The American Shorthair (ASH) is a breed of cat believed to be descended from English domestic cats (the forebears of today’s British Shorthairs) brought to North America by early British settlers to protect valuable cargo from mice and rats. According to the Cat Fancier’s Association for 2006–2007, it is the 8th most popular breed of cat in the United States.
When settlers sailed from Britain to North America they carried cats on board ship as working cats to protect the stores from mice. Many of these cats “settled” in the New World, interbred, and developed special characteristics to help them cope with their new life and climate. Early this century a selective breeding program was established to develop the best qualities of these cats. The American Shorthair is also called the Mouser because they caught mice on ships.
A very athletic cat, American Shorthair has a larger, leaner, and more powerfully built body than its relation, the British Shorthair. It is also known as a “working cat.”
American Shorthairs are a pedigreed cat with strict standards and a distinctive appearance as set by the various Cat Fanciers Associations worldwide.
Originally known as the Domestic Shorthair, the breed was renamed in 1966 to the “American Shorthair” to better represent its “All American” character and to differentiate it from other shorthaired breeds. The name “American Shorthair” also reinforces the notion that the American shorthair is distinct from non-pedigreed, short-haired cats in the United States.
According to the CFA, American Shorthairs are low-maintenance cats that are generally healthy, easy-going, affectionate with owners and social with strangers. Males are significantly larger than females, weighing eleven to fifteen pounds when fully grown. Mature females weigh eight to twelve pounds when they achieve full growth at three to four years of age. American Shorthairs can live fifteen to twenty years, like most felines, and often only requiring only annual vaccinations, veterinary checkups, a quality diet and plenty of tender loving care. These cats have long tails and usually slender bodies. 
The American Shorthair is recognized in more than eighty different colors and patterns ranging from the striking brown patched tabby to the glistening blue-eyed white, the beautiful shaded silvers, smokes and cameos to the flashy calico van, and many colors in between. Some even come in deep tones of black, brown, or other blends and combinations. The most well-known American Shorthair color today is the silver tabby, with dense black markings set on a sterling silver background.
In the American Shorthair and other breeds of cats, heart disease can be inherited. Hypertrophic Cardiomyopathy (HCM) has been confirmed as an autosomal dominant inherited trait. While there is no cure for HCM, early diagnosis and medication can help significantly prolong an affected cat’s life.