Chapter V: Part 5

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.

CHRONIC HYDROCEPHALUS. DROPSY OF THE VENTRICLES. IMMOBILITY.

Horse especially suffers. Enzootic in given Alpine Valleys, along
Rhone, in Mississippi Valley and bottom lands. Acclimatizing fever.
Old, lymphatic, large heads, narrow foreheads predisposed. Geldings.
Causes, heredity, cerebral and meningeal congestion, cranial traumas,
venous obstruction, tumors, false membranes, fodder or water
poisoning, overwork, insolation, prolonged moist heat, hepatic,
gastric, and pulmonary disorders. Symptoms: form of head, stupid
expression, irresponsive ears, pendent lips, sluggish movements,
crossed legs, slow mastication, dips face in water, intractable by
halter or rein, unable to back with rider, or wagon, drags back fore
limbs, worst in hot damp weather, in sunshine, or after work, or with
full stomach. Paroxysms of excitement. Lesions: excess of arachnoid,
subarachnoid or ventricular fluid, atrophy of ganglia and
convolutions, ependyma thick, opaque, sclerosis, brain anæmic. Tumors,
nature. Experimental cases. Prognosis, incurable, better in cool
season. In cattle, sheep, swine and dogs. Treatment: derivatives,
nerve stimulants (nux), puncture, pilocarpin, purgatives,
Jurisprudence. Notify seller in 9 days (France), 15 (Bavaria), 21
(Wurtenberg, Baden), 28 (Hesse, Prussia), 30 (Austria). Examination by
expert.

Dropsy of the ventricles is common in the horse in certain countries and districts, yet even there it is uncommon in cattle, sheep, swine and dogs, save as a congenital affection. It is reported as enzootic in some Alpine valleys and along the Rhone, attacking especially the mares and immature horses so that breeding becomes impossible. Mauener who reports this says that in the same localities encephalic diseases are more common in man. In America it appears to be most frequent in the rich bottom lands of the Mississippi valley and of the Southern States. Northern horses taken to the Gulf States though they may not suffer to this extent, are liable in the first year to show weakness, debility, and lack of vigor which is spoken of as the =acclimatizing fever=. Elsewhere the affection is one of the old horse in which the vital powers begin to fail. Common breeds of horses with lymphatic temperament, large head and narrow forehead have been found to be especially predisposed. Geldings are said to be most liable on account of the arrested development of the brain, but with the great preponderance of geldings among work horses, it is dangerous to generalize too far.

_Causes._ Acute encephalitis may lapse into the chronic form and then assumes the symptoms of this disease. Cases that come on slowly and imperceptibly appear at times to be hereditary, as might be expected from the fact that it usually goes with a lymphatic temperament. The conditions which cause cerebral or meningeal hyperæmia in chronic form conduce to the affection. Injuries to the cranial vault from traumatism or disease are infrequent causes. Renault records a case associated with two bony tumors, each as large as an egg, projecting inward from the frontal bone and which had produced extensive absorption of the convolutions and increase of the cerebro spinal fluid. In a case of my own with an abscess in the diplöe above the frontal sinus, and pressing inward on the brain a similar condition existed. In other cases Renault noticed that the cerebro spinal fluid was largely in excess.

Much more commonly, however, the accumulation of liquid takes place in the ventricles, and is associated with different causes: as tumors or false membranes near the base of the brain pressing on the veins returning blood from the ependyma, tumors in the ventricles (cholesteatomata, etc., of the ependyma or choroid plexus) obstructing the circulation or giving rise to local hyperæmia and chronic congestions from the other causes such as faulty conditions of fodders, or water, exposure to undue heat, overwork, etc. The enzootic prevalence of the disease in certain localities, (Alps, Rhone Valley, bottom lands) would suggest that local conditions in food or water are factors, though we cannot as yet fully explain the mode of causation. In the same way we must recognize the influence of hepatic and gastric disorders, which arise from such faulty regimen and affect the brain by nervous sympathy and by the action of toxic elements thrown into the circulation. Then again we must take sufficient account of the congestions resulting from obstructions in the lesser circulation, disease of the lungs, and of the right heart, and compression of the jugulars by a tight or badly fitting collar, or compulsory curving of the neck as set forth under vertigo and cerebral congestion.

_Symptoms._ Among the symptoms must be recognized the conformation with which it is usually found associated. The predisposed animals are usually low bred, common horses, with narrowness of the cranium and space between the ears and with a retreating of the head from the orbits to the poll. Other horses suffer but the majority are of this conformation, and thus the disease acquires a hereditary basis.

