Part 45

The predominance of the spasm in special groups of muscles has been the occasion of giving different names to individual cases.

Trismus or lockjaw is that condition in which the muscles of the jaws are violently contracted so that the incisors can only be separated slightly or not at all.

Orthrotonos is that condition in which the muscles in tonic spasms keep the neck, back and loins rigid, straight and unbending, in one horizontal line.

Opisthotonos is when the muscles of the spine are in rigid spasm, so that the back and loins are slightly depressed, the tail elevated and trembling, the neck drawn upward with a concave superior border (“ewed”), the head extended and the nose elevated.

Emprosthotonos is caused by spasms of the muscles of the ventral aspect of the body, with arching of the back and tucking up of the abdomen.

Pleurosthotonos is when the trunk is spasmodically bent to one side, right or left.

Spasms of the muscles of the eyeball, cause sinking and apparent diminution of that organ, with the protrusion of the membrana nictitans over one-third, one-half or even more of its front surface. This is often referred to by owners as “hooks”.

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.

Symptoms in the horse. When the symptoms are fully developed, they are very characteristic. The neck is raised, often concave along its upper border, the nose raised and protruded more or less, the nostrils widely expanded, the eyes sunken, fixed and anxious, with diluted pupils and protrusion of the haw outward and upward from the inner canthus, the ears are pricked, rigid, and drawn toward each other at their tips, the facial muscles may stand out visibly and are firm, the angle of the mouth is drawn back, the veins of the head are full and prominent, saliva froths or drivels from the lips, the tail is elevated and during paroxysms will tremble, and the muscles of the back and limbs are projecting and hard. The limbs are extended outward to give a wider base of support. If moved, the general stiffness is at once seen. The patient cannot be turned round in his stall, he may not even be able to turn the neck to one side, and if backed he resists, or accomplishes the movement only with the greatest difficulty. In walking, the limbs are used as stilts with little or no bending of the joints, and if turned, the body is not bent but moved around with difficulty as if one rigid mass. The pulse is small and hard, the breathing slightly hastened, and the mucosæ congested and reddened. The jaws may be firmly closed, or they may still part for a time half to one inch. In all severe cases the patient obstinately stands, and if he should drop, or lie down, the breathing and spasms are usually encreased and, in the efforts to rise, the respiratory muscles may become spastic with promptly fatal results.

In cattle the same general symptoms prevail. The stiffness of neck and back, the habitual elevation of nose and tail, the stiffness of the legs, propped outward for support, and moved like unbending posts when made to walk, the hardness of the muscles, standing out under the skin, the rigidity of the lips, firmly closed or slightly opened, the general fixity of the erect, retracted ears, and the sunken appearance of the eyes with marked protrusion of the haw, are largely as in the horse. The muzzle is usually dry and hot, the jaws clenched, the tongue firmly compressed against the palate and covered with thick, tenacious mucus, and the flanks are often flattened by the contraction of the oblique muscles, so that they descend almost vertically from the lumbar transverse processes. There is great difficulty in turning and the trunk moves in rather a rigid mass without bending laterally, and the limbs are stiff and stilted. Tympany of the rumen sets in early with oppressed breathing and arrest of defecation and urination, which had been already difficult. The reflex excitability to noises, or other causes of disturbance is often less than in the horse. In cases following metritis, this may be due in part to the depressing poisons absorbed.

Sheep and Goat. Show the same general rigidity of trunk and limbs, the drawing of the head and neck upward and backward, the elevation of nose and tail and the firm closure of the jaws. As the disease advances they may lie on the side with legs straitened and rigid and head and tail raised toward the back. The occlusion of the eye by the haw is the same as in the horse.

In swine the spasms begin with the jaws and face, and extend to the neck, back and limbs with the same general symptoms as in other animals. Champing of the jaws and profuse frothing at the mouth have been noted and the protrusion of the haw is characteristic. As in sheep, the animal may lie on its side with head and limbs rigid and an early death may be looked for. Convulsions are easily distinguished by their transient character.

In dogs tetanus is rare. Möller had two cases in 50,000 sick dogs, Friedberger and Fröhner but one out of 70,000. Cadiot saw two cases in ten years of the Alfort clinic. Labat had several cases in sheep dogs. A slight transient trismus has been noticed as common in puppies. When generalized there is stiffness of the trunk and limbs, abduction of the members. The spine may be straight and rigid or drawn upward and backward, and the loins depressed. The haw covers the eye more or less, the lips are rigid, the jaws clenched, and the skin of the forehead wrinkled. The ears are stiff and drawn toward each other, or backward. The reflex excitability is as great as in the horse, the slightest touch or sudden noise producing violent paroxysms. Inability to bark is a marked feature. Temperature may be normal or up to 107° F.

In birds it is very rare, in keeping with the insusceptibility to strychnia, ergot and other tetanizing agents. Dreymann gives one case in a turkey, and Babes’ experimental cases in pigeons and chickens from a specially virulent bacillus obtained from the horse. The pigeons suffered much more certainly and severely than the chickens, in which there was a marked power of resistance. Dreymann’s turkey moved with stiff limbs and body, had the wings clinging firmly to the body, the head and neck extended and the bill firmly closed. The haw protruded over the eye, and there was hurried and oppressed breathing.

