no means confined to that product. Paul Bert found the bronchial mucus
virulent in dogs in which the saliva was non-virulent. The flesh has
conveyed the disease when eaten, though probably only because of sores
or abrasions on the alimentary tract. Smith records the death of
negroes in Peru from eating rabid cows;[5] Schenkius, that of persons
who ate of a rabid pig; and Gohier and Lafosse have infected dogs by
feeding the flesh of rabid dogs and ruminants; Rossi and Hertwig have
separately induced rabies by inoculating sound animals with portions
of nerves from rabid ones. No absolute proof can be adduced that the
disease has been conveyed through consumption of the milk. Cases
quoted to show its virulence are open to the objection that the dam
probably licked the offspring. A similar uncertainty attaches to the
spermatic fluid. Women are alleged to have acquired hydrophobia by
coitus, but no such case can be adduced among animals, though rabid
males have often had connection with healthy females. The alleged
cases in women were therefore probably the result of an excited
imagination or caused by virus introduced through some other channel.
The breath and perspiration seem incapable of becoming media for the
transmission of the disease. The blood was supposed to be non-virulent
by Breschet, Majendie, Dupuytren, Blaine, Youatt, etc., but has been
shown by Eckel and Lafosse to be rabific. Eckel successfully
inoculated the blood of a rabid he-goat on a sheep and that of a rabid
man on a dog. Lafosse accomplished the same in one of three attempts
by inoculation from dog to dog. The blood is probably only virulent in
the advanced stages of the disease, and its virulence implies the
virulence of all vascular tissues.
[Footnote 5: _Peru as it Is_.]
The saliva of rabid Herbivora and Omnivora, long held to be harmless,
is now known to be virulent. Berndt has successfully inoculated it
from an ox to four sheep; Eckel from a goat to a sheep; Rey from sheep
to sheep; Lessona from an ox to two horses and a sheep; Tombaro from a
heifer to a sheep, a horse, and two dogs; Youatt from horse and ox
respectively to dogs; Ashburner from an ox to fowls; King from a cow
to fowls; and Majendie, Breschet, Eckel, Hertwig, and Renault from man
to dog; and Earle from man to rabbits. Besides these are a series of
accidental cases, as from horse to man (Youatt), from a sheep to its
shepherd (Tardieu), and from man to man (Aurelianus, Enaux,
Chaussier).
Experiments by Hertwig and Eckel seem to show that saliva loses its
virulence on the supervention of cadaveric rigidity or putrefaction in
the dead body. Haubner even believed dried saliva to be innocuous. Yet
Count Salm successfully inoculated the dried saliva of a rabid dog,
and Schenkius reports a case of hydrophobia produced by a scratch of a
hunting-knife that had been used to kill a mad dog some years before.
A veterinary student at Copenhagen cut his finger while dissecting
{892} the body of a rabid dog twelve hours after death, and died of
hydrophobia six weeks later. These cases in man may, it is true, have
resulted from fear, but the same cannot be said of the infection of
hound after hound placed in empty infected kennels, as recorded by
Blaine, Youatt, and others. In the face of this it would require very
strong negative testimony, indeed, to prove that the virus of rabies
is devitalized in drying--a process which prolongs the vitality of
other virulent matters.
Up to the present time the germ of rabies has not been demonstrated.
That it is a particulate living organism may be reasonably deduced
from its power of indefinite increase--a quality possessed by no mere
chemical nor mechanical agent, also from the saliva proving
non-virulent after filtration through plaster, while the solid residue
left on the filter was virulent (Bert). But, although bacteria have
been found in the saliva, those demonstrated up to the present are
manifestly ordinary aërial bacteria, such as in Pasteur's experiments
produced septicæmia rather than rabies. It still remains, therefore,
for some future observer to discover that germ of which we cannot
doubt the existence.
The point of election of this germ appears to be mainly the nervous
tissue. Pasteur found the brain-matter of rabid animals invariably
infectious, and has preserved the moist brain in an infecting
condition for three weeks at a temperature of 12° C. He found that by
direct inoculation in the brain-substance the period of incubation was
abridged, rabies often showing itself in six, eight, or ten days. In
the face of Rossi's successful inoculation of nerves and Pasteur's
results with brain-matter it is difficult to account for the
unsuccessful inoculation of nerve-tissue in six successive experiments
by Hertwig. It seems to show that though the virus is concentrated in
the brain, and especially in the medulla and pons, yet it does not
equally permeate the entire nervous system. This election of the
poison for the nervous tissue led Dr. Douboue in 1851 to advance the
theory that it is propagated from the seat of inoculation to the brain
through the medium of the nerves--a position now assumed by Pasteur.
