Metabolism Masks for Dogs

Abstract

In energy metabolism experiments in which the same dogs are used for a year or more, it is desirable to have masks which are sufficiently durable to be used for all of the experiments, and which fit the individual animal, therefore causing a minimum of dead space. These ends are readily accomplished by making the masks on casts of the heads to be fitted, by a method similar to that which is used by makers of orthopedic appliances.

The lower jaw of the animal is padded from the angles to the snout with a piece of felt, one half inch in thickness. The felt is secured by means of a gauze bandage which also binds down the ears. Stockinette is drawn over the animal's head, and plaster bandages are then applied until a mould varying from one-eighth to one-fourth inch in thickness has been made. After the plaster has set sufficiently the mould is readily pulled off if its posterior portion has not been applied too tightly. The felt pad and stockinette are removed from the mould, which is allowed to harden and is then filled with plaster of Paris mortar. Into the mortar a piece of gas pipe is inserted, to serve later as a handle. When the plaster has hardened, the mould is cut away, leaving a cast of the dog's head. Any modifications desired in the final mask, such as providing more space for the ears, or lengthening the mask posteriorly, can be made at this time by applying fresh plaster to the cast in the appropriate places. Space to permit the animal to open its mouth slightly has already been provided by padding the lower jaw before making the mould.