Hydrophobia (Gr. water, and fear; Lat. rabies canina, canine madness), a rare but well marked disease in the human subject, characterized by excessive nervous excitement, the secretion of an unusually viscid saliva, a difficulty and sometimes a dread of swallowing liquids, and a rapidly fatal termination. It is caused by inoculation from the bite of a dog, already in a similar rabid condition. Although hydrophobia in the human subject is so infrequent that many practitioners of considerable experience have never met with a case, it is still of sufficient importance to merit serious attention, and to demand every possible precaution for its prevention ; particularly since, when once developed, it is invariably fatal, no single well authenticated case of recovery having yet been recorded, and because the affection itself is so terrible in the distress suffered by the patient, and the horror which it excites in the minds of the spectators. In France, with a population of 36,000,000, during the six years from 1853 to 1858 inclusive, there were 107 cases of hydrophobia, or one case annually for every 2,000,000 inhabitants.
In the department of the Seine, with an average population of upward of 1,000,000, during the 40 years from 1822 to 1862, there were 94 cases, or a little more than 2 1/3 per annum. The greater proportional frequency of the disease in the metropolis and its immediate vicinity is no doubt due to the greater concentration of the population, both human and canine, which would of course be favorable to its communication from one animal to another and from animals to man. In the city of New York, with a population of 1,000,000, during the six years from 1866 to 1871 inclusive, there were 22 cases, or an average of 3 2/3 per annum. - When a man is bitten by a rabid dog, the wound does not differ in any visible character from that inflicted by a healthy animal. It is seldom severe and often slight, the animal frequently making only a single momentary attack. The wound thus made heals without difficulty, and is not especially painful or otherwise troublesome. In a majority of instances no further trouble comes of it. The danger from the bite of a rabid dog consists in the inoculation of the animal's saliva, which, owing to the disease under which he is suffering, contains a subtle but communicable organic poison.
But there are various circumstances which may interfere with the poison's taking effect. First, the individual may be, habitually or at the time, insusceptible to its action. There is reason to believe that the human species as a whole are decidedly less susceptible to the poison of hydrophobia than dogs; and according to the experiments of M. Renault, at the veterinary school of Alfort, the proportion of dogs themselves, bitten by a rabid animal, who afterward become rabid, is not more than 33 per cent. Secondly, when the bite is inflicted upon parts of the body covered with clothing, the saliva, which is the only vehicle of the poison, may have been arrested by the garments and may not have come in contact with the wound at all. Thirdly, the poison may have been extracted from the wound immediately afterward by the free discharge of blood; or by the instinctive manipulations of the wounded person, or may have been neutralized by surgical appliances. At all events, statistics seem to show conclusively that the bite of a rabid animal by no means invariably causes hydrophobia. M. Bouley, professor in the veterinary school at Alfort, estimates that in the department of the Seine no fewer than 100 dogs annually become rabid.
In 25 cases of hydrophobia recorded at Alfort in the year 1861, 10 of these animals were known to have bitten 15 persons; that is, 15 bites had been inflicted by 25 rabid dogs. This would give, for 100 dogs annually affected by hydrophobia, 60 persons bitten during the same time. But there are only from two to three cases of death from this disease annually in the department of the Seine; and, according to these results, not more than 3 in 60, or 5 per cent. of the persons bitten by rabid dogs, afterward become hydrophobic. But even this proportion of cases constitutes a terrible danger, considering the nature of the disease with which the individual is threatened. - For some time after the infliction of the wound no symptom manifests itself. The poison may have found its way into the tissues, but it is quiescent, and it remains so usually for several weeks. The exact period during which it may thus lie dormant, and afterward become fully developed, undoubtedly varies in different cases. Instances have been related in which hydrophobia has declared itself after an interval of several years, but these statements are evidently wanting in authenticity, and are almost universally regarded as extremely doubtful.
