RABIES, a virulent disease, developed primarily in and peculiar to the canine species. Its occurrence in the same manner in other carnivorous animals, as the fox, wolf, hyaena, jackal, raccoon, badger, and skunk, has been asserted ; but there is every probability that it is originally a disease of the dog. It is communicated by inoculation to nearly all, if not all, warm-blooded creatures. The transmission from one animal to another only certainly takes place through inoculation with viruliferous matters. The malady is generally characterized at a certain stage by an irrepressible desire in the animal to act offensively with its natural weaponsdogs and other carnivora attacking with their teeth, herbivora with their hoofs or horns, and birds with their beaks, when excited ever so slightly. In the absence of excitement the malady may run its course without any fit of fury or madness. Transmission of the disease to man produces HYDROPHOBIA (q.v.) or dread of water, but in animals this symptom is rarely, if ever, observed. Rabies has been known from the very earliest times, and serious outbreaks have been recorded as occurring among dogs, wolves, and foxes in different parts of the world, particularly in western Europe and in North and South America. It is very frequent in Europe and appears to be on the increase. France, Germany, upper Italy, and Holland evidently suffer more than other Continental countries. England is becoming more frequently visited than before, though Scotland and Ireland are much less troubled than England. Spain is also sometimes severely scourged by it; but it is rare in Portugal. On the American continent it is well known, though on the eastern side, of the Andes it is rarely if ever seen; and it has never been heard of in Quito. In the West Indiesin Hispaniola, Jamaica, Domingo, Havana, Guadaloupe, and Haytias well as in Ceylon, it is frequently witnessed, and in 1813 it was introduced into Mauritius. It exists in North and South China, and has been reported in Cochin China and the kingdom of Anam. It is frequent and fatal in India; and it is by no means rare in Syria, Palestine, and Turkey. It has been observed in the Hijáz in Arabia, and in North Africa and Egypt. Hydrophobia has been reported in Algeria; but Rohlfs asserts that it is unknown in Morocco. Gibraltar and Malta have been seriously invaded at times, and in Sweden, Denmark, Norway, Russia, and Lapland it has been frequently seen in an epizootic form; but it is not yet positively decided whether it exists in the Arctic regions. Steller and Erman assert that it is unknown in Kamchatka and Greenland; but Hayes (The Open Polar Sea) gives us the particulars of an outbreak of disease in South Greenland, which persisted for several years, caused him the loss of his sledge-dogs in 1870, and in 1872 extended from Smiths Sound to Jakobshavn, threatening the utter extinction of the species, and with it the disappearance of the, Eskimo. In most of its features it appeared to be rabies. The scourge is unknown, according to reliable evidence, in Australia and New Zealand, Tasmania, the Azores, and St Helena, as well as the island of Madeira; it has not been seen at Sumatra, nor in East, South, and West Africa, nor in the island of Réunion.
Rabies (hydrophobia) is almost invariably fatal in man, and in the dog it nearly always terminates in death, though instances of recovery are recorded ; and it is extremely probable, that in those cases in which people have been bitten by dogs and subsequently perished from hydrophobia, without the animals themselves offering any marked indications of illness either at the time or afterwards, these have been suffering from a mild form of the disease. It is also fatal to horses, cows, pigs, goats, and cats, but not to fowls, many of these recovering from accidental or experimental inoculation. Indeed rabies varies considerably in intensity and in the character of its symptoms in different species of creatures. Pasteur has shown that, if it is transmitted from the diseased dog to the monkey and ultimately from monkey to monkey, at each transmission it becomes more attenuated in virulence, and remains so attenuated when passed again to the dog, rabbit, or guinea-pig, nor will it any longer produce the disease in dogs by hypodermic inoculations. Even inoculation by trepanning the cranium, which is so infallible in conveying rabies, may produce no result, the dog thenceforward being protected, and no longer capable of receiving the disease. On the other hand, the rabific virus is intensified when passed from rabbit to rabbit, or from guinea-pig to guinea-pig; and after several transmissions through the bodies of these animals it regain, the maximum virulence which it possessed before it was enfeebled by being passed through the monkey. And the same thing holds with respect to the virulence of the ordinary rabid dog: when virus which is far from having reached its maximum intensity is conveyed to the rabbit, it requires to be passed through several of these animals before it reaches its maximum. It may be mentioned that the disease is not readily conveyed from man to animals, either accidentally or experimentally. The virus appears to exist in greatest intensity in the salivary glands and their secretion, in the brain and spinal cord, and perhaps to a lesser degree in the blood; doubtless it exists also in other fluids and tissues of the diseased animal. The principal alterations found in the bodies of rabid animals after death are located in the spinal cord, especially its upper portion, the medulla oblongata, certain parts of the brain, and the salivary glands, more particularly the submaxillary and sublingual,less in the parotid. The stomach, kidneys, and other organs also present alterations which are more or less significant, especially the former, in which foreign bodies, as hair, wood, stones, earth, pieces of cloth, &c., are very frequently found. But the nature of the lesions, as well as the symptomatology, shows that the action of the poison is more especially exerted on the brain or spinal cord, though the eighth pair of nerves, and branches of the fifth and seventh pairs, are not involved in animals, as in man.
