Respiratory Mask and Valves for Dogs

The units to be described were developed in this laboratory for the purpose of collecting expired air of unanesthetized, trained dogs. The avoidance of leaks, minimization of resistance to breathing and of dead space were prime factors considered in designing the apparatus. No new fundamental principles are involved; rather, the apparatus embodies good features of older designs, eliminates some of the bad and utilizes new devices, to our knowledge never previously described.

Mask. The mask consists of a copper wire frame, on the order of carefully shaped commercial wire muzzle, made to fit loosely the snout of a 15 kg mongrel hound. The nasal end is projected about 1” beyond the nose and fitted with a No. 9 stopper with a single 3/8” bore. The open end is bent to fit the snout near the lip corners with about 1/4” clearance. Eight longitudinal wires spaced evenly around the frame serve to give good support and shape to the covering material. The finished frame (Fig. 1) is wrapped with 3 or 4 thicknesses of plaster bandage, allowed to dry overnight and soaked for an hour in melted paraffin. A latex surgeon's glove, size 8, from which the fingers are removed is stretched over the open end of the mask and secured by wrapping tightly with string and brushing with molten paraffin; about 3” of the wrist end of the glove is allowed to project as a sleeve. In use, the sleeve is stretched over the dog's muzzle to beyond the lip corners and invaginated into the mask by sliding the latter toward the eyes. Two rubber strips cemented to the end of the sleeve and tied together behind the ears prevent rolling of the glove and exposure of the lip corners during a measurement.