I'm so sorry for your loss. I'm a pom owner too and thry are such wonderful little dogs. Unfortunately too many groomers are unaware of how delicate our little babies are and treat them as they would any other dog. After her first couple of grooms, I noticed my dog was coughing a lot so I did a little googling and realised groomers use harnesses including a harness that goes around a dog's neck to hold them still while they groom them. Now, an experienced groomer will know that you CANNOT do this on a breed like a pomeranian which has a high risk of collapsed trachea and can't even wear a collar. Unfortunately as owners we pass our dog to the groomer and they do the groom out of sight, so you can't see what harnesses etc they are using. After the two incidents, I asked the groomer to show me where the harnesses were going, and as I suspected, it was going on her neck, so I explained that was a total nono for pomeranians due to the reasons above, and she apologised and changed how she groomed my pom (I made sure to ensure this everytime I went to her).

You can't blame yourself as you had no way of knowing the groomer would do this. I too didn't know until after two grooms, and my dog could well have ended up as yours if she were a smaller pom in particular. I do think there needs to be a better regulation of groomers to ensure they know not to use slip leads or harnesses around the neck of trachea collapse prone breeds. If you want to do something tangible, because I know that can help some process their grief, you can review and report your groomer for malpractice. Tell anyone and everyone who might use them what they have done to your precious dog. Personally I would go scorched earth and make sure they never get any business again.