Hey there.
I’m so sorry to hear about this. It’s not easy, watching our pets go slowly.
After Dr. Magnifico posted about this awhile back, I had a list of Things my cat liked to do. As the list shrank, I knew we were closer and closer to letting him go. My list included eating, drinking, cuddling, playing, etc. I would make a similar list for your dog, and monitor based on that.
For the puppy, I would honestly keep them separate when pup is acting like a puppy. This could be as simple as tethering him to someone when he can be supervised (something I recommend anyway for the first 6 months to help with housebreaking and general naughty behavior) and crating when he can’t.
Hello. This is a question for a veterinary nutritionist. Maybe the folks at balanceit.com might be helpful?
Thank you!