You know, it's been awhile since I had a little one (who used to call me "BigFatMommyDog" btw, I was none of those at the time lol), but I'd be hard pressed to believe that a not yet 3 year old was counting to 45 in any language, at least with an comprehension. I suspect she might be able to repeat back, but not actually count -- sounds like exaggeration to me, not that KC has be known to stretch the truth or anything...
?
I did searched a bit, and came upon a notation that 3 year olds should be able to count to and understand the concept of 15.
That being said, if she was around a situation where 45 was counted out (in Spanish) often, she could have picked it up just from the sheer repitition. Odd number though -- why not 50?