Common throughout family farms in the 1920s and 1930s, they are now recognized by the United (UKC) and American Kennel Clubs (AKC) and are considered a rare breed.

However, merle is widely considered to be the result of recent outcrosses and, because of associated health problems, is rejected by most Rat Terrier breeders.

Proper socialization of a Rat Terrier puppy includes exposing the animal to a wide variety of people and places, particularly during the first three months of life.

Like most active and intelligent breeds, Rat Terriers tend to be happier when they receive a great deal of mental stimulation and exercise.

Rat terriers are usually loyal to their owners and are very respectful if they receive the proper amount of training at a young age.

The Canine Health Information Center (CHIC) recommends that Rat Terriers be tested for patellar luxation, cardiac abnormalities, pancreatic issues, hip dysplasia, and Legg–Calvé–Perthes syndrome.

The earliest-known record of a rat-catching dog is that of "Hatch", whose remains were recovered from the Mary Rose, the flagship of Henry VIII, sunk in 1545 and re-raised in 1982.

[4] The breed name comes from the occupation of its earliest ancestors brought to the US by working-class British migrants as the dogs were used in rat-baiting.

After the 1890s, as the breed type became popular in the United States, they were bred with beagles, Italian Greyhounds, and Manchester Terriers.

Rat Terriers were cherished as loyal hunting companions and efficient killers of vermin on 20th-century American farms: as a result, they were one of the most popular dog types from the 1920s to the 1940s.

In contrast, the Rat Terrier has benefited from a long history of refinement with regular outcrosses to bring in useful qualities and genetic variability.

Their affectionate and calm temperament along with small size has made them popular as service dogs in hospice, treatment for depression, in Assisted Living, and other human-care jobs.

This registry's mission is to keep all the qualities that set the Decker aside from the standard Rat Terrier, while retaining and improving upon the hunting ability.

The first AKC Champion Rat Terrier was "Annie" GCH GRCH King Pen RnB's Queen Ann bred, owned by Sherry & Dud Lee Hendrix of Modesto, California.