Same here, especially the bigger types. Our bitch is 29" tts and we only had her doing the usual exercise routine of a bit of roadwork and a few runabouts, every day, and only started her jumping over nothing more than fallen trees when out walking until she was over a year old, she was still puppyish and gangly at that age, then as her balance and coordination improved we started her over low jumps of about 18" and gradually built up the heights over a few months. Now she's a terrific jumper and will clear anything. Overcautious some might say, but I don't want to risk giving any of my pu