I've not had a rabbit who wouldn't have cleared that. 90cm has been fine for everybun: Lopsy could easily jump that high, but the fact there's nothing but straight up and straight down over a pen panel stopped him. If he had had a place to even momentarily place his feet, he might have done it more often. He easily climbed his 2.5' run to get over the top though, so yeah, anything with paw-holds would be out! If you can't get one 120cm (I'd say if it's got a 1cm+ wide top) you can add some pretty trellis or something to the top?
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