I'd love to send this one in an email to this guy ...
Ok so I've said it once, I'll say it again. If you have a dog that's reached it's senior years, you should keep it for the last few it'll be around!! It's selfish of you to try to get rid of her at this point and it's even worse on her - you'll likely break her heart if not her spirit. Here's an ad from a person who has an 11 year old JRT who is admittedly agressive towards other dogs!! She's free to a good home.
Come on, are you really that stupid? How can you be such an asshat?? Even if you are able to find someone to take your old, dog agressive *DA* dog, do you really think they'll keep her around if she snarls, barks, lunges, or anything else at any other dog?? What about kids? Other people? Cats? How long do you really think she'll last?
If you take her to a shelter, chances are good that they'll euthanize her if she shows agression. Unless you were to take her to a No Kill, which are few and far between and even then there's not really a good guarantee. How long before she shows her DA and is forced to redirect her frustration on the handler? Not all No Kill shelters have people who are trained to work with these dogs (and I for one already have a full house and a waiting list!).
If you've kept this dog this long than why not keep her around? You've shown that at one point you did want her. She's probably going to want to rest a lot of the time since she's older. She won't need as much exercise now as she once did anyway!
Good grief. She's small. You could always crate her in a large sized dog crate in the back seat of your vehicle for the time you're at work. Then take her out at your scheduled breaks (you're in Ontario which means that by law you should have two 15 minute breaks and one 30 minute minimum if you are working 8 hours a day). Then walk her when you get to work and when you get off work. She'll probably have more walks doing this than normal for her anyway! Give her access to water and crack a window in your vehicle. Yes, this is easier done with vans, SUVs and other cars with back hatches, but it's entirely doable.
Don't give me the line about how that's "cruel". Do you crate her when you leave? Do you lock her in the house when you go to work? Your house is just a large crate with some comfy couches she can use as dog beds - nothing more. Give her a soft bed to lie on in the crate and she'll be just as happy. Taking your dog to work and keeping it in a crate in the car (if not just in the car w/no crate) is just as "cruel" as leaving it at home. The only difference is the temperature - cold in the winter, hot in the summer. You make sure the dog always has water and a cracked window (if not two or three) and it will be quite comfortable - though your windows may be foggy when you get back.