or other rabid animal or by other means, a variable time elapses before
the development of any symptoms. This time may be eight days or it may
be several months; it is usually about four weeks. The first symptom is
an irritation of the original wound. This wound, which may have healed
completely, commences to itch until the horse rubs or bites it into a
new sore. The horse then becomes irritable and vicious, and it is
especially susceptible to moving objects, excessive light, noises, the
entrance of an attendant, or any other disturbance will cause the
patient to be on the defensive. It apparently sees imaginary objects;
the slightest noise is exaggerated into threatening violence; the
approach of an attendant or another animal, especially a dog, is
interpreted as an assault and the horse will strike and bite. The
violence on the part of the rabid horse is not for a moment to be
confounded with the fury of the same animal suffering from meningitis or
any other trouble of the brain. But in rabies there is a volition, a
premeditated method, in the attacks which the animal will make, which is
not found in the other diseases. Between the attacks of fury the animal
may become calm for a variable period. The writer attended a case in
which, after a violent attack of an hour, the horse was sufficiently
calm to be walked 10 miles and only developed violence again an hour
after being placed in the new stable. In the period of fury the horse
will bite at the reopened original wound; it will rear and attempt to
break its halter and fastenings; it will bite at the woodwork and
surrounding objects in the stable. If the animal lives long enough it
shows paralytic symptoms and falls to the ground, unable to use two or
more of its extremities, but in the majority of cases in its excesses of
violence it does physical injury to itself. It breaks its jaws in biting
at the manger or fractures other bones in throwing itself on the ground
and dies of hemorrhage or internal injuries. At times throughout the
course of the disease there is an excessive sensibility of the skin
which, if irritated by the touch, will bring on attacks of violence.
Throughout the course of the disease the animal may have appetite and
desire water, but on attempting to swallow has a spasm of the throat
which renders the act impossible. This latter condition, which is common
in all rabid animals, has given the disease the name of hydrophobia
(fear of water).
In a case under the care of the writer a horse, four weeks after being
bitten on the forearm by a rabid dog, developed local irritation in the
healed wound and tore it with its teeth into a large ulcer. This was
healed by local treatment in 10 days, and the horse was kept under
surveillance for more than a month. On the advice of another
practitioner the horse was taken home and put to work; within 3 days it
developed violent symptoms and had to be destroyed.
_Diagnosis._--The diagnosis of rabies in the horse is to be made from
the various brain troubles to which the animal is subject; first by the
history of a previous bite of a rabid animal or inoculation by other
means; second, by the evident volition and consciousness on the part of
the animal in its attacks, offensive and defensive, on persons, animals,
or other disturbing surroundings. The irritation and reopening of the
original wound or point of inoculation is a valuable factor in
diagnosis. Diagnosis after death may be made by microscopic examination
for Negri bodies or by the inoculation of rabbits, as already mentioned.
Recovery from rabies may be considered as a question of the correctness
of the original diagnosis. Rabies is always fatal.
_Treatment._--No remedial treatment has ever been successful. All the
anodynes and anesthetics, opium, belladonna, bromid of potash, ether,
chloroform, etc., have been used without avail. The prophylactic
treatment of successive inoculations is being used on human beings, and
has experimentally proved efficacious in dogs, but would be
impracticable in the horse unless the conditions were quite exceptional.
DOURINE.
By JOHN R. MOHLER, V. M. D., _Assistant Chief, Bureau of Animal
Industry_.
Dourine (also known as maladie du coit, equine syphilis, covering
disease, breeding paralysis) is a specific infectious disease affecting
under normal conditions only the horse and ass, transmitted from animal
to animal by the act of copulation, and due to an animal parasite, the
_Trypanosoma equiperdum_.
_History._--It is described as having existed as early as 1796 in the
Eastern Hemisphere, and was more or less prevalent in several of the
European countries, including France, Germany, Austria, and Switzerland,
during the first half of the nineteenth century. Its presence was
recognized for the first time in the United States in 1886, when an
outbreak occurred in Illinois. Since then the existence of the disease
has been observed at irregular intervals in numerous other States,
including Nebraska, Iowa, Montana, Wyoming, New Mexico, North Dakota,
and South Dakota.
