That could be true--I've heard countless horror stories of parents who refuse to get an IEP because of the stigma attached that it means their child is "retarded." Of course, there are plenty of horror stories on the other side as well.
My understanding is that if the school needs to make some sort of accomodation based on a disability, an IEP is needed. In your example, a wheelchair, the school doesn't need to make any accomodations (outside of things already covered by the ADA), whereas in this instance there would need to be significant modifications because of the presence of a dog in the classroom.
That being said, I do think the mom is being a bit of a prima donna.
I disagree, but I thank you for toning down your rhetoric.
I have some experience with IEPs in a very restrictive state - NY - and my understanding is that IEPs are not required for non-educational disabilities. Unfortunately, I cannot state that categorically, but that is the way it was expained to me. Also, I believe that the dog is covered under ADA, and is not considered an educational accomodation.
Take care.