Disadvantage of lack of subjective symptoms. Causes, varied,
narcotics, overloaded stomach, cerebral anæmia or hyperæmia,
degenerations, parasites, tumors, jugular obstruction, valvular heart
disease, disease of internal ear, plethora. Susceptible animals,
horse, ox, dog, pig, sheep. Direct causes: tight collar, or throat
latch, flexion of head, heart disease, pulmonary disease, embolisms,
gastric distension, hepatic disorder, optic vertigo, aural vertigo,
injections into ear, rhigolene, chloral, acariasis, seasickness,
railroad sickness, cholesteatoma, cœnurus, concussion, degeneration,
softening, œstrus, linguatula, narcotics, essential oils: essential
vertigo. Symptoms: in irritable animal, highly fed, and without
exercise, crowds pole, his mate or a wall, shakes or jerks head,
staggers, trembles, rears, plunges, falls, struggles, sweats, rolls
eyes, recovers. In gastric or hepatic cases, dullness, pendent head,
swaying gait, dull eye, dilated pupil, pendent lids and lips, leans on
adjacent object, staggers, falls. In optic cases are obvious cause in
transition to light, etc., and palliation by covering the eyes. In
aural cases, rolling eyes, constrained position of ear, deafness,
pharyngeal or Eustachian trouble, wax or acari in ear, tender or itchy
ear. Plethoric cases in spring, in overfed, etc. Brain lesions may
have fever and disordered innervation, but retained consciousness, and
no marked spasm. Duration. Sheep: parasitic vertigo. Turning.
Rotation. Treatment: according to cause: restrict ration, give
exercise, purgative, adjust collar, breast strap, check, avoid sudden
transitions of light, overdraw check, blinds, treat nasal, pharyngeal,
ocular or aural trouble; during attack, stop in shade, cold to head,
deplete, bleed, purge, shady pasture or light work, bromides,
blisters, etc.
In dealing with vertigo or giddiness in animals we are confronted by the
impossibility of realizing the subjective feelings of the animal, as we
can so easily ascertain by interrogation in the case of man, and thus
our conclusions are largely inferences drawn from certain unsteady,
reckless or uncontrollable movements, or from an apparent inability to
maintain a stable equilibrium. The condition is rather a symptom of a
variety of morbid conditions, functional and structural, than a disease
_sui generis_. It may be due to alcoholic or other narcotic
intoxication, to overloaded or otherwise deranged stomach, to shock, to
a stroke of lightning, to disturbances—anæmic or hyperæmic—in the
circulation in the encephalon, to degenerations, parasites or tumors in
the brain, to compression of the jugular veins, to valvular or other
disease of the heart, to disease of the internal ear, to the plethora of
spring or early summer, to the qualms of sea sickness, to insolation.
The purely toxic cases are more clearly defined and temporary so that
they may be eliminated from consideration at present, yet their possible
occurrence must always be borne in mind by the practitioner especially
when called to pronounce upon cases of vertigo in connection with
veterinary legal questions. The cases that are due to a persistent
neurosis, or to circulatory troubles may well be placed in a list by
themselves, yet in their legal relations it is highly important that the
practitioner should as far as possible discriminate among these as well.
_Susceptible Animals._ Vertigo undoubtedly exists among all domestic
animals. The symptoms by which it is recognized have been noted
especially in the horse and much less frequently in ox, dog, pig and
sheep.
Among _horses_ it especially attacks the mature or aged, and family
harness horses, pampered and irregularly exercised; (saddle horses
rarely suffer); it is more likely to appear for the first time in spring
though when established it happens at all seasons; it may come on when a
horse is driven in blinders and fail to appear in the absence of these.
_Causes._ 1st. =Compression of the jugular veins= by a too tight collar
is the cause of one of the simplest forms of vertigo and is observed, in
growing or fattening animals in which the neck has become gradually too
large for the collar. The supply of a larger and well fitting collar
will soon confirm the diagnosis by a complete and permanent removal of
the trouble. In other cases the veins may be compressed by undue flexion
of the head, the chin being drawn toward the breast, or by a throat
latch buckled too tightly. The substitution of an overdraw check rein,
or a loose throat latch will show the true source of the trouble.
2nd. =Disease of the valves= _of the heart_ or their insufficiency from
cardiac dilatation is a common cause of vertigo, and may be recognized
by auscultation and by the general symptoms of chronic heart disease.