_Symptoms._--There are many variations in the symptoms of dourine, and
this is particularly true of the disease as it occurs in this country.
Two distinct stages may be noted which vary somewhat from those
described in textbooks, but probably no more than could be expected when
differences of climatic conditions and methods of handling are taken
into consideration.
The first stage chiefly concerns the sexual organs and therefore differs
somewhat in the male and female. In the second stage the symptoms
indicating an affection of the nervous system are more prominent and are
not dependent upon the sex of the animal.
Following a variable period of incubation of from 8 days to 2 months,
there is seen in the stallion an irritation and swelling about the penis
and sheath. In a few days small vesicles or blisters may appear on the
penis, which later break, discharging a yellowish, serous fluid and
having irregular, raw ulcers. The ulcers show a tendency to heal
rapidly, leaving scars which are permanent. There may be more or less
continuous dripping from the urethra of a yellowish, serouslike fluid.
Stallions may show great excitement when brought in the vicinity of
mares, but service is often impossible because of the fact that a
complete erection of the penis does not occur.
In the mare the first symptoms may be so slight as to be overlooked. The
disease, being the result of copulation, usually begins with
inflammation of the vulva and vagina. There may be a mucopurulent
discharge, which may be slight or profuse in quantity, agglutinating the
hairs of the tail. The mare may appear uneasy and urinate frequently.
Vesicles may appear on the external vulva and mucous membrane of the
vulva and vagina which later rupture and form ulcers. On the dark skin
of the external vulva the scars resulting from healing of the ulcers are
white, more or less circular in outline, from one-eighth to half an inch
in diameter, and pitlike. This depigmentation of the skin about the
external genitals is permanent.
Urticarial eruptions or plaques which break out over various parts of
the body are a frequent symptom seen in animals of either sex. These are
sharply defined and edematous swellings of the skin about the size of a
half dollar or may be even larger. The usual locations of these plaques
are the croup, belly, and neck.
The intensity of the symptoms mentioned which are significant of the
early stage of the disease may vary to a wide extent and in many
instances be so mild as to escape the attention of any but the most
careful observer. They commonly disappear after a brief period. The
apparent recovery, however, is not permanent, for such animals after a
period of variable length manifest constitutional or nervous symptoms.
These may not appear for several months or even years. They consist of a
general nervous disorder with staggering, swaying gait, especially in
the hind limbs. The animal generally becomes emaciated, the abdomen
assuming a tucked-up appearance. The first indication of paralysis will
be noted in traveling, when the animal fails to pick up one of the hind
feet as freely as the other, or both may become affected at the same
time, at which time knuckling is a common symptom. Labored breathing is
occasionally noted. When the paralysis of the hind limbs starts to
appear the disease usually progresses rapidly. The horse goes down, is
unable to rise, and dies in a short time from nervous exhaustion. The
appetite usually remains good up to the last.
Although a case of dourine may now and then recover, as a rule the
disease is present in the latent stage. Bad weather, exposure,
insufficient feed, and complicating diseases like influenza, distemper,
or in fact any condition which tends to lower the vitality of the
animal, may hasten the termination of the disease.
_Diagnosis._--The complement-fixation test furnishes by far the most
reliable means of diagnosis and is especially valuable in a chronic
affection of this character, when the symptoms manifested are variable
and frequently so obscure as to escape observation. This is a laboratory
test requiring special facilities and the services of a trained
bacteriologist.
_Treatment._--Little benefit can be obtained from medicinal treatment,
nor is such treatment desirable in this country, where the disease has
existed only in restricted areas, and where sanitary considerations
demand its prompt eradication.
INFECTIOUS ABORTION IN MARES.
