SECTION V.. Nervous System.

NERVOUS SYSTEM.

CEREBRAL CONGESTION.

According to Cruzel, cerebral congestion is somewhat frequent in working oxen subject to continued concussion from the yoke, especially among animals working on a rocky soil. The condition may also be produced by prolonged exposure to the sun, as well as by sudden and intense cold.

Passive cerebral congestion by stasis may be produced by any cause markedly interfering with the return circulation (pericarditis due to foreign bodies). Clinically it is of no importance.

The animals, previously in good health, suddenly appear comatose. They are insensible to stimulation of any kind, the head is rested on any convenient object or is held stationary, the animal looks drowsy, the gait is hesitating or vacillating, the respiration slow or irregular. Left at liberty, the animal does not seem to know where it is going; indeed, sometimes it is absolutely blind and strikes against any obstacle in its path, or falls and suffers from epileptiform convulsions. The cranial region is abnormally warm. The =course= of the attack is rapid, and the animal either dies in a state of coma or convulsions or else recovers rapidly.

=Diagnosis.= The diagnosis is decidedly difficult; and the =prognosis= should be reserved.

=Treatment= commences with free bleeding, the amount of blood drawn being proportioned to the animal’s size. The sides of the body may then be stimulated and a purgative administered.

MENINGITIS.

The generic term “meningitis” includes all inflammations of the arachnoid, pia mater and internal surface of the dura mater.

These forms of inflammation occur in diseases such as tuberculosis and in parasitic diseases of the brain. Under other circumstances, they are rare, and may be produced by very varying causes.

An epizootic cerebro-spinal meningitis of the bovine species has also been described, principally in Germany. It seems almost unknown in France, and French literature contains no well-authenticated case.

Furthermore, an epizootic cerebro-spinal meningitis of sheep, or rather of lambs, has been described in Germany, in Italy, and in France. These descriptions are all open to many objections. It seems that under the term “cerebro-spinal meningitis” have been grouped cases of enzootic tetanus, doubtful cases of poisoning, and particularly cases of cœnurosis in the first stage of development. We therefore discard these descriptions, which differ too much among themselves to be of any value.

=Causation.= Meningitis occurs in the ox and sheep as a complication of wounds in the cranial region, accompanied by fissuring of the bone, periostitis, abscess formation, etc.

It is also seen as a complication of fractures of the horns, and old-standing catarrh of the facial sinuses. In the sheep it follows parasitic catarrh due to the larvæ of œstridæ.

The meningitis appears, according to circumstances, in the forms of local meningitis, anterior frontal meningitis, basilar meningitis, etc. Finally, it may develop as a complication of different diseases, such as gangrenous coryza, purulent infection, subparotid abscess, suppurative phlebitis, suppuration of the eye or of the orbit, etc.

=Symptoms.= It is difficult to detect and interpret the first symptoms shown, because these chiefly consist in dulness, want of appetite and constipation, without any particular fever. At a later stage, excessive excitability is produced by noises, by changes of light, or by handling. Careful examination of the patients shows a change in their expression, rapidly followed by contraction and inequality of the pupils or deviation of the visual axis (strabismus, squinting). The pulse becomes irregular, as also the respiration. The appetite is entirely lost, and it is not uncommon to note a contraction of the muscles of the neck and jaws, as well as inability to move about and symptoms similar to those of dropsy of the cerebral ventricles.

The chronic form is rare.

=Lesions.= The lesions comprise local or general hyperæmia and exudative inflammation of the pia mater and arachnoid, together with the formation of false membranes or of pus in the subdural space. The meninges are partially adherent, and the superficial layers of the brain are also inflamed by contiguity of tissue.

=Diagnosis.= The diagnosis must be based on the disturbance of vision, movement, and appetite, and on the course of the symptoms, as well as on the external signs in the case of such diseases as are prone to become complicated with meningitis.

=Prognosis.= Sooner or later the case is likely to end fatally, and there is no practical use in treating the patient.

=Treatment.= If in exceptional cases slaughter is objected to, setons and blisters may be applied to the poll or the parotid region, or the parts may be enveloped in ice bags or compresses of iced water frequently renewed.

ENCEPHALITIS.

Encephalitis, i.e., inflammation of the cerebral substance, is very closely allied to meningitis; in a great number of cases meningitis and encephalitis co-exist. In other cases encephalitis may be found apart from meningitis, and vice versâ. Moreover, many of the symptoms of meningitis are to be found in cases of encephalitis.

Encephalitis may develop as a complication of meningitis. Encephalitis may also follow abundant parasitic infestation, as in cœnurosis (which will be particularly studied as it affects sheep), or microbic infection, the commonest form of which in the ox is tuberculosis. The encephalitis may be diffuse or circumscribed, according to the cause, while the symptoms are varied and numerous. Very frequently, particularly in cases of tuberculosis, encephalitis assumes a chronic form.

=Symptoms.= The earliest symptoms are extremely difficult to detect, because they are scarcely characteristic and because it is impossible to ascertain the sensations of the animal.

It is only when the disturbances in walking, in the eyesight, in swallowing, etc., are noted that suspicion is aroused.

The symptoms may appear suddenly. Nevertheless it is beyond doubt that there are certain slightly marked prodromata, indicated by diminution of appetite, wasting, and changes in vision. Soon afterwards occur other forms of disturbance, which may be classified under the heading of “motor, visual, nervous, and impulsive.” The patients appear stunned, their movements are slow and hesitating, they partially lose control over their limbs and display lameness, with spasmodic movements of one or two limbs. Examination of the joints shows no injury. The lameness may simultaneously affect two diagonal limbs or two fore and two hind limbs, or even three limbs. This lameness is of central origin.

The ocular disturbance is marked by diminution or loss of vision, by strabismus, or by frequent unconscious movements of the eyes and eyelids, and also more particularly by inequality, contraction or dilatation of the pupils.

Nervous, impulsive disturbance is most readily noted when the animals are at liberty. Even when the sight remains, they seem quite incapable of avoiding obstacles or as though absolutely forced to move to the right or left, etc.

Attacks of giddiness, moreover, are not unusual under the influence of the slightest excitement. During such attacks the animals thrust the head against a wall, or they involuntarily recoil or make lateral movements. In many cases these vertiginous attacks end by the animal falling and showing epileptiform convulsions, during which it may die.

The symptoms are never the same in two different animals, but they may easily be classed according to the above indications. The indications furnished by the condition of the eyes and by the peculiar impulsive movements are particularly significant.

On the other hand, there are modifications in breathing without apparent local cause, and difficulty or even impossibility of swallowing, etc., although there exists no material obstacