Robert Kaleski, in an article on Cattle Dogs in the August 1903 issue of the Agricultural Gazette of New South Wales, describes the "Welsh heeler or merle, erroneously known as the German collie," as a "blue-gray dog about the size and build of a smooth-haired collie, generally with wall eyes."

The Koolie is a "herding dog", one which has a natural instinct to circle widely round sheep and bring them back to their owner.

With the demand for farming dogs no longer being what it was, the Koolie has proven its worth in many other fields where it is renowned for its sensitivity, athleticism and obedience, excelling in agility, tracking, therapy, disability & emotional support service, and as the ultimate outdoor & family companion, providing they are well trained.

In the north of Queensland and New South Wales they are tall, medium boned and agile, bred for mustering cattle over many miles.

In New South Wales, they are thicker set and shorter to flush low lying cattle from the dense bush and gullies.

Koolies are bred to meet the needs of the stockman, grazier and farmer; all agile, all with the same ability to adapt to any situation, all with a strong willingness drive.

Graziers, stockmen and dairy farmers across Australia since days long past have typically selected breeds which display the abilities required to meet their working needs.

There are times when an uninitiated dog owner or a new enthusiast mistakes the Koolie as a shy, reserved or even a timid animal.

Koolies have a diverse but small gene pool and can suffer from the many genetic problems found in recognised breeds.

Koolies are much sought-after in rural Australia, and interest is now being shown in America, Canada, Germany, Finland, New Zealand, Switzerland and Holland.

Koolies have a reputation for being upright workers with a good eye, who can easily shift their focus from holding the group to casting around a flock or gathering breakaways.

As well as working anything from ducks to bulls, like all dogs of their kind they will herd family members and children in the absence of other charges.

Many be breeders still out cross both Kelpie and Border Collie lines, which are accepted practices with the Koolie breed registries.

In the states of Victoria, New South Wales, and Queensland, registered Koolies may compete in, herding, obedience, tracking, jumping, gambles and dog agility events through registration on their State's Sporting Register as members of the Koolie Club of Australia or the Australian Koolie Association In May 2006, the Stockdog Committee of the Australian Shepherd Club of America[5] voted to accept the "Koolie/German Coolie" into their list of recognised and accepted herding breeds, admission was granted June 2006.