RABIES AND HYDROPHOBIA.
Synonyms. Definition: Acute, infectious, cerebral disease, of domestic and wild carnivora, shown by intellectual, emotional, and aggressive nervous disorder, and extreme nervous excitability. Animals susceptible: canine and feline animals, biting animals and those bitten, of all warm blooded kinds; receptivity greatest in carnivora. Geographical distribution: where population is most dense, trade and movement most active—north temperate zone. Australia, Tasmania, New Zealand, Azores, St. Helena immune—protected by quarantine. Islands in Elbe, places with enforced muzzling. Causes: contagion; inoculation; rutting; skunk bites; absence of flowing robes (men, children). Virulent matters: saliva, bronchial mucus, flesh, blood (not in sheep?), milk, (in advanced stages), nerve tissue. Morbific agent particulate; filtered liquid noninfecting: blastomyces, bacillus, found but not uniformly: claims of brain symptoms from each. Viability; saliva virulent for 11 days; brain 3 weeks at 32° to 63° F., for months aseptic and in contact with carbon dioxide; water 20 to 38 days; body in grave 44 days; virulence lost by drying in thin layer yet kennels remain long infecting; glycerine preserves; robbed of virulence by iodine, citric acid, bromine, chlorine, sulphurous and mineral acid and cupric sulphate. Bites of men effective to 50 per cent., protection by clothes, wool, flow of blood, cleaning of teeth by succession of bites. Infection by licking, sneezing, coughing, inhaling, feeding. Incubation 15 to 60 days in dog, 20 to 45 days in horse, 14 to 60 days in sheep, swine and cattle, 14 to 64 days in man. Prolonged cases doubtful. Symptoms in dogs: change in disposition, more amiable or morose, dull, apathetic, excitable, unwonted silence or howling, restless, depraved appetite, swallowing small objects, searching, tearing sticks or clothes, licking cold stone or genital organs, hiding in dark corner, dull expression, irritation where bitten, hoarse voice, rabid howl, eyes follow unreal objects, snaps at them, listens for unreal sounds, irritability, fury when threatened with stick or shown another dog, bites without growl, bears master’s blow in silence, eyes red, fixed, pupils dilated, squinting, lonely wandering, biting, swimming rivers; restless excitement alternates with torpor and seclusion, slouching gait when worn out; in paralytic form; weakness, paresis, palsy of lower jaw, hind limbs, body, dull, prostrate, apathetic; in lethargic form; no fury nor paralysis, but profound prostration and apathy, no coaxing, threat, punishment not even another dog will rouse. Paralytic and apathetic forms wind up the furious; cases with intermittent attacks. Diagnosis: by marked change of disposition or habit, voice, appetite, any hypersæthesia, strabismus, watching or snapping at unreal objects, taciturnity, fury in presence of other dog or stranger, snapping, biting without giving voice, fury when threatened with stick, open mouth without disposition to paw it, lack of muscular coördination, paresis, paralysis. Distinction from lactation anæmia, bone in palate or throat, dislocation of maxilla, stomato-pharyngitis, cutaneous hypersæthesia, pharyngeal anthrax, epilepsy, pentastoma, cysticercus, filaria immitis, nematodes, and tæniæ, auricular acariasis. Symptoms in cats: changed voice, depraved appetite, hiding, restlessness, irritability, bites, scratches, man or dog. Symptoms in solipeds: trembling, hyperæsthesia, easily startled, ears and eyes alert, dilated flashing pupils, roused by dog or stranger, attacks with teeth and heels, mischievous, pawing, kicking, rolling, rising, straining to urinate or defecate, neighing, sniffling, snorting, everting upper lip, grinding teeth, biting, stiffness or impaired control of limbs, generative excitement, spasms, paralysis, hyperthermia, perspiration. Symptoms in cattle: irritability, restlessness, alert head, ears, eyes, squinting, dilated pupils, loud bellowing, lashing tail, or docility, yet pursues a dog, using horns, heels, (exceptionally teeth), stamps, paws, has genital excitement, anorexia, spasms, weakness, paraplegia. Symptoms in sheep and goat: hyperæsthesia, irritability, genital excitement, fury in presence of dog, stamps, butts, paws, snorts, bleats, grinds teeth, becomes paretic, and paraplegic. Symptoms in camels and deer: camels show furious and paralytic forms, biting and snorting; deer have hyperæsthesia merging into paralysis. Symptoms in swine: extreme irritability, restlessness, start at slightest cause or none, tremors, squealing, jerking, grinding teeth, clenching jaws, bite especially a dog, or not, weakness, lethargy, paralysis. Symptoms in rabbits and Guinea pigs; may be furious, more often paralytic. Symptoms in birds: restlessness, ruffling of feathers, pecking or striking man or dog, or at phantom, palsy. Symptoms in wild carnivora: lose fear of man, approach and attack him, are furious and later paralytic. Skunks bite slyly. Symptoms in man: irritable cicatrix, anxiety, sighing, tremor, insomnia, bad dreams, fever, thirst, spasms of throat when seeing, hearing or taking liquids, dyspnœa, retching, vomiting, spasms, roused by noise, squinting, dilated pupils, mental delusions, reticence, taciturnity, suspicion, mania, exhaustion, paresis, paralysis. Lyssophobia, its detection and cure.
Synonyms. Canine madness; Rabidus Canis; Lyssa; Lytta; Cynolyssa.
Definition. Rabies is an acute, infectious disease, affecting the cerebral and medullary nervous centres and characterized by intellectual, emotional, aggressive and other nervous disorders and by extreme reflex excitability.
Animals susceptible. While the disease is seen most frequently in the canine races (dogs, wolves, foxes and jackals), and in the cat family (cat, lion), it is liable to spread widely among animals that use the teeth as weapons of offense, and such as they can readily attack. When inoculated, all warm blooded animals contract the disease. Thus the carnivora and omnivora (dog, wolf, fox, hyena, jackal, cat, lion, badger and skunk and, to a less extent, the pig and horse) may become active propagators of the infection, which may spread widely among their herbivorous victims (cattle, sheep, goats, deer, rats, mice, chickens and pigeons) through their bites. Man suffers mainly through the attacks of dogs, cats and, in certain localities, wolves or skunks, but he is also liable to become infected from handling rabid domestic herbivora. Different genera differ in susceptibility, the receptivity being apparently greatest in the carnivora.
