My daughter is raising service dogs (for autism). We are told that there is a 40% failure rate in training. The lady who runs the organization has tons of stories of dogs who washed up, usually in training, but some after completion. The ones who have to be “pulled” in late training or after usually have a bad experience that “ruins” them for their job.
She had a particularly sad story about a young seeing-eye dog who was attacked by another dog while in harness (and unable by circumstance and training to defend itself). Despite a lot of additional work with this promising dog, it had to be retired.
(Here I was going to go long about my family’s experience with dog raising, but then I realized that it was not to the point…
Quick precis: Our first dog washed up in traing and is now our “forever” dog. We are training a second dog who should finish training in a few months.)
A friend of mine had to “forcibly retire” a guide dog who was simply not good at his job after several months on the job. He had teenage kids, so was able to keep the dog as just a dog, and was still assigned another guide dog. He may have been higher priority since he works full time, but I once knew another blind woman who had three labradors - one her guide, one her retired guide, and one who was supposed to have been her guide but didn’t work out.