Part 138

This view would imply that in ordinary cases (inoculation with a moderate amount of the poison) the virus is for a time localized in the vicinity of the wound; and this is further supported by the fact that thorough excision and cauterization of the wound some time after it has been received is still often protective. It is weakened by the fact that bites of dogs in the stage of incubation sometimes produce rabies, but it must be borne in mind that there is still a period between the passage of the living germ to the salivary glands and brain and the growth of the germ in the nerve-centres, so as to produce pathognomonic symptoms, during which both blood and saliva must be virulent.

The ratio of successful inoculations to the bites is very varied. Thus, out of 555 dogs reported to have been bitten by rabid dogs, 188 contracted rabies; out of 183 experimentally exposed till bitten or inoculated, 91 became mad; out of 73 cattle bitten, 45 became rabid; out of 121 sheep bitten, 51 succumbed; and of 890 persons bitten, 428 took hydrophobia (48 per cent.). Of 440 bitten by rabid wolves, 291, or 66 per cent., took the disease. Such statistics are, however, far from satisfactory. Of dogs {894} reported mad, some have only suffered from epilepsy, convulsions, or colic, while of those bitten by the really mad dog, some have sustained simple bruises without any real abrasion; in other cases the teeth have been wiped clean by passing through thick wool, hair, or clothing, or even the flesh of other animals just bitten; in other cases the bite has been inflicted at a time when the virulence of the saliva was at its minimum, or in a subject which was naturally insusceptible. The protective effect of clothing was well illustrated in a case which came under my notice in London. Six animals bitten by a rabid dog all contracted rabies, whilst a man bitten a few hours before through the coat-sleeve, and who did not have the wound cauterized for a full hour after the bite, escaped. Bouley found that in 32 persons bitten in the face, 29 died of rabies (90 per cent.); of 73 bitten on the hands, 46 died (63 per cent.); of 28 bitten on the arms, 8 died (28 per cent.); of 24 bitten on the lower limbs, 7 died (29 per cent.); of 19 bitten on the body (usually multiple wounds), 12 died (63 per cent.). The high mortality from the bites of rabid wolves and skunks is mainly due to this habit of attacking the face and hands. As illustrative of insusceptibility may be quoted the poodle of Hertwig, which was inoculated nine times with unquestionably rabic virus without effect; also the pointer of Rey, which was seventeen times bitten by rabid dogs without harm; also the acquired immunity of Galtier's sheep and rabbits, above referred to.

INCUBATION.--In the dog this varies from 6 days (Pasteur) to 240 days (Bollinger). In the majority of cases it ends in from 20 to 50 days. Pasteur, by inoculating into the brain substance direct, reduced the incubation from 20 days to 6 days. In the horse the limits of reported cases are from 15 days to 92 days. In the ox incubation varies from 20 to 30 days; in sheep, from 20 to 74 days; and in swine, from 20 to 49 days in recorded cases.

In man incubation is believed to be often much more prolonged. In 6 per cent. of all cases it is from 3 to 18 days; in 60 per cent., from 18 to 64 days; and in 34 per cent. it exceeds 64 days (Hamilton, Thamhayn). Quite frequently symptoms of hydrophobia appear from three to six months after the bite; in a few the period is prolonged to one or two years, and in rare instances to seven (Schule), and even twelve years (Chabert). But all such cases of prolonged incubation in man are at the least extremely doubtful. Man often contracts a pseudo-hydrophobia as the result of fear, and is curable by moral suasion alone; and as no such protracted incubations are noticed in the lower animals, and as no one of these abnormally deferred attacks in man has been verified by successful inoculation on animals, it is prudent to reserve a full assent until they are supported by better testimony. A specimen of such cases is that recorded by Chirac, in which a cadet bitten at Montpellier afterward spent ten years in Holland, and then, returning and hearing that his fellow-cadet bitten by the same dog had died of hydrophobia, he also manifested the disease and died. Another is the case of a man who, after having been bitten, spent two years in prison, and then developed hydrophobia and died. A mind naturally erratic and rendered weaker and more susceptible by prolonged confinement would prey upon itself and exaggerate the danger when the subject had been forcibly presented. In all such cases the attending physician should feel bound in the interests of humanity to {895} inoculate a dog or other animal and ascertain whether or not the disease is virulent. The value of such results in dealing with future cases of the same kind cannot be overestimated.

The period of incubation appears to be relatively shorter in the young (average 45 days) than the old (average 70 days), and is believed to be shortened by constitutional excitement from violent passion, fever, the heat of the weather, or electrical disturbances.

