Start under the tail of the Andalusian foal
The under-tail check is the clearest way to sex a young Andalusian foal. Stand to the side, never directly behind, have a helper hold the mare and the foal settled, and lift the tail gently. A filly shows two openings in a neat line: the anus directly under the tail, and below it the vulva, a short vertical slit whose lower end tapers to a point. A colt shows only the anus under the tail. On a grey Andalusian — and most of the breed is grey — the skin there is dark and the contrast is easy to read in decent light, so take the look in the stable doorway rather than in a shadowed box where everything merges.
Confirm a colt by the sheath, not the testicles
Owners often go straight for the testicles and confuse themselves, because a young colt's testicles are unreliable witnesses. They may be descended at birth, they may drop over the following weeks, or they may sit up in the inguinal canal where you cannot feel them at all. The dependable colt sign is the sheath: a distinct fold and pocket of loose skin roughly midway along the belly, housing the penis. Run a flat hand along the foal's underside and you will feel it clearly, where a filly's belly is smooth all the way back to a small udder area between her hind legs. Two smooth, oval testicles in front of the hind legs confirm a colt when you can feel them, but not feeling them does not make him a filly.
Things that do not sex an Andalusian foal
Several favourite guesses fail on Andalusians in particular. This breed produces elegant, refined heads on both sexes, so a 'pretty' foal is not automatically a filly, and a bolder, pushier foal at the mare is not automatically a colt. Both sexes are born with small teats, so nipples prove nothing. Colts urinate from the belly through the sheath and fillies from under the tail, which can confirm what you found if you happen to watch a relaxed foal pass urine properly — but a quick squat half-seen across the field is not evidence. Even the mare's behaviour tells you nothing; she mothers a colt and a filly exactly the same way.
Handling an Iberian foal safely for the check
Andalusian foals are people-oriented but quick, and the mare's opinion governs the whole exercise. Work with the mare held close and calm, keep the foal between her and a wall or fence so he feels contained rather than cornered, and keep one hand resting on his quarters so the tail lift is not a surprise. Keep sessions short: a foal who is fussed over will plant, spin, and make the anatomy impossible to read, and a stressed mare unravels the lesson further. If the foal will not settle, walk away and look again at evening stables — the answer keeps, and a quiet thirty-second look beats a scuffle.
Getting it confirmed and recorded
If your checks disagree — sheath felt but something seen under the tail, or nothing clear anywhere — do not guess on paperwork, because an Andalusian's sex goes on registration and sale documents where errors are expensive to unwind. Ask your vet to confirm at the foal's first examination, or ask the breeder to show you on a settled morning; experienced eyes settle it in seconds. Once it is certain, the result belongs with the foal's identity from the start: enter it in KinsLe, and Pet Pass becomes the foal's quick proof of who he or she is whenever a new yard asks.