Unfortunately I also think it can be in the nature of any breed to chase something if it runs. My blue heeler Shadow was soon put in his place by the cats as was my BC cross. 4, now 3 pups are a bit much at once for 2 of my cats so they run, so they are chased. I have just spent a few hundred dollars on a pup;s ulcerated eye that could very well have been from a cat scratch. Once I just have the two I am keeping here it will be much easier.