Why is it harder to train some dogs than others?
In the case of pure-bred dogs, those which are used to working with people on a one-to-one basis are likely to be the most responsive to training, such as members of the retriever group, and the toy breeds such as the papillon (evolved purely as companions.

In contrast, problems are most likely to arise with dogs that have evolved a relatively independent lifestyle, such as the pack hounds like the beagle.

Although affectionate and friendly by nature, these dogs will follow a scent with great determination, and they are not generally responsive under these circumstances. They tend to relate better to other dogs however, because of their social natures.