My dog doesn't react to his shock collar. Is it safe or effective?

I personally recommend against them. Most bark collars work by delivering a shock to your dog, in an attempt to "stop" them from whatever behavior they are doing. However, this often either causes pain to your dog, or starts an association of the shock with other things, such as you, or a nearby child or person, which may cause redirected aggression instead. Instead of shocking your dog when they bark or do something they shouldn't redirection through positive reinforcement is a better option. it can help build a bond with your dog without resorting to pain or fear, and while still stopping the problem. If your dog likes to bark, say, when someone walks past the house, you can instead get your dog's attention with a favorite treat or chew toy, moving them to a different room and refocusing their behavior on that, instead of the person causing them to bark. If they are distracted or upset, refocusing them into a sit or down (far enough away that the stimulus causing them to bark isn't as distracting) can help change the behavior from "bad" (barking) to "good" (sitting), which you can then start to reward if they present that behavior instead of the bark in the future. It does take longer to work with positive reinforcement and redirection training, but the overall result is a change in your dog's underlying behavior, rather than just a band aid that can lead to fear, redirected aggression, and at worse severe injury. If you're curious to work on more positive reinforcement behaviors, speaking with a local dog trainer or animal behaviorist (specialists in behavior training specifically) is best as they can work with you in person on any specific problems you're having.

I'm so glad that you found a good training method for Timber. The problem with shock collars is that often people do not use them correctly. If you are shocking your dog inappropriately, they will get confused about what is going on and everyone will be frustrated with training. When used appropriately, shock collars can be a very effective training method. I'm so glad that it is working well for Timber, so you must be doing it right. Congrats! Thanks for using Petco Pet Education Center, formerly Petcoach!

Shock collars, bark collars, and clicker training are all acceptable ways of training pets. The down side is they are ineffective if not done properly. They are great modalities in the correct hands that know how to implement them and do it correctly to where the dog understands what is being asked of them. Consulting a behavioral/trainer that is experienced is the best way to achieve positive results.

I suggest you try a citronella bark collar as the first option. They work well in most cases and are not harmful. This is not a shock collar. This video should explain more about them and how they work. ( https://www.youtube.com/watch?v=SXwstVpzALY&t=102s )

No, I never recommend shock collars. They are cruel and can make things worse. I also never recommend owners work with aggressive behaviors on their own, it's too dangerous. Jackson needs to see a professional behavioral therapist to help deal with his aggression. Ask his vet on Monday for a recommendation to one. Best of luck.

No, there are no known links between shock collars and cancer that I am aware of. It sounds like a horrible coincidence for your previous dog. I would recommend working with a dog trainer to teach Bailey how to walk politely on a leash. There is also a brand called Gentle Leader that has both a chest harness and a head harness that will help with pulling. They include instructions on proper use so that Bailey learns to walk politely while using the harness.

No. This is not acceptable. If your dog's behavior is so severe that you are considering this type of punishment then I suggest you seek the help of a professional dog trainer or re-home the dog to someone that can potentially get the dog trained. This time of punishment will only make things worse and is cruel.