern you have for the well-being of their loved pet. Items such as colognes, flea repellent, dry bath help protect and make pets further enjoyable. Adding retail in a well thought-out manner capitalizes on the firm relationship you already have with your clients.