Geographical Distribution. Rabies is confined to no country nor climate but it attains its greatest prevalence in the north temperate zone, where there is the densest population and where activity of travel favors the propagation of infection. The facility for inoculation is the one determining cause, thus the islands of Australia, Tasmania, New Zealand, the Azores and St. Helena have never suffered and the first three exclude the disease by rigid inspection and quarantine. During the Hamburg epizoötic of 1852–53, the islands in the Elbe escaped though both banks were ravaged. Again, where the muzzling of all dogs has been rigidly enforced, as in many German cities and districts the disease has been practically extirpated.
Etiology. Long before the days of pathological bacteriology rabies was recognized by veterinarians as a disease due to infection alone. Its absence from the various countries above named, and from South and West Africa, its rapid propagation in other countries (La Plata, Malta, Hong Kong) into which it had been introduced for the first time, and its restriction and disappearance wherever muzzling had been strictly carried out, had practically settled this question. The development of the disease in animals which had been experimentally inoculated was no less significant of this truth.
Other alleged causes are based on secondary factors that favor inoculation. The alleged evil influence of the hot season (dog days) is accounted for by the period of rutting of the dog which occurs in spring, and brings together troops of jealous dogs following individual bitches and fighting for their favors. This gives a great impetus to the propagation of the disease which accordingly becomes more prevalent during succeeding months. The statistics of Bouley show, however, that the season of its greatest prevalence in France is March, April and May, that it subsides slowly up to midwinter and encreases again in spring. Boudin’s statistics show the greatest number of cases in man toward midsummer which is explained by the long period of inoculation after bites sustained in the spring, but also because clothing is lighter in summer and infection more likely to reach the skin, and because the heat of the weather tends to cause hyperthermia and encrease susceptibility.
The large preponderance of male dogs among the victims of rabies (7:1) has led to the theory that sex predisposes, but the explanation is rather that the males bite each other in their jealousy while they respect the female, the object of their sexual passion. In inoculated cases, males, females, and castrated contract the affection indifferently and with equal readiness.
The skunk is found to be infected in certain localities, and it has been claimed that the affection is native to this animal, and that the form differs from that which prevails in the dog, but the restriction of the disease to sharply circumscribed areas in Michigan and Kansas, while skunks elsewhere show no such malignant quality, demonstrates that this is but an accidental infection of the family of the Mephitis in a given locality.
Men and children suffer in far greater numbers than women, the difference being mainly due to the protection furnished the female by the flowing skirt, though also in part because of the more frequent contact of men with dogs.
Virulent Matters. In 1813 Gruner and Count Salm demonstrated the virulent properties of the saliva of the rabid dog. This has been many times repeated, though as shown by Pasteur, Raynaud, and others, inoculations with saliva often kill in one or two days by reason of the presence of other infective germs, or suppuration ensues and destroys the rabific virus so that oftentimes not more than one in four develops rabies. Galtier succeeded in inoculating 3 rabbits, 1 dog and 1 sheep with the juice expressed from the salivary glands, and Nocard, Leclainche and Peuch have found this to be very virulent. Paul Bert found the bronchial mucus virulent. Rabies has been frequently conveyed by consuming the bodies of rabid animals, yet Peuch and Galtier have failed to convey infection by the flesh. Eckel and Lafosse successfully inoculated the blood of goat to sheep, of man to dog and of dog to dog. Yet many of the older observers agree with Peuch and Galtier in pronouncing the blood non-virulent. Pasteur, Roux, Bujwid, and Helman failed to obtain virulent cultures from blood. Peuch and Nocard have found the milk virulent, and Bardach found the same to be the case in a woman for two days before her death of rabies. In some partially refractory animals like the sheep, the blood seems to destroy the virus, as intravenous inoculations have been made with impunity. The probability is that the blood is habitually non-virulent in the early stages and in mild cases, but becomes virulent in violent and advanced cases. Pasteur first showed that the virus has a special election for the brain and nervous matter and that the central nervous organs are constantly infecting. Rossi inoculated with a piece of nerve trunk, and Doubouc and Babes advanced the hypothesis that the virus advances along the nerve to reach the brain.
It was formerly supposed that the saliva of omnivora and herbivora was non-virulent but repeated experiment has proved it to be infecting. The blunder was due to the fact that these animals did not often transmit the disease by biting. Some writers even deny that rabies exists at all as an infectious disease. One alleges that the danger of rabies is “less than the gallows.” Experiment shows most conclusively that it is much more certain when the conditions are fulfilled. One may live a long lifetime without seeing a genuine case of rabies, but so he may without seeing leprosy or plague, and he is no more entitled to doubt their existence than he is the existence of Manila, or of the other side of the moon.
Morbific Agent. The actual factor which produces rabies is not certainty known so that we cannot speak of its bacteriology. That it is due to a specific particulate germ is now indisputable. Paul Bert and Nocard filtered the virulent fluid through plaster and found the clear fluid that had passed through non-virulent. Rivolta, Babes, Bouchard and Peuch severally passed a solution of the rabific brain matter through a Chamberland filter and found the clear filtrate harmless. The virulent agent is therefore not a body in solution but a solid (organism) which is held back by the filter. Hallier, Klebs, Galtier, Gibier, Pasteur, Fol, Babes and Dowdeswell have respectively attempted the cultivation and inoculation of organisms found in rabific liquids but none has stood the test of further experiment. Memmo found a blastomyces in the brains of six rabid rabbits and one hydrophobic child. It stains with the aniline dyes but not by Gram’s method; when thrown into the peritoneum of Guinea pigs it produced clonic spasms and death in 24 hours, and in the dog, after an incubation of 8 days caused emaciation, salivation, a disposition to bite, paralysis of the hind limbs and death in 48 hours. Bruschettini using agar or bouillon, containing lecithin or cerebrin and defibrinated dog’s blood, inoculated with pieces of the brain of an inoculated rabbit, obtained in 24 to 36 hours a group of small transparent drop-like colonies at first microscopic, but becoming larger with each new culture on fresh media. These colonies contained a very small, short, thick bacillus, which stains readily in Ziehl’s carbol-fuchsin, and then presents a central clear band giving the appearance of a diploccus. In fluid media spherical forms are produced, but in fresh cultures the diploccus aspect reappears. Injected subdurally in rabbits it gave rise to what appeared to be paralytic rabies and could be inoculated from animal to animal, with similar results. It failed to grow in the usual culture media from which the brain products are absent, thus fulfilling the conditions, of a microbe the point of election of which was the nerve cells. Marx who has sought for Bruschettini’s organism in 60 cases of rabies has only once found anything resembling it and concludes that it was merely a contaminating organism, which caused a paralysis (Centr. f. Bacter. 1896.)
