iM3 Soft Anaesthesia Masks. Available in five sizes with replaceable diaphragms. Bird/Rodent – this is our latest mask, designed for birds and rodents. Cat – designed (with low dead space) for quicker mask downs, also suitable for small rabbits. Small – slightly larger than the cat mask, used for small dogs, rabbits and large cats. Mask induction for dentals means quicker recovery. Long Nose – medium sized dogs with (you guessed it) long noses, and of course low dead space for quicker mask downs. Large – suits a wide range of animal sizes including large breed dogs. Also available in a complete set of 5.