The period in which the symptoms of the disease become manifest, especially after accidental inoculations, as bites, varies extremely; indeed there is no disease in which the period of latency or incubation is more variable or protracted, this being sometimes limited to a few days or weeks and extending in rare cases to more than twelve months. In experimental inoculations the period is greatly shortened and the results more certain,all the more so if the virus is introduced into the cranial cavity by trepanning, or into the bloodstream by intravenous inoculation. In accidental inoculations, as in wounds from rabid dogs, a certain but varying percentage escape. This immunity may be due to natural non-receptivity, to the wound not having been inflicted in a very vascular part, or to the saliva having been expended from frequent bites on other animals, or intercepted by clothing, hair, wool, &c.
Symptoms.The disease has been divided into three stages or periods, and has also been described as appearing in at least two forms, according to the peculiarities of the symptoms. But, as a rule, one period of the disease does not pass suddenly into another, the transition being almost imperceptible; and the forms do not differ essentially from each other, but appear merely to constitute varieties of the same disease, due to the natural disposition of the animal, or other modifying circumstances. These forms have been designated true or furious rabies (Fr. rage vrai; Germ. rasende Wuth) and dumb rabies (Fr. Rage muc; Germ. stille Wuth).
The malady does not commence with fury and madness, but in a strange and anomalous change in the habits of the dog: it becomes dull, gloomy, and taciturn, and seeks to isolate itself in out-of-the-way places, retiring beneath chairs and to odd corners. But in its retirement it cannot rest: it is uneasy and fidgety, and no sooner has it lain down than suddenly it jumps up in an agitated manner, walks backwards and forwards several times, again lies down and assumes a sleeping attitude, but has only maintained it for a few minutes when it is once more moving about. Again it retires to its corner, to the farthest recess it can find, and huddles itself up into a heap, with its head concealed beneath its chest and fore-paws. This state of continual agitation and inquietude is in striking contrast with its ordinary habits, arid should therefore receive attention. Not unfrequently there are a few moments when the creature appears more lively than usual, and displays an extraordinary amount of affection. Sometimes there is a disposition to gather up straw, thread, bits of wood, &c., which are industriously carried away; a tendency to lick anything cold, as iron, stones, &c., is also observed in many instances; and there is also a desire evinced to lick other animals. Sexual excitement is also frequently an early symptom. At this period no disposition to bite is observed; the animal is docile with its master and obeys his voice, though not so readily as before, nor with the same pleased countenance. There is something strange in the expression of its face, and the voice of its owner is scarcely able to make it change from a sudden gloominess to its usual animated aspect. These symptoms gradually become more marked: the restlessness and agitation increase. If on straw the dog scatters and pulls it about with its paws, and if in a room it scratches and tumbles the cushions or rugs oil which it usually lies. It is incessantly on the move, rambling about, scratching the ground, sniffing in corners and at the doors, as if on the scent or seeking for something. It indulges in strange movements, as if affected by some mental influences, or a prey to hallucinations. When not excited by any external influence it will remain for a brief period perfectly still and attentive, as if watching something, or following the movements of some creature on the wall; then it will suddenly dart forward and snap at the vacant air, as if pursuing all annoying object, or endeavouring to seize a fly. At another time it throws itself, yelling and furious, against the wall, as if it heard threatening voices on the other side, or was bent on attacking an enemy. Nevertheless, the animal is still docile and submissive, for its masters voice will bring it out of its frenzy. But the saliva is already virulent, and the excessive affection which it evinces at intervals, by licking the hands or face of those it loves, renders the danger very great should there be a wound or abrasion. Until a late period in the disease the masters voice has a powerful influence over the animal. When it has escaped from all control and wanders erratically abroad, ferocious and restless, and haunted by horrid phantoms, the familiar voice yet exerts its influence, and it is rare indeed that it attacks its master.