Viability of the poison. Galtier found that the virulent saliva remained potent for 11 days if preserved from drying. It persists for 3 weeks in the brain and medulla kept at 0° to 12° C., for a month in sealed tubes, or for several months if protected against septic microbes and in contact with carbon dioxide.
In water it is preserved for 20 to 38 days so that water soiled with saliva may easily become a means of infection. In graves it has been found virulent as long as 44 days after burial so that in medico-legal cases results may be obtained by exhuming a suspected animal (Galtier).
Haubner found that drying the saliva in thin layers rendered it non-virulent and Pasteur has shown that the rabbit’s medulla loses its virulence in 14 or 15 days when dried in contact with air, and apart from putrefaction. Such laboratory results must however be qualified by the facts recorded by Blaine, Youatt and others in which hound after hound died of rabies from living in a dry kennel in which a rabid animal had preceded them. Until we know something of the living germ itself of rabies, it is unwise to infer too positive results from experiments on that microbe, in what may be but one stage of its existence.
The virus is very resistant to cold, having survived a temperature of −60° C. (−76° F.) for several hours (Roux), −10° C. (−14° F.) for ten months (Jobert). Virulence is destroyed however by a temperature of 48° C. (118.4° F.) in five to twenty minutes (Galtier). Light destroys the virulence in 14 hours at 30° to 35° C. (Celli), but encreased pressure has little effect on it (16 atmospheres, Nocard and Roux).
Glycerine at room temperature preserves the medulla in its full potency for four weeks, but destruction ensues if it is heated (Protopopoff). An aqueous solution of iodine (6:100) destroys the virulence (Galtier), as does also citric acid, bromine, chlorine, sulphurous acid, the mineral acids and cupric sulphate.
Ratio of successful inoculation to bites of rabid animals. As rabies is usually transmitted by the bite, it is well to note that not all the bites of rabid animals are effective. Of 183 dogs confined with and bitten by a rabid dog 91 contracted rabies; of 73 cattle bitten 45 became rabid; out of 121 sheep bitten 51 succumbed and of 890 persons bitten, 428 took hydrophobia. Of 440 persons bitten by rabid wolves 291 contracted the disease. The escape of such a large proportion is variously accounted for. Wolves naturally attack the face, throat or hands where there is no protection by clothing, and inoculation is therefore much more certain. Dogs, especially in cold weather usually bite man through the clothes which wipe off the virus from the smooth conical teeth before they reach the skin. Long haired animals are often protected in the same way. In other cases the bite is sustained on a very vascular part and the free flow of blood washes out the poison. In still other cases the rabid animal making a number of snaps in rapid succession comes to the last with the teeth wiped clean and harmless. Again the prompt washing or cauterizing of the wound tends often to protect against infection.
Under favorable circumstances however every bite infects, and the writer has seen six animals, bitten in the same stable, all contract rabies, while a man bitten through the coat sleeve by the same dog, and cauterized an hour later entirely escaped. If the bites are multiple, deep and irregular, the danger is greater.
The licking of wounds is an occasional mode of infection, the rabid dog in the early stages of the disease sometimes showing an unusual disposition to fawn upon his owner.
Again particles of saliva may be projected by sneezing or otherwise and lodge on sores, or on the mucosa of the nose, eye or lip so as to cause infection. Galtier has conveyed the disease experimentally to rabbits in 11 cases out of 75 by making them breathe the atomized infecting liquid, or by dropping it into the nose. In the same way he infected Guinea pigs and sheep.
Galtier and Bujwid have conveyed the disease, exceptionally, to rabbits and rats by feeding infecting emulsions. Galtier has also produced rabies in ⅒th to ⅓d of the cases operated on by instilling the virus into the eye.
Incubation. The duration of incubation varies with the species, individual, the seat and character of the bite, the amount of virus instilled, the potency of the virus, the age, size and weight of the subject, the excitement of rutting, climatic or weather vicissitudes, fatigue, and nervous or febrile disorders.
In the dog incubation ranges from 15 to 60 days, and perhaps 4 to 6 months. It is claimed to have lasted a year but this is somewhat doubtful. In cats it has varied from 15 to 60 days.
In solipeds it ranges usually from 20 to 45 days. The extremes stated are 15 days and 20 months.
In cattle it ranges from 14 to 50 days (exceptionally 70 days), in sheep and swine from 14 to 60 days. It has been claimed to have lasted 4 months in swine and 5 months in sheep.
In rabbits subdural inoculation has an incubation of 15 days, shortening in 25 removes to 8 days, and finally to 6.
In man incubation is alleged to be even more varied. The rule is from 14 to 64 days, but it is claimed to have been as short as three days and as long as 1 to 12 years (Chabert). In the human being, however, there is always the danger of the disease caused by simple dread (lyssophobia) and until these protracted cases can be verified by successful inoculation on the lower animals, they must be held as extremely doubtful. The Montpellier cadet has been often quoted who left, a few days after he had been bitten, spent ten years in Holland, then returning to the school and learning for the first time that his fellow cadet, who had been bitten by the same dog, had gone mad, he too became rabid without loss of time. Such cases have often been cured by moral suasion and have been seized upon to corroborate the heresy that there is no such thing as genuine rabies in man.
