Border Collies are a working and herding breed and extremely energetic and intelligent. The motion of the cat triggers their herding instinct and they start to chase. The cognitive connections of "cat = chase" and "chase = fun" are not at all hard to establish. So the puppy acquires a habit... The longer this habit exists, the harder it will be to break, so you want to start training as soon as possible.
This article provides several great techniques to break the habbit of chasing in a puppy.
- Place your kitty in a protective carrier while the puppy is in another room. Provide a cat toy or catnip to help keep the cat calm.
- Bring the puppy into the room and give him favorite treats one after another to keep him focused on you and to reward him for behaving calmly.
- Ask the pup to practice a sit, to follow you on the leash in a heel position or to stay on command. Practice obedience commands your puppy knows very well and reward him for obeying.
- Offer the BEST treats for moving or looking away from the cat. The idea is to teach your puppy he gets better attention and rewards by ignoring the cat than by pestering her.
Another one, including clicker training:
- Ensure the cat’s safety by keeping your dog under leash control and prevent ANY chase from taking place. Most puppies prefer cat-chasing to any other reward so don’t allow your pup to get his first taste.
- Have plenty of smelly, tasty treats handy. These should be irresistible and something the puppy ONLY gets for this exercise.
- Don’t confine the cat at all. Allow her to move around at will while you keep the puppy’s attention on you as much as possible by teasing with the treats.
- Each time the cat makes an appearance, moves or otherwise draws the puppy’s attention, give a tiny taste of a treat—partner this with the CLICK cue of the clicker if you’ve clicker-trained.
- Be consistent. Offer this treat-CLICK reward every single time whether your puppy is calm, excited, looks at the cat, barks or anything else. The equation should be: CAT’S PRESENCE = DOG TREAT.
- Use the leash to keep your puppy safely out of paw-reach of the cat, but not to force his attention. You want the puppy to choose to look at you for the treat, not be forced to do so. Given time, his puppy brain will connect the dots and figure out that when he sees the cat, he should look to you for a treat—and he can’t chase when he’s accepting that yummy treat!
- Continue to reinforce this behavior for at least a week or more. With consistency, most dogs will get it within only a few sessions.
- Make sure the dog stays leashed and the pets separated when not supervised until you're confident the new canine response has become ingrained.