There is no dread of water in the rabid dog; the animal is generally thirsty, and if water be offered will lap it with avidity, arid swallow it at the commencement of the disease. And, when, at a later period, the constriction about the throatsymptomatic of the diseaserenders swallowing difficult, the dog will none the less endeavour to drink, and the lappings are as frequent and prolonged when deglutition becomes impossible. So little dread has the rabid dog of water that it will ford streams and swim rivers; and when in the ferocious stage it will even do this in order to attack other creatures on the opposite side. The evidence on this head is overwhelming.
At the commencement of the disease the dog does not usually refuse to eat, and some animals are voracious to an unusual degree. But in a short time it becomes fastidious, only eating what it usually has a special predilection for. Soon, however, this gives place to a most characteristic symptomeither the taste becomes extremely depraved or the dog has a fatal and imperious desire to bite and ingest everything. The litter of its kennel, wool from cushions, carpets, stockings, slippers, wood, grass, earth, stories, glass, horse-dung, even its own faeces and urine, or whatever else may come in its way, are devoured. On examination of the body of a dog which has died of rabies it is so common to find in the stomach a quantity of dissimilar and strange matters on which the teeth have been exercised that, if there was nothing known of the animals history, there would be strong evidence of its having been affected with the disease. When a dog, their, is observed to gnaw and eat suchlike matters, though it exhibits no tendency to bite, it should be suspected.
The mad dog does not usually foam at the mouth to any great extent at first. The mucus of the month is not much increased in quantity, but it soon becomes thicker, viscid, and glutinous, and adheres to the angles of the mouth, fauces, and teeth. It is at this period that the thirst is most ardent, and the dog sometimes furiously attempts to detach the saliva with its paws; and, if after a while it loses its balance in these attempts and tumbles over, there can no longer be any doubt as to the nature of the malady. There is another symptom connected with the mouth in that form of the disease named "dumb madness" which has frequently proved deceptive. The lower jaw drops in consequence of paralysis of its muscles, and the mouth remains open. The interior is dry from the air passing continually over it, and assumes a deep red tint, somewhat masked by patches of dust or earth, which more especially adhere to the upper surface of the tongue and to the lips. The strange alteration produced in the dogs physiognomy by its constantly open mouth and the dark colour of the interior is rendered still more characteristic by the dull, sad, or dead expression of the animals eyes. In this condition the creature is not very dangerous, because generally it could not bite if it tried,indeed there does not appear to be much desire to bite in dumb madness; but the saliva is none the less virulent, and accidental inoculations with it, through imprudent handling, will prove as fatal as in the furious form. The mouth should not be touched,numerous deaths having occurred through people thinking the dog had some foreign substance lodged in its throat, and thrusting their fingers down to remove it. The sensation of tightness which seems to exist at the throat causes the dog to act as if a bone were fixed between its teeth or towards the back of its mouth, and to employ its fore-paws as if to dislodge it. This is a very deceptive symptom, and may prove equally dangerous if caution be not observed. Vomiting of blood or a chocolate-coloured fluid is witnessed in some cases, arid has been supposed to be due to the foreign substances in the stomach, which abrade the lining membrane; this, however, is not correct, as it has been observed in man.
The voice of the rabid dog is very peculiar, and so characteristic that to those acquainted with it nothing more is needed to prove the presence of the disease. Those who have heard it once or twice never forget its signification. Owing to the alterations taking place in the larynx the voice becomes hoarse, cracked, and stridulous, like that of a child affected with croup,the "voix du coq," as the French have it. A preliminary bark is made in a somewhat elevated tone and with open mouth; this is immediately succeeded by five, six, or eight decreasing howls, emitted when the animal is sitting or standing, and always with the nose elevated, which seem to come from the depths of the throat, the jaws not coming together and closing the mouth during such emission, as in the healthy bark. This alteration in the voice is frequently the first observable indication of the malady, and should at once attract attention. In dumb madness the voice is frequently lost from the very commencement,hence the designation.