Course. Duration. The course of tetanus varies with the genus affected, with the individual susceptibility and above all with the length of the incubation, and severity of the attack. Cases that set in with great violence after an incubation of two or three days or less are likely to advance to an early death. An early generalization of the spasms, with high temperature (104° F), hurried breathing, congestion of the mucosæ and extreme excitability may end fatally in twenty-four hours or within a week.

If on the other hand the incubation appears to have extended over one, two or three weeks; if the disease is at first equivocal, with some stiffness and firmness of the muscles, but with little or no trismus; if the patient can open the jaws an inch or more and masticate even slowly for a number of days after the onset of the first symptoms; if the haw projects only slightly over the eyeball and the excitability is not extreme the prospect for recovery is much better. Such tardy cases may seem to stand still for a week and then have a slight aggravation and this may be repeated, or a slow improvement may set in and go on gradually to complete convalescence. Improvement may be manifested by a softer or more relaxed condition of the muscles, by a slightly freer movement of the limbs and jaws, by a greater ease in swallowing, by encreasing movements of the ears and eyes, by the lessened projection of the haw, by the freer breathing and circulation and by the permanent lowering of temperature to the normal standard. Convalescence is always slow, but especially slow in severe cases in which time must be allowed for repair not only of the central nervous lesions but also of the ruptures and trophic changes in the muscles.

In cattle the disease is usually slow in its progress and improvement may not set in till the close of the third week. In sheep, goats and dogs on the other hand it is habitually acute, and death may supervene from the third to the eighth day. In the horse all forms are met with and the result will vary according to the severity of the attack.

Mortality. Friedberger and Fröhner sets the mortality in sheep and pigs at nearly 100 per cent.: in horses at 75 to 85 per cent.: and in cows at 70 to 80 per cent. In tetanus neonatorum in lambs, the deaths reach about 100 per cent. In this case the disease usually sets in within forty-eight hours after birth, and with a very high temperature difficult deglutition becomes a marked feature, so that if the patient is not speedily killed by dyspnœa, it soon perishes from starvation and exhaustion.

The cause of death is usually asphyxia, hyperpyrexia, or exhaustion.

Lesions. There are no constant or pathognomonic structural changes in tetanus. Those that are found are inconstant and as a rule secondary. A wound (entrance channel) can usually be made out, often in the region of the foot, or in connection with castration. In the new born there is the unhealed navel, and in parturient cows the catarrhal, septic or injured womb. In the seat of such wound may be found the foreign body (nail, splinter, etc.), and some pus or simple congestion or even necrosis. The nerve trunks leading from such infected wound may be hyperæmic. The presence of the bacillus in the wound may be determined by microscopic examination or inoculation on a small animal.

The changes in the nerve centres may be congestion of the horns of gray matter, and there may be slight hæmorrhage, exudation, especially shown in the encrease of the cerebro-spinal fluid, softening, cell proliferation, and granular invasion of the nervous tissue. In separate cases the myelon, the corpus striatum and the cerebellum have shown lesions. The meninges are occasionally hyperæmic. Spinal lesions have been noted especially in the bulbo-cervical and lumbar regions. Exceptionally in the horse there are blood extravasations from fractures or dislocations of the vertebræ.

In subjects dying of asphyxia the lungs and right heart are congested, and the blood may be black, only loosely coagulable and with free hæmoglobin. There is congestion of the intestinal as of the respiratory mucosa, and also of the liver, spleen and kidneys. The congested bladder usually contains urine contrary to what is the case in rabies.

Diagnosis. From strychnia poisoning tetanus is distinguished by the gradual and progressive approach of the spasms and by the absence of the intervals of complete relaxation which separate the rapidly recurring and violent spasms of strychnia. In tetanus the spasms may be modified but never completely intermitted, and more or less stiffness, trismus and protrusion of the haw constantly persist. In strychnia too, the paroxysm is far more intense than in the early stages of tetanus. The spasms of strychnia are general, while those of tetanus are often most intense in particular groups of muscles often at first in the vicinity of the inoculation wound.

From rabies, tetanus is easily distinguished by the absence of any history of a bite; by the persistence of the tonic spasms especially of the masseters and abdominal muscles during the intervals between the more violent paroxysms (in rabies there is temporary complete relaxation); by the absence of clonic spasms which alone occur in rabies; by the absence of the paralysis which characterizes advanced rabies; by the mental clearness and the absence of hallucinations or mischievous disposition which are marked features of rabies; by the absence of the depraved appetite of rabies; and by the fact that the brain does not contain the infecting germ as is the case in rabies.

From rheumatism of the neck (torticollis) tetanus is easily distinguished by the permanent trismus which is not shown in rheumatism, and by the fact that spasms are easily roused by any artificial excitement, indicating an extraordinary hyperæsthesia and excitability which are nearly absent in rheumatism. The steady unmistakable progress of tetanus is in itself diagnostic.

From meningitis tetanus is to be diagnosed by the presence of trismus without impairment of the mental faculties or fever. In meningitis the spasms are usually confined to particular groups of muscles and do not become generalized under active excitement as in tetanus. Even if the spasms of meningitis affect the jaws and pharynx they are rarely paroxysmal or roused by excitement as in tetanus. They may even be clonic.