I have been asked by many people over the years how to get an animal to stop trying to kill other (usually smaller, prey) animals. For example: How do you get a cat to stop killing birds (or mice, or rats, or bats, etc)? and, how do you get your dog to stop hunting small animals (like cats, rabbits, birds, chickens, etc)?
There is no easy answer to this question. Our carnivorous pets are doing what their instincts are driving them to do. In most cases, growing up with another type of animal (like a puppy growing up with a cat(s)) is enough to make the bigger one not too keen to rip the smaller one apart - but not always.
There are things you can do to try minimise the harm your pet can cause - let's have a look at some of those ideas here:
The bottom line is that you may not be able to change this killing-spree-inclined behaviour in your beloved pet. Some dogs and cats have this killing drive more or less than others. Shepherd-type dogs have been known to carry abandoned baby animals to safety. They have also been known to eat helpless baby animals. If your pet likes to kill despite your best efforts, then do what you can (and what is fair to them) to minimize their access to small creatures. They are doing what they were designed to do.
It is also possible to have a pet become more aggressive towards other animals that they used to accept without issue. This can be caused from a wide range of factors, including: not enough exercise (too much pent-up energy that gets released as aggression, excess weight often comes with this particular factor), pain causing aggression, psychopathy, neurological issues, etc.
You don't have to like your pet's killing sprees, but try not to be angry with them - they are doing what they were literally born to do.
I originally wrote this post here: https://www.patreon.com/posts/18397158