Besides the fact that both sport short coats, the rat terrier and the Chihuahua are very different canines. Care considerations for the rat-cha mix depend on which side of the family the dog most takes after. Also known as the ratchie or the Chirat, this hybrid dog combines a working terrier and tiny companion canine.
The Rat Terrier
An American breed, the rat terrier received recognition by the American Kennel Club in 2013. He's a blend of fox terrier, beagle and Italian greyhound, developed by Midwestern farmers in the early 20th century to keep down the rat population. The rat terrier comes in two sizes. The miniature rat terrier matures between 10 and 13 inches tall at the shoulder, while the standard version exceeds 13 inches and can grow to 18 inches. These dogs are never solid shades, but always have white coloring with black, brown, red, blue, fawn or lemon. The dog might have tan points, along with speckling on some of the white body parts.
The smallest of all dog breeds, at maturity Chihuahuas can't weigh more than 6 pounds for AKC show purposes. Don't equate small size with gentleness. Without proper socialization, the Chi can become a tiny terror. However, he's a smart little dog, and positive reinforcement goes a long way in training. The Chi doesn't need much exercise, making him a favorite pet for apartment dwellers. The breed appears in various colors.
The rat-cha generally results from a cross between the miniature rat terrier and the Chihuahua. If the cross is between the Chi and the standard rat terrier, expect a larger dog. Usually, the rat-cha's ears take after the Chi, so he looks somewhat like a big-eared, smaller than average rat terrier. While rat terriers are generally friendly dogs, Chihuahuas often bond solely to one person, and nippiness isn't uncommon. It's important to "nip" any such biting behavior in the bud, and firmly let your rat-cha know that sort of behavior is unacceptable. Rat terriers are good with children -- Chis, not so much. The rat-cha should make a good family dog for older kids, as most are too small for handling by little ones. The rat-cha should get along with other dogs and cats.
Unless one of the parents was a longhaired Chi, your rat-cha likely will sport a short coat. He might require a coat or sweater while outdoors in cold weather. With luck, your rat-cha will inherit the hardiness of the rat terrier, as well as the rattie's ease of training. Chis are notoriously difficult to housebreak, but that's not the case with the rat terrier. Both breeds are good watchdogs, but make sure your rat-cha doesn't overdo the barking. If he takes after the rattie, expect typical terrier behavior such as digging, and a fairly active dog.