It seems positive, however, that the period of quiescence may be extended to one year, and possibly to 17 or 18 months. Nevertheless these instances, if they exist, are very rare exceptions; and in the immense majority of cases the disease shows itself, if at all, between the end of the first and the end of the third month; so that after the lapse of three months from the date of the injury, the chances of escape increase rapidly with every succeeding week. By the end of six months the patient may be pronounced practically safe. When, however, the disease is to show itself, usually during the second or third month, its first manifestation is a sense of itching or discomfort at the seat of the wound. The cicatrix may become swollen and reddened, and a red line, following the course of the lymphatic vessels, is said to appear upon the limb, between the cicatrix and the trunk. This is the preliminary period of the disease, and may last for two or three days, rarely more than six, during which the patient is only slightly uncomfortable. - Then the unmistakable signs of hydrophobia come on with great rapidity, and are aggravated from hour to hour. There is a feeling of stiffness about the neck, extending to the jaw and the base of the tongue.
An indescribable anxiety and agitation of mind takes possession of the patient, often accompanied with paroxysms of momentary delirium and hallucinations. The breathing is hurried and irregular. There is great thirst; but there is also a difficulty of deglutition, apparently consisting in an irresistible spasm of the pharynx or glottis, which is so distressing that the patient sometimes rejects fluids after vainly attempting to swallow them, with violent de-.monstrations of irritation and despair. This is what has given rise to the idea that the patient dreads the liquid itself, and has unfortunately attached the name hydrophobia to the disease in question. The saliva becomes remarkably viscid and tenacious, and appears to add much to the distress of the patient, who endeavors constantly to detach it and expel it from his mouth. This condition of nervous irritation rapidly exhausts the strength of the system, and death takes place, usually on the second or third day. - Such are the symptoms and course of hydrophobia in man. The treatment includes only a single measure, but this must be adopted at once on the receipt of the injury, and must be carried out in the. most thorough manner. It consists in neutralizing the poison by cauterization of the wound.
Some authorities recommend first cutting out the wound by an incision passing all round it through the sound flesh, and subsequently cauterizing the fresh surface. The objection to the procedure is that it requires some time and skill to perform it thoroughly, particularly as the wound is generally narrow and deep; and also that if the knife or the blood happen to penetrate the wound itself, they may become themselves contaminated with the virus and thus bring it in contact with a new and larger surface. It seems desirable to cauterize thoroughly the original wound without delay. Then, if thought proper, the eschar may be cut out, and the caustic again applied to the fresh surface of the new wound. On the whole, the particular caustic which is recommended by the highest authorities for this purpose is a solid stick of nitrate of silver. Its advantages are: 1, that it can almost always be readily procured; 2, that it can easily be cut into a form adapted to penetrate to the bottom of a deep and narrow wound; 3, that it readily dissolves in the animal fluids, and, when held for a few minutes in contact with the tissues, forms a tolerably deep and firm eschar, and coagulates thoroughly all the organic matters which may be present.
It has been thought that during the period of quiescence the virus remains localized in the original cicatrix, and does not begin to disseminate itself through the system until the appearance of signs of irritation in the part. If this be so, it would of course be highly proper to cut out the cicatrix and cauterize the wound, in cases where this operation had not already been performed at any time between the receipt of the injury and the first manifestations of the disease. - But for the protection of the community from hydrophobia, the prevention of the bite of a rabid animal is much more important than its treatment. Any well educated surgeon, if within reach and called in time, will apply the proper remedies after the wound is inflicted. But he may not be applied to in season. The animal may not be suspected of rabies at the time of the injury; and even if everything be done for the sufferer which circumstances permit, he must still pass through several weeks or months of anxious uncertainty, until the extreme limit of possible incubation has been reached.
The most important thing, in every point of view, is to diminish as far as possible the chance of a bite being inflicted at all; and by far the best means of accomplishing this object is to put the public on their guard by an accurate knowledge of the symptoms of hydrophobia in the dog. The great danger at present consists in the fact that these symptoms are not usually recognized until after a wound has been inflicted; and animals may thus propagate the disease among their own species and communicate it to man at a time when they are not themselves known to be hydrophobic. There are three capital errors, commonly entertained by the public in this respect, which add very much to the danger spoken of: 1, that the mad dog has a horror of water and will not drink; 2, that ho is liable to the disease more especially or exclusively in hot weather; and 3, that he always manifests a ferocious and aggressive disposition. Neither of these things is true; and the consequence is that a dog in cool weather, who is seen to drink freely, and is not especially ferocious, is looked upon without suspicion and treated with familiarity; and yet he may be hydrophobic and capable of inflicting a mortal wound, or of communicating a fatal disease by licking an abraded spot upon the hand of his master.
