American Staffordshire Terrier (Canis Lupus Familiaris)
The American Staffordshire terrier also known as Amstaff is a medium-sized, short-coated American dog breed. In the early part of the twentieth century the breed gained social stature and was accepted by the American Kennel Club as the American Staffordshire Terrier in 1936. The name was changed to reflect difference from the Staffordshire Bull Terrier of England.
Despite its name, the Staffordshire Terrier was first bred in the nineteenth century in Birmingham, West Midlands, rather than in the English county of Staffordshire where it was then later bred. The early ancestors of this breed came from England, where until the first part of the 19th century, the Bulldog was bred in England. Bulldogs pictured as late as 1870 resemble contemporary American Staffordshire Terriers to a greater degree than present-day Bulldogs. Some writers contend it was the White English Terrier, Fox Terrier, or the Black and Tan Terrier that was crossed with the Bulldog to develop the Staffordshire Terrier; all three breeds shared many traits, the greatest differences being in color, and spirit. The cross of Bulldog and Terrier was called by several names, including Bull-and-Terrier Dog, Pit Bull, or Half and Half. Later, it assumed the name of Staffordshire Bull Terrier in England. These dogs began to find their way into America as early as 1870.
In 1936 Amstaffs were accepted for registration in the American Kennel Club (AKC) Stud Book as Staffordshire Terriers, belonging to the terrier and molosser groups. The name of the breed was revised January 1, 1969 to American Staffordshire Terrier; breeders in the United States had developed a variety which was heavier in weight than the Staffordshire Bull Terrier of England. The name change was to distinguish them as separate breeds.
The breed’s popularity began to decline in the United States following World War II. In 2013 the American Kennel Club ranked the American Staffordshire Terrier as the 76th most popular purebreed in the United States 
According to the American Kennel Club “The Am Staff is a people-oriented dog that thrives when he is made part of the family and given a job to do. Although friendly, this breed is loyal to his own family.”
Health and well-being
The American Staffordshire Terrier should give the impression of great strength for his size, a well put-together dog, muscular, but agile and graceful, keenly alive to his surroundings. He should be stocky, not long-legged or racy in outline. Height and weight should be in proportion. A height of about 18 to 19 inches (46 to 48 cm) at shoulders for the male and 17 to 18 inches (43 to 46 cm) for the female is to be considered preferable.
American Staffordshire Terrier pups should not be bought weaned before they are 8–10 weeks old. Their life expectancy is generally 12 years with good care. Notable issues related to health and-well being include:
- Congenital heart disease
- Elbow dysplasia
- Hip dysplasia
- Luxating patella
- Thyroid dysfunction
- Cerebellar ataxia
More Info in WIKIPEDIA