The Australian Shepherd is a breed of working dog that was developed on ranches in the Western United States. Despite its name, the breed, commonly known as an Aussie, did not in fact originate in Australia. They acquired their name because of its association with sheepherders who came to the United States from Australia.

Australian Shepherds rose rapidly in popularity with the boom of western riding after World War II. They became known to the general public through rodeos, horse shows and through Disney movies made for television.

For decades, Aussies have been valued by stockmen for their inherent versatility and trainability. While they continue to work as stockdogs and compete in herding trials, the breed has earned recognition in other roles due to their trainability and eagerness to please and are highly regarded for their skills in obedience. Like all working breeds, the Aussie has considerable energy and drive and usually needs a job to do. It often excels at dog sports such as dog agility, flyball and frisbee. They are also highly successful search and rescue dogs, disaster dogs, detection dogs, guide, service and therapy dogs. And, above all, they are beloved family companions. Aussies are very protective and may not be kind to strangers, but do not have a tendancy to be aggressive. Aussies will also try to herd anything that moves, including people and all other types of animals.

Appearance
The breed's general appearance varies greatly depending on the particular line's emphasis. As with many working breeds that are also shown in the ring, there are differences of opinion among breeders over what makes an ideal Australian Shepherd. In addition the breed can be split into two distinct lines - working and show dogs. Working dogs tend to have shorter coats, thinner and are sometimes smaller while the show lines are bred according to breed standard and can have long fur.

Size
The Australian Shepherd Breed Standards for all major registries state that males should stand 21-23 inches at the shoulder; females 18-21 inches. Weight is not specified in the standard, though males normally weigh 55-70 pounds, and females normally weigh 35-55 pounds.

Color
Aussie colors are black, red (sometimes called liver), blue merle (marbled black and gray), and red merle (marbled red and silver or buff); each of these colors may also have copper points and/or white markings in various combinations on the face, chest, and legs. A black or red dog with copper and white trim is called tricolor or tri, a black or red dog with white trim but no copper is called bicolor or bi. White should not appear on the body of the dog from topmost point of the shoulder blade to the tail. The ears should be covered by and completely surrounded by pigment other than white to decrease the risk for white related deafness. Eyes should also be surrounded by color, including the eye rim leather. Excessive white on the face and ears can place an individual dog at greater risk for sunburn and subsequent skin cancer. The wide variation of color combinations comes from the interaction between the a color allele, which is either black (B) dominant or red (b) recessive, and the dominant merle allele (M). Together, these provide four coat-color aspects that can appear in any combination:

• Black or Red tri, which is a combination of red/black, tan, and white

• Merle, which is a olr combination of blue/red with many grays and spots. Many merles have two different colored eyes.

• Fully black, or fully copper

• Solid color or trimmed with white

The merle allele, which produces a mingled or patchwork combination of dark and light areas, is the most common coat pattern associated with the breed. This merle (M) is dominant so that affected dogs (Mm) show the pigmentation pattern; however, when two merles are bred, there is a statistical risk that 25% of the offspring will end up with the two copies of the merle gene (homozygous). These dogs usually have a mostly white coat and blue irises, and are often deaf and/or blind. In this case, the deafness and blindness are linked to having two copies of the merle gene, which disrupts pigmentation and produces these health defects.

All black and blue merle dogs have black noses, eye rims, and lips. All red and red merle dogs have liver or brown noses, eye rims, and lips.

Eyes
Blue merle with copper points with blue eyesThere is also great variety in the Aussie's eye color. An early nickname for the breed was "ghost-eye dog". Aussie eyes may be green, hazel, amber, brown, or blue; they may have two different colored eyes, or even have bicolored or "split eyes" (for example, a half-brown, half-blue eye), which appear to be linked to the merle coloration. Merled eyes occur as well, where one color is mixed in and swirled with another. Any combination of eye color is acceptable in the breed standard, so long as the eyes are healthy. In general, however, black Aussies (self, bi-color or tri-color) tend to have brown eyes, while red (self, bi-color or tri-color) Aussies tend to have amber eyes, though these Aussies may also carry the blue eyed gene.

Tail
A hallmark of the breed is a short bobbed or docked tail in countries where docking is permitted. Some Aussies are born with naturally short bobbed tails, others with full long tails, and others with natural partial bobs, where the tail is midlength and appears stubby. Breeders have historically docked the tails when the puppies are born. Even without a tail, the wagging movement of the hind end still occurs. Some Australian Shepherd breeders try to keep the tail on the dog for the natural look, which can still be shown in the breed ring.

Temperament
The Australian Shepherd is unique with regard to its temperament. There are two distinct types of personality to look for depending on the lines, as well as many shades within these two types.