During incubation no sign of the disease can be detected; it is even said that the wounds heal with unusual rapidity; but it is certain that toward the end of the latency the cicatrix, alike in man and animals, tends to become sensitive, itchy, congested, and even the seat of papular eruptions. The vesicles (lyssi) which, according to Xanthos, Marochetti, and Magistel, appear near the opening of the sublingual glands within a few days (6 to 20) after inoculation, have not been found by any recent observer.

SYMPTOMATOLOGY.--Three forms of rabies in the dog are recognized--the furious, the paralytic, and the lethargic. The prodromata are, however, the same in all, so that these may be conveniently considered before the different types are noticed.

The premonitory symptoms are by far the most important, as if these are recognized the dog may be safely secluded or destroyed before there is any disposition to bite. Any sudden change in a dog's habits or instincts is ground for suspicion. Bouley well says that a sick dog is always to be suspected. In some cases there is unusual dulness and apathy, in others great restlessness, watchfulness, and nervousness. A morbid appetite, in house-dogs a tendency to pick up and swallow straws, thread, paper, pins, and other objects, or to devour their own dung and urine, is highly characteristic. A desire to lick cold smooth objects, as a stone, a boot, a piece of metal, or the nose of another dog, is often seen. Smelling and licking the anus or generative organs of another dog and the exhibition of sexual desire are frequent manifestations. An increased fondness for the owner, shown by fawning and licking, is occasionally seen, though more commonly there is a change from a formerly amiable temper to a morose, sullen, retiring, and resentful disposition. If a naturally quiet dog flies into a violent passion at the sight of another dog or a cat, and attempts to bite it, he should be carefully watched. If a social dog seeks seclusion and darkness, or if while crouching and shrinking from a blow (hyperæsthesia) he yet bears it without howl or whine, he is to be strongly suspected. Barking without object, constant moving, searching, and scraping, a disposition to tear wood, clothing, etc. to pieces, and, above all, an absence from home for a day or two, should beget grave apprehensions. The rabid bark or howl which is often heard early in the disease is hoarse, low, and muffled, partaking of the nature of both bark and howl, the first running into the second, and consists of one loud howl followed by three or four others progressively diminished in force and uttered without closing the mouth. Some rub the chaps with the forepaws as if to dislodge an offending body from the mouth; others reject bloody matter by vomiting; and others turn the head and eyes as if following imaginary objects, and snap at them. Finally, a tendency to bite, rub, or gnaw the wound is significant, and usually draws attention to the fact that the wound, long healed, is still red, sensitive, and swollen, {896} or even papular. The conjunctivæ are usually congested, there is an increased nasal defluxion, and the skin of the forehead and over the eyes is drawn into wrinkles. This stage lasts from a half to two or three days.

Following one or more of the above symptoms, paroxysms of wicked fury come on, alternating still with periods of quiet, in which prodromata only are observed. The red congested eyes assume a fixed stare, often squint or roll as if following an imaginary object, at which the dog presently snaps. A paroxysm is ushered in by increasing uneasiness, frequent change of position, and a desire to escape, shown in rushing at the door, tugging at the chain, or gnawing the post and walls of the kennel. The tendency to bite and gnaw is further shown by seizing the straw or tearing to pieces wooden and other articles within reach, or even by the victim lacerating its own body.

The rabid howl becomes more frequent, and the rage and disposition to bite strange animals and persons merge into a mischievous desire to worry all that come in the way, the respect for former companions and friends being steadily lost as the paroxysm increases in violence. Yet for a considerable time the voice of a loved master recalls the suffering animal to some degree of self-control. If free to escape during such paroxysms, the dog expends his excitement in wandering, making long journeys of five, ten, or twenty miles, and flying at every animal or man he meets, especially if they increase his excitement by any noise or outcry. If the victim escapes destruction during one of these wanderings, he returns during a lucid interval exceedingly dangerous, for, though he may recognize or even fawn upon his friends, yet the demon of mischief is even more potent within him, and may be roused to sudden violence by any noise or excitement. The intervals of quiet are attended by a prostration proportionate to the violence of the previous paroxysm, and the animal usually seeks seclusion and darkness, where he may lie dull and torpid, but he may be roused at any time to a renewed paroxysm by any noise, disturbance, the presentation of a stick, or, above all, by the approach of another animal. During the paroxysm the animal is manifestly the subject of acute delirium, has hallucinations, snatches and bites at unreal objects, turns on his best friends, even his master, seizes and holds on to a stick or iron bar until the teeth are detached and the gums lacerated, bites his own body, even amputating tail, testicles, or toes with his teeth; a bitch deserts her puppies or worries them, and all follow the unconquerable impulse to wander and to wound living beings. The victim will sometimes manifest incredible strength in breaking his chain and scaling high walls. Twitchings of the muscles of the face, and even general convulsions, are sometimes seen. Food is usually rejected, or if swallowed is soon vomited. In the course of two or three days the furious stage merges into the paralytic one, first shown by paresis of the hind extremities and a swaying motion in walking, then by paralysis of the lower jaw, which hangs pendent and allows the escape of a viscid saliva. The palsy gradually extends over the whole body--a sure precursor of approaching death, which is rarely delayed beyond eight days, and never more than ten, from the onset. In this last stage the animal has become extremely emaciated, with dry withered hair, hollow flanks, and small weak pulse; he may at first rise on his fore limbs when {897} disturbed, and even attempt to snap, but there is now little danger of a bite. Convulsions may alternate with the paralysis. The result is invariably fatal.