Any incubation, in man or beast which has exceeded 40 days should be considered as doubtful, until certified by the successful inoculation of rabbits or other small animals. For casual inoculations the incubation rarely varies much from the time embraced between 16 and 30 days. It is abridged by a special receptivity; by an overdose of the poison; by the inoculation of a virus of unusual potency; by the youth of the animal inoculated; by great heat of the weather; by all forms of violent excitement; by rutting; and by the inoculation of the virus on the head and above all on the cerebral meninges. By this last method incubation may be reduced to 6 days.
Symptoms in Dogs. In dogs as in other animals rabies is manifested in two great types: the furious and the dumb or paralytic, which, however, usually succeed each other in fully developed cases. Yet the furious phenomena may be entirely omitted, and again the victim may die in the early furious stage so that the paralytic does not appear. The prominence of one form over the other is to some extent determined by the germ derived from a previous case of the same kind or by the family, temperament and habits, bull dogs and hounds being specially subject to the furious type, and house and pet dogs having rather the paralytic form.
The premonitory symptoms are in the main the same for both types, and as these may enable us to recognize the disease before the period of extreme danger, it is especially important that they should be well understood.
Some marked change in the disposition or habits of the animal is the first obvious variation from health, and in a district or country where rabies exists any such change should be the warrant for instant seclusion of the dog before there is any disposition to bite. The unwonted habit may be of almost any kind. The lively, amiable dog may become suddenly dull, apathetic or taciturn; the quiet, unexcitable dog may become unusually affectionate, fawning and demonstrative, licking the owner’s hands and face and perhaps infecting him before any suspicion is aroused. Sudden capricious changes from fawning to apathy or sullenness, or the opposite, should be dreaded. The noisy dog may become suddenly silent; while the silent dog may take to howling without apparent cause. A great restlessness, watchfulness or nervousness, a tendency to start at the slightest sound, and a disposition to move at frequent intervals in search of an easier position or place to lie in, are most dangerous symptoms. A morbid appetite, with a disposition to pick up and swallow all sorts of nonalimentary objects (straw, thread, cord, paper, pins, nails, coal, marbles, pebbles, cloth, earth, dung or urine), in a mature dog is most suggestive. Searching around, scraping, tearing sticks, clothes and other objects to pieces, licking of smooth cold stone or metal, of his penis, or of the generative organs of a bitch, are often early phenomena. The dog may hide in a dark corner, going to sleep and grumbling or growling when disturbed. He may make night hideous with his howls, baying at the moon. He may stand with a dull, melancholy, hopeless expression of countenance, as if beseeching his master for relief from his nameless suffering. But as yet there is no disposition to bite. The dog still responds to the call of the master, but with dulness and apathy, in marked contrast with his usual prompt, alert and loving response. There may be congestion, itching and irritation in the seat of the bite, and it may be licked, scratched or gnawed until raw, tender or bleeding. An early change in the voice may be noticeable. There is at first a certain hoarseness, which gradually develops into the pathognomonic rabid howl which is quite recognizable at a distance. The dog turns his nose upward, and with open mouth, emits a howl which, at first hoarse and low, rises into a shriller and higher note before completion and which may be repeated several times without closing the mouth. It is not an ordinary howl but rather a cry of distress, and, to the educated ear a grave note of warning. Sometimes the dog is dumb from the start.
Close observation will often detect evidence of mental delusions and hallucinations even at this early stage. The apparently sleeping dog suddenly starts up with an air of suspicion and excitement. His eyes may turn after phantom flies or other objects at which he will presently snap. He moves hither and thither with a curious, inquisitive air, searching in dark corners, or under curtains or articles of furniture for some imaginary object. He may stand in attentive attitude listening to fancied sounds, and then bound in that direction in spite of an obstructing wall or utensil. If recalled to reality by his master’s voice his healthy attitude and affection may be completely though temporarily restored. He may compose himself to rest or sleep, and soon again start a victim to further delusions.
The furious stage is ushered in by a more pronounced manifestation of the above symptoms. The rabid howl is more frequent and characteristic. The insomnia and the restless movements, change of place, searching, scratching or tearing are likely to be more prominent. The delusions and the watching or snapping at phantoms are more marked. The causeless sniffing and scraping may imply disorder of the sense of smell. The exalted hyperæsthesia and reflex excitability is usually a most marked feature, frequently modified by a sinister, inimical or malevolent disposition. Some subjects show evidence of intense itching, most marked perhaps in the seat of the wound; others are abnormally sensitive to currents of cold air; they start at the slightest noise, a flash of light, a touch, or the approach of a stranger. A paroxysm of fury may be caused at once by shaking a stick at the patient, but, above all, by the test of presenting a dog before his eyes. He at once rouses himself and, with flashing eyes, dashes himself on his supposed enemy and bites viciously, but without bark or growl. The sudden and mute attack is pathognomonic. But there may be symptoms suggestive of some hypoæsthesia. A blow from the dog’s master is usually borne in silence. The animal shrinks from the blow but does not yelp nor howl. During a paroxysm he will lacerate his gums or loosen his teeth by biting on a stick or iron bar; he will even seize a red hot bar without shrinking. He will often gnaw his limbs or body so as to expose and even lacerate the muscles, driven by the pruritus, or the insatiable disposition to bite. Yet he has still an instinct of self preservation, retiring from a light, or blazing brand, and seeking to evade the tongs used to seize him.
The eyes assume a remarkable expression. They are often fixed, and at times the pupils are widely dilated allowing the reflection of light from the brilliant tapetum lucidum, resembling flashes of fire, and adding greatly to his ferocious appearance, and the sense of terror that he inspires. The conjunctiva is congested, of a dark red and the general expression of the eye is very striking. The soft, trusting, affectionate eyes may still for a moment meet those of the loved master, but there is in them a dull, hopeless, anxious and suffering expression, which appeals for pity and should be viewed with dread. To others there is likely to be less of the affectionate appeal and more of the sinister, suspicious, resentful and malicious expression. To the stranger, therefore, the eye may be a better guide than even to the owner. Squinting of the eyes and closure of the lids for a few seconds are not uncommon. As the disease advances the dilatation of the pupils is more marked, indicating the paralysis of the optic nerve.