The sensibility of the mad dog appears to be considerably diminished, and the animal appears to have lost the faculty of expressing the sensations it experiences: it is mute under the infliction of pain, though there call be no doubt that it still has peripheral sensation to some extent. Burning, beating, and wounding produce much less effect than in health, and the animal will even mutilate itself with its teeth. Suspicion, therefore, should always strongly attach to a dog which does not manifest a certain susceptibility to painful impressions and receives punishment without any cry or complaint. There is also reason for apprehension when a dog bites itself persistently in any part of its body. A rabid dog is usually stirred to fury at the sight of one of its own species; this test has been resorted to by Bouley to dissipate doubts as to the existence of the disease when the diagnosis is otherwise uncertain. As soon as the suspected animal, if it is really rabid, finds itself in the presence of another of its species it at once assumes the aggressive, and, if allowed, will bite furiously. All rabid animals indeed become excited, exasperated, and furious at the sight of a dog, and attack it with their natural weapons, even the timid sheep when rabid butts furiously at the enemy before which in health it would have fled in terror. This inversion of sentiment is sometimes valuable in diagnosing the malady; it is so common that it may be said to be present in every case of rabies. When, therefore, a dog, contrary to its habits and natural inclination, becomes suddenly aggressive to other dogs, it is time to take precautions.
In the large majority of instances the dog is inoffensive in the early period of the disease to those to whom it is familiar. It then flies from its home and either dies, is killed as "mad," or returns in a miserable plight, and in an advanced stage of the malady, when the desire to bite is irresistible. It is ill the early stage that sequestration and suppressive measures are most valuable. The dogs which propagate the disease are usually those that have escaped from their owners. After two or three days, frequently in about twelve hours, more serious and alarming symptoms appeal, ferocious instincts are developed, and the desire to do injury is irrepressible. The animal has an indefinable expression of sombre melancholy and cruelty. The eyes have their pupils dilated, and emit flashes of light when they are not dull and heavy they always appear so fierce as to produce terror in the beholder; they are red and their sensibility to light is increased; and wrinkles, which sometimes appear on the forehead, add to the repulsive aspect of the animal. If caged it flies at the spectator, emitting its characteristic howl or bark, and seizing the iron bars with its teeth, and if a stick be thrust before it this is grasped and gnawed. This fury is soon succeeded by lassitude, when the animal remains insensible to every excitement. Then all at once it rouses up again, and another paroxysm of fury commences. The first paroxysm is usually the most intense, and the fits vary in duration from some hours to a day, and even longer; they are ordinarily briefer in trained and pet dogs than in those which are less domesticated, but in all the remission is so complete after the first paroxysm that the animals appear to be almost well, if not in perfect health. During the paroxysms respiration is hurried and laboured, but tranquil during the remissions. There is an increase of temperature and the pulse is quick and hard. When the animal is kept in a dark place and not excited, the fits of fury are not observed. Sometimes it is agitated and restless in the manner already described. It never becomes really furious or aggressive unless excited by external objects,the most potent of these, as has been said, being another dog, which, however, if it be admitted to its cage, it may not at once attack. The attacked animal rarely retaliates, but usually responds to the bites by acute yells, which contrast strangely with the silent anger of the aggressor, and tries to hide its head with its paws or beneath the straw. These repeated paroxysms hurry the course of the disease. The secretion and flowing of a large quantity of saliva from the mouth are usually only witnessed in cases in which swallowing has become impossible, the mouth being generally dry. At times the tongue, nose, and whole head appear swollen. Other dogs frequently shun one which is rabid, as if aware of their danger.