This, we fear, is not well founded. The poison, advancing for a month
or more along the lines of the nerves, would probably derange and
abolish their functions, as it does so speedily and effectually that
of the nerve-centres after it has gained a seat in them, whereas, in
reality, the local paralysis only appears in the last stages and after
the symptoms of cerebral disorder are well established. Furthermore, a
common premonitory symptom of rabies is congestion, swelling, and
irritation of the inoculation wound, showing a sudden extraordinary
activity at that point as a herald, if not a condition, of the general
infection, whereas under a slow propagation along the nerves from the
first this irritation would probably have been greatest in the wound
at the outset, and would have thereafter kept pace with the progress
of the virus along the nerves. Again, the blood is not always
infecting. Blaine, Youatt, and others of the older observers had no
fear of the blood. Hertwig obtained rabies in two cases only out of
eleven inoculations with the blood of rabid subjects. The blood in
this, as in some other diseases (variola equina, v. ovina, lung plague
of cattle), proves to a certain extent inimical and destructive to the
poison. Galtier inoculated nine sheep and one goat by intravenous
injection of the saliva of mad dogs, in no case with fatal results nor
indeed with any manifestation of rabies, but with the effect of
fortifying the system so, {893} that subsequent inoculation into the
tissues of the saliva of rabid animals was harmless. Test inoculations
made in the tissues of other animals with the same virus used in his
intravenous injections, and his subsequent inoculations of the animals
so treated, invariably determined rabies. Pasteur repeated these
intravenous injections in dogs with the result of rapidly inducing
rabies in a fair proportion of cases. One of his cases produced in
this way recovered, and thenceforward resisted all further inoculation
with the virus. Others that did not perish from intravenous injection
afterward died of rabies after inoculation in the brain.
Unfortunately, neither Galtier nor Pasteur have reported how much
virulent saliva was injected in any one case, so that we have no data
as to whether the difference was due to the varying quantity of the
virus introduced in the various cases. Lussana, an Italian physician,
had already in 1878 experimented on two dogs by injecting into their
veins the blood of a physician who died of hydrophobia. The blood was
drawn by leeches and cupping-glasses, and five grammes were injected
into each dog. One died on the twenty-fourth day, presenting the
symptoms and post-mortem appearances of rabies. The second at the end
of one hundred and forty days developed symptoms of rabies which
lasted a month, when the animal was sacrificed, and nothing special
found at the autopsy. The data do not warrant a very positive
conclusion, yet they seem to imply that the receptivity on the part of
the dog is greater than that of the small ruminants. They suggest,
further, a greater relative potency in the battle for life of the
blood-globules of the small ruminants with this unknown rabific germ.
This antagonism between the blood of the ruminant and the germ of
rabies finds a parallel in the case of other disease-poisons in their
relations to the nuclei of the tissues. Thus animals may prove
refractory to a small dose of the poison of anthrax, yet Chauveau has
shown that this virus will overcome all native or acquired
insusceptibility when administered in excess. The same is true of the
poison of chicken cholera, which Salmon dilutes until it is non-fatal,
though still affecting the system and conferring an immunity from its
attacks in the future. So with the lymph of variola ovina, which Peuch
diluted to 1/50 and injected with the effect of producing slight fever
and immunity without vesiculation.
This view would imply that in ordinary cases (inoculation with a
moderate amount of the poison) the virus is for a time localized in
the vicinity of the wound; and this is further supported by the fact
that thorough excision and cauterization of the wound some time after
it has been received is still often protective. It is weakened by the
fact that bites of dogs in the stage of incubation sometimes produce
rabies, but it must be borne in mind that there is still a period
between the passage of the living germ to the salivary glands and
brain and the growth of the germ in the nerve-centres, so as to
produce pathognomonic symptoms, during which both blood and saliva
must be virulent.
The ratio of successful inoculations to the bites is very varied.
