Why dont you try a Mikki muzzle they can still whoof so to speak but not full on bark..they can still drink water with them on but should not be left unattended for long period's..
http://www.google.co.uk/search?q=mikki+muzzle&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=IozrTqW9FM_e8QOw-rihCg&ved=0CIgBELAE&biw=1280&bih=854