This question came from the owner of a Boxer and Boxers have high prey drive.
My recommendation to curb this behavior is a prong collar and a five or six foot leash. Begin to do leash training. If you are not familiar with that, we do have several videos available, here on our youtube channel. Of course, I would also be happy to coach you.
I would tether the dog to my waist for the next couple of weeks, with a prong collar on the dog and start walking. This will make a significant impact on your dog. Your dog will be uncomfortable and there is a small risk of injury, if the dog decides to go after something, while tethered to you. However, that is minor, compared to the possibility of a lawsuit against you and your dog being labeled as aggressive.
Longoriahaus Dog Training is a dog training service in the Kingwood, Humble and Houston, Texas area. Longoriahaus Dog Training can help you raise a happy and reliable dog.