Thus, out of 555 dogs reported to have been bitten by rabid dogs, 188
contracted rabies; out of 183 experimentally exposed till bitten or
inoculated, 91 became mad; out of 73 cattle bitten, 45 became rabid;
out of 121 sheep bitten, 51 succumbed; and of 890 persons bitten, 428
took hydrophobia (48 per cent.). Of 440 bitten by rabid wolves, 291,
or 66 per cent., took the disease. Such statistics are, however, far
from satisfactory. Of dogs {894} reported mad, some have only suffered
from epilepsy, convulsions, or colic, while of those bitten by the
really mad dog, some have sustained simple bruises without any real
abrasion; in other cases the teeth have been wiped clean by passing
through thick wool, hair, or clothing, or even the flesh of other
animals just bitten; in other cases the bite has been inflicted at a
time when the virulence of the saliva was at its minimum, or in a
subject which was naturally insusceptible. The protective effect of
clothing was well illustrated in a case which came under my notice in
London. Six animals bitten by a rabid dog all contracted rabies,
whilst a man bitten a few hours before through the coat-sleeve, and
who did not have the wound cauterized for a full hour after the bite,
escaped. Bouley found that in 32 persons bitten in the face, 29 died
of rabies (90 per cent.); of 73 bitten on the hands, 46 died (63 per
cent.); of 28 bitten on the arms, 8 died (28 per cent.); of 24 bitten
on the lower limbs, 7 died (29 per cent.); of 19 bitten on the body
(usually multiple wounds), 12 died (63 per cent.). The high mortality
from the bites of rabid wolves and skunks is mainly due to this habit
of attacking the face and hands. As illustrative of insusceptibility
may be quoted the poodle of Hertwig, which was inoculated nine times
with unquestionably rabic virus without effect; also the pointer of
Rey, which was seventeen times bitten by rabid dogs without harm; also
the acquired immunity of Galtier's sheep and rabbits, above referred
to.
INCUBATION.--In the dog this varies from 6 days (Pasteur) to 240 days
(Bollinger). In the majority of cases it ends in from 20 to 50 days.
Pasteur, by inoculating into the brain substance direct, reduced the
incubation from 20 days to 6 days. In the horse the limits of reported
cases are from 15 days to 92 days. In the ox incubation varies from 20
to 30 days; in sheep, from 20 to 74 days; and in swine, from 20 to 49
days in recorded cases.
In man incubation is believed to be often much more prolonged. In 6
per cent. of all cases it is from 3 to 18 days; in 60 per cent., from
18 to 64 days; and in 34 per cent. it exceeds 64 days (Hamilton,
Thamhayn). Quite frequently symptoms of hydrophobia appear from three
to six months after the bite; in a few the period is prolonged to one
or two years, and in rare instances to seven (Schule), and even twelve
years (Chabert). But all such cases of prolonged incubation in man are
at the least extremely doubtful. Man often contracts a
pseudo-hydrophobia as the result of fear, and is curable by moral
suasion alone; and as no such protracted incubations are noticed in
the lower animals, and as no one of these abnormally deferred attacks
in man has been verified by successful inoculation on animals, it is
prudent to reserve a full assent until they are supported by better
testimony. A specimen of such cases is that recorded by Chirac, in
which a cadet bitten at Montpellier afterward spent ten years in
Holland, and then, returning and hearing that his fellow-cadet bitten
by the same dog had died of hydrophobia, he also manifested the
disease and died. Another is the case of a man who, after having been
bitten, spent two years in prison, and then developed hydrophobia and
died. A mind naturally erratic and rendered weaker and more
susceptible by prolonged confinement would prey upon itself and
exaggerate the danger when the subject had been forcibly presented. In
all such cases the attending physician should feel bound in the
interests of humanity to {895} inoculate a dog or other animal and
ascertain whether or not the disease is virulent. The value of such
results in dealing with future cases of the same kind cannot be
overestimated.
The period of incubation appears to be relatively shorter in the young
(average 45 days) than the old (average 70 days), and is believed to
be shortened by constitutional excitement from violent passion, fever,
the heat of the weather, or electrical disturbances.
During incubation no sign of the disease can be detected; it is even
said that the wounds heal with unusual rapidity; but it is certain
that toward the end of the latency the cicatrix, alike in man and
animals, tends to become sensitive, itchy, congested, and even the
seat of papular eruptions. The vesicles (lyssi) which, according to
Xanthos, Marochetti, and Magistel, appear near the opening of the
sublingual glands within a few days (6 to 20) after inoculation, have
not been found by any recent observer.
