You have to take the training very slowly. I got mine used to the harness in the house before I ventured outside. I then took them to my in-laws and let them walk around in the field (they live on a farm). Mine have never tried to climb anything whilst wearing it, you just have to be vigilant. You cant just let them get on with it like you would a dog. You have to second guess what might spook them or what they may want to chase.
Paddington loves stalking the sheep on the farm, especially when there were lambs earlier in the year and he was bigger than them!! I've now got an extendable dog lead for him so he feels he has a little freedom. They love chasing flies and moths and butterflies.
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