how can i tell if my sister is going to be allergic to chihuahuas?

my sister is allergic to cats, rabbits, and some breed of dogs, b ut i want to buy 2 chihuahuas as pets. how can i tell if she will be allergic? i dont want to buy them and then she be allegic and we have to get rid of them. thanks.

if she is, is there any weay to stop the reaction.
There is no way she can be around them for very long as i do not know anyone who has them.

Can she be around chihuahuas before you buy them? Like where are you planning to get them and can she go with you to see if she has a reaction? There's really no other way to tell. She has to find out if she'll have a reaction to them by being around them. Or do you know anyone who already has some and would let you and your sister visit to test her allergies?