5 Cute Jack Russell Terrier puppies play together Jack Russell Puppies - 3 weeks old.

The Jack Russell terrier is a high-energy, extremely prey-driven little dog bred in the 1800s to hunt foxes. Jack Russell terriers may be aggressive toward other dogs if they are not socialized at an early age. Well-trained and socialized Jacks make wonderful, lively family dogs and can coexist peacefully with other dogs. However, some dogs will be able to adapt better than others to life with a typical Jack Russell terrier. Not all dogs behave according to the standard expectations for their breeds, so it's important to observe how your own dogs behave rather than assuming two dogs will get along because of the normal characteristics of their breeds.