What do you think the stockman meant by "taking out a dog's license"?

In the United States, most cities and counties require dogs to be registered. Their owners must pay for the license, and it would be applicable for around one year period.

This requirement is created to ensure that the dogs are free of diseases, and could be tracked down in case it let loose from safe environment. Owners that failed to follow this requirement are subjected to some amount of fine payment as punishment.