More striking and pathognomonic than the above is the extreme hyperæsthesia and irritability which rouse into activity or aggravate the symptoms under the slightest cause of disturbance. The effort required to feed from the ground, the stretching of himself to urinate or defecate, the rustling of straw litter under his feet, loud talking, or other sudden noise, banging of doors or windows, hammering in the vicinity, a current of cold air, a flash of light, moving the patient in the stall, attempts at mastication, simple handling, administering medicine, or sudden jerking of the head upward promptly brings on a paroxysm of spasm. Pushing the head suddenly upward or jerking on the halter, is often resorted to as a means of diagnosis, the sudden resulting rigidity of the muscles generally, the rolling of the eye, its retraction toward the depth of the orbit and the protrusion of the membrana nictitans over one-half, one-third or more of the cornea, bringing out the diagnostic symptoms in a striking manner. In very severe cases the head may be drawn upward and backward almost to above the loins (Henry), or one or more of the dorsal or lumbar vertebræ may be broken or crushed (Zundel). A sudden loud noise will sometimes cause the exhausted animal to drop to the ground. Perspiration is not uncommon. Breathing is usually accelerated, the encrease being in ratio with the violence of the spasms. Pulse and temperature are usually normal at first and may be in slight cases throughout. Even in severe cases the pulse does not rise so much as the respiration. In violent and fatal cases the temperature often rises excessively before death (104° to 110° F.). When the jaws are not absolutely closed, the tongue is often wounded by the teeth, and, in any case is covered by a tenacious mucus, which may hang in strings from the lips. If the jaws are still movable, mastication is still carried on, but slowly, painfully and imperfectly, and deglutition is more or less difficult. Young animals are unable to suck.