The peculiarity of dumb or paralytic rabies in dogs is that the last or paralytic stage supervenes at once on the prodromata, without any intervening period of acute delirium and fury. The animal is throughout dull, quiet, and depressed, and shows little tendency to bite, to wander, or to restless movement. The excitement of the sexual passion is the same as in the furious forms, and the howl is still emitted, though much more rarely. Soon the lower jaw drops from paralysis, allowing the saliva to drivel from the mouth, and the animal can only succeed in closing it momentarily under the greatest provocation to bite. Paralysis of the hind limbs and of the whole body speedily follows, and death ensues in from two to three days. As soon as the jaw is paralyzed the subject is unable to drink, eat, bite, or bark, and emaciation advances with extraordinary rapidity.

The lethargic or tranquil form of rabies in dogs is manifested neither by furious madness nor by palsy of the jaws, but the nervous prostration is shown in a profound lethargy and apathy. The patient curls himself up, and will not be roused by his master's voice, by any noise, disturbance, or even punishment; he makes no response to the caresses of his friends, and pays no attention to the food or drink they bring him, but remains in his place, growing daily more emaciated and lethargic, until relieved by death toward the tenth or fifteenth day of the illness.

Besides the three typical forms there are intermediate varieties, which are classed with one or other according as the symptoms of that type seem to predominate. The same virus, inoculated, will produce different types in separate individuals, the result seeming to depend more on the susceptibility of the subject than any special quality in the poison. With many notable exceptions it may be stated that, on the whole, furious rabies predominates in hounds, bull-dogs, and other less domesticated or naturally vicious and courageous breeds, while the paralytic and tranquil types attack especially house and pet dogs.

POPULAR FALLACIES.--It is a dangerous delusion to suppose that mad dogs have a dread of water and polished surfaces, that they will not eat or drink, that they froth abundantly from the mouth, and that they run with the tail drooping between the hind limbs. There is no hydrophobia in the dog or other domestic animal. The rabid dog drinks freely in the early stages of the disease, lapping even his own urine; later, he still laps, and even plunges his nose in water, though often unable to swallow; and in his wanderings he swims rivers without the slightest reluctance. The appetite is not entirely lost, though greatly impaired and usually depraved, all sorts of unsuitable, noxious, and disgusting objects being picked up and swallowed with avidity. Frothing from the mouth is exceptional in rabies, and the flow of saliva is rarely seen unless when the jaw is paralyzed and pendent. Carrying the tail between the legs is a symptom of all diseases attended by abdominal pain, and is by no means constant in rabies. During the paroxysms the tail is usually carried erect.

Foxes, jackals, and badgers attacked by rabies lose their natural {898} shyness, enter villages, follow and bite other animals and men, and, like rabid dogs, die in an unconscious and paralytic condition. Wolves are affected like foxes, but are more dangerous because of their power, the ferocity of their attack, and their habit of flying at the face and hands. Rabid cats are more retiring than dogs, and show less disposition to attack, but when they do, use both claws and teeth, and especially on bare portions of the body. The cry is hoarse like that emitted during the period of rut. They usually die about the third or fourth day.

The rabid horse is the subject of violent excitement, nervousness, and fear. There are trembling, loss of appetite, rubbing and eversion of the upper lip, neighing, sexual excitement, and inclination to bite and kick. Delirium may be suspected, but during the paroxysms the true nature of the disease is betrayed by the unconquerable desire to bite, kick, and otherwise injure those about him. He will even gnaw the manger and kick the stall to pieces, or lacerate his fore limbs and flanks with his teeth. In the early stages there is the same tendency to lick and rub the wound, which becomes red and irritable, the same red glaring or squinting eyes, and the same jerking of the muscles, as seen in the dog, and the affection winds up in the same way, in paralysis and death in four or five days.

