On paper these two are twins: tireless, very trainable herding dogs that shed, need a real job and score the same on every one of our ratings. They differ in origin, herding style, wariness of strangers and one gene, MDR1. Despite the name, the Australian Shepherd is American: livestock producers developed it in the western US, and the name comes from Basque shepherds who arrived there from Australia in the 1800s. The Border Collie is named after the border regions of England, Scotland and Wales, and since 1906 the International Sheep Dog Society (ISDS) has registered it on working ability, proven at trials.
- Working style. The Border Collie is the classic "strong-eyed" dog: it runs wide around the flock, crouches, creeps and controls the sheep with an intense stare, the "herding eye" its breed club calls a hallmark. The Aussie has a looser eye, works closer and stays upright; the Australian Shepherd Club of America (ASCA) calls it an "aggressive, authoritative worker" and a ranch dog that also guarded the homestead.
- With strangers. The Aussie standard notes "strong herding and guarding instincts" and says it may be reserved at first meetings. The AKC rates the Border Collie a little more open to strangers.
- At home. The AKC warns that Aussies bond so strongly with their family that they can turn territorial and overprotective, and destructive if left alone too often. Border Collies tend to herd people, so the AKC suggests homes with older children, and a Finnish study of almost 14,000 dogs found more compulsive staring and light or shadow chasing in Border Collies than in other breeds.
- Brains. Both score 5/5 for trainability here. In Stanley Coren's The Intelligence of Dogs, which ranks working and obedience intelligence, the Border Collie is No. 1 and the Aussie shares 42nd place.
- Looks. The Aussie comes in just four colors: blue merle, red merle, solid black and solid red, each with or without white and tan markings, and may be born with a natural bobtail. The lighter Border Collie comes in many colors and two coats, rough or smooth.
- Build. The Aussie standard asks for a solidly built dog; the Border Collie's for bone that is "strong but not heavy". A smaller version is the Miniature American Shepherd, bred down from small Aussies in the 1960s.
- Merle. In both breeds, two merles must never be mated: double-merle puppies are at high risk of deafness and small, often nonfunctional eyes. The Royal Kennel Club has refused to register merle-to-merle litters since 2013.
The biggest health difference is MDR1, a gene defect that makes some common drugs, such as loperamide, dangerous. Washington State University puts its frequency at about 50% in Aussies and under 5% in Border Collies; test an Aussie before any sedation. For breeding dogs, the Aussie's AKC parent club, the USASA, requires hip and elbow scores and yearly eye exams, and recommends DNA tests for hereditary cataracts (HSF4), MDR1 and collie eye anomaly (CEA). The Border Collie Society of America asks for hips and eyes. The UK's Royal Kennel Club goes further: an eye exam with gonioscopy, hips, elbows and a BAER hearing test, plus DNA tests for CEA, trapped neutrophil syndrome (TNS, an immune disorder), neuronal ceroid lipofuscinosis (CL, a degenerative brain disease) and Imerslund-Grasbeck syndrome (IGS, an inherited inability to absorb vitamin B12), among others.
Choose the Aussie if you want a sturdier all-round farm or family dog, as long as you socialize it well to keep its protective streak in check and rarely leave it alone. Choose the Border Collie if you want a lighter, more intense specialist for sheep, agility or obedience and can give it work every day. With either, ask for both parents' health results.