The rabid dog, if lodged in a room or kept in a house, is continually endeavouring to escape; and when it makes its escape it goes freely forward, as if impelled by some irresistible force. It travels considerable distances in a short time, perhaps attacking every living creature it meets,preferring dogs, however, to other animals, and these to mankind; cats, sheep, cattle, and horses are particularly liable to be injured. It attacks in silence, and never utters a snarl or a cry of anger; should it chance to be hurt in return it emits no cry or howl of pain. The degree of ferocity appears to be related to natural disposition and training. Some dogs, for instance, will only snap or give a slight bite in passing, while others will bite furiously, tearing the objects presented to them, or which they meet in their way, and sometimes with such violence as to injure their mouth and break their teeth, or even their jaws. If chained, they will in some cases gnaw the chain until their teeth are worn away and the bones laid bare. The rabid dog does not continue its progress very long. Exhausted by fatigue and the paroxysms of madness excited in it by the objects it meets, as well as by hunger, thirst, and also, no doubt, by the malady, its limbs soon become feeble; the rate of travelling is lessened and the walk is unsteady, while its drooping tail, head inclined towards the ground, open mouth, and protruded tongue (of a leaden colour or covered with dust) give the distressed creature a very striking and characteristic physiognomy. In this condition, however, it is much less to be dreaded than in its early fits of fury, since it is no longer capable or desirous of altering its course or going out of its way to attack an animal or a man not immediately in the path. It is very probable that its fast-failing vision, deadened scent, and generally diminished perception prevent its being so readily impressed or excited by surrounding objects as it previously was. To each paroxysm, which is always of short duration, there succeeds a degree of exhaustion as great as the fits have been violent and oft repeated. This compels the animal to stop; then it shelters itself in obscure placesfrequently in ditches by the roadsideand lies there in a somnolescent state for perhaps hours. There is great danger, nevertheless, in disturbing the dog at this period; for when roused from its torpor it has sometimes sufficient strength to inflict a bite. This period, which may be termed the second stage, is as variable in its duration as the first, but it rarely exceeds three or four days. The above-described phenomena gradually merge into those of the third or last period, when symptoms of paralysis appear, which are speedily followed by death. During the remission in the paroxysms these paralytic symptoms are more particularly manifested in the hind limbs, which appear as if unable to support the animals weight, and cause it to stagger about; or the lower jaw becomes more or less drooping, leaving the parched mouth partially open. Emaciation rapidly sets in, and the paroxysms diminish in intensity, while the remissions become less marked. The physiognomy assumes a still more sinister and repulsive aspect; the hair is dull and erect; the flanks are retracted; the eyes lose their lustre and are buried in the orbits, the pupil being dilated, and the cornea dull and semi-opaque; very often, even at an early period, the eyes squint, and this adds still more to the terrifying appearance of the poor dog. The voice, if at all heard, is husky, the breathing laborious, and the pulse hurried and irregular. Gradually the paralysis increases, and the posterior extremities are dragged as if the animals back were broken, until at length it becomes general; it is then the prelude to death. Or the dog remains lying in a state of stupor, and can only raise itself with difficulty on the fore-limbs when greatly excited. In this condition it may yet endeavour to bite at objects within its reach. At times convulsions of a tetanic character appear in certain muscles; at other times these are general. A comatose condition ensues, and the rabid dog, if permitted to die naturally, perishes, in the great majority of cases, from paralysis and asphyxia.
In dumb madness there is paralysis of the lower jaw, which imparts a curious and very characteristic physiognomy to the dog; the voice is also lost, and the animal can neither eat nor drink. In this condition the creature remains with its jaw pendent and the mouth consequently wide open, showing the flaccid or swollen tongue covered with brownish matter, and a stringy gelatinous-looking saliva lying between it and the lower lip and coating the fauces, which sometimes appear to be inflamed. Though the animal is unable to swallow fluids, the desire to drink is nevertheless intense; for the creature will thrust its face into the vessel of water in futile attempts to obtain relief, even until the approach of death. Water may be poured down its throat without inducing a paroxysm. The general physiognomy and demeanour of the poor creature inspire the beholder with pity rather than fear. The symptoms due to cerebral excitement are less marked than in the furious form of the disease; the agitation is not so considerable, and the restlessness, tendency to run away, and desire to bite are nearly absent; generally the animal is quite passive. Not unfrequently one or both eyes squint, and it is only when very much exited that the dog may contrive to close its mouth. Sometimes there is swelling about the pharynx and the neck; when the tongue shares in this complication it hangs out of the mouth. In certain cases there is a catarrhal condition of the membrane lining the nasal cavities, larynx, and bronchi; sometimes the animal testifies to the existence of abdominal pain, and the faeces are then soft or fluid. The other symptomssuch as the rapid exhaustion and emaciation, paralysis of the posterior limbs towards the termination of the disease, as well as the rapidity with which it runs its courseare the same as in the furious form.
