2. _Encephalitis_ (_Cerebritis_). Inflammation of the nervous
substance. These are further subdivided into:
_A._ _Pachymeningitis._ Inflammation of the dura Mater.
_B._ _Leptomeningitis._ Inflammation of the pia Mater.
_C._ _Purulent Meningitis._
_D._ _Serous Meningitis._
_E._ _Tubercular Meningitis._
_F._ _Traumatic Meningitis_, etc.
_G._ _Cerebro-Spinal or Infective Meningitis._
_H._ _Acute Meningitis._
_I._ _Chronic Meningitis._
_J._ _Polioencephalitis Corticalis._ Inflammation of the brain cortex.
_K._ _Polioencephalitis Superior._ Inflammation of convolutions around
the Sylvian fissure, palsy of the eyeball.
_L._ _Polioencephalitis Inferior._ Inflammation of the Medulla, bulbar
palsy.
_M._ _Interstitial Inflammation of the Brain._ Resulting often in
sclerosis.
In the lower animals, however, where we cannot avail of subjective
symptoms, such fine distinctions can rarely be made in diagnosis and
except in case of an uncomplicated meningitis, or a circumscribed
encephalitis, which affects only a limited group of muscles like those
of the eye, arm, or leg, we have to fall back upon a more general
diagnosis. Again meningo-encephalitis is more common than the
uncomplicated affection of the brain, or the membranes, and therefore,
we shall follow Trasbot in dealing with the combined affection, and
noting incidentally the distinctions that can be made in the more purely
limited affections.
_Causes._ =Mechanical Injuries=. Pachymeningitis occasionally results
from blows or other injuries upon the head, especially in stallions and
vicious horses struck with a heavy whip or club, cattle and sheep
injured in fighting, and oxen hurt by the yoke. These injuries may also
affect the brain as in concussion, or by the extension of the disease
into the nervous tissue. In the cranium of a stallion in the New York
State Veterinary College Museum the whole of the meninges are greatly
thickened by a traumatic meningitis of old date and the subjacent
cerebral convolutions of the right hemisphere are deeply encroached on,
flattened and absorbed over an area of 1¾ inches in the longest
diameter.
=Diet.= Among the most common causes of encephalitis in horses is an
injudicious dietary. Overfeeding with grain, but especially with grain
and seeds that are rich in albuminoids deserve the first mention. The
various leguminous seeds, peas, beans, tares, vetches, and the ripened
leguminous fodders, clover, alfalfa, and sainfoin, are especially to be
incriminated. These are usually most dangerous when in the stage of
advanced ripening and yet not fully matured, evidently indicating the
development of narcotic poison at this stage. Such poisons are found
habitually in certain species, like the chick vetch (vicia cicera) which
produces paralysis when fed to the extent of more than one-twelfth part
of the ration. This danger is not, however, confined to the leguminosæ;
an over abundant ration of cottonseed meal has a similar effect, and
indeed this rich alimentary product has been practically discarded from
pig feeding, and largely as the main constituent from the ration of
dairy cows. Gluten meal, another product rich in proteids, is attended
by similar dangers. But it is not alone the seeds that are rich in
nitrogen that are to be dreaded, forced feeding even on the carbonaceous
maize induces disorder of the digestion and brain, especially in dairy
cows. Buckwheat, also, and indeed all the heating carbonaceous grains
tend to similar disorders, and are especially injurious in internal
ophthalmia (recurring ophthalmia) which is so closely related to brain
congestion. With sound judgment and in well balanced rations, all such
agents can be fed to advantage; it is only when fed exclusively or to
excess as the heavy ration that they are to be feared.
=Narcotics.= Next must be noted those alimentary matters which are
hurtful by reason of narcotic constituents. At the head of this list may
be placed the lolium temulentum or intoxicating ryegrass. like the vicia
sativa or cicera, the seeds of this are always poisonous, hence its
significant name. Then the other ryegrasses, perennial and annual
(Italian), though perfectly safe in ordinary circumstances, develop at
the period of ripening a narcotic principle, which produces cerebral
congestion or inflammation in whole stables of horses at a time. The
lolium temulentum is poisonous to man and animals alike. Baillet and
Filhol obtained from the seeds an etherial extract containing a bland
oil to the amount of two fifths and a yellow extract to the extent of
three-fifths. The amount of this extract derived from three ounces of
the seeds often developed the most violent symptoms in the dog, while
that furnished by six pounds of the seeds proved fatal to the horse.
