There is a door in my bathroom.
How many of your clients come in daily to purchase refills, preventatives, food and other pet supplies? Chances are it is a good number...but it's declining. Competition from online providers, like Chewy and Amazon.com, has never been tougher. Some of these companies are so well-funded that they are willing to LOSE money in order to get your clients' online pharmacy business because they know that, once they get them away from you, they'll never buy medications/food from you again. We've even seen some online providers with retail prices that are less than the average veterinary practice pays wholesale!
Despite this trend, and while convenience and low price are important to the modern consumer (Are you really any different?), a significant number of clients would still prefer to buy these items directly from you. Why? Because they trust you.