It is evident, therefore, that it is of the greatest consequence that the true signs of canine hydrophobia should be recognized at an early period; for as soon as a dog is known to be rabid, there is but little danger of his being allowed to bite. Rabies in the dog may occur at any season, and is not more likely to show itself in warm than in cool weather. Consequently all police regulations intended to suppress or exterminate hydrophobia, which are enforced in the summer months and suspended at other times, fail of their object, and may even do harm by inducing a fancied security during the cool season. According to the observations made by Prof. Rey at the veterinary school of Lyons, in France, the number of cases in that district was greater during the rainy than during the dry months. Of 190 cases recorded at the veterinary school of Alfort, during the ten years from 1853 to 1863, the following list shows the aggregate numbers in each month of the year, arranged in the order of their frequency: In April, 25; March, 21; January, 20; June, 18; May, 16; August, 16; September, 16; November, 14; July, 12; December, 12; February, 10; October, 10; total, 190. The first symptoms of hydrophobia in the dog, as described by Youatt and Bouley, consist in a gloomy and sombre disposition, together with a nervous agitation and disquietude, which is betrayed by frequent changes of position.
The animal, usually cheerful and desirous of companionship, seeks to avoid his master or his playmates. He skulks into his kennel, into a closet, into the corners of the enclosure, underneath pieces of furniture, and endeavors to escape notice. If called out, he obeys, but slowly and unwillingly, and as soon as possible again betakes himself to his retreat. In a few minutes he is dissatisfied with it, and leaves it for another. Then he goes back to his litter, and takes it apart or arranges it in a variety of ways, without being able to suit himself with any. The expression of his eye is suspicious and uneasy; and in a few minutes he is again wandering from place to place. Now these signs, when taken- singly, are not decisive indications of rabies. It is natural to the dog, when suffering under almost any temporary illness, to withdraw himself from observation, and seek a retreat in some dark corner; but he generally remains there quiet until he begins to recover. It is this desire to avoid observation, combined with an incessant restlessness, which is peculiar to commencing hydrophobia; and whenever an animal shows these two symptoms together, moving constantly from place to place, and searching in every corner as if looking for something which he never finds, he should at once be an object of suspicion, and properly watched until his malady either disappears or becomes distinctly pronounced.
The next sign of hydrophobia is that the animal has slight and temporary attacks of hallucination. He thinks he hears a sound or sees an object which does not exist. This condition is fully recognized by veterinary experts, although its signs are often overlooked by others. The dog suddenly pricks up his ears and runs to a particular spot, as if he had heard a noise on the other side of a door or partition. Sometimes he will snap at the empty air, as if he were catching a fly. Sometimes he will stand immovable and attentive for a few moments, as if he were listening or watching for something which is only an illusion. These signs are exceedingly important, and should redouble the vigilance of those having charge of the animal, who should from this moment be kept in a position to prevent his doing an injury. All this time the animal may show no disposition to bite. A rabid dog often varies in this tendency according to his individual character. The evidence of all the best observers shows that a dog, naturally good-tempered and mild in disposition, will sometimes refrain from biting until very late in the disease.
Furthermore, the same dog will often show no tendency to bite his master, for whom he still retains his natural affection, but may at the same time be easily provoked by a stranger. This circumstance forms one of the most insidious sources of danger in the case of a rabid dog not yet known to be such. Even the master may be misled by finding the animal submissive as usual to his word, and even to a slight correction, while a second blow or a threatening gesture may be followed by a sudden and ungovernable attack on the part of the animal, and the infliction of a fatal wound. During all this period, furthermore, and also during the entire course of the disease, there is no hydrophobia in the strict sense of the word. The rabid dog has no horror of water, and he does not refuse to drink. On the contrary, he drinks frequently, and when, the disease being fully established, the constriction of the fauces renders deglutition difficult, he no less endeavors to satisfy his thirst, sometimes by plunging his muzzle deeply under the surface of the water. No single error in regard to the disease is more unfortunate than this; for when a dog drinks, the bystanders conclude that he is not hydrophobic, and consequently overlook the other symptoms which might indicate the nature of the malady.