3d. =Disease of the lungs= interfering with the flow of blood through
the right heart and more distantly with the return of blood from the
brain. It further effects the brain functions through the circulation of
a highly carbonized blood, which fails to maintain the normal functions
of the ganglia.
4th. =Disease of the blood vessels=, it may be by emboli washed on from
clots in the pulmonary veins or the left heart and arrested in the
vessels of the brain; it may be by aneurism of the anterior aorta as
reported of a horse (Lustig); it may be by phlebitis and thrombosis of
the jugulars; it may be by adjacent tumors pressing on the vessels.
5th. =Gastric Vertigo=, =Abdominal Vertigo=, is a complication of
gastric or hepatic disorder with giddiness and unsteady movement. The
abdominal disorder may be at once a cause and result of the vertigo and
it is not always easy to decide which predominates. The unsteady
movements in certain cases of overloaded stomach, in the horse are
illustrations of purely abdominal vertigo, while on the other hand in
vomiting animals nausea, retching, emesis, and other gastric disorders
promptly attend on the primary cerebral disorder. There is also a
special tendency to vertigo in the fat, idle, gorged horse and in those
with torpor or other disorder of the liver occurring in pampered horses
in spring and early summer.
6th. =Optic vertigo= is a reflex disorder, determined in the excitable
nerve centres by the visual influence. Thus it has been seen in horses
and sheep from the intense glare of the sun’s rays, reflected from a
lake or river or from white snow or ice, or even from the glistening
inner surface of the blinds. The effect is intensified if the animal has
just emerged from a dark stable or a darker mine. The overdraw check may
be a factor by reason of its turning the eyes upward and exposing them
continuously to the full glare of the sun. The sense of motion conveyed
through the eyes contributes to bring on giddiness and a sense of
swimming. In man this is notorious, the sense of nausea and vertigo
being precipitated by looking at the nearby, moving objects in cabin or
on deck, while it may be retarded by directing the eyes to steady
distant objects. As dogs, horses and other animals suffer from
seasickness, and even railroad sickness, this attendant factor may be
logically accepted. The mere limitation of the field of vision, by the
use of blinds, and the disappearance in rapid succession of near objects
behind this narrow screen probably has an influence similar to the
visible motions in the ship between decks, in cases in which these
portions of the harness are manifest factors.
7th. =Aural Vertigo= is determined by irritations of different kinds
affecting the external, middle or internal ear. Experimental sections
show that this is especially due to injuries of the semicircular canals.
If the _horizontal canal_ is divided there are pendulum-like movements
of the head alternately to the right and left, also lateral rolling of
the eyes. If the _posterior canal_ is cut there is a vertical movement,
or nodding of the head and vertical rolling of the eyes. If the
_superior vertical canals_ are injured there are pendulum-like vertical
movements of the head and the animal tends to fall forward. Injury to
the _anterior canal_ causes diagonal rolling of the eyeball. In
destruction of _all the canals_ various pendulum-like movements are
performed, and standing often becomes impossible. Stimulation of one
auditory nerve is followed by rotation of the eye and rotation of the
body on its axis toward the injured side. The passage of a galvanic
current through the head _between the mastoid processes_, or _from one
external auditory meatus to the other_, causes rolling of the eyeballs.
_Injection of water violently into a rabbit’s ear_, or of _iced water_
or of a _rhigolene_ jet, causes rolling of the eyes, and rotation of the
body toward the side operated on. Dr. Weir Mitchell had a similar
experience in his own person. If the injections are repeated a permanent
vertiginous condition is induced, and the rabbit or Guinea pig, which
has been kept in darkness for a few hours and is then suddenly exposed
to sunlight, is unstable on its limbs for a few seconds. Lucæ found that
with perforation of the membrana tympani, an _ear air douche_, at 0.1
atmospheres caused abduction of the eyeball, dyplopia, giddiness, sense
of darkness, and disturbed respiration. Vulpain found that a 25 per
cent. solution of _chloral hydrate dropped into the ear_ of a rabbit
caused vertiginous movements. McVey records the case of a music teacher
who had intense vertigo induced by the _low bass notes_ of a piano. Crum
Brown noticed that if a person with bandaged eyes, is rotated for some
time as on a potter’s wheel, he can at first estimate the degree of
rotation, but after a time he fails to do so, and the rotation may be
stopped, without checking his sense of whirling. The familiar method of
subduing an intractable or vicious horse by _running_ him rapidly around
_in a very narrow circular course_, or by tying head and tail together
and letting him circle around until he staggers or falls, is another
manifest example of this aural vertigo. Rabbits and dogs suffering from
_acariasis of the external ear_ move around in a circle, or even turn
somersaults tending toward the affected side. Trasbot has found larvæ of
insects (simulium cinereum?) in the ears of vertiginous horses, which he
successfully treated with injection of chloroform. Even hard pellets of
wax pressing on the tympanic membrane have been found to give rise to
vertigo.