SYMPTOMATOLOGY.--Three forms of rabies in the dog are recognized--the
furious, the paralytic, and the lethargic. The prodromata are,
however, the same in all, so that these may be conveniently considered
before the different types are noticed.
The premonitory symptoms are by far the most important, as if these
are recognized the dog may be safely secluded or destroyed before
there is any disposition to bite. Any sudden change in a dog's habits
or instincts is ground for suspicion. Bouley well says that a sick dog
is always to be suspected. In some cases there is unusual dulness and
apathy, in others great restlessness, watchfulness, and nervousness. A
morbid appetite, in house-dogs a tendency to pick up and swallow
straws, thread, paper, pins, and other objects, or to devour their own
dung and urine, is highly characteristic. A desire to lick cold smooth
objects, as a stone, a boot, a piece of metal, or the nose of another
dog, is often seen. Smelling and licking the anus or generative organs
of another dog and the exhibition of sexual desire are frequent
manifestations. An increased fondness for the owner, shown by fawning
and licking, is occasionally seen, though more commonly there is a
change from a formerly amiable temper to a morose, sullen, retiring,
and resentful disposition. If a naturally quiet dog flies into a
violent passion at the sight of another dog or a cat, and attempts to
bite it, he should be carefully watched. If a social dog seeks
seclusion and darkness, or if while crouching and shrinking from a
blow (hyperæsthesia) he yet bears it without howl or whine, he is to
be strongly suspected. Barking without object, constant moving,
searching, and scraping, a disposition to tear wood, clothing, etc. to
pieces, and, above all, an absence from home for a day or two, should
beget grave apprehensions. The rabid bark or howl which is often heard
early in the disease is hoarse, low, and muffled, partaking of the
nature of both bark and howl, the first running into the second, and
consists of one loud howl followed by three or four others
progressively diminished in force and uttered without closing the
mouth. Some rub the chaps with the forepaws as if to dislodge an
offending body from the mouth; others reject bloody matter by
vomiting; and others turn the head and eyes as if following imaginary
objects, and snap at them. Finally, a tendency to bite, rub, or gnaw
the wound is significant, and usually draws attention to the fact that
the wound, long healed, is still red, sensitive, and swollen, {896} or
even papular. The conjunctivæ are usually congested, there is an
increased nasal defluxion, and the skin of the forehead and over the
eyes is drawn into wrinkles. This stage lasts from a half to two or
three days.
Following one or more of the above symptoms, paroxysms of wicked fury
come on, alternating still with periods of quiet, in which prodromata
only are observed. The red congested eyes assume a fixed stare, often
squint or roll as if following an imaginary object, at which the dog
presently snaps. A paroxysm is ushered in by increasing uneasiness,
frequent change of position, and a desire to escape, shown in rushing
at the door, tugging at the chain, or gnawing the post and walls of
the kennel. The tendency to bite and gnaw is further shown by seizing
the straw or tearing to pieces wooden and other articles within reach,
or even by the victim lacerating its own body.
The rabid howl becomes more frequent, and the rage and disposition to
bite strange animals and persons merge into a mischievous desire to
worry all that come in the way, the respect for former companions and
friends being steadily lost as the paroxysm increases in violence. Yet
for a considerable time the voice of a loved master recalls the
suffering animal to some degree of self-control. If free to escape
during such paroxysms, the dog expends his excitement in wandering,
making long journeys of five, ten, or twenty miles, and flying at
every animal or man he meets, especially if they increase his
excitement by any noise or outcry. If the victim escapes destruction
during one of these wanderings, he returns during a lucid interval
exceedingly dangerous, for, though he may recognize or even fawn upon
his friends, yet the demon of mischief is even more potent within him,
and may be roused to sudden violence by any noise or excitement. The
intervals of quiet are attended by a prostration proportionate to the
violence of the previous paroxysm, and the animal usually seeks
seclusion and darkness, where he may lie dull and torpid, but he may
be roused at any time to a renewed paroxysm by any noise, disturbance,
the presentation of a stick, or, above all, by the approach of another
animal. During the paroxysm the animal is manifestly the subject of
acute delirium, has hallucinations, snatches and bites at unreal
objects, turns on his best friends, even his master, seizes and holds
on to a stick or iron bar until the teeth are detached and the gums
lacerated, bites his own body, even amputating tail, testicles, or
toes with his teeth; a bitch deserts her puppies or worries them, and
all follow the unconquerable impulse to wander and to wound living
beings. The victim will sometimes manifest incredible strength in
breaking his chain and scaling high walls. Twitchings of the muscles
of the face, and even general convulsions, are sometimes seen. Food is
usually rejected, or if swallowed is soon vomited. In the course of
two or three days the furious stage merges into the paralytic one,
first shown by paresis of the hind extremities and a swaying motion in
walking, then by paralysis of the lower jaw, which hangs pendent and
allows the escape of a viscid saliva. The palsy gradually extends over
the whole body--a sure precursor of approaching death, which is rarely
delayed beyond eight days, and never more than ten, from the onset. In
this last stage the animal has become extremely emaciated, with dry
withered hair, hollow flanks, and small weak pulse; he may at first
rise on his fore limbs when {897} disturbed, and even attempt to snap,
but there is now little danger of a bite. Convulsions may alternate
with the paralysis. The result is invariably fatal.
