=Dog Mask.= The use of dogs in messenger service and in Red Cross work, in which gassed areas must be passed, led to the designing of a mask to give the animals suitable protection. The same materials and method of impregnation were used as in the horse mask. With eight layers of cheesecloth, adequate protection against mustard gas was secured with practically no pressure drop. The eyepieces were made of thin sheets of cellulose acetate bound around the edge with adhesive tape and sewed directly over openings cut through the mask fabric. The ear pockets were made round and full enough to fit pointed or lop-eared animals. The mask is continued to form a wide neck band which may be drawn up by two adjustable straps. It is made sufficiently full to allow a free movement of the dog’s jaws and yet tight enough around the neck to avoid the possibility of being pawed off. The dog apparently soon became accustomed to wearing the mask. =Horse Boots.= The increasing amount of mustard gas used on the Western front made it seem necessary to develop some form of protection for the horse’s hoof and fore-leg. It has been found that mustard gas vapors attack the fleshy portion of the leg, especially around the coronary band and causes inflammation of the frog of the foot. The problem was solved by devising a special hoof pad and a boot. The pad was made of sheet iron imbedded in a hoof protector (composition rubber) to which the shoe is applied. The shoe just overlaps the metal plate on the inside and provides a solid metal surface for the bottom of the foot. Such a pad not only offers protection against gas but against shell splinters, barbed wire, etc., and would be useful at all times on the front. [Illustration: FIG. 84.—Impervious Boots and Pads to Protect Horses’ Legs and Hoofs against Mustard Gas.] [Illustration: FIG. 85.—Protective Gas Outfit—Gas Mask, Gas Suit, Gloves, Boots, Horse Mask, Horse Boots, Horse Pads.] The boot was made of satin, treated so as to be impervious to mustard gas. It covers all of the foot except the bottom and extends to just below the knee. The boot is held in contact with the hoof by a sewed cloth strap, which passes around the bottom of the hoof and is held in position by projections extending from the spur or toe clip. Special care is taken to insure a perfect joint at the rear of the boot since the small cavity in the back of the hoof is one of the most sensitive parts. The boot is wrapped about one and a half times around the leg and is clipped with five loops through which passes a ¾-inch strap.