The simultaneous occurrence of furious and dumb madness is frequently observed in packs of fox-hounds. Dumb madness differs, then, from the furious type in the paralysis of the lower jaw, which hinders the dog from biting, save in very exceptional circumstances; the ferocious instincts are also in abeyance; and there is no tendency to aggression. It has been calculated that from 15 to 20 per cent. of rabid dogs have this particular form of the disease. Puppies and young dogs chiefly have furious rabies.
These are the symptoms of rabies in the dog; but it is not likely, nor is it necessary, that they will all be present in every case. In other species the symptoms differ more or less from those manifested by the dog, but they are generally marked by a change in the manner and habits of the creatures affected, with strong indications of nervous disturbance, in the majority of species amounting to ferociousness and a desire to injure, timid creatures becoming bold and aggressive. (See Fleming, Rabies and Hydrophobia.)
In order to prevent injury from this disease in countries in which it is prevalent owners of dogs should be well acquainted with its symptoms, especially the premonitory ones; of these a change in the demeanour and habits of the animalunusual irritability, depraved appetite, restlessness, and a tendency to wander from homeare the most marked. One of the chief police measures is diminution in the number of useless dogs. This is best enforced by the imposition of a dog-tax or licence, which may be large or small in proportion to the number of dogs or the urgency of the case. On the licence-paper the chief symptoms of the malady should be described so as to warn dog-owners. Every dog should wear a collar with a brass plate, on which are inscribed the name and address of the owner as well as a police register-number stamped thereon, or some particular mark affixed by the police or inland revenue authorities, for purposes of identification; all stray dogs without a collar of this description ought to be captured, and sold or destroyed after three or more days if not claimed. Blunting the canine and incisor teeth of dogs has also been proposed as a precautionary measure. All dogs suspected of rabies should be captured and, when the existence of the disease is confirmed, destroyed. Rabid dogs should be destroyed at once. It is also well as a precautionary measure to kill dogs or cats which have been bitten or "worried" by rabid animals. During an outbreak of rabies all dogs should be securely muzzled and if possible led. It is a great mistake to destroy immediately suspected dogs which have bitten people; they should be kept until their condition is ascertained, as, if they are found to be healthy, this will greatly relieve the mind of those who have been bitten. Suspected dogs should be carefully kept under observation and frequently inspected by a veterinary surgeon or other competent person. All wounds inflicted by strange or suspected dogs should be immediately attended to and treated by suction, washing, and expression, until proper surgical treatment can be adopted. In those countries in which the disease has not yet appeared, in order to prevent its admission, the importation of dogs should be forbidden or an extended period of quarantine imposed.
We may here allude to the results of Pasteurs experiments in rabies. By passing modified virus into the bodies of dogs he has discovered that they are protected from an attack of the diseaseare, in fact, rendered refractory to rabies. For instance, rabific virus is obtained from a rabbit which has died after inoculation by trepanning, and after a period of incubation longer by some days than the shortest period in these animals, which is invariably between seven and eight days subsequent to inoculation with the most active virus. The virus of the rabbit in the period of long incubation is inoculated by trepanning into a second rabbit, the virus of this into a third; and on each occasion the virus, which becomes more and more potent, is inoculated into a dog. The latter at last becomes capable of supporting what would be to other dogs a deadly virus, and is entirely proof against rabies either by intravenous inoculation, by trepanning, or by the virus of a rabid animal. By using the blood of rabid animals in certain determinate conditions Pasteur has been able to greatly simplify the operations of inoculation, and to render dogs most decidedly refractory to the malady. There is great importance attached to the suggestion that now, and until rabies has been extinguished altogether by inoculation, it may be possible to prevent development of the disease after bites from rabid dogs, owing to the long duration of the incubative period. Admitting that rabies is produced by the bite of rabid animals only, and that Pasteurs inoculations are really protective, it is suggested that a law compelling all dogs to be so protected would in the end extirpate the disease. But certain important points have yet to be decided before any definite conclusion can be arrived at. (G. FL.)
The above article was written by: George Fleming, LL.D., Principal Vetinerary Surgeon, War Office, London.