Pigs and cattle seemed to be unaffected by the agent when given by the
mouth. Sheep suffered more but required large doses. Ducks and chickens
were practically immune, being affected only by very large doses.
Rabbits were not poisoned by the yellow etherial extract, but succumbed
to a watery extract. Brydon found that lambs suffered extensively from
eating the heads of the ryegrass.
Lupins on certain lands produces an icteric disorder accompanied by
cerebral symptoms but the result is not the same under all conditions
and it has been suspected that the symptoms were caused by cryptogams
and their products. The same remark applies to the brain symptoms
sometimes produced by trefoil, equisetum and other plants.
A great number of =narcotic= and =narcotico-acrid= plants produce
nervous symptoms indicating cerebral congestion or inflammation such as
ranunculus, wild poppy, digitalis, fennel, œnanthe crocata, hellebore,
veratrum, conium, yew, tobacco, box, aconite, cicuta virosa, even
buckwheat at the time of flowering, vetch and flax.
Fodders affected with =cryptogams= or =bacterial ferments= are
undoubtedly at times the cause of encephalitis. Veterinary records
furnish many instances of wide spread attacks of stomach staggers,
abdominal vertigo, and cerebro-spinal meningitis in wet seasons, when
the fodders have been harvested in poor condition, or when from
inundation or accidental exposure they have become permeated by
cryptogams and microbes. Among comparatively recent accounts of this are
those of Martin and Varnell (musty oats), Lombroso, Depre, Erbe,
Pellizi, and Tireli (smuts), Bouley and Barthelemy (musty fodder), and
Ray (fermented potatoes). One of the most extended local outbreaks of
cerebro-spinal congestion I have seen, occurred in the pit mules of the
Wilkesbarre coal mines, while fed on Canadian hay which had been soaked
with rain in transit and had undergone extensive fermentation. It should
be noted that there were the attendant factors of overwork, in
anticipation of a strike, and a Sunday’s holiday above ground in a
bright summer sunshine.
The experimental administration of moulds, smuts and microbes, have in
the great majority of cases led to little or no evil result (Gamgee,
Mayo, Dinwiddie, etc.) and there is a strong tendency to discredit the
pathogenic action of these agents in reported outbreaks. The safer
conclusion perhaps would be, to recognize the fact that they are not
equally pathogenic under all conditions of their growth and
administration. The oft-recurring epizootics of brain disease in
connection with wide spread spoiling of the fodders in remote and recent
times, probably imply that cryptogams or microbes and their products,
plus some condition not yet fully understood are efficient concurrent
factors. If we can discover this as yet unknown factor and demonstrate
that it operates with equal power in the absence of the cryptogams and
ferments, as in their presence, it will be logical to pronounce these
latter as nonpathogenic under all circumstances. Until then cryptogams
and bacteria must be held as probable factors.
A continuance of =high temperature= is an undoubted factor and becomes
more potent, if conjoined with a close, damp, ill-aired stable.
=Violent exertion= especially in hot weather produces active congestion
of the brain and occasionally merges into meningo-encephalitis. If the
animal has been for sometime confined to the stable on rich aliment the
condition is aggravated.
=Railroad travel= is another recognized cause.
Any considerable =change of the conditions of life= may operate in the
same way. A sale and transport to a distance with change of feed, water,
work, stabling and even of climate is at times a potent factor. Prietsch
has seen a horse attacked three times in a single year, and on each
occasion after a change of ownership and locality. Trasbot quotes an
Algerian veterinarian to the effect that many of the percheron horses
imported into the Mitidja are attacked by encephalo-meningitis during
the extreme heats of summer.
A careful observation of cases will however show that in the majority of
cases an attack comes not from one individual factor alone but from a
concurrence of several operating together.
Other cases are caused by =embolisms= and =infections= from diseases
localized in other parts of the body. Thus we have cerebral abscess in
pyæmia, strangles and omphalitis, and cerebral congestions and
inflammation in canine distemper, equine contagious pneumonia,
laminitis, and angina.
Among mineral poisons, =lead= is notorious as a cause of acute cerebral
disorder often leading to inflammation. Other mineral poisons like
=arsenic= and =phosphorus= may lead to encephalitis symptomatic of
gastro intestinal irritation, or caused by the toxic products of
indigestion.