In this stage the disposition to wander is characteristic. The rabid dog leaves his home and wanders off a long distance, say ten or twenty miles, snapping in his travels at man or beast that may irritate him, returns dirty and exhausted, and seeks anew his dark place of seclusion, or he may snap at and bite even his master. To those who come in contact with him at this time the dog is especially dangerous from his extreme irritability though weak and exhausted.
If the wandering rabid dog meets a strange dog he attacks him and bites without growling or barking. If the bitten dog does not yelp nor retaliate, but simply flees, the rabid animal moves on, but if he bites back, or howls, he worries him, rolling him over and biting again but always in silence, in marked contrast with an enraged but healthy dog. If he comes up with a herd of cattle or pigs or a flock of sheep or fowls, the result is similar. If they remain perfectly still they may possibly entirely escape, but if they scamper off with noise as usually happens, he rushes at them and bites one after another, so that in a confined yard or park all may suffer. A man meeting the dog increases his danger by making an outcry, whereas if he remains perfectly quiet he may possibly escape. Bouley says that a canine attendant is, in a sense, a measure of protection to a man, as the rabid dog attacks first the animal of his own species, giving the man a chance to escape.
In his wanderings the rabid dog will swim rivers, having no dread of water, just as at home he will plunge his nose in water though unable to swallow. When abroad in this way he exhausts himself by his paroxysms and may perish in one of them, or he may meet his death from man or animal. He may in his exhausted state seek a dark secluded place where he may remain for a time and renew his travel later, or he may pass into the paralytic condition and gradually sink.
When shut up, and his vagrant disposition curbed, the paroxysms are liable to appear intermittently, a period of torpor and quiet alternating with one of restless movement, searching, scraping, howling, biting of any animals within reach and later of men, beginning with strangers. A paroxysm can usually be roused by shaking a stick at him and always by presenting another dog.
There is sometimes a difficulty in deglutition, the dog acting as if he had a bone in his throat which he was trying to dislodge, and fatal bites have been sustained during well meant attempts to remove the hypothetical bone. This bears a resemblance to the pharyngeal spasms which are such a marked feature in the hydrophobic man. But it is not roused, as in man, by the sight or sound of water. On the contrary, water is sought and often swallowed at first and even, exceptionally, throughout the disease. He may even take his usual food for a time. The bowels are usually torpid, and any fæces passed are black and fœtid. Diarrhœa may set in later.
In the early stages the rabid dog walks or trots like any other dog. It is only when exhausted by wandering, or violent paroxysms, or both, that he droops his head and ears, hangs the tail between the legs, and slouches along with arched back, and unsteady, swaying limbs. The appearance of these last symptoms implies advancing debility and paresis, and the near approach of paraplegia. The symptoms may, however, be temporarily relieved by a period of seclusion and quiet.
In dumb or paralytic rabies the striking peculiarity is the omission of the preliminary furious stage, and the disease merges at once into paralysis after the premonitory symptoms. In these cases the early nervous symptoms tend to prostration, weakness and dulness or even stupor, there is no disposition to escape, but rather to seek seclusion and quiet, there is rarely howling and then only at first, and soon there is paralysis of the masseters and dropping of the lower jaw, and there is neither ability nor desire to bite. From this the paralysis extends to the hind limbs and then to the fore limbs and trunk. In other cases one limb is the first to suffer, followed by the face, limbs and body. The most prominent feature is the widely opened mouth, the flaccid, hanging tongue and drivelling saliva. The buccal mucosa, at first red and moist, becomes bluish, dry and powdery. The eyes are dull, mournful, suffering or altogether without expression and the pupils are usually widely dilated. The hind limbs are usually utterly helpless and often the fore ones as well, the prostration is extreme and the patient lies quiet and helpless until released by death in two or three days.
A third form, known as the lethargic, is a modification of the paralytic. There may be neither delirium nor marked paralysis, there is no drooping maxilla, pendant tongue nor stringy, hanging saliva, but only a profound, nervous prostration and complete apathy. The patient curls himself up in some dark, quiet corner and cannot be roused by coaxing or punishment, by hunger or thirst. In this, as in the dumb rabies, the common test of presenting another dog fails to rouse excitement or paroxysm. If left undisturbed, these patients may live to the tenth or fifteenth day.
Beside the typical forms there are all intermediate grades, inclining more or less toward the furious, or the paralytic or lethargic. Galtier mentions cases that showed aphasia, scarcely any disposition to bite, swaying movements of the body and limbs, muscular incoördination, tucked up, tender abdomen, rolling the body like a barrel, and marked dyspnœa. Others show at first a slight disposition to bite which is quickly checked by a very early paralysis of the masseters. In still others the attempts to bite are still seen after dropping of the jaw, but though still moved, it cannot be completely closed.
In exceptional cases rabid dogs have shown intermissions of apparent soundness extending over eight days (Youatt), two months (Pasteur), or even six months (Perrin). Rare as these are they must apparently be accepted, and must qualify to some extent the trust reposed in immunization.
Diagnosis. The early diagnosis of rabies in the dog is of supreme importance as enabling the owner to destroy or seclude the dangerous animal before he has developed the disposition to bite and to propagate the disease. If the dog himself is known to have been bitten, every premonitory symptom should be carefully looked for and critically studied. Any change in the general habit, unusual liveliness or dulness, restlessness, or somnolence, unwonted affection or taciturnity, special watchfulness with vision, or hearing, change in the character or tones of the voice or the disposition to use it, propensity to swallow foreign nonalimentary bodies, retching, vomiting or costiveness, propensity to hide away in a dark corner or to leave home and disappear for a day or more, disposition to gnaw and tear up wood or clothing, or hyperæsthesia affecting any of the senses should be carefully noted. Note especially any exaggeration of the generative instinct, any strabismus, or redness of the eyes, any turning of the eyes or head after imaginary objects or snapping at them, any disposition to anger or attack when another dog or cat is presented and any disposition to growl at or to bite a stranger. This tendency to anger and resentment though not always present is usually a symptom of the very greatest value. If a dog is known to have bitten or attempted to bite any person or animal he should be tied or shut up in a safe place for four days at least, under veterinary supervision, and set free only on condition that no symptoms have developed at the end of this period. A hasty decision that a suspected dog is not rabid must lay a veterinarian open to the most serious charges, in case rabies occurs in man or beast from the bites.