Infectious abortion (also known as contagious abortion, epizootic
abortion, enzootic abortion, slinking of colts) is a disease of mares
which from a specific cause results in the premature expulsion of the
fetus and its membranes from the uterus. It is characterized by an
inflammatory condition of the female reproductive organs.
The contagious nature of the disease had not been recognized until
recently, the disease being principally attributed to various
conditions, such as traumatic influences, various infectious diseases,
spoiled feed, drugs, and other factors. Ostertag was the first to study
premature births in mares, attributing as the cause of the same a
streptococcus, which he was supposed to have been able to use
successfully in artificially producing abortion, either by inoculations
or feeding. His findings could not be substantiated by other
investigators.
The earliest appearance of the disease in this country was in 1886, at
which time it caused considerable damage to the horse-breeding industry
in the Mississippi Valley. Smith and Kilbourne investigated an outbreak
in Pennsylvania in 1893, at which time they incriminated another germ
belonging to the paratyphus B group as the causative factor of the
disease. These findings have been subsequently substantiated by many
investigators abroad, as well as in this country, notably so by De Jong,
Dassonville, and Riviere, and by Good and Meyer. More recently very
valuable information was contributed to our knowledge on this disease by
Schofield, of Canada, especially with regard to the biological tests for
diagnosis. Good suggested "_Bacillus abortivus equinus_" as the name for
the specific organism.
The causative agent of this disease is not identical with the germ
causing abortion in cattle. It exerts its action, however, in a similar
manner, and appears to have, under certain conditions, a predilection
for the genital organs of the mare, where it induces certain morbid
changes whereby a premature expulsion of the fetus is the result. The
germ is usually present in the fetal membranes and also in the aborted
fetus. Mares may harbor the infection without disclosing any apparent
ill effects. It appears to exert its influence mainly upon the female
genital organs, where it may induce an inflammatory condition of the
uterus.
The infected animals may carry the fetus through the normal period of
pregnancy, giving birth to either a normal or a weak colt, or again
abortion may take place at any time during pregnancy, mostly, however,
from the sixth to the ninth month.
_Symptoms._--The symptoms suggestive of abortion are frequently entirely
absent. At times the abortion may be ushered in by symptoms of colicky
pains, restlessness, and periodical straining; these, however, are by no
means constant, especially if the abortion takes place in the early
months of pregnancy. The genital organs are usually swollen, showing a
mucous discharge. Immediately before abortion the symptoms are more
aggravated. Following abortion the discharge is more characteristic,
being of a dark-brown color, sometimes even bloody, and contains streaky
or flaky pus. The fetal membranes in all cases are not expelled with the
aborted fetus, but there is a tendency toward retention of these
membranes, which frequently has serious consequences upon the health of
the animal. At times it becomes necessary to resort to manual removal of
the afterbirth, and the inflammation of the uterus and a chronic
discharge usually follow such conditions. The expelled fetuses, as a
rule, die soon after the abortion, and if the expulsion has taken place
at a time close to its full term the fetuses are usually poorly
developed and subject to various kinds of digestive and septic
disorders. The fetuses do not disclose any particular abnormal
appearance on external examination; in many cases, however, the
post-mortem examination reveals inflammatory changes of various organs.
The method of infection has not yet been satisfactorily established;
nevertheless it is essential that we consider as the principal mode of
infection the ways which have been proved for the contagious abortion
in cattle. These are especially by ingestion; that is, by taking up the
germs with the feed, water, or other means, which have become
contaminated with the germs. The infection through the genital organs is
probably not so frequent, but in this regard the stallion no doubt plays
an important role in the spreading of the disease. Schofield considers
this method of infection as the principal source of spreading the
disease.
It must be considered that in infected stables the germs may be present
throughout the premises, and by keeping animals which have aborted in
such stables a contamination of feed and utensils may continually take
place, since the aborted mares usually discharge a considerable quantity
of material which is often heavily charged with the germs. The germ is
taken up by the body with the feed or water, passing from the intestines
into the blood, and from there is carried to the genital organs, where
it finds suitable conditions for its development. Milk from an infected
mare may also contain the germ, and colts may become infected by sucking
the milk of infected mothers. In such instances the infection may remain
dormant until the colt develops and becomes pregnant, when the organism,
finding a condition suitable for its development, produces the disease.