The explanation of cases of aural vertigo, has been sought in the
physiological action of the endolymph and perilymph on the end filaments
of the nerve in the membranous labyrinth, the turning of the head from
one side to the other having the effect of changing the pressure in
different parts and establishing currents by which the change of
position is recognized; on the other hand any injury to the canals, by
disturbing the pressure of the perilymph and interfering with the
relative position of the canals, and the direction and force of the
currents of the endolymph and perilymph, destroys all proper sense of
balance. The rotation of the subject as on a wheel or in turning in a
narrow circle, is held to cause circular currents in and around the
membranous labyrinth which temporarily destroy all sense of equilibrium.
Seasickness and railroad sickness are doubtless in part due to the
swaying motions causing disturbance in the canals. The intimate relation
between the root of the auditory nerve and that of the vagus in the
medulla, may serve to explain the mutual interdependence of derangement
of the stomach and liver on the one hand and the occurrence of vertigo
on the other. Again the relation of vertigo to visual troubles, both as
to cause and effect, has been attributed to the close relations of the
ganglia presiding over the 3d, 4th, 5th and 6th nerves and those of the
nerve of hearing.
There is a degree of deafness in nearly all cases of aural vertigo, a
circumstance which may be utilized in the diagnosis of such cases, the
presence of disease of the guttural pouch, or Eustachian tube, and
evidence of deafness on one side rather than the other, may be taken as
corroborative evidence of the affection. On the other hand James shows
that the stone deaf are much less subject to both seasickness and
vertigo than those that hear. The disorder that leads to vertigo implies
a retention of a measure of the normal function of the internal ear, and
therefore of hearing, whereas the disease that has caused complete
destruction of the internal ear and consequent loss of hearing has
equally destroyed the function of the labyrinth in maintaining a sense
of balance, and has obviated the aural sensations of equilibrium and
loss of balance.
8th. =Cerebral Vertigo= may be associated with derangement of the
circulation, or disease in the brain or its meninges. Anæmias and
congestions resulting from disease or impaired function of heart, lungs,
arteries or veins have been already noticed. It remains to note the
presence of cholesteatomata and other tumors, and of parasites
(cysticercus cellulosa in pig; cœnurus cerebralis in sheep) in the
encephalon, and of injuries from concussion, degeneration and softening
of the brain substance.
9th. =Nasal Vertigo= has been noted by Cadeac in connection with
irritation in the nose and especially by the larva of œstrus ovis
(sheep), and the linguatula (dog, horse). In certain of the cases
manifested by jerking of the head and diverging to one side, the
recovery after section of the pes anserina indicates a nasal origin.
10th. =Vertigo from Narcotics= (alcohol, lolium temulentum, belladonna,
solanum, various essential oils, carbon monoxide, etc.), have been
already referred to.
11th. There remains to be noted cases in which no narcotic poison, no
mechanical disturbance of the circulation, no visual, aural nor nasal
trouble, no gastric nor hepatic disorder, and not even a distant nervous
lesion can be found; the disease may in such cases be ranked for the
present as =essential vertigo=.
_Symptoms._ As usually seen in the horse, vertigo often attacks the
nervous, irritable animal in which the slightest occasion of irritation
or disturbance causes intense suffering and quick response. This is
often aggravated by the plethoric condition of the animal, kept on a
liberal ration of grain and having little exercise. In some forms of the
affection, however, and especially the gastric and hepatic, the subject
is dull, carries the head low, and lacks vivacity and energy.