Diagnosis is less difficult after the paroxysmal stage has set in. Then there is the extreme irritability and hyperæsthesia, the appearance of reflex spasms of the pharyngeal muscles and chest under the influence of any peripheral excitement, the derangement of the senses, the dilated pupil, the flashing eye, the squinting, the taciturnity and the propensity to bite. Later still the lack of coördination of movement or the paralysis, especially of the hind limbs and of the jaws.
The symptoms may be simulated by those of some other diseases. Thus the bitch which has been exhausted by lactation may show delirium with taciturnity and a disposition to snap. The dog, which is habitually struck or threatened by passers by, may acquire a sinister look and a disposition to bite on every occasion. The presence of a bone or other foreign body fixed between the upper molars, and various injuries of the jaws, teeth or throat may cause inability to swallow, change of the voice and a morose disposition and expression. In such cases there may be vomiting, rubbing the jaws with the paws as if to disengage something and salivation, but there is neither delirium, fury, muscular weakness nor paralysis. In paralytic rabies on the other hand, along with the open mouth and drivelling saliva, there is no disposition to paw the mouth nor face, the buccal mucosa is not simply red but of a deep violet, and there is attendant weakness or paralysis of the hind parts.
Galtier has seen inability to swallow and dropping of the lower jaw from violent stomato-pharyngitis, and from dislocation of the maxilla.
Great tenderness of the skin from inflammation due to blistering or caustic agents or from rheumatism may cause such alert apprehension and disposition to bite in self defense that it may simulate hyperæsthesia of rabies.
From pharyngeal anthrax and violent angina, rabies is distinguished by the extreme exaltation of the special senses, the marked hyperæsthesia and reflex excitability, and, as in the other diseases mentioned, by the perfectly lucid intermissions. Epilepsy is not to be roused by sudden noise, movement nor attempts to swallow, it is not associated with hyperæsthesia and in the haut mal the spasms affect the muscular system more generally. A disposition to bite, and spasms and other nervous symptoms, resembling to some extent those of rabies, have been seen in cases of pentastoma in the nasal sinuses, cysticercas in the brain, filaria immitis in the blood, nematodes, and tænia in the bowels, and auricular acariasis, but there is no such hallucination nor visual delusion, no alteration of the voice, no cutaneous anæsthesia, no exalted reflex excitability. Cadeac finds rabiform symptoms with disorders of the special senses in animals dosed with various essential oils, but the odor of these essences about the mouth and in the breath would serve to distinguish.
Symptoms in Cats. The disease makes a rapid progress, and often ends in death in three or four days. There is a marked change of voice, the calls being hoarse and bass, having been compared to that of a cat in heat. As in the dog, there is a disposition to pick up and swallow objects that are in no sense food, perhaps even its own urine or fæces. There is a great tendency to hide away under furniture or in secluded corners so that the malady may be far advanced before anything is suspected. If seen the patient shows restlessness and frequent movement, with a marked excitability under noise or other disturbing influence. Any disturbance may arouse a paroxysm, accompanied by occasional wide dilatation of the pupils, with flashes from the bright carpet in the vitreous chamber, and the patient may spring at human beings and bite or scratch the hands, face or other uncovered portion of the body. It shows the same disposition to bite small animals, and especially dogs. A glairy often frothy saliva is found in the mouth and often around the lips. As the disease advances and paresis sets in, the cat usually crawls into some dark secluded corner and there dies.
Symptoms in Solipeds. These may vary much in different cases but the leading characteristics, as seen in the dog, are prominent also in the soliped. There is marked restlessness, trembling, and extraordinary hyperæsthesia, as seen in starting at sounds, sudden flashes of light or other causes of disturbance. The ears are held erect and watchful for sounds; the eyes are red and mostly vigilant with at times pupillary dilatation and flashing. The sight of a dog rouses him instantly to attack it with teeth and heels. A stranger is liable to be similarly treated though the horse is still docile and kind to his keeper. There may be itching of the skin and above all of the seat of the bite. During a paroxysm the movements are usually violent, dangerous and even mischievous. There is constant restless movement, pawing, kicking the ground, the stall or attendants, lying down, rolling, rising, straining to urinate, or defecate, eversion of the rectum, shaking the head, muffled neighing, sniffing, snorting, everting of the upper lip, grinding of the teeth, or biting. In the absence of such paroxysms deglutition may be difficult, and the appetite depraved, the patient preferring earth or manure to the natural food. With spasms or paralysis of the pharynx, the food may be returned through the nose. In some cases a stiffness or impaired control of the limbs has suggested inflammation of the feet. In the uncastrated male and female generative excitement is the rule, the protrusion and erection of the penis, the swelling and rigidity of the clitoris, with frequent straining to pass water, the whinnying of the animal for its mate; attempts at copulation and even ejection of semen may be observed. The seat of the bite may be red, angry and itchy, so that the horse rubs, nibbles or gnaws it, often breaking it open anew. There is usually ardent thirst, and no dread of water, even when swallowing is difficult or impossible.
During a violent paroxysm the horse often bites the halter, blanket, manger, rack or stall, seizes the adjoining horse with his teeth, or gnaws, or tears strips of skin from his own shoulder, breast or limbs. In the same way he uses his feet with the most evident purpose of injuring man or beast that may approach him, or he breaks down his stall.
