The American Kennel Club recognizes two size divisions for the breed. Miniature rat terriers are between 10 and 13 inches in height at the withers. Standard rat terriers are between 13 and 18 inches.

The short, straight rat terrier coat is described as pied or parti-colored. White must be present in the coat. Many combinations and patterns are acceptable, but a body color of 10 to 90 percent white is preferred, according to the AKC. The other colors may include black, blue, chocolate, apricot, red, tan, fawn or lemon. A rat terrier may or may not have tan points.

The rat terrier coat requires at least weekly brushing to deal with shedding. Tails may be docked by a veterinarian for show purposes.

Rat terriers enjoy human companionship. They often will follow their owners around the house like a shadow, and given the opportunity, rat terriers will curl up with their owners, especially under the covers. Most rat terriers get along well with other dogs. If not raised with cats, rat terriers will view them as prey and will chase them and possibly injure them. The breed may not be the best choice with very young children. They tend to be possessive of their toys, and will guard them. Rat terriers make good watchdogs.

Rat terriers were bred to work and are high-energy dogs. They require at least 30 minutes of exercise daily. Without sufficient exercise, a rat terrier will be bored, and may be destructive. These dogs enjoy digging, and can cause damage to a yard as they go after an interesting scent. They can also use those digging skills to tunnel under a fence, unless the fence was installed with sufficient barriers against that possibility. The larger rat terriers also may find ways to get over fences if the attraction is strong enough. Always supervise your rat terrier outdoors, and make sure your dog always wears identification.

Setting up a sandbox where a rat terrier can satisfy the innate drive to hunt and dig may help to spare the backyard some unwanted excavations, but if there is real prey to go after -- a mole or a mouse, for example -- it is unlikely the sandbox will be a sufficiently enticing alternative to the hunt.

Keep your rat terrier on a leash during outings beyond the confines of the fenced yard; this dog can easily detect potential prey and give chase without warning.

Indoors, rat terriers are known for being good house dogs. They are content to be with their owner, and are easily housebroken. If you must leave your rat terrier alone at home, it is a good idea to leave some indestructible treat-filled puzzle toys to occupy the time and help prevent destructive behaviors.

Rat terriers are highly intelligent and eager to please their owners. Training that utilizes positive, reward-based methods works well with this breed and raises few issues. Rat terriers show talent in agility work, and enjoy the competitions. The agility training can be incorporated into the daily exercise routine, and it offers a way to forge a working partnership with your dog. Training with an agility group also is a good way to socialize your rat terrier to other dogs and people.

Rat terriers have few health issues, but many suffer from skin, inhalant and food allergies. Consult with a veterinarian before using topical insecticides, flea dips or wormers, because rat terriers tend to be sensitive to these chemicals. When bathing your rat terrier, use gentle soap-free and scent-free shampoos and conditioners. A genetic immune system problem can cause demodectic mange in some rat terriers. Always consult a professional if you encounter any health issue with your dog.