On the other hand, stallions used in covering infected mares may be
carriers of the germs, and when used for the breeding of healthy animals
may in this manner readily transmit the disease to them.
_Diagnosis._--Contagious abortion may be diagnosed by the changes which
occur in the fetal membranes, and also in the expelled feces. In order,
however, to substantiate a diagnosis with certainty, demonstration of
the germ by microscopical examination is necessary. The occurrence of
frequent abortions among the mares in a stable is also an additional
evidence of the contagious character of the malady. It must be
considered that at times infected mares may carry the fetus to full
maturity, in which case the diagnosis is possible only by blood
examinations in a laboratory.
Infected animals usually abort only once; however, in a certain
proportion of cases they may abort even two, three, or four times in
succession.
Animals which establish a tolerance for the infection, and carry the
fetus to full maturity, may nevertheless remain a source of danger for
spreading the disease.
The tests used in laboratories for the diagnosis are the agglutination
and complement-fixation tests, by which the disease may be diagnosed
from a sample of blood from a suspected animal. Such tests, however,
have to be confined to the laboratories, which are equipped for such
work.
_Treatment and prevention._--Medicinal treatment is usually of no avail,
and all efforts should be directed toward the prevention of the
disease. Various medicinal agents have been recommended and are being
exploited for the treatment, but to the present time no satisfactory
evidence has been established as to their merits. Bacterial vaccines
prepared from the specific organism have been given limited trials, but
to date they can not be considered as entirely satisfactory, since it
will require considerable experience with them before their usefulness
can be definitely established.
The prevention should consist largely in sanitary measures directed
toward the disinfection of premises and animals. (For a method for
disinfection of premises see article under that heading.)
The following procedure is advised for the disinfection of animals: To
prevent a stallion from carrying the infection from a diseased mare to a
healthy one the sheath and the penis should be disinfected with a
solution of 1/2 per cent of compound cresol solution, lysol, or
trikresol, or a 1 per cent carbolic acid or 1 to 1,000 potassium
permanganate solution in warm water. For this purpose it is advisable to
use a soft-rubber tube with a large funnel attached to one end, or an
ordinary syringe and tube would serve the purpose. The tube should be
inserted into the sheath, and the foreskin held with the hand to prevent
the immediate escape of the fluid. In addition to this the hair of the
belly and inner side of the thighs should be sponged with an antiseptic.
This disinfection should invariably precede and follow every service.
With regard to the mares, a period of three months should elapse between
abortion and a subsequent breeding, and especially if there is any
evidence of a discharge the breeding of the animal should not be
undertaken. The mare showing signs of abortion should be immediately
isolated and the fetus and membranes should be burned. The fetus should
never be dragged across a barnyard or stable, but should be removed by
other means by which the contamination of the premises may be prevented.
The stall in which the animal aborted should be thoroughly disinfected
and the genital organs of the mare washed daily with a disinfectant. The
antiseptic washing recommended for the treatment of the stallions prior
to and after breeding should be also used for the irrigation of the
uterus of mares which have aborted. This treatment should be continued
daily until all evidence of discharge has ceased. The isolation of the
animal should be carried out for at least one month after the evidence
of a discharge has ceased.
By carefully and persistently carrying out the sanitary measures it may
be possible to control and finally eradicate the disease.
NAVEL ILL OF COLTS.
Navel ill of colts is also known as joint ill, omphalophlebitis, septic
arthritis of sucklings, and pyosepticemia of the newly born. The
unfavorable outlook after the appearance of the disease, together with
the fact that the disease when present requires the attention of a
veterinarian, demands that the breeder concern himself with its
prevention.