Even at an early stage there may be spasmodic movements of the eyes, face or body, and later there appear signs of paresis, often commencing in a hind limb and extending to paraplegia and general paralysis. Sometimes paralysis begins in the muscles adjoining the seat of the bite. The temperature, at first normal, may rise to 104° F. in the advanced stages, breathing and pulse are greatly accelerated, and the skin may be bathed in perspiration. Spasms are not entirely superseded by paralysis, and death often takes place during a convulsion, from the fourth to the sixth day. In apoplexy death may ensue in one day.
Cases in which paralysis is not preceded by a furious stage are not uncommon in horses.
Symptoms in Cattle. Cattle are frequent victims of rabies, which assumes mostly the furious type, yet in certain outbreaks the paralytic or lethargic form predominates. There is first a strange irritability and restlessness, very unlike the habitual quiet disposition of the animal. The head is raised, the ears alert, the eyes prominent, red, fixed, with occasionally widely dilated pupils and brilliant flashes from the tapetum lucidum. Sometimes they roll or squint. They may appear wild and ferocious or dull and hopeless. Loud and terrified bellowing is not uncommon, switching of the tail, drivelling of saliva, and exceptionally there are attempts to bite. More commonly the natural weapons of offense are employed, the animal kicks, stamps, paws and, above all, tries to gore man or beast, but especially any dog which may appear. They even make such attacks on purely imaginary beings and without any real, tangible enemy present. The bull, cow or heifer present the usual signs of genital orgasm. Appetite is lost or depraved and rumination arrested. Pharyngeal spasms or paralysis is not uncommon, and signs of colic with frequent defecation may be seen. Violent paroxysms are easily roused by the sight of a small animal and especially of a dog. In these attacks the animal may break his horns or teeth or otherwise injure himself. Sometimes the infection wound becomes irritable, itchy and red or even abraded and raw by licking.
The animal becomes rapidly exhausted and even emaciated by the violence of the paroxysms, and paresis sets in with dragging movements of the hind limbs, which advance to paraplegia and general paralysis. Rolling of the eyes, squinting and pupillar dilatation may be present. Death usually takes place from the fourth to the sixth day.
The purely paralytic rabies is not uncommon in cattle. There may be persistent yawning or other sign of nervous exhaustion or depression, halting on one or more limbs, usually behind, which advances to complete paralysis. In other cases the symptoms are those of mental dulness, and profound lethargy with gradually advancing emaciation. In paretic and paralytic cases the characteristic paroxysms on presentation of a dog may be absent.
Ladague claims to have seen intermittent cases with an interval of 27 and even 36 days.
Symptoms in Sheep and Goat. In these there is the same regular succession of symptoms through intense hyperæsthesia and excitability, fury and genital excitement to the terminal paralysis, or the palsy may set in early without premonitory violence. Among the marked features have been noticed, a change of expression, the pupils dilate, eyes flash, they lick or mount their fellows, they lick or rub the bitten part, snort, stamp or scrape with the fore feet, setting themselves in the attitude of attack, they may butt other sheep, fowls, and other animals, above all dogs, or they may deliver the attack in the air only, at some phantom enemy. They may bleat hoarsely or brokenly, grind the teeth, or work the jaws with the formation of froth about the lips. Galtier says they may even attempt to bite. Sooner or later weakness of the limbs, muscular incoördination, swaying and staggering bespeak enervation, the sheep lies constantly, and if raised stands with unsteady semi-flexed limbs, has trembling or convulsions and dies paralytic in from two to five days. Death has been delayed till the twelfth day (goat) or thirteenth (sheep). In some cases paralysis has been present from the start, the subject lying prostrate from the first.
Rabies in the Camel and Deer. In Algiers camels are often times bitten by rabid dogs and contract the disease showing both furious and paralytic symptoms. They are especially dangerous because of their propensity to bite, and to scatter the virulent product by sneezing.
In England rabies has prevailed extensively in parks of deer, which shut inside high walls have been bitten remorselessly by rabid dogs that had gained admittance. The symptoms of hyperæsthesia and paralysis followed the same general course as in other animals.
Symptoms in Swine. Rabid pigs are usually very restless, excitable and sensitive to all causes of disturbance. They will hide under the litter in the darkest corner but soon start without apparent cause, turn around and lie down again, or they bound up with grunt or scream and rush off as if pursued, push or leap against the wall, stand with ears pricked as if listening, and start violently at any noise or a flash from a lantern, trembling, squealing, or having muscular jerking. The eyes are at times fixed, or may roll, squint or flash from pupillary dilatation. The voice is hoarse, deglutition difficult, there is frequent clenching of the jaws, or grinding of the teeth, and frothing around the mouth. The victim may tear with his teeth the boards of his pen, or gnaw pieces of wood, he may swallow wood, pebbles or earth, and plunge his face in water or other liquid without fear or apparent dread or dislike. The disposition to bite may be viciously shown, and he may strike dangerously with his tusks, while in other cases it may be entirely absent. Peuch quotes cases in which no paroxysm was aroused by the sight of a dog, and others in which the pig would rise and grunt without showing any desire to bite.
Sows will sometimes bite or devour their offspring during a paroxysm, yet nurse and care for the survivors during the intervals.
Emaciation, weakness, exhaustion, lethargy and paralysis appear early, the victim remains down, or, if raised, moves weakly and unsteadily and no longer pays attention to noises nor blows. Death may ensue from the first to the sixth day.
Symptoms in Rabbits. Experimental cases in rabbits are now very common and usually assume the paralytic or lethargic type, there is weakness in the hind parts, advancing in a few hours to paraplegia, the fore limbs may be used for a time while the hind are flaccid and dragged behind, or the animal lies on the sternum and belly with the head sunken and resting on the feet, or he lies extended on his side, in a state of insensibility. In the early stages he may still masticate, with froth collecting on the lips, but there is difficulty in swallowing. If a foot is pinched it is drawn up often with a cry. The bowels are torpid though a few small, round, hard pellets are sometimes passed or a little urine. Incubation is shorter than in the dog, and the virus retains this habit when inoculated on other animals.
In the experimental cases in the Anti-rabic Institute in St. Petersburg, Helman found that the rabbits inoculated with virus from dogs having furious rabies, contracted furious rabies, while those inoculated from the less furious type of street rabies had the disease in the dumb form.
