Mom's dog is gone. What should I expect?

Mom is in assisted living where each resident has their own apartment. There a lots of activities, shopping opportunities ect. She has however self isolated herself often just sitting with the dog. I recognize this could opportunity for her to get out and socialize with others. She has routinely fought this and refers to herself as not being a "joiner."

i think she will be fine one the initial mouring period is over. She made the decision herself it was not forced on her which is an important part of this. Get her a nice photo of the dog in healthier times if you think this might help. if she wants to talk about it just let her. The dog was a big part of her life and to her it was like loosing a person. Let her cry after all she is mouring and that should be respected.

Your mom made the right decision to have the dog put down. Too often, people let a terminally ill animal suffer because they can't bear to be parted with it.
She'll probably grieve for awhile, but that's natural. Getting another dog would be a bad idea, in her condition, but maybe she'd enjoy visiting with someone else's dog?
You didn't mention what her current living situation is, but she might benefit from the distraction of going to a senior center, and having people her age to talk to. Isolation is bad for depressed people.

Thank you, we were at the Dr yesterday. Loss of the dog was discussed and the current Meds should suffice.

Maybe I'm over thinking this, but just wondering what others have experienced.

Call mom's MD and ask about anti-depressant meds.