Chihuahua

Height: 6 to 9 inches at shoulder

Weight: 3 to 6 pounds

Coat: smooth or long

Life span: 10 to 18 years

The Chihuahua is a saucy little hot tamale and not just because of his association with a certain fast-food Mexican restaurant. He's renowned for being the world's smallest dog, but he may well have the world's biggest personality stashed inside that tiny body. That larger-than-life persona makes him appealing to men and women alike.

Fun loving and busy, Chihuahuas like nothing better than to be close to their people. They follow them everywhere in the house and ride along in tote bags when their people run errands or go shopping. It's not unusual for Chihuahuas to form a close bond with a single person, and they can become very demanding if they're overindulged.

Besides being affectionate housemates, Chihuahuas are intelligent and fast learners. They can compete in agility and obedience trials with just as much enthusiasm and success as larger dogs. That said, they're willful little dogs. You'll be most successful if you can persuade them that competing--or simply doing as you ask--is fun. Use positive reinforcement in the form of praise and food rewards when training your Chihuahua. He won't respond to harsh treatment.