The peculiarity of dumb or paralytic rabies in dogs is that the last
or paralytic stage supervenes at once on the prodromata, without any
intervening period of acute delirium and fury. The animal is
throughout dull, quiet, and depressed, and shows little tendency to
bite, to wander, or to restless movement. The excitement of the sexual
passion is the same as in the furious forms, and the howl is still
emitted, though much more rarely. Soon the lower jaw drops from
paralysis, allowing the saliva to drivel from the mouth, and the
animal can only succeed in closing it momentarily under the greatest
provocation to bite. Paralysis of the hind limbs and of the whole body
speedily follows, and death ensues in from two to three days. As soon
as the jaw is paralyzed the subject is unable to drink, eat, bite, or
bark, and emaciation advances with extraordinary rapidity.
The lethargic or tranquil form of rabies in dogs is manifested neither
by furious madness nor by palsy of the jaws, but the nervous
prostration is shown in a profound lethargy and apathy. The patient
curls himself up, and will not be roused by his master's voice, by any
noise, disturbance, or even punishment; he makes no response to the
caresses of his friends, and pays no attention to the food or drink
they bring him, but remains in his place, growing daily more emaciated
and lethargic, until relieved by death toward the tenth or fifteenth
day of the illness.
Besides the three typical forms there are intermediate varieties,
which are classed with one or other according as the symptoms of that
type seem to predominate. The same virus, inoculated, will produce
different types in separate individuals, the result seeming to depend
more on the susceptibility of the subject than any special quality in
the poison. With many notable exceptions it may be stated that, on the
whole, furious rabies predominates in hounds, bull-dogs, and other
less domesticated or naturally vicious and courageous breeds, while
the paralytic and tranquil types attack especially house and pet dogs.
POPULAR FALLACIES.--It is a dangerous delusion to suppose that mad
dogs have a dread of water and polished surfaces, that they will not
eat or drink, that they froth abundantly from the mouth, and that they
run with the tail drooping between the hind limbs. There is no
hydrophobia in the dog or other domestic animal. The rabid dog drinks
freely in the early stages of the disease, lapping even his own urine;
later, he still laps, and even plunges his nose in water, though often
unable to swallow; and in his wanderings he swims rivers without the
slightest reluctance. The appetite is not entirely lost, though
greatly impaired and usually depraved, all sorts of unsuitable,
noxious, and disgusting objects being picked up and swallowed with
avidity. Frothing from the mouth is exceptional in rabies, and the
flow of saliva is rarely seen unless when the jaw is paralyzed and
pendent. Carrying the tail between the legs is a symptom of all
diseases attended by abdominal pain, and is by no means constant in
rabies. During the paroxysms the tail is usually carried erect.
Foxes, jackals, and badgers attacked by rabies lose their natural
{898} shyness, enter villages, follow and bite other animals and men,
and, like rabid dogs, die in an unconscious and paralytic condition.
Wolves are affected like foxes, but are more dangerous because of
their power, the ferocity of their attack, and their habit of flying
at the face and hands. Rabid cats are more retiring than dogs, and
show less disposition to attack, but when they do, use both claws and
teeth, and especially on bare portions of the body. The cry is hoarse
like that emitted during the period of rut. They usually die about the
third or fourth day.