and sort of surprised your other dogs haven't started to have problems.

You should ask the Vet for Capstar. After administration any flea that bites dies instantly during the first 24 hrs. Then administer Program which will sterilize any female flea that bites. Heart worm medications such as Sentenal have the Program incorporated.

Dogs with cataracts will usually try to stay close to their owner, as they are uncertain of their environment. Dogs can partially navigate with their whiskers, although cats seem to do better in that regard.

With the history of the rotting teeth the chances are this dog will probably die very suddenly from a heart attack (e.g. heart valve damage from bacterial infections caused by the gum disease).

As long as the dog seems content around you, and isn't suffering weight loss (e.g. anorexia), or in pain then let time take its course.