The rabid dog does not at first' refuse his natural food, but soon ceases to take it with his accustomed relish. An important sign, however, is an unnatural or depraved appetite. The animal gnaws and even swallows all kinds of indigestible substances. Pieces of wood, bits of stone, furniture, clothing, the stuffing of cushions, leather, horse dung, and even his own excrements, are torn, gnawed, and swallowed. This is always a very suspicious circumstance. Some dogs are habitually mischievous in this respect, but even they only injure or destroy these substances; they do not swallow them. And particularly the disposition in question, manifesting itself in an animal to whom it is not habitual, and who is also evidently sick from some cause or other, should always put his owners upon their guard. Another symptom is now to be spoken of which is decisive and pathognomonic, namely, the rabid bark. It is difficult to give an accurate idea of this sound by mere verbal description; but the best authorities all agree that, when once recognized, it is entirely conclusive. The natural voice of the animal is altered.
Instead of the usual succession of explosive sounds, equal in intensity and duration, it is hoarse, veiled, lower in tone, and begins with a single open bark, followed immediately by three or four diminishing howls from the bottom of the throat, during which the jaws, instead of closing completely at each bark, are only partly approximated to each other. Prof. Bouley says that both he and his pupils have been able to recognize distinctly the rabid dog by his bark alone, when the animal was not yet in sight, and was still at the other extremity of the courtyard of the Alfort veterinary school. The saliva is at first increased in abundance; but this symptom is of short duration, lasting, according to Youatt, not more than 12 hours, and is never so abundant as in the profuse salivation which attends an attack of epilepsy, a malady very common in dogs, but perfectly harmless. The true salivation of hydrophobia consists in a secretion of saliva which is scanty, but viscid and ropy, and which the animal endeavors to clear away from the mouth by the aid of his paws. This often gives the idea that he is annoyed by a bone accidentally lodged in his teeth; and fatal accidents have happened from attempting to aid the animal to get rid of the supposed annoyance.
This preliminary period of the disease may last for one or two days. Now, however, comes the second and fully developed stage of the disorder, characterized by sudden paroxysms of fury, the true rabies or canine madness. A very characteristic and important fact is that an animal in this condition is especially excited by the appearance of one of his own species. The sight of another dog drives him into an excess of sudden and immeasurable fury, followed by an immediate and aggressive attack. This often happens while he is still inoffensive toward other animals, and particularly toward his master. But it is a sign that the full development of his disorder is at hand, and in an hour or two afterward he may snap at every bystander indiscriminately, in the blind insanity of his excitement. At this time, or even at an earlier period, he often disappears from home, probably with the instinct of finding some more solitary place in which to hide. But meeting constantly with new sources of irritation, and his nervous excitability increasing at the same time, he becomes more furious, haggard, and threatening with every hour. He is now at the height of the disease.
Wandering along the streets or open highways, with head and tail drooping, his hide disordered and dusty, the ropy saliva hanging in strings from his open jaws, every man and animal that he encounters provokes him to a fresh attack. After 24 or 36 hours of this continuous excitement, without food or rest, and incessantly upon his feet, exhaustion begins to come on; his motions are less vigorous, his steps grow vacillating and irregular, and he no longer leaves the direct path, and offers violence only to those whom he Unavoidably meets. At last, if not pursued and killed, a general paralysis takes possession of his system, and he dies exhausted by the intensity and continuance of the nervous agitation. The entire duration of the malady in the dog, from the first signs of disordered health until its fatal termination, is from two to six days. No distinct morbid change in any of the internal organs has ever been found after death, either in the dog or in man, which could be regarded as the pathological cause of this singular disease.
Finally, the important symptoms of commencing hydrophobia in the dog, which should always be borne in mind, maybe summed up as follows: 1, an unaccustomed gloomy and suspicious disposition, with nervous agitation and restlessness; 2, momentary attacks of hallucination both as to sights and sounds; 3, an unnatural and depraved appetite for indigestible or innutritious substances; 4, a peculiar and unnatural bark;
5, a ropy and viscid condition of the saliva, with dryness of the mouth and fauces; and
6, an insane and aggressive irritability of temper, most easily excited by the sight of other dogs, and at first manifested only toward them. - The best accounts of hydrophobia are to be found in the chapter on "Hydrophobia" in Gross's "System of Surgery" (Philadelphia, 1866); the chapter on "Rabies" in Youatt "On the Dog" (London, 1859); and Bouley, Rapport sur la rage (Paris, 1863).