Rabid cattle lose appetite, become very restless and excitable, grind the teeth, lick the cicatrix, evert the upper lip, and otherwise show sexual excitement, bellow often in a loud, terrified manner, as if still apprehensive of the attack of the dog, paw and scrape the ground with the fore feet, butt and kick viciously, have twitching of the muscles, and finally paralysis and death in from four to seven days. When paralysis is coming on the hind feet are often drawn forward as in inflammation of the feet. The pulse and breathing are accelerated during the paroxysms, but I have not found the temperature raised.

Rabid sheep and goats present the same general symptoms, bleat hoarsely, but viciously, have sexual excitement, nibble the cicatrix, have muscular weakness, emaciation, and paralysis, and die in from five to eight days.

Rabid swine show much fear, restlessness, and excitability, hide under the litter, start violently at noises, grunt hoarsely, champ the jaws, show a great disposition to bite and to gnaw and tear objects to pieces, have dark red, glaring eyes, gape and yawn, and become weak and paralytic. Breathing is often labored, and the mucosæ and white skin assume a dull red or leaden hue. Death ensues as early as the fourth or fifth day.

In Herbivora and Omnivora a paroxysm is usually induced by the sight of a dog--a fact of importance in diagnosis.

Rabid skunks have naturally received but little study. They tend, however, to steal up to men and animals and bite some exposed part of the body, like the finger, ear, or nose, and as stealthily retire. It is claimed that their odorous secretion is suppressed.

Symptoms of Hydrophobia in Man.

In some cases the prodromata are altogether omitted, the disease setting in suddenly with spasms of the pharynx and inability to swallow. More commonly, the premonitory symptoms last from one to three days. The first symptom is often an itching, prickling, or more or less violent {899} aching in the seat of the bite, and even of an aura, a numbness, or shooting pain extending from that point toward the heart. In such cases the wound is red or bluish, and even swollen. In other cases there is chilliness, a general feeling of headache, malaise, and prostration, with lack of appetite or nausea, gloomy forebodings, taciturnity, nervous excitability, and restlessness. That restlessness which in patients cognizant of the consequence of the bite often induces insomnia during incubation, now often shows itself in an inability to keep quiet or to remain in one position or place--the exact counterpart of the initial restless stage shown in the canine patient. The sleep is now even more broken and unrefreshing and disturbed by fearful dreams. The restlessness soon merges into intense nervous irritability. Though devoured by thirst, the patient is afraid of water, and the attempt to drink will cause slight spasms with a sensation of filling of the throat and difficulty of deglutition. Even the air blowing upon his surface produces nervous irritation and apprehension, and a sudden glare of sunshine or other strong light is still more injurious. The pulse is increased in frequency, hard, and small; the breathing accelerated, oppressed, with at times yawning, sighing, or sobbing; there is some redness of the fauces, vascular injection of face and eyes, with, in some cases, dilated pupils; nausea or oppression at the epigastrium, sometimes vomiting; and usually constipation, which cannot, as in dogs, be referred to the earth, sand, and unsuitable materials swallowed. Intelligence is unimpaired.

With or without some or all of the premonitory symptoms above described the patient is sooner or later seized with constrictive spasms of the pharynx and respiratory muscles, the immediate occasion being an attempt to swallow liquid or some sudden fright or excitement. So great is the agony produced by this attack that, though consumed by thirst, the patient will rarely afterward attempt to drink, and the mere sight or offer of water, the noise of liquid flowing from one vessel to another, or even the sight of the vessel in which liquid was contained, suffices to bring on a violent paroxysm. This hydrophobia is peculiar to the human being suffering from this disease, being rarely seen in rabid animals; and it serves to enormously enhance the agony and horror of the affection. During a paroxysm the dyspnoea is usually extreme; there is a gasping or sighing respiration, and shrill, inarticulate sounds or screams are emitted which have been likened to the bark of a dog. These are manifestly due to the threatened suffocation rather than to an attempt to bark. The sensations have been described as a rising of the stomach into the throat, while others felt as if the throat had turned into bone and could not admit nor pass on the liquid. The abdominal contractions are often well marked, and retching and vomiting ensue. This reflex irritability of the nerves of deglutition and respiration is followed or attended by a condition of the most intense hyperæsthesia and a great exaltation of the special senses. A deaf and dumb child is said to have heard distinctly at this stage. There are, besides, during a paroxysm, general muscular trembling and clonic spasms of the muscles of the trunk and extremities. The facial muscles are contracted, the nostrils dilated, the face and eyes red and injected, and the pupils dilated, producing a spectacle of the most intense agony. Even in the intervals the hyperæsthesia is so extreme that the slightest touch of an attendant, a {900} current of air, the approach of a candle, or even the ordinary tones of conversation, produce extreme agitation and may precipitate a violent convulsive paroxysm. The duration of the paroxysms and of the intervals varies much, but in general terms the former increase rapidly in number and severity, while the latter are correspondingly shortened. Restraint serves to aggravate the paroxysm, while, according to Hunter, the earlier and lighter ones may be relieved by running. The intense excitement sometimes becomes manifest in the persistent talking, and it is noticeable that the patient is free from mental delusions. As it is impossible to swallow, the patient spits out the now viscid saliva on all sides--a feature, like the fear of water, peculiar to man. As the disease advances the paroxysms are marked by the most perfect hallucinations and delirium, which impel the victim to acts of insane violence toward every one and every thing about him. In these fits he will use every available means of offence, even to the snapping of the jaws, though on the subsidence of the fit he will often express the greatest regret and warn his victims to be on their guard when he finds another paroxysm coming on. In some few instances the delusions continue even during the remissions, and the patient remains possessed of a sense of suspicion and horror of all about him, and yet the fear of being left alone is usually greater still. The convulsions may become tetanic (as opisthotonos). They are habitually more severe in men than in women and children. During a convulsion the victim will at times become black in the face, and may die from suffocation, apoplexy, or nervous exhaustion.

