Pet dogs still possess certain traits that are reminiscent of their ancestors’ behavior in the wild. Even if they have been kept as pets for a very long time, some of these unique canine behaviors are still being displayed, and some breeds are even more pronounced at displaying certain behaviors than others. One of these distinct canine behaviors is ‘herding’.
Some canine breeds have been originally bred to assist in farm work. Among these are dogs that belong to the herding class. The herding instinct of these dogs can be so strong that even if they are being kept as pets, they are often observed to herd other pets in the house or even the humans of the pack. Even if it’s a normal canine behavior, it can become a problem when a pet dog starts herding very small kids or senior citizens. However, proper training can tech these dogs to herd only when given the command.
Source: Herding Behavior In Dogs