In the first form (the most common in the horse) the animal which has
been full of life and vigor, slackens his pace and the tension on the
reins, or stops suddenly, shakes the head, vertically or horizontally,
or jerks it to one side, trembles, staggers, props his legs outward for
more stable support, presses against the pole, or the other horse, or a
wall, leans on the breeching or hangs on the breast strap, plunges
forward, or to one side, or rears up and even falls backward, and comes
to the ground. Profuse perspiration ensues, the eyes roll, the face is
pinched and drawn, the prostrate animal may struggle in a helpless way,
and, if the harness is loosened, he may get up in a few seconds and
slowly recover. Often, however, he remains for an hour or more, nervous,
sensitive, bedewed with sweat, trembling and with anxious expression.
Such are the more common manifestations of what is familiarly known as
blind staggers. The symptoms will vary however, with the cause.
In =gastric= or =hepatic= cases there may be more particularly dullness
and lack of energy, low carriage of the head, unsteadiness of gait, lack
of lustre in the eye, pupils dilated, semi-closed eyelids, pendent lips,
a tendency to lean on the stall or hang on the harness, and though the
animal may stagger and fall, there is not the abrupt transition from
life and energy to the active excitement and uncontrollable movements.
The same remarks apply in a measure to narcotic vertigo.
With =optic vertigo=, the attendant conditions will help to a diagnosis.
The animal has come from darkness to full sunshine; there is the white,
icy or snowy reflection everywhere which the animal was facing when
attacked, or the glistening lake or river, the overdraw check rein, or
the blind with perhaps a shining inner surface. The pupil is closed, and
the eye is rolled back or oscillates in one direction or another. The
symptoms are checked by covering the eyes or removing the subject into a
dark building or even into the shade of a tree or shed.
With =aural vertigo= there may be similar rolling of the eyes, without
the pupillary closure, the ear may be drawn down or back, and the
shaking or jerking of the head is likely to be a marked feature. If
there is more motion of one ear than the other, if the head is jerked to
the one side, if there is a measure of deafness in the one ear (to be
ascertained rather in the intervals between attacks), if there is
disease of the pharynx, the Eustachian tube or pouch, or swelling about
the root of the ear, if there is wax, scurf, or acarus in the ear, if
the animal rubs it frequently, aural vertigo may be suspected.
=Nasal vertigo.= Those forms in which the head is jerked horizontally,
vertically, or diagonally, the animal pressing against its mate or the
pole, or outward in the harness, and getting out of its track, even if
it should stop short of falling, and which appear only during work, or
are aggravated by exertion, have been attributed to lesions of the ear
(Fleming), but in some cases they can be warded off by wearing a net
over the nostril, and can be entirely stopped by complete transverse
section of the pes anserina, so that in a certain number at least they
must be accounted nasal. These are not usually attended by sneezing. The
simple expedient of driving with a rather close net over the nostril may
enable one to diagnose many of the purely nasal forms.
=Plethoric vertigo= may be suspected when the attack comes on in spring,
in a fleshy or fat horse, overfed and little exercised, when there is
dark red congestion of the nasal mucosa and conjunctiva, and a
subsidence with rest.
In the _vertigo_ of brain lesions, the acute forms are attended by fever
and marked signs of delirium or disordered nervous functions, while in
the chronic forms there may be permanent hyperæsthesia or anæsthesia,
general or with rather diffuse limits, and the vertiginous attacks
repeat themselves frequently irrespective of weather, though they may be
precipitated by faults of feeding, indigestion, severe exertion, or some
of the other exciting causes above mentioned.
These cases are to be distinguished from epilepsy by the absence of any
spasmodic contraction, aside from the jerking of the head and rolling of
the eyes, and by the fact that consciousness is retained throughout.
During the attack the animal may fail to respond to irritation of the
nasal mucosa, but this appears to be due to the fact that his whole
attention is engaged with a more serious trouble.
The duration of an attack is from one to two, or exceptionally five
minutes. The form which is represented by jerking of the head and
deviation from the direct line of motion may continue so long as
exercise is kept up.
In the =nasal vertigo= of sheep and dogs, due to parasites, sneezing,
and congestion of the mucosa are to be looked for.
