Buying a pet isn't something to do on a whim. That's especially true with Sealyham Terriers puppies. Before you contact a Sealyham Terriers breeder, consider what attracts you to these particular dogs. The Sealyham terrier is a relatively new dog breed with a unique and often murky history. This terrier breed is exceptionally smart, but itâ??s also a very strong and hard-working dog that makes an excellent companion, too.