Generally the breed is an energetic dog that requires exercise and enjoys working, whether it is learning and practicing tricks, competing in dog agility, or any other physically and mentally involving activity. Other Aussies would rather be with their humans and enjoy being couch potatoes. It is usually a sweet and affectionate dog which is faithful to its owners and great with children. Most Australian Shepherds make wonderful family dogs, provided there is at least one shepherd-figure to act as a leader and mentor to the dog.

Dogs with strong working instinct may show more reserved, guarding behaviors along with a tendency to chase or nip at running children or strangers if not properly trained. Its protective instinct and behaviors can be frightening to children, strangers, and small animals. Those bred for a more family-oriented temperament are more friendly and affectionate with strangers and generally more reliable around children. Because the breed was developed to serve on the ranch, a job which includes being protective of its property, it sometimes can be annoying with its inclination to bark warnings about neighborhood activity, but it is not generally an obsessively barking dog.

The Aussie is intelligent, learns quickly, and loves to play. This means that a bored, neglected, unexercised Aussie will invent its own games, activities, and jobs, which to a busy owner might appear to be hyperactivity: for example, an Aussie may go from being at rest to running at top speed for several 'laps' around the house before returning to rest, all apparently for no purpose. Without something to amuse them, Aussies often turn destructive of yard or property. Aussies also do best with plenty of human companionship: they are often called "velcro" for their strong desire to always be near their owners and for their tendency to form intense, devoted bonds with select people.

The Australian Shepherd has a reputation as a highly intelligent and versatile stock dog with a range of working styles. While improperly trained or frustrated Aussies may exhibit excessive running and barking, a good working Aussie is quick, thoughtful, and easy with its stock. The ability for the breed to adapt to the situation and think for itself makes it an excellent all-around worker. For this reason the Aussie is often chosen to work unusual livestock such as ducks, geese, and commercially raised rabbits.

Mortality
Results of a 1998 internet survey with a sample size of 614 Australian Shepherds indicated a median longevity of about 12.5 years, but also that longevity may be declining. A 2004 UK survey found a much shorter median longevity of 9 years, but their sample size was low (22 deceased dogs).

The median life spans for breeds similar in size to Australian Shepherds are mostly between 11 and 13 yrs,[6] so, assuming the results of the UK study are not representative of the population there, Aussies appear to have a typical life span for a breed their size. Leading causes of death in the UK survey were cancer (32%), "combinations" (18%), and old age (14%).

Morbidity
Based on a sample of 48 still-living dogs, the most common health issues noted by owners were eye problems (red eye, epiphora, conjunctivitis, and cataracts). Dermatological and respiratory problems also ranked high.

Collie eye anomaly (CEA) and cataracts are considered major health concerns in Aussies. Other conditions of note include iris coloboma, canine hip dysplasia (CHD), Pelger-Huet syndrome, hypothyroidism, and nasal solar dermatitis. Prior to breeding, the Aussie should be checked for Hip and Elbow Dysplasia, DNA tests performed to show the dog to be free of the MDR1 mutation, cataract mutation, and CEA. Tests should also include those for thyroidism and clearances for other known eye diseases like colobomas, PRA and retinal folds. The Australian Shepherd (as well as Collies, German Shepherds and many other herding dogs) are susceptible to toxicity from common heartworm preventatives (anti-parasitics) and other drugs. This is caused by a genetic mutation of the MDR1 gene. The most common toxicity is from the heartworm medicine Ivermectin found in products such as Heartgard. (Only at very high doses. Most dogs will not have problems with Ivermectin found in products such as Heartgard Plus.) A test is available to determine if a particular dog carries the mutated gene.

Double Merle
Double merling or homozygous merle, also known as lethal white, occurs when the resulting offspring of two merled parents inherit two copies of the dominant merle gene. Double merles are often mostly white and can have resulting hearing and visual problems as a result of having two copies of the merle gene. Homozygous merles can be deaf, blind, express iris colobomas and micropthalmia. Not all homozygous merles are affected, but most are, making the breeding of two merles an ethical question among the fancy. Breeders will either euthanize mostly white pups or in the case of poorly qualified breeders, sell them as "rare" white Aussies without disclosing the potential for health defects. A large percentage of homozygous merles sold eventually end up in rescue and shelters as the average family is ill prepared to take on a deaf and/or blind pet.

History
The Australian Shepherd's history is vague, as is the reason for its misleading name. It is believed by some the breed has Basque origins in Spain and was used there by shepherds. What is known is that it developed in western North America in the 19th and early 20th centuries.