Rapidly growing =tumors=, like cholesteatomata, are liable to induce
recurrent attacks of encephalitis in connection with periodic
irritation.
Finally =parasites= in the cranium are sufficient causes of attacks. In
the New York State Veterinary College Museum is the brain of a cat with
a nematoid wound round the hypophysis. In equine subjects suffering from
the strongylus armatus the larval worm or clots caused by its presence
in other arteries sometimes invade the encephalic blood vessels causing
disturbances of the circulation, embolism, inflammation or degeneration.
(Albrecht, Von Heill). The larvæ of the œstrus has also been found in
the brain substance producing inflammatory or degenerative foci
(Brückmüller, Megnin, Siedamgrotzky). Their presence in the nasal
sinuses at times cause encephalitis by contiguity. The cestoid worms,
cœnurus in sheep and other ruminants, and cysticercus in swine, find
their natural larval habitat in the brain and by their movements produce
more or less congestion and inflammation. Cases of cœnurus in the horse
have been described by Rousset, Frenzel, Zundel, and Schwanefeldt.
_Symptoms._ The symptoms of uncomplicated meningitis on the one hand and
encephalitis on the other are rarely seen, the disease usually
implicating more or less both brain and meninges, in a common
inflammation or the symptoms of the one involving those of the other
through proximity or interdependence of function. And yet in traumatic
lesions of the cranial walls, the symptoms may be those of pure
meningitis, and in thrombosis, embolism or parasitism of the brain, and
in certain tumors they may be those of simple encephalitis. The
distinction consists largely in the predominance of fever,
hyperæsthesia, active delirium and convulsions in _meningitis_, and
especially in its earlier stages; and the prominence of dullness,
stupor, somnolence, muscular weakness, paralysis, anæsthesia, coma, and
the clouding of special senses, with much less pronounced febrile
reaction, or vascular excitement in _encephalitis._
There is usually, however, a mixing of symptoms so that the benumbing or
paralysis of the nervous functions alternates with periods of their
exaltation, and with both conditions hyperthermia exists, though usually
higher with meningitis.
The manifestations of benumbing or paresis may be continuous or
interrupted, and are exhibited in stupor, coma, somnolence, lethargy,
paresis or paralysis. The manifestations of excitement are not
continuous but occur in paroxysms or at least exacerbations, which may
show in visual or mental illusions, active, violent delirium, trembling,
rigors, clonic or tonic spasms. The onset is usually abrupt, the animal
passing in a few hours from apparent health, to pronounced nervous
disorder. The horse seems drowsy and stupid, standing with semi-closed
eyes, often drooping lower lip and ears, head pendent and resting in the
manger or against the wall in front, the back arched and the limbs drawn
together. When moved, it walks unsteadily and often the limbs are left
out of plumb, one extending unduly forward, backward or to one side, and
often crossing over its fellow. Some cannot be made to back, others back
spontaneously hanging on the halter. Turning short in a circle is
difficult or impossible and tends to throw the patient down. Yet some
exceptional cases will turn around spontaneously to the right or left,
and an animal tied to a post goes around it at the end of its halter in
its effort to pass straight forward. The circling movement may be due to
the irritation on the one side of the brain or to irritation of
particular ganglia and nervous tracts as noticed under cerebral
hyperæmia.
Appetite is usually lost, or, more properly, the animal no longer takes
notice of surrounding things, not even of its food. In some cases,
however, in which stupor or coma is not extreme the animal will eat a
little during his quiescent intervals. In ryegrass and other dietetic
poisoning, the animal may still eat and fall asleep with the month full.
The digestion is impaired or suspended, the bowels costive, and
fermentations with tympanies and rumbling are frequent complications.
When originating from poisonous food this often contributes to these
abdominal complications.
Respirations in the comatose condition are deep and slow, sometimes not
more than four or five per minute. The heart usually beats strongly,
often tumultuously, and the pulse varies greatly—infrequent or frequent,
strong or weak, full or small. With cerebritis it is often abnormally
slow.
Hyperthermia is always present to a greater or less extent, being often
more marked in the more violent forms or those in which meningitis
appears to predominate than in the purely cerebral forms. The
temperature may vary from 101° to 106°.
The optic disc is congested.