The expression of the face is characteristic. The eye is dull, often sunken, lacking in vivacity and life, the eyelids are semi-closed, the ears do not prick up to sounds, the muscles of the face are relaxed, so that the lips hang flaccid, and the nostrils fail to dilate freely and rhythmically. The animal is apparently unconscious of all that goes on around him, and is not aroused by the entry or exit of men or horses, by voice or slap, by food or water. His head is probably dropped and resting in the manger, and he raises it sluggishly when compelled; when moved from side to side of the stall his legs may retain a position turned outward or crossed one over the other; if energetically roused he wakes up slowly, and almost immediately relapses into his former lethargy, without accomplishing what was called for. When left with legs crossed he often remains so until wearied by the constrained position, or in danger of falling from loss of balance. Not only the legs but the head will retain for a time an abnormal position given to it,—bent, dropped, turned to one side or the other.

This same lethargy extends even to mastication, which is usually performed slowly and indifferently, and is often interrupted in the middle of the trituration of a morsel which remains in the cheek, on the tongue, or between the teeth, and perhaps hanging out of the mouth. Hence the horseman’s expression, _he smokes his pipe_.

His mode of drinking is no less singular. Usually the lower part of the face is dropped deeply into the water, and he will only withdraw it when it becomes necessary to breathe. He may continue to masticate while drinking.

When walked or trotted he may move a short distance all right; he may even hasten his progress for a short distance without refusing meanwhile to respond to the rein, then he may stop and for a short time longer resist all efforts with voice, whip, or spur to start him anew. In other cases he will turn to one side, getting into ditches or fences by an apparently involuntary action and in defiance of whip or reins.

One of the most striking features of the disorder is the difficulty of backing. In some cases he will back a few steps and then prove unable to back farther; in others he will show it best when heated with a journey; in other cases still he will back well enough under his own weight, but prove utterly unequal to the act if a heavy man is placed on his back, or if hitched to a loaded wagon. In backing with or without a rider the horse, pulled back by the reins, inclines backward with his hind limbs extended forward beneath the abdomen, his forefeet extended in front, and his back arched; he extends his head or turns it to one side, and when the change in the centre of gravity endangers his equilibrium, he draws back his forefeet without lifting them, each making a groove in the ground, and at the same time he makes a disorderly motion of the hind limbs to one side to restore the balance. In default of this he may drop his quarter on the ground and perform a back somersault on his rider. Even when he succeeds in balancing himself after dragging the forefeet back, the difficulty of further backing is rather increased, as the nervous irritability is enhanced by a continuance of the excitement.

When hitched in a carriage the phenomena are virtually the same; when backed he extends or flexes the head, inclines the body backward, and after a time loses his equilibrium, sometimes executes a few disorderly steps backward, or throws himself violently to one side, or turns over backward in the shafts.

The symptoms are always worse during hot, damp weather, and when the animals are exposed to the full glare of the sun. The milder cases can be worked without great inconvenience in winter, while they become utterly useless in summer.

Active exertion and increased rapidity of the circulation has a similarly injurious effect. After a period of rest nothing amiss may be noticed, while after a period of work in the sunshine the symptoms become well marked and the difficulty of backing pronounced. Plethora or full feeding aggravates, while spare, laxative diet, laxatives, rest or bleeding relieves.

The affection may become complicated by more active inflammatory action leading to paroxysms resembling those of meningo-encephalitis;—pushing against the wall, rearing up with the fore feet in the manger, acting as if walking or trotting, etc. In other cases the paroxysms resemble those of vertigo; the animal plunging forward, starting to one side, or rearing up and falling back.

_Lesions._ The pathological anatomy of this disease is that of chronic hydrocephalus. Renault records cases in which the subarachnoid and arachnoid fluids were under the normal while the fluid in the ventricles was increased to a marked extent. This accumulation is often so great that the whole of the surrounding nervous matter is greatly attenuated, the convolutions of the cerebral hemispheres are flattened so that the sulci are all but effaced, the water may shine through at points and even bulge after the manner of a hernia, the ganglia in the ventricle (corpus striatum, optic thalamus, hippocampus) are flattened and atrophied, the base of the cerebrum is thinned and bulges downward, and the olfactory lobes may have their internal cavity greatly distended so that they look like little bladders of fluid. The ependyma may have lost its normal thinness and translucency, having become thick and opaque, and sometimes its surface is granular and rough. The choroid plexus is congested and swollen with infiltration. The brain tissue adjacent is firmly adherent and there is a hyperplasia of its connective tissue constituting a veritable sclerosis. At some points, however, the compressed nervous tissue has undergone degeneration and softening. As might be expected from the pressure of the liquid, anæmia of the brain tissue is a marked feature of the morbid condition.

Other conditions have at times been found in chronic hydrocephalus.

Renault found two long tumors each as large as a hen’s egg projecting from the dura mater into the cerebral hemisphere. In other cases there have been fibrous thickening of the dura mater, exudations on the pia mater, and false membranes on the arachnoid (Röll). Chabert and more recent writers have observed cysts and tumors of the choroid plexus in such cases, but these have been met with not unfrequently in the entire absence of the characteristic symptoms of this disease.

_Nature._ The affection before us is evidently one in which the majority of the higher brain functions are profoundly depressed or debilitated, and this is accounted for by the accumulating intraventricular liquid pressing on the ganglionic centres in the cerebral hemispheres, and in the floor of the lateral and third ventricles.

Experimentally an approximate loss of sensation, intelligence, spontaneity, will, and muscular power is produced in birds or mammals deprived of their cerebral hemispheres. Colin’s heifer, which had been thus mutilated, would lie in torpor, and though it could be made to get up and walk, it struck its head heedlessly against the wall, and retained in its mouth unchewed, the food that had been placed there. He says of such cases: “they live a long time, move automatically, respire, digest, but they lose, with the sensations, memory, judgment, will, and the most vital instincts of their kind.”

In the dropsy of the ventricles the attenuation and atrophy of the cerebral convolutions produce symptoms which approximate closely to those resulting from their experimental ablation, so that one may fairly attribute the general symptoms in the two cases to the loss of their function. Many of the attendant symptoms, and especially the aberration of smell, sight, hearing and taste, may be referred to the concomitant injuries of the basal ganglia of the brain.

We need not seek in one general answer to resolve the question whether the dropsy or inflammation is the initial lesion. For our present purpose it must suffice, that dropsy with anæmia and atrophy of the cerebral convolutions and basal ganglia produce the symptoms of immobility.

At the same time it is only logical to conclude that any morbid condition of the cerebral circulation or of the brain or membranes which leads to a corresponding amount of ventricular effusion, or atrophy or destruction of the nerve centres already designated, will produce the symptoms characteristic of this disease. Thus the different forms of meningitis, traumatic injuries to the cranium, chronic encephalitis, cerebral softening or degeneration, sclerosis, neoplasms of all kinds affecting the brain (cysts, cholesteatoma, psammoma, melanoma, etc.), and parasites may occasion this disease.

_Prognosis._ The disease is essentially incurable. It may last for years with little change except the winter improvement, but it rarely subsides permanently. It is only in those cases in which the symptoms have been determined by a transient or removable cause, as a moderate exudation or a parasite with a short term of life that a favorable result may be looked for. Usually the improvements seen in cool seasons or stables, under good hygiene, are not recoveries but temporary amelioration only.

_Symptoms in other animals._ Corresponding conditions produce similar symptoms in cattle, sheep, swine and dogs, but the disease receives less attention in these animals because they are not called on for steady work. The animals are lazy, dull, insensible to excitement, stupid, show a lack of muscular power and control, stagger or move disorderly and show tympanies or other indications of indigestion.

_Treatment._ Majendie and others had a few apparent recoveries after violent counter-irritation over the spinal cord (cervical and dorsal). Coculet and Lafosse claimed recoveries from the prolonged use of nux vomica in large doses (up to 5 drachms). Hayne attempted evacuation of the fluid by puncture through the perforated plate of the ethmoid bone, but had evil results from the ensuing hæmorrhage and encephalitis. Aseptic puncture through the plate of the frontal bone would be much more promising. Klemm suggested hydrochlorate of pilocarpin (15 grains), and this would promise better than any other measure to induce absorption of the liquid. The fatal drawback to this as to other measures is that it is not applied until the slow, steady pressure has caused such extensive cerebral atrophy that, even if the liquid could be removed and its reproduction prevented, the lost functions can never be restored. If the disease could be diagnosed and treated before this change of structure had taken place, the hope of recovery would be much better founded. Even in cases which make a temporary recovery during cold weather one would be warranted in using active derivatives toward the bowels and kidneys, also pilocarpin, counter-irritation to the spine and even tapping of the ventricles.

Legal Aspect of Chronic Hydrocephalus.

