Border Collie or Australian Shepherd? Look at the Tail

Both are medium herding dogs with double coats, high drive and a habit of trying to herd whatever is in the room. The tail separates them first.

The tail

Border Collie — a full tail, set low, carried low, with a distinct upward swirl at the tip. It is part of the breed standard.

Australian Shepherd — usually a naturally bobbed tail, or one that has been docked. A minority are born with full tails.

If the dog has an obvious full low-set tail with a swirl, that is a Border Collie. If there is barely a tail, an Aussie.

The ears

Border Collie — semi-erect, standing up with the tips folding over. Highly variable, since the breed was selected on work rather than looks.

Australian Shepherd — triangular, set high, and breaking forward as drop ears rather than standing.

The build and the coat

Border Collie — lighter, more athletic, moderate coat. Built for covering ground for hours.

Australian Shepherd — heavier-boned, squarer, with a noticeably thicker coat and more feathering.

Merle, and the thing worth knowing about it

Merle — mottled patches of diluted colour over a solid base, often with blue or marbled eyes — is common in Aussies and occurs in Border Collies.

Breeding two merles together produces double-merle puppies, a quarter of the litter on average, with high rates of deafness, blindness and eye malformation. It is entirely avoidable and it is why merle-to-merle breeding is condemned by every serious breeder.

If you are buying a merle puppy, ask what the other parent was. A responsible breeder will tell you immediately.

MDR1 — the practical one

Both breeds carry the MDR1 mutation at high frequency, and it is a clinical matter rather than a curiosity.

Affected dogs cannot clear certain drugs from the brain, and ordinary doses of several common medications — ivermectin, loperamide, some chemotherapy agents and some anaesthetics — cause severe neurological reactions.

There is a cheap genetic test. If you have a herding-breed dog or a herding-type mix, get it done and put the result on the file at your vet. This is the single most useful thing on this page.

Temperament, honestly

Both are among the most commonly rehomed breeds, and for the same reason: people acquire them for the looks and the intelligence and discover that a working dog without work is a destructive one.

They need a job — training, sport, actual stock work — rather than a longer walk. A bored Border Collie invents work, and the invented version is rarely convenient.

The third possibility

Herding-type mixes are extremely common, and they carry the coat and the ears without the pedigree. The general caution about visual identification applies with full force here — a black-and-white medium dog with a moderate coat is a very common outcome of mixed ancestry.

The eye, and what it means

Both breeds work stock with "eye" — a fixed, crouching stare that moves animals without contact.

Border Collies have it most strongly, and it is the origin of nearly every problem people report: staring at children, stalking cyclists, herding the vacuum cleaner, fixating on shadows or light. It is not misbehaviour but an instinct with nothing appropriate to point at.

The management is the same as the exercise answer: give it a legitimate target. Herding balls, formal training, scentwork or actual stock. Suppressing it works badly; redirecting it works.