Symptoms in the Guinea-pig. In this animal as in the rabbit the disease has been mainly seen in the experimental form, and has assumed the paralytic type. It trembles, moves stiffly or weakly, lies most of its time and passes rapidly into paralysis. There is usually no tendency to bite, yet Peuch in a case of intraocular inoculation from a rabid cat observed the most violent excitement, loud hoarse screaming, bounding in different directions, biting of the wires of the cage, and other manifestations of violent rabies. In both forms there are liable to be convulsive movements of the jaws, accumulation of frothy saliva, and a free discharge of urine.
Symptoms in Birds. Chickens bitten by mad dogs have been seen to prove restless, erecting the feathers and moving aggressively toward man or dog or phantoms of their imagination and attacking with bill or spurs or both. This, however, rapidly advances to paralysis and death. In cases due to intracranial inoculation on the other hand, somnolence, lethargy, or coma appeared early, and was quickly followed by paralysis. This affects especially the legs and neck. Recoveries are common and the animal is thereafter immune. Subsidence, with complete intermission of symptoms, is more common than in rabbits, the disease reappearing later, and perhaps finally ending in recovery.
Symptoms in Wild Carnivora. The rabid wolf, fox, jackal, hyena, coyote, ferret, polecat and skunk lose their fear of man, and approach and attack him either in field, village or city. The disease has its furious and paralytic stages as in the dog, and the animals attack according to their nature, wolves being dangerous from flying at the face and throat, and skunks from stealing up and biting without warning.
Symptoms in Man. After the period of incubation prodromata may be present, or there may be suddenly and without any premonition, violent spasms of the pharynx and inability to swallow. The premonitory symptoms when present consist in irritability of the cicatrix which becomes red or blue, swollen, itchy or pricking, and an aura or shooting pain may extend from this toward the heart. There is anxiety, sighing, tremor, restlessness impelling to frequent change of place, insomnia, disagreeable or painful dreams, weariness, and gloomy forebodings. The face is pale and drawn, and the eyes wander or have a look of apprehension. There is some fever and often marked thirst, and the attempt to swallow rouses slight spasm or a sensation of tightness in the throat. The fauces, pharynx and eyes are congested, reddened and it may be swollen. Pulse and respiration are both quickened, the inspiration being often prolonged and sighing, and the expiration sobbing. At first the intellect is unimpaired; there is no illusion nor hallucination.
In cases in which premonitory symptoms are lacking, violent spasms of the throat and chest are commonly roused by an attempt to drink and this is so painful that the patient cannot again be induced to try. After this any suggestion of drinking, the offer of drink, the noise of trickling water, the sight of water, the sight of a vessel in which the water was contained, or even of a clear shining surface of glass or metal is likely to bring on a paroxysm. This hydrophobia is peculiar to man being rarely seen in rabid animals. During a paroxysm dyspnœa is extreme, respiration is gasping or sighing, and in the attempt to dislodge the tenacious mucus which is present in the throat, hoarse or shrill inarticulate sounds are emitted which have been supposed to resemble the bark of the dog. There is a sense of closure of the throat and of rising of the stomach, and retching or even vomiting may ensue. Hyperæsthesia, reflex irritability, and exaltation of the special senses, now become extreme, so that a paroxysm may be brought on by the slightest disturbance, a current of air, a bright light, the rustling of a dress, the noise of a footfall, the noise even of talking, or a slight touch. The “tendon reflex” and skin reflex are often much encreased. During a paroxysm there are muscular trembling and clonic spasms,—sometimes opisthotonos. The intervals of complete relaxation, however, serve to distinguish from tetanus. The face is red and drawn, the eyes congested and sometimes squinting, the pupils dilated and the expression one of suffering, apprehension and horror. Mental disorder appears sooner or later, the speech is disconnected, with indication of delusions from which the patient may at first be recalled by the attendant. There is, however, a constant disposition to be reticent, morose and above all, suspicious, as shown by the absence of a direct look, and the frequency of side glances as though in expectation of a hidden danger. This may even rise to mania, the patient charges those about him with having caused his sufferings, or with conspiracy to injure him, and he may seek to defend himself with hands, feet, teeth or any available object. The necessary restraint aggravates and prolongs the attack. On its subsidence the patient collects his scattered senses, regrets, apologizes, and warns against future occurrences of the same kind which he realizes to be beyond his control. Sometimes the delusions continue during the remission as well. Sexual excitement is common in man as in animals.
The convulsive paroxysms may last ½ to 1 hour, and they tend to encrease in duration and force. A violent paroxysm may cause sudden death from asphyxia or apoplexy.
Sooner or later exhaustion and paresis appear. The convulsions become gradually weaker, the reflex irritability and hyperæsthesia abate, and the patient may become once more able to swallow, but an ascending paralysis, beginning in the limbs spreads over the body and death occurs in from one to eighteen hours. In the paralytic stage there may still be slight jerking of the muscles, or tremors, but violent convulsion no longer occurs, and there is extreme prostration, with hurried, rattling breathing, small, weak, irregular pulse and finally, stupor and coma.
Diagnosis in man. The only additional point, to those already stated for animals, is in regard to lyssophobia. This false form of hydrophobia is usually fortified by the fact of a bite, but as a rule it lacks the exaltation of common sensation and of the special senses which characterizes genuine hydrophobia. Very often also there is a flaw in the history, the dog that inflicted the bite is unknown and may still be alive, in which case no medicine is so good as to bring the healthy dog into the presence of the patient. The dog may have been killed by an excited community without any identification of his symptoms as those of rabies or any post mortem examination to throw light on his case. The attack may have come on after a conversation on the subject of the bite, or of rabies, and perhaps, as in the case of the Montpellier cadet, long after and when the patient had for the first time heard that the dog that bit him had been mad. It may be that rabies does not exist in the district and that no other victim in man nor beast can be adduced. It may be that the patient has a nervous organization or is subject to hysteria, and therefore specially predisposed to any disease of the imagination. Such cases cannot be accepted as rabies until a successful inoculation has been made on one or more animals.