Why the Arabian face will mislead you
A young Arabian is the easiest foal to mis-sex by looking, because the breed's hallmark dished face, large eyes and fine bone appear on colts and fillies alike, and a particularly elegant colt is routinely mistaken for a filly by visitors. Ignore the head entirely. The reliable evidence sits at the back and underneath: the openings under the tail and the structures along the belly. Lift the tail of the young Arabian and count. Two openings close together, anus above and vulva below, mean a filly. One opening only, the anus, means you are looking at a colt whose genitalia are carried forward on the belly.
Reading the colt's underside
For a young Arabian colt, look midway along the underside of the belly for the sheath, a neat fold of skin that houses the penis and points backward. On a fine-skinned Arabian this is usually visible without much searching once the foal stands square and relaxed. What you should not rely on is finding descended testicles: in a young colt they may still be up inside the body or sitting too small and high to feel confidently, and they can appear at different times in different foals. A missing pair of testicles at a few weeks old tells you nothing; the sheath and the single opening under the tail tell you everything you need.
Reading the filly's underside
A young Arabian filly shows her evidence in two places. Under the tail, the vulva sits immediately below the anus as a short vertical opening, distinct from the round anus above it. Between her hind legs, on the belly line where the udder will develop, are two small teats that a colt does not carry in the same form. Checking both places takes a moment and removes all doubt, which matters because Arabian fillies are often finer and more reactive than colts of the same age, and owners subconsciously sex the flighty one as a filly and the bold one as a colt. Temperament in an Arabian foal is individual, not a sex marker.
Handling a reactive young Arabian safely
Young Arabians can be sharp and quick, and their dams are often intensely attentive, so set the check up properly: mare held by a helper, foal in a corner or against the mare's side, and your movements slow and announced. Crouch at the foal's hip, keep a hand on its hindquarters so it knows where you are, lift the tail once and look properly rather than making repeated grabs that teach the foal to kick at hands near its rear. If the foal will not stand for it, fold the check into the vet's first visit rather than escalating a handling battle you will both remember next time.
Confirmation and why the record matters
Have the vet confirm the sex during the Arabian foal's first examination and write it into the foal's records that day, with its colour and markings. Breed paperwork, future turnout decisions and even which youngstock group the foal joins all depend on that one fact, and an error that survives into the registration stage is far harder to correct than a ten-second check in the first weeks. Keep your own note consistent with the vet's, so every later form copies a fact rather than a first impression. KinsLe's Pet Pass shows a young Arabian's identity and owner contact details on its verified ID card, so its recorded sex stays attached to the foal from the beginning.