You could feed it more so it will gain weight . Setters are known to be able to jump 6' fences but I bet its more like climbing. Luckily, my dog is overweight even then she once climbed a vertical rock wall about 5' high to run away from me.

Strange things about dogs. My first dog could easily clear the 3' high fence as she was moreathletic. She routinely cleared her dog house and jump into a raised 4 wheeler with tailgate up.She never jumped the fence but did learn toopen the top mounted latch which I had to fix. Later she was kenneled and she figured how to open that latch too.

As to your problem, throw a net over the kennel.