In order to develop a counterclaim to the benefits, first we have to consider the benefits themselves, so that we know what we are arguing against.
Therefore, we have to establish what the benefits of purchasing a pet from a pet store as opposed to the pound are. One benefit could be the fact that a dog from a pound is more likely to have behavioural issues as opposed to a pet from a store. This becomes even more important when we think of the fact that we are more likely to find babies at the pet store, while most pounds only have adult pets.
A counterclaim to this idea would be that, although it is true that pets from a pound are more likely to be unfriendly, they are also more likely to have suffered abandonment and mistreatment in the past. Their behaviour is often a reaction to this. Therefore, they would particularly benefit from someone offering them a home.