I can only tell you that if you found his bottle of
methadone, then he is taking
methadone pills. Some people go to a
methadone clinic, and drink methadone in a cup,(or take pills, like yr Dad) but they never shoot methadone with a spoon and syringe, that would be heroin.
Your dad wouldn't be in the bathroom, "doing methadone", and he wouldn't be in the bathroom, fixing the dogs medicine...he would just do that out in the open, like in the kitchen, I would think.