We have an 18 month old Springer/Cocker, who has recently shown a surge in his prey drive. My DD walks him most of the time, and since the warmer weather, has seen the dog catch and kill a rat, a rabbit and a squirrel. She finds this very distressing, and I'm worried that a) the dog loses all sense of recall and b) is upsetting his digestion. Any suggestions out there?
Firstly, muzzle the dog while you deal with the issue. I wouldn't be suggesting it if he wasn't catching the animals, but he is, and it's to everyone's detriment. You need to go through a process of muzzle training (YouTube is a good source eg Chirag Patel has a video on the topic) rather than just bunging one on without any forewarning, but it will deal with the messy side of the problem.
Prey drive can be very hard wired and you're unlikely to fully rid him of it, but impulse control games (eg using a flirt pole) won't hurt.
If he's in a place where he could hurt himself or others, keep him on a lead or long line - for his safety.
(FWIW I have heard of some people using their dog's prey as part of a raw food diet, but that's probably not what you wanted to hear!)
My cocker has never caught animals but when younger used to chase anything (deer, rabbits, birds).
The only thing that stopped him was working with his prey drive rather than against it. We no longer go for long strolling walks because they are boring for him so he will seek out animals to hunt and chase. What we do now is find areas to chase and throw balls and to hide them in long grass so he has to hunt them out. He is so fixated on the ball because it's fun we can actually walk close to deers (the deers around here are very tame and only run when you get extremely close) and he doesn't even look at them. That would have been unheard of previously.
You possibly need some help from a trainer and to start a campaign of getting his attention focussed on to you, through games and play. It does really boil down to making yourself more interesting on walks, so that he will chose you over the prey. Easy to say, not necessarily easy to do but he has a high prey drive in theory that drive can be redirected.
Just popping in to say - be really careful how much he gets to ‘practice’ the hunting behaviour while you’re sorting it out. I’ve got a Spaniel with a massive prey drive thanks to a past life as a hunting dog - I can’t ever let him off lead unless it’s in a fenced enclosure, he’s just unreachable once he’s seen something (I once got truly hacked off and decided to sit on a bench with him tied next to me until he looked at me. After 20 minutes I cracked.) I find it very sad that he doesn’t often get to go and run, but it’s just not safe as I have no control at all once he’s off lead.