Should he survive this danger the final paralytic stage sets in. The spasms gradually become weaker, reflex irritability is lessened, and a period of quiet, and even comparative composure, may ensue, during which the former sights and sounds fail to produce a paroxysm, and some patients even recover the power of deglutition; but muscular weakness and prostration become more extreme, the lower jaw may even drop, and the viscid saliva drivel from the lips; finally, stupor supervenes, and the patient dies in a state of profound coma or complete exhaustion. This last stage lasts from one to eighteen hours.

Cases are met with in the human subject, as in the dog, in which the paroxysmal stage is omitted in greater part or entirely. The patient complains only of oppressed breathing, and sighs deeply when he attempts to swallow, and paroxysms, if they occur at all, are very mild. Decroix indeed claims that if a person suffering from hydrophobia is kept in a dark room and perfectly quiet, no paroxysms appear. The malady is, however, none the less fatal.

DIAGNOSIS.--The diagnosis of rabies and hydrophobia is not usually difficult if the disease has progressed to its paroxysmal stage. The most pathognomonic features are the fact of a bite by a rabid animal and the evidence of lesions and an extraordinary irritability of the medulla oblongata, inducing severe reflex spasms of the muscles of deglutition and respiration under the influence of any peripheral irritation. The clonic nature of the spasms and the entire absence of trismus serve to distinguish it from tetanus. From pharyngeal anthrax and diphtheria attended with spasm it is diagnosed by the extreme exaltation of the special senses and the absence of any marked febrile reaction; from acute mania by the difficulty of breathing and deglutition, the more rapid heart-beats during {901} a paroxysm, and by the marked hyperæsthesia and exalted reflex susceptibility, as well as by the perfectly lucid intermissions; and from epilepsy, in that the latter is not associated with the same hyperæsthesia, that the paroxysm is not developed by noise, movement, attempts to swallow, sight of water, etc., that the spasms are more universal, and that they do not recur often, nor can they be roused by the causes immediately producing those of hydrophobia. Hysterical cases can usually be recognized by the imperfection of the symptoms; the subject, not knowing all the manifestations of hydrophobia, naturally fails to produce them.

The most difficult to distinguish from the genuine disease are those cases in which hydrophobia occurs as a disease of the imagination, the result of fear--the lyssophobia or hydrophobie non-rabique of the writers. In these there is always the history of a bite; the cicatrix even may have become the seat of congestive redness, itching, or neuralgic pains, and these, acting on a susceptible brain, develop a disease which is hardly distinguishable from true hydrophobia, and which is quite as fatal if left to run its course. These cases have usually less reflex susceptibility than genuine hydrophobia; the attack mostly occurs shortly after some conversation on the subject, and especially about the effects of the bites on others; and the victim is seen to have a nervous organization, and may even be known to have been subject to hysteria or other nervous disorder. At the same time, the concentration of the mind on this subject sometimes produces even structural changes in the medulla, and the reflex susceptibility in co-ordination with the other symptoms may be almost perfect. In a case reported a few years ago by Hammond the symptoms appeared perfectly characteristic, and at the necropsy circumscribed points of congestion were found near the roots of the vagus; yet the dog that bit this man was said to be alive and well, and in the absence of any successful inoculation from biter or bitten the case must be presumed to have been lyssophobia.