No you can still make them out when they are young there was a video on this site explaining I'll try and find it. Otherwise if it is a reptile vet they might be good at probing baby tegus but it won't be cheap
My vet used the probing technique for my tegu, because when I brought her in (not knowing if she was a girl or a boy, but having been told she was a boy...), she had some leftover shed in the area so bumps were undetectable. Also, tail width can be a good indicator too once they are a bit older, but not when they are young.
Vet can tell using ultrasound
The vet can only tell if the vet knows what they're doing. This is a rather important issue, many vets simply don't have the experience necessary (ie. vets are not trained to a high degree with all animals, in fact most vets are not trained with reptiles at all). You can tell the sex from day one, because yes while the males develop the bumps with age, the underlying tissues are still there. The "bumps" are where the hemipenal retractor muscles anchor. They become bumps as the scales thicken with age. Thing is, the scales are there from the day they hatch. The scales are different between males and females.
Among us, we should be able to do it. Sharp close-up of vent include a little above and a little below the cloacal smile! Make sure it is flat, not her body curling in.Why don't you just take a really detailed photo of the area around the cloaca and post it. We should have no problem sexing it for you. You might have to take a few photos to get the right area and the right detail, the scales we are looking for are very small. It's free, though.
Ok a little misunderstanding... I don't have my tegu yet, but I have been looking at the ones in the store (east bay vivarium).Why don't you just take a really detailed photo of the area around the cloaca and post it. We should have no problem sexing it for you. You might have to take a few photos to get the right area and the right detail, the scales we are looking for are very small. It's free, though.