Naturally she can jump anything - when our stable had an open house I took her up to the barn and ran her over the horse jumps set up in the ring. Three feet plus is no problem for her at all. After she jumped everything in the ring, the kids up on the hill applauded like mad, and she went nuts and got the "zoomies" - I don't know if Shadow does the "Labrador butt tuck" but when Labs get really excited they kinda run while sitting down. Shelley made an entire victory lap of the ring in full "butt tuck" with her ears flying and eyes rolling white - and got another round of applause.
That's why we switched her from obedience competition to agility. At least she can run around, jump, and bark.