Chasing cats is more important than eliminating

I realised this was how Jon prioritised between these two activities. This morning when we were at his favorite stretch of road, Jon began to be in position to eliminate big time. Just as he was in the hunched position, there was a hissing sound 10 meters ahead, and two cats came out from behind a car. One was chasing another. Almost at the same time as I looked at Jon's response and said "Oh no, this can't be happening now", Jon quickly "got up" and sprinted after them. With the leash on him, 6 feet was the most he could go. I looked back to see only one piece of poo excreted. As I picked it up, I told Jon that he has one more kilometre before reaching home to get rid of the rest. He never did eliminate the rest, and I hope he can hold it in till tonight. Do any of your dogs place more emphasis on fulfilling their natural urges of chasing cats than the necessity of eliminating?