In the =cerebral parasitic vertigo= of sheep and pigs, the symptoms vary
according to the seat of the parasite. These may be blindness, turning
in a circle, moving straight ahead regardless of obstacles, jerking
upward of the head with nose protruded, hemiplegia, hemianæsthesia,
cross hemiplegia, cross hemianæsthesia, and any one of the many forms of
paralysis, or exaggerated nervous action. The animal usually turns to
the side on which the parasite lies and is paralyzed on the opposite
side of the trunk. A peculiarity of these cases is that while the
symptoms are continuous, yet there are periodic aggravations which bear
no relation to feeding, exertion or excitement, but depend on the
protrusion at intervals of the heads of the parasites into the brain
substance. If there are several parasites in the brain and they do this
at different times the symptoms are liable to vary according to their
seat, and the special organ which is irritated. This variability of
symptoms is suggestive of parasitism.
While turning around in a circle has been already noticed there remains,
in certain cerebral forms, the peculiar phenomenon of the animal
rotating rapidly on its longitudinal axis. The patient falls on its side
and rolls over and over. Among the brain lesions with which it has been
experimentally identified are injuries to the _middle peduncles of the
cerebellum_, or of the _superoexternal portion of the cerebral
peduncles_, or of the _posterior part of the encephalon_, or of
different parts of the hemispheres.
Cases of vertigo that occur without any appreciable lesion have been
named _essential vertigo._ Guibert has attributed some cases to
irritation of the lower part of the limbs by contact with the litter but
this could only occur in an animal in which the nervous system was in a
morbidly excitable condition.
_Treatment._ The prophylactics and therapeutics of vertigo will vary
with the cause. The diagnosis of the cause is therefore the most
important step. In pampered, overfed, idle horses a reduced ration and
daily exercise or work will often suffice. It is usually desirable,
however, to remove intestinal irritants and deplete the vascular system
by an active purgative. If the attacks appear only in Spring this care
should be especially given at such seasons. A tight or badly fitting
collar should be corrected, also a position of the breast strap which
causes it to press on the jugular veins. A short bearing rein causing
undue flexion of the head must be lengthened or abandoned. A too dark
stable should be avoided, also the sudden exposure to white, dusty roads
and, still more so, to the glare of snow, ice, or water. A short,
overdraw check rein, turning the eyes up directly into the sun’s rays,
or blinds with a glistening inner surface may require correction. It may
be better to abandon blinds altogether, or to cover the eyes by a piece
of leather, 2 to 4 inches wide, extending across the forehead from one
eye to the other; or a sunshade attached to the headstall may be worn so
as to protect the eyes. Horses which become seasick or carsick may
sometimes be helped by covering the eyes. Other indications would be to
treat any existing trouble which interferes with a normal circulation in
the brain (pulmonary congestion, aneurisms, tumors pressing on carotids
or jugulars, phlebitis, etc.), and such as affect the ear (disease of
the pharynx, guttural pouches, adjacent glands, petrous temporal bone,
membrana tympani, external ear). Indurated wax, insects or insect larvæ
may be removed by careful irrigation with warm water, and perhaps by
chloroform. Nasal parasites must be washed out or destroyed by benzine,
and any hyperæsthesia of the nasal mucosa may be met by covering the
nostril with a net, or radically by cutting the facial branch of the 5th
nerve as it emerges from the infra-orbital foramen.
When attacked the horse should be at once stopped and put under the
shadow of a roof or tree, or in their absence a blanket or lap robe may
be used to cover his eyes. If there is danger of falling remove the
harness, and secure a soft piece of ground, free from stones or other
hard bodies. Cold water applied to the head will sometimes check. A
common practice is to bleed from the palate, and in plethoric cases
especially, and in such as are dependent on congestion, tumors or other
lesion of the brain it is to be commended. The action will be rendered
more prompt and effective if the blood is taken from the jugular. A
laxative diet, and carefully regulated work are desirable to obviate the
tendency to the affection, and this may often be accomplished by a run
at pasture. Otherwise daily small doses of Glauber salts in the feed may
suffice. Bromides may be used to calm nervous excitement.
In cases of =gastric vertigo= an active cathartic, followed by smaller
laxative doses or a laxative diet and a course of bitters may prove
useful. Such cases should never be worked on a full stomach but should
be left at rest for at least an hour after a meal.
In =aural vertigo= special attention must be given to the throat, and
external ear. Bromides may often be useful, and sometimes benefit may be
derived from an occasional blister or light firing back of the ear.
In =cœnurus cerebralis= in sheep the only resort is to trephine and
remove the parasite.