My 10yo rat terrier (have had since 6months old) is ppl and dog aggressive. He bit my 10 month old son twice this summer, no blood but snaps every chance he’s near baby.he has bitten people in the past. He has severe anxiety & is afraid of everything. he’s always been this way. His fur is falling out, he has hard black patches all over, and soft pink skin showing I’m other places. After biting my son’s face, hubby is talking about euthanasia. Is this the right choice?