My guess is, is that the waiting lists for these dogs are long long long. Also, many of the dogs are usually adopted by their handlers. You need to consider the amount of exercise that your dog is going to need. Your profile says your are disabled and a GSD often times needs a lot of strenuous exercise - ours takes several miles of running on an ATV at 20+ mph to really wear him out. A retried police/military dog really isn't that old - usually just too old to be at their prime for their job. If exercising your dog will be an issue - you may want to consider a small breed or a senior dog. If you are worrier about being home alone, a bark is a bark and can deter any one and a wet nose for comfort is the same on a yorkie as it is on a golden retriever
You may want to consider contacting a local rescue group with your needs/wants/concerns and they can help you - maybe you can even foster some and get an idea of what kind of dog is really the right kind of dog for you. If you are really set on a retired police/military dog - I would say just google it and you should find several organizations.
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