The disease is caused by a microorganism and several bacteria have been
suspected of being responsible. Every one of the suspected organisms is
found abundantly in manure and objects contaminated with manure. The
infective material gains entrance into the colt through the open
umbilical cord as a result of its coming into contact with litter,
floors, or discharges from its dam contaminated by one of the organisms
which cause the trouble. There are cases on record in which the
infection has taken place before birth, and while some investigators
assert that this method is the principal mode of infection still, in a
large number of cases, the prophylactic measures adopted to guard
against the infection through the navel cord have given good results.
Since infection before birth can not be controlled satisfactorily, we
are justified, for all practical purposes, in preventing navel ill by
guarding against the infection through the cord at birth or soon
afterwards.
Cleanliness of stables where pregnant mares are kept must be insisted
upon. This is especially necessary where outbreaks of navel ill have
been known to exist. Mares in the last stages of gestation should be
placed in a box stall which has previously been cleaned and disinfected.
The bedding should be frequently renewed and the external genitals and
neighboring tissues should be kept clean and disinfected with a 2 per
cent solution of carbolic acid or 1 per cent liquor cresolis compositus,
or any other reliable disinfecting agent. Operations for opening
abscesses and removal of afterbirths from cows should not be executed in
the immediate vicinity of mares in an advanced stage of pregnancy.
The foal when dropped should be placed on clean bedding. In any event
the cord of the foal should be washed in a disinfectant solution and
tied at about 1-1/2 inches from the navel with a band or string which
has previously been soaked in a disinfectant solution. With a sharp pair
of scissors the navel cord is then severed about one-half inch below the
band and again disinfected. The ligature should not be tightened,
however, until pulsation of the vessels in the cord has ceased. The
stump of the cord is then painted with strong carbolic-acid solution,
tincture of iodin, or a mixture of equal parts of tincture of iodin and
glycerin. The stump should be washed daily with a disinfectant and
either painted with iodin mixture or carbolic acid or dusted with some
reliable antiseptic healing powder. After five days the parchmentlike
dried stump may be cut off and the navel wound washed with a
disinfectant solution and dusted with powder until healed.
The cases of navel ill resulting from infection before birth can not
well be guarded against. By keeping mares, advanced in pregnancy, in
good physical condition, the fetus will be expelled immediately upon the
opening of the uterine cavity.
Once the infection of the navel cord has set in, the cord should not be
ligated but should be washed in a disinfectant solution and a
veterinarian called for the subsequent treatment.
INFECTIOUS ANEMIA OR SWAMP FEVER.
By JOHN R. MOHLER, V. M. D., _Assistant Chief, Bureau of Animal
Industry_.
Infectious anemia of horses, known also by a number of other names, as
swamp fever, American surra, malarial fever, typhoid fever of horses,
the unknown disease, no-name disease, plains paralysis, and pernicious
anemia, has recently been the subject of much investigation. The cause
of the disease has now been definitely determined as an invisible virus,
which is capable of passing through the pores of the finest porcelain
filters, like the infection of foot-and-mouth disease, rinderpest, hog
cholera, and similar diseases. The disease is most prevalent in
low-lying and badly drained sections of the country, although it has
been found on marshy pastures during wet seasons in altitudes as high as
7,500 feet. Therefore proper drainage of infected pastures is indicated
as a preventive. It is also more prevalent during wet years than in dry
seasons. It usually makes its appearance in June and increases in
frequency until October, although the chronic cases may be seen in the
winter, having been contracted during the warm season.
_Cause._--It has been conclusively proved that infectious anemia is
produced by an invisible filterable organism which is transmissible to
horses, mules, and asses by subcutaneous inoculation of blood serum. The
virus which is present in the blood may be transmitted to a number of
equines in a series of inoculations by injecting either the whole blood,
the defibrinated blood, or the blood serum which has been passed through
a fine Pasteur filter, thus eliminating all the visible forms of
organismal life, including bacteria, trypanosoma, piroplasma, etc. This
virus has also been found to be active in the carcass of an affected
animal 24 hours after death.