As small as he is, the Sealyham Terrier is a strong, substantial dog, with an outgoing, charming personality. He makes an excellent companion, if you remember that he's first and foremost, all terrier. He may have a stubborn streak, tempered with a sense of humor that can't help but amuse. Your Sealyham Terrier puppy is trainable and friendly. He needs exercise, both physical and mental and lots of time with his family. The breed excels at dog sports, like agility, earthdog and rally.