To claim relief in case a horse affected in this way is sold as sound, the seller must be notified at an early date. In the different countries of Europe a limit is set after which such notification will have no legal value. The seller must be notified, in France in 9 days, in Saxony in 15 days, in Bavaria, Wurtenberg and Baden in 21 days, in Hesse and Prussia in 28 days, and in Austria in 30 days.

_Diagnosis._ The veterinarian called to act as expert in such cases must examine the suspected animal along the different lines in which the cerebral aberration is manifested in the disease. He will see the animal standing quietly in the stall apart from all sources of excitement. See if there is a defect in the breadth of the cranium, or a deflection backward of this region from the straight line of the front of the face, together with a heavy clumsy head. Is the head pendent, resting on the manger, with dull eye, drooping lids, lack of expression, loose hanging lower lip? Does he hold morsels unchewed projecting from the mouth or over the tongue, or in the cheek? Does he plunge both mouth and nose in the water to drink, and masticate meanwhile? Are his legs found crossed or in abnormal positions, and if put in such positions, does he fail to rectify them at once? Is the head left in an abnormal flexed, depressed or lateral position if placed in it? Does the subject find it difficult or impossible to back? Does he pay the customary attention to the going or coming of other horses, to feeding, etc.?

If no distinct symptoms are found he should then be examined under other conditions. In taking out of the stable how does he turn in the stall or back out of it, and in what way does he approach the door, clumsily or with difficulty? When moved in a circle, does he sway or stagger? Can he back when mounted or attached to a heavy carriage? Can he execute all these movements satisfactorily after the respiration and circulation have been excited by walking, trotting or galloping in hand or otherwise? In case of difficulty in backing, in the absence of the other diagnostic symptoms, he must see that this does not arise from other causes. Some untrained horses have not been taught to back and cannot be made to do so at once. Some refuse to back from indocility or stubbornness, but can perform the act if induced in other ways, as in having a narrow stall. Sometimes a sore mouth, from a hard bit may make a horse nervous and obstinate so that he will seek to escape in any other way rather than by backing under steady pressure of the bit. Sometimes he will back all right under a halter. In all such cases of simple obstinacy or fear of pain, the absence of the other symptoms is strongly suggestive. If the horse has a well-developed cranium, a full bright, alert eye, firmness of lips, intelligent expression, readiness to appreciate and respond to all noises, words, touches or other causes of excitement, plenty of fire and spirit, and an absence of any apathy, dulness, awkwardness of movement or position of the limbs, or of any other sign of failing nervous power he may be considered free from this affection, even if he refuses to back in a docile manner. In other cases there is a distinct physical incapacity quite apart from any brain disorder. Sprains or anchylosis of the back or loins or anchylosis or painful arthritis of the hocks, may hinder backing.

The diagnosis from encephalitis and other inflammatory affections associated with stupor, rests on the absence of hyperthermia, of the congestion of the orbital and nasal mucosæ, of the heat of the head and of the paroxysmal attacks of excitement which characterize these diseases.

CEREBRO-SPINAL MENINGITIS.

Definition. Epizootic manifestations. Faulty hygiene, insanitary
stables, impure air, defective drainage, fermenting food, overwork,
overfeeding, excitement, heat exhaustion, electric tension. Probably
complex. Horse, ox, sheep, goat, dog. Microbian factors in man and
rabbit. Lesions: meningeal, brain and spinal congestion, effusion,
suppuration, circumscribed necrosis, softening, petechiæ. Blood dark,
fluid or a diffluent clot. Symptoms: _horse_: paresis, anorexia,
dysphagia, mucous congestion, reddish brown: in severe cases, chill,
stupor, apathy, debility, palsy, tonic spasms of neck, back or loins,
hyperæsthesia, twitching, trismus, hyperthermia, delirium, coma,
convulsions, and early death. Duration averages 7 to 15 days. _Ox_, as
in encephalo-meningitis. _Sheep_, microbes. _Dog_, dulled senses,
stupor, coma, palsy, hyperthermia, heat of head, spasms, etc.
Diagnosis: by brain and spinal symptoms; cases in groups. More sudden
than tetanus, or rabies, and shows no mischievous purpose, nor
depraved appetite: from tubercular meningitis. Treatment: Avoid
suspected stable, food, water, or suspicious environment, disinfect,
correct local diseases, unload bowels, belladonna, atropia, chloral,
bromides, ergot, phenacetin, potassium iodide. Bleeding. Cold to head
or back. Derivatives. Sling. In convalescence, regulated diet and
tonics.

_Definition._ Concurrent inflammation of the meninges of the brain and spinal cord.