Breeds as we know them today did not exist before Victorian times, but local variations of the ancestors of different breeds that we know today came into America along with their owners and livestock. Included are some that are now extinct or that have merged into other breeds. These probably included the English Shepherd, Kelpie, Dorset Blue Shag, Cumberland Sheepdog, Scottish Collie, Glenwherry Collie, Australian Cattle Dog, Welsh Sheepdog (which still includes a blue merle variety) and Bouvier des Flandres, as well as dogs from Germany and Spain. For many centuries, shepherds had more interest in dogs who performed well when helping to manage flocks of sheep than they had in the specific appearance of the dogs. As a result, over time, shepherds interbred dogs that they believed would produce better workers for the given climate and landscape. In the eastern U.S., Terrain and weather conditions were similar to that of Europe, however, so the existing imported breeds and their offspring worked well there.

However, in the American West, conditions were quite different. In the primarily arid and semiarid areas inhabited sparsely by early Spanish settlers, temperatures reached extremes of hot and cold, and fields varied in altitude from sea level into the higher, rougher Sierra Nevada and similar mountain ranges. The ranchers in these areas often pasture livestock on remote ranges without attention for months at a time. They prefer aggressive herding dogs that can be taken to remote pastures and work unfamiliar cattle that are not accustomed to the dogs.

With the 1849 California Gold Rush, a massive migration occurred into to the west coast, and along with easterners came flocks of sheep and their eastern herding dogs; from the southwest came people and their dogs of Spanish descent. But it was just as effective to bring sheep in by ship, and in they came, including flocks from Australia and other regions, along with shepherds and their own herding breeds.

Black and white (bicolor) Australian Shepherd stopping cowsDogs from Australia had already begun to be selected and bred for climates and terrains that were often similar to California.

As shepherds selected dogs who could handle stock in harsh storms, high arid heat, and chilling cold, and who could think on their own in challenging terrain, reacting instantly to the movement of sheep and to their handlers' commands, the type that became known as the Australian Shepherd was born.

It is not clear where the name "Australian" came from, although it is possible that many of the dogs coming from Australia were blue merle and, somehow, the adjective "Australian" became associated with any dogs of that coat color.

Recent history
Development of the breed began in Arizona, California, Colorado, Idaho and the Pacific Northwest. The breed's foundation bloodlines are depicted in the Australian Shepherd Genealogy Chart showing the relationship between the early families of dogs.

Selective breeding for many generations focused on aspects of the dog that enabled it to function as an effective stockdog in the American west. It had to handle severe weather; have plenty of speed, athleticism, energy, and endurance; and be intelligent, flexible, and independent while remaining obedient. The Australian Shepherd remained more of a type than a breed until the 1950s, when they became popular as performing dogs in rodeos. Their stunts and skills earned them places in several Disney films, including Run Appaloosa Run and Stub: The Greatest Cowdog in the West.

Activities
Like other herding breeds, these dogs excel at many dog sports, especially herding, dog agility, frisbee, and flyball. The dog has a stride in which its front and back legs cross over, making for an appearance of "on the edge" speed. The dogs instinctively use a "pounce" position (see above) to deal with cattle trying to kick them. They also have strong hips and legs, allowing for fast acceleration and high jumping, sometimes as high as 4 ft (1.3m).

An Australian Shepherd named Pockets is credited as being the oldest dog to earn a title in AKC history, having earned the Rally Novice title at the age of 15 years, 5 weeks.

Miscellaneous
The Australian Shepherd Club of America (ASCA) was founded in 1957 to promote the breed. The National Stock Dog Registry became its official breed registry, which continued until ASCA took over in the 1972.

In 1975, ASCA created a breed standard, describing exactly how an Australian Shepherd should look and be constructed (its conformation to the Standard). It developed more uniformity in the breed and standardized the type.

In the United States, the AKC is the primary registry for purebred dogs. However, many Aussie breeders felt that AKC put too much emphasis on conformation and not enough on performance, so ASCA declined to join the AKC. Those breeders who felt that AKC membership had its advantages split off from ASCA to form their own Australian Shepherd club, the United States Australian Shepherd Association, created their own breed standard, and joined the AKC in 1993. The decision about affiliation with the AKC remains controversial, as it does with many performance breeds.

In addition to the Miniature Australian Shepherd, the western United States are now seeing the emergence of an even smaller version, referred to as the Toy Australian Shepherd, with adult males tipping the scales at a mere 12 to 15 pounds (5.5 to 7 kg). The genetic consequences of breeding the standard Australian Shepherd down to one-quarter size remain to be seen. Many breeders and owners of Australian Shepherds consider the Mini and Toy to be separate breeds; others consider them to be downsized versions of the same breed. ASCA and AKC considers all such variants to be separate breeds.