help

Oh, I just feel bad about the whole situation.  I really don't know what to tell you, but you might want to post this in the general chat section as it gets more traffic.  I am sure someone there will be able to help you.
 
Good Luck!

I don't think you will ever be able to train him not to do this.  You need to be very aware of this and manage it effectively.  That's all I can suggest.

I'm sorry that this happened, but your dog did not know any better and a cat paid with it's life.

There are several ways to go with this. 100% management and no chance of contact with another cat (or any other small animal) ever again, or get yourself a top notch trainer who is experienced with e-collars.

The e-collar is a shock collar. I do not use them, but I understand their uses in dogs who are animal killers or need to be proofed against poisonous snakes.

How this works is that the experienced handler uses the collar in such a way so as the dog does not associate the shock with either the handler or the collar, but with the animal itself which you want to proof the dog against.

Harsh though it may be, I can't get the vision of that poor cat in your original post out of my head. []

I agree with Angelique. If it's gotten to the point where you can't desensitize him to being around cats (or that would be too risky to begin with), consult an experienced trainer about using an e-collar. Please do as much research as possible about the proper use of e-collars, and make sure you get a trainer who will not use it in an abusive/nagging way. Other than that, you just have to make sure he has no contacts with cats. 

Your dog has a high prey drive.

I would keep in mind that this is pretty normal. Dogs are predators, they are made to be out there killing small animals and eating them.

And I would make sure the dog is on a leash in your neighborhood, or other places where cats are around. Just because it's normal doesn't mean that you don't have to control your dog.

I think that just leashing a dog is easier than getting into the intricacies of e-collars. It is really really important to use an e-collar well. And while I am sure it was terrible to watch, I wouldn't get too upset about it. Your dog doesn't have to get put down. Your dog does need to be managed around cats. A lot of dogs do.

Oh my heart goes out to you - I can only imagine how you feel.  Just remember that there's really no way you could have foreseen how far he'd take his prey drive.
Can you describe what you mean by "he's not as soft" as he was before this incident.   

This is normal behavior, unfortunately for the cats and the people who love them. If my dogs weren't on leashes at all times while outside they'd do the same thing if they could get their paws on a cat (the neighborhood cats are all well aware that our yard is a no trespassing zone). Keep in mind, however that I actually have two inside-cats that the dogs live with quite happily. But something about being outside activates the prey drive of dogs who are even able to live well with cats inside.

I'd only go the e-collar route if there was something preventing you from keeping this dog on a leash when he's outside, or if he is constantly escaping from the house to go and attack cats. And even if it's the latter, there are ways to train a dog to sit and wait whenever a door to outside is opened so he doesn't bolt out whenever someone opens a door. E-collars are typically used to break dogs of running a particular kind of prey when the dogs are constantly in situations that give them the chance to engage in the behavior (working farm dogs and chickens, hunting dogs and dangerous animals such as wild boar--in both cases the dogs in order to do their jobs must be off leash and in close proximity with the unwanted prey). If the dog doesn't get a chance to get out without a leash, there's no need to use an e-collar because you will always have control of the dog via the leash.

i have scars from prying a cat out of the jaws of my otherwise lovely and wonderful boy, tek.  this cat wasn't killed (thankfully), but it would have been.  i'm sorry you had to see that, and i'm glad your neighbors have been understanding.  i was shaken to the core after my cat incident, so i know how you feel.

while there are surely some people here who think this is a training issue, i happen to think that there are some dogs who just cannot control themselves in the presence of prey.  i suppose that with comprehensive and intensive training, it could be possible to redirect the prey drive, but you would always have to be one step ahead of your dog- always knowing where the cats were, and sometimes that's not possible.

i agree with everyone else here: you need a management solution.  it's up to you now to supervise your dog all the time, and to remove him from potential prey drive triggers.  example:  i left one of my backyard windows open.  tek was surveying the yard and a cat waltzed through.  he broke through the screen to get at the cat, and proceeded to chase the cat over a 5 foot fence through the neighborhood.  the only reason the cat got away was because it ran under a house.  he would've had it.  and he could've been killed by a passing car, or shot be someone who didn't like him on their property.  there even came a point when i leashed him in my own backyard for fear he would see a neighborhood cat and jump the fence.  the point is, i THOUGHT i had him under control.  i was home... i had no way of knowing he would break through a screen.  moral:  no more open windows in my house.  ever.  sad, but i had to weigh my comfort against the life of my dog......

This is normal behavior, unfortunately for the cats and the people who love them. If my dogs weren't on leashes at all times while outside they'd do the same thing if they could get their paws on a cat (the neighborhood cats are all well aware that our yard is a no trespassing zone). Keep in mind, however that I actually have two inside-cats that the dogs live with quite happily. But something about being outside activates the prey drive of dogs who are even able to live well with cats inside.

 
I am sorry that you had to go through this situation.
 
I am right inline with Houndlove's post... my two greyhonds would kill ANY outdoor cat in a heartbeat and yet they live with 2 indoor cats. You cannot blame the dog for doing what he did but you muct be able to manage this situation better. I guess I am not quite clear...are you saying that your dog is an "indoor dog" that got out or is your dog primarily outdoors??    
 
 

My lifelong best buddy, a 14 year old cat named Perry was brutally killed by 3 off leash dogs about 8 years ago. I was devistated and really hated dogs for a while after that. Kudos to you for being a sensitive neighbor, and kudos to your neighbors for being understanding. In my situation the dog owners were jerks, they hid their dogs to weasel out of paying the $300 emergency vet fee I paid to try to resuscitate the cat.

Well, now I am absolutely in love with my new dog (cattle dog/chow/x), and she would be more than happy to take down a cat. [] I never saw this coming! I've already seen her take down a possum, not pretty. I am proactively desensitising her to cats by putting her near them, on leash, and calming her. She's getting less reactive. I thought that since she'd already tasted blood with the possum, this wouldn't be possible. I'm also teaching her to "watch" rather than lunge. While my dog may never be "reliable", I feel good about our progress.

Angelique: I'm guessing the ecollar is sort of the Hummer of corrections. We'll be exposed to it in snake aversion training this month (snakes are something I WANT her to be AFRAID of). It never occured to me to consider it for cat aversion!

I hope this question is productive for this thread topic, and helps the OP, too:
I've been using treats/praise to calm my dog during desensitising sessions, and we're making progress. However, when I taught "wait" at street crossings, I did it with a leash correction and harsh voice, because I WANT her to be AFRAID of the street. It turns out that "wait" is her most reliable command/cue. What would be the downside in using corrections to train for cat aversion? I actually would like to have a cat again someday, so I'm trying to reason out the long term effects of corrections vs counter-conditioning regarding prey drive.

I don't see why he'd have to stay outside for the rest of his days; instead, maybe you could train him to wait before going out the door? Practice having him sit and wait to be invited to go outdoors, so he will be less likely to sneak out after a cat.
 
Is your backyard fenced? This would allow him an off-leash space without the worry of having him go after any other cats.
 
Good luck!