[ciiiicii]

A friend of mine has a cat, which she's had since a kitten. When the cat was given to her, she was told it is male. However, when she took the cat to the vet for vaccinations, she was informed that the cat is in fact female.

A mistaken assumption doesn't change the underlying reality.

If she hadn't taken the cat to the vet and hadn't otherwise realized that the cat is female, and later, the cat had become pregnant, then she wouldn't be exclaiming how amazing it is to see a male pregnancy. No, she would understand that the cat is female, because only female cats can be pregnant.