Probably in all cases or nearly all there is a preliminary stage of
excitement, in which the eye is clear, the eyelids open, the aspect
alert and the whole skin affected by a marked hyperæsthesia. In some
cases the symptoms of excitement are much more violent at the outset of
the disease, as marked by trembling, nervous movements, pawing, pushing
the head against the wall while the motions of walking or trotting are
performed by the limbs, or those of plunging forward, rearing up,
drawing back on the halter, etc.
But even when the disease seems to have started with stupor and coma,
these paroxysms of excitement almost invariably appear at intervals as
it advances. Some, however, plunged in stupor or coma at the first,
remain in this condition until they end in paralysis or death, or start
in convalescence.
During one of the paroxysms the trembling animal may push his head
against the wall as if pulling a heavy load; at other times he will
plunge with his feet in the manger and recoiling, fall to the ground,
where he struggles violently in an apparent effort to rise; others rear
up, pulling on the halter or breaking it and falling back over; some
pull back on the halter and throw themselves down; some grind the teeth,
or seize the manger, or strike blindly with the fore limbs. When seized
out of doors the horse may be quite uncontrollable and refuse to return
to the stable even when led by two men with double halters. In all such
cases the eye has a fixed, glaring aspect which is the more pronounced
when the pupils are dilated, the conjunctiva is deeply congested, of a
deep, brownish red with a tinge of yellow. This is usually greatly
enhanced by the bruises and extravasations caused by pushing or knocking
the head against the wall. The same violence may lead to serious bruises
and injuries elsewhere, even fractures of the orbital process or zigoma,
of the ilium or ischium, of the poll or the base of the brain; also of
the incisor teeth.
These paroxysms may be so frequent that they seem to be subject to
remissions only, and not separated by complete intermissions. During the
paroxysms breathing and pulsations are both greatly accelerated.
The gravity of the attack may be judged in part by the violence and
frequency of the paroxysms. Yet some cases, marked by profound coma from
the first, prove the most rapidly fatal, and the paroxysms of excitement
and violence are not incompatible with recovery. Improvement may usually
be recognized by the increased length of the intervals between the
paroxysms, and by the shortening and moderation of the periods of
excitement. After the paroxysms have ceased the drowsiness or stupor
gradually disappears, and the hyperthermia subsides.
Even after recovery from the acute or violent symptoms there is liable
to remain some aberration or perversion of function, due to the
persistence of some encephalic or meningeal lesion. The general hebetude
known as _immobility_ may bespeak dropsy of the ventricles, pressure of
a tumor or clot, or degeneration of ganglionic centres. Diseases of the
eyes (amaurosis, glaucoma, cataract), or of the ear (deafness, disease
of the internal or middle ear) are less frequent results.
The supervention of general or facial paralysis or of hemiplegia during
the active progress of the malady, is an extremely unfavorable symptom.
_Duration._ A fatal result may take place at any time by self inflicted
injuries (dashing the head against a wall, or falling backward and
striking the head on a solid body). Apart from this, death may come
within twenty-four or thirty-six hours. If the animal survives two to
seven days recovery is more probable. Hering records a case of recovery
after five weeks illness. Hot weather hastens a fatal result, while
cool, cloudy weather is favorable.
_Prognosis._ Under rational treatment about one-fourth recover. One-half
of the victims make a partial recovery but remain in a condition of
dementia or hebetude, blindness, deafness, local or general paralysis
which renders them more or less useless. Not more than one-fifth or at
most one-fourth of all cases recover. Even in these there is left an
increased predisposition to recurrence. It is noted by Trasbot that the
mortality is higher in highbred, nervous, irritable animals, which show
a tendency to greater frequency, force and duration of the paroxysms of
excitement. When decubitus is constant, death may take place from septic
poisoning starting from bed sores, and gangrenous sloughing. In other
cases there is fatal starvation from inability to eat.
_Lesions._ In =pachymeningitis= due to mechanical injury there is
usually cutaneous and subcutaneous, blood extravasation, and there may
be fracture of the cranial bones. The dura mater is dark red, hyperæmic,
thickened, covered with exudation and small blood clots mixed with pus
cells, and has contracted strong adhesions to the cranial bone. Bony
spicula may project into the fibrous neoplasm.
=Leptomeningitis= usually coexists from extension of the inflammation
into the adjacent arachnoid and pia mater. There is then a reddish
serous effusion into the arachnoid and beneath it, and the substance of
both membranes is thickened by exudate, and discolored by congestion and
minute hæmorrhages. Whenever the pia mater is thus inflamed, the
superficial layer of the brain is implicated, œdematous, soft and
doughy. The extension is also made into the ventricles and a serous
effusion takes place often to two, three or more times the normal amount
(82 grammes Schütz). The choroid plexus forms a yellowish gelatinoid
mass, and the ganglia (corpora striata, optic thalamus, etc.), are
flattened.
In =encephalitis= the affected superficial gray matter of the ganglia or
convolutions, is deepened in color, usually in limited areas
corresponding to the disease of the meninges. Sometimes the color
becomes of a distinctly reddish tinge, and when cut into shows unusually
prominent red points where the capillaries have been cut. Somewhat
larger areas of blood staining indicate hæmorrhagic extravasations. The
nervous substance is more or less infiltrated with liquid and softened.
The nerve cells are swollen, and in process of granular degeneration and
the same is true of the myelin, while the axis cylinder is uneven in its
outline. Apart from the numerous minute petechial hæmorrhages there is
an abundant migration of leucocytes which are found scattered in the
degenerating and softened nervous tissues.
The softening of the nervous tissue may result in a pulpy material,
which in the comparative absence of blood is grayish (=gray softening=),
if abundantly infiltrated with blood is red (=red softening=), if older
and discolored is yellow, as in an old extravasation, (=yellow
softening=), if thick and viscous is =gelatinoid softening=. If the
exudate becomes organized into fibrous material it is a =connective
tissue sclerosis= or a =cicatrix=. If the softening exudate becomes
purulent it constitutes a =cerebral abscess=. Cerebral abscess is
especially common as secondary abscess in strangles or contagious
rhino-adenitis in the horse, but may occur as the result of the presence
of any pyogenic germ.
_Diagnosis._ While there is a certain similarity to =rabies=, the horse
with encephalo-meningitis is distinguished by the absence of the extreme
hyperæsthesia and irritability, of the persistent neighing and
squealing, of the rapid alterations of the voice, hoarse and shrill, of
the hallucinations, as following imaginary objects with the eyes, of the
readiness to attack with teeth or heels when in any way disturbed or
excited, of the disposition to get violently excited when a dog is
brought near, or in the case of a stallion to show generative
excitement.
From =cerebral congestion= it is to be distinguished by the greater
severity of the paroxysms, or the deeper character of the stupor, but
above all by the presence of the hyperthermia and other indications of
fever.
=Immobility= which presents the symptoms of drowsiness, stupor and
hebetude, is also unattended by fever, or anorexia, shows a healthy
condition of the functions, of respiration, digestion and assimilation
and a restful condition when left quiet and still.
The _cerebral excitement_ that sometimes appears in =influenza= is
really an encephalitis complication, but its specific cause is
recognized in the local prevalence of the infectious disorder, and the
inflammatory or catarrhal condition of the mucous membranes.
The diagnostic manifestations of _meningitis_ and _encephalitis_
respectively are given under symptoms.
_Symptoms in Cattle._ In cattle encephalo-meningitis supervenes on
congestion, and sometimes comes on abruptly in connection with traumatic
injuries, acute gastric disorder, leadpoisoning, or narcotism. The cases
of cerebral parasitism are usually slow in their onset.
Upon the preliminary dullness and somnolence there supervenes
excitement, manifested by loud bellowing, pushing the horns, forehead or
teeth against the wall, labored often stertorous breathing, a fixed eye
often with dilated pupil giving it a peculiar glaring appearance,
movements of the jaws, frothing at the lips, tremors, muscular spasms,
twitching, or a restless disposition to move, in a circle, in a straight
line or less frequently backward. The patient seems to see nothing and
is utterly regardless of obstacles. Sometimes the animal plunges
violently into manger or rack, against or through the partition of his
box, through fences, into ponds, pits, quarries and other dangerous
places that may be accidentally in his way. The paroxysms may be
intermitted by intervals of comparative calm, and tend to merge into a
condition of dulled sensation, staggering, stupor, hebetude and
paralysis. The congested conjunctiva and, when it can be seen, the optic
disc will correspond to the cerebral congestion. These cases usually
proceed to a fatal issue in a few hours. Some cases, however, make a
good recovery after a few days of dullness and prostration. In cases
that are connected with lead poisoning, or the toxic action of narcotics
in the fodder, the attendant circumstances will assist in the diagnosis.
From malignant catarrh implicating the encephalon, it may be
distinguished by the absence of the catarrhal inflammation of the
conjunctiva, pituita, sinuses, buccal mucous membrane, and
genito-urinary passages. Also of the tendency to implication of the hair
follicles and the keratogenous tissue of the frontal horns.
In the _Edinburgh Veterinary Review_, Dundas describes a form of
alcoholism in cows caused by feeding these animals on “burnt ales” in
the vicinity of distilleries. The ale is given by steeping straw in it,
and the animals will also drink it freely. They often sleep soundly
after such a beverage or give evidence of intoxication. The head is
turned singularly to one side and slightly elevated. The pupils are
widely dilated, and the eyes have a remarkably wild appearance. On being
approached the animals wink rapidly and tremble. There is marked heat of
head, horns, and ears. When pressed with the finger in the axilla they
fall instantly and when pulled by the head they incline to turn over.
The pulse is 70 to 80 per minute. Delirium and loss of coördination of
the muscular movements set in, and in case of survival various forms of
chronic brain disease are manifested. In one cow the violent symptoms
came on with the near approach of parturition. The post mortem lesions
consisted in ramified redness and punctiform blood extravasations in the
pia mater and meninges. The brain substance was softened and clots of
blood were found in the lateral ventricles. Congestion and
extravasations were also found around the cervical myelon. (See
Alcoholic Intoxication).
_Symptoms in Sheep._ The sheep is often drowsy, dull and stupid, lying
by itself with head low or laid backward. During the periods of
excitement it works the jaws, froths at the mouth, carries the head
turned in one direction, upward or lateral, bleats piteously, pushes
against the wall, has uncertain, stiff or staggering gait, or
convulsions, and finally paralysis. The head is hot, and the eye fixed,
congested or sometimes rolled upward or squinted. Symptoms in the goat
are nearly the same. The cœnurus disease is more gradual in its onset,
and produces periodic paroxysms corresponding to the activity of the
heads of the parasite when protruded into the brain substance. It is
mainly confined to sheep of one year and under and that are kept where
dogs have access.
_Symptoms in Swine._ Pigs may at first have a period of dullness or
restlessness, the latter merging into active delirium. The patient
champs his jaws, froths at the mouth and nose, sometimes vomits,
squeals, raises himself with fore feet on the wall, walks round and
round, or falls and rolls over, has tremors or convulsions.
_Symptoms in the Dog._ There may be preliminary indications of illness,
anxiety, restlessness, irritability and a desire for seclusion. Vomiting
may occur. This is liable to merge into prostration, a dullness of the
special senses, utter inattention to calls, yet a disposition to resent
any interference, a readiness to bite, at least to howl, when handled.
Some will constantly howl or moan. The eye is fixed, the pupils dilated,
the conjunctiva deep red, the head and roots of the ear are hot. The
expression of the face is pinched and drawn, the muscles may twitch, the
eyes roll, twitching of the neck or limbs may appear, and even
epileptiform attacks. In exceptional cases the symptoms approximate to
those of rabies, in the tendency to seek seclusion, to wander off, to
bite on any interference, and even to gnaw the bars of the cage or any
object within reach. After more or less of such excitement, the period
of stupor, coma, paresis, or paralysis comes on, and the animal dies in
a state of complete nervous prostration. In cases associated with the
linguatula tænioides the sneezing, nasal discharge and nasal congestion,
even in the early stages, betray the true character of the disorder.
The rabiform cases usually lack the intense heat of the head, the deep
conjunctival congestion, the depraved appetite, the alteration of the
voice, and the mischievous desire to attack without reason which
characterize rabies.
_Treatment._ In all cases of phrenitis, quiet, darkness, and coolness
are especially demanded. For the horse a roomy, loose box or a well
fenced yard may be secured, and if he can be secured by a halter from a
point above the level of the head and in the centre of the box it will
obviate the increase of congestion by hanging of the head. The
application of cold to the cranium in the form of wet cloths, ice bags
or irrigation is always in order, and should be continued so long as
heat of the head and other indications of cranial hyperæmia last.
In the _horse_ suffering, as is so often the case, from narcotic
poisoning an active purgative is one of the first considerations to
clear away any remains of the poison from the _prima viæ_. An ounce of
aloes may be safely given, as there is in this case little danger of
superpurgation, and, to secure an even more prompt response, eserine (1½
grain) or barium chloride (½ drachm) may be given subcutem. Or an ounce
or two of glycerine by the rectum might be used as a substitute for
these last. The action of the purgative proves not only eliminant and
therefore antidotal, but it is a most effective derivative from the
brain. When the restlessness or excitement is very great we may use
acetanilid, trional, sulphonal or some one of the many brain sedatives
and antithermics. Sedatives, or anodynes like opium, which tend to
increase cerebral congestion are dangerous.
Bleeding from the jugular or temporal artery, has been objected to on
the ground that it tends to increase the exudate and therefore the
pressure and cerebral anæmia. On the other hand it often proves of great
value in vigorous, muscular and plethoric horses in temporarily
lessening the blood pressure in the brain, and affording the walls of
the overcharged capillaries an opportunity to resume a more normal tone
and to control that very exudation which is so much dreaded. It is most
effective in the early stages when little or no exudation has taken
place and may then be pushed to the extent of producing a perceptible
softening of the pulse (4, 6 or 8 quarts). Even in the advanced stages
when exudation has led to stupor or coma a moderate and carefully
guarded bleeding may favor reabsorption of the liquid exudate. In weak
and anæmic cases in which general bleeding appears to be
contra-indicated the shaving of the cranial surface followed by leeching
or wet cupping can be safely resorted to.
Counter-irritants like bleeding are denounced and advocated by different
practitioners. In cases of extreme hyperæsthesia where excitement and
fever would be dangerously increased by their use, they must be
discarded, or used only in the modified form of soothing hot
fomentations to the extremities. Where there is less sensitiveness
mustard poultices or pulp applied on the sides of the neck, or upon the
limbs, or even more energetic blisters will be of great service.
After the action of the purgative the bowels may be kept free by calomel
in ½ drachm doses twice daily and as much sulphate of soda as may be
necessary.
Iodide of potassium (1–2 drs. twice a day) is beneficial as an
antithermic a circulatory sedative, an eliminant, and probably at times
as an antidote but it cannot be given while calomel is used. Certain it
is that it often seems to act well in succession to the purgative, in
cases of poisoning by ryegrass and leguminosæ.
When fever runs very high it may sometimes be admissible to give
aconite, but the coal tar products are much more prompt and powerful,
and may therefore be more hopefully employed for a short time.
In conditions of extreme prostration, stupor, or coma, stimulants are
resorted to, but too often with no good effect, the exudation and
compression which many times cause such symptoms being rather aggravated
than benefited by such agents.
During convalescence a restricted, non-stimulating laxative diet (bran
mashes, gruels, apples, potatoes, carrots) is demanded. Pure cool water
should be always accessible.
In other forms of meningo-encephalitis the same general principles
should be applied, due attention being paid to the removal of the active
cause when that can be discovered.
When indications point unequivocally to abscess, and its seat can be
accurately located by a circumscribed paralysis, an operation for its
evacuation is fully warranted. Otherwise death or permanent uselessness
is almost certain.
In _cattle_ and _other ruminants_ the same general principles of
treatment must be applied. As a cathartic Epsom or Glauber salts are
preferred to aloes and may be supplemented by barium chloride or
eserine. Croton, sometimes useful, is liable to dangerously increase the
gastric irritation in cases in which this is a marked determining
factor. When the animal is down, raise the head by bundles of straw, or
by a halter tied to a beam overhead. In lead poisoning, sulphuric acid
largely diluted may be added to the sulphates so as to precipitate the
insoluble sulphate of lead. Potassium iodide is of value to dissolve the
lead in the tissues and lead to its elimination. Cases of cœnnrus
require trephining and extraction; the larvæ of the œstrus should be
washed out with tobacco water or destroyed by benzine.
In _dogs_ the stomach is usually emptied spontaneously by emesis. A
purgative of castor oil, followed by daily doses of calomel may be
given, and attention given to the cooling of the head and general
system. Antipyrin or acetanilid may be usefully employed. The diet
should be restricted to milk or thin, well-boiled gruels.
The linguatula in the nose must be met as are the œstridæ of the sheep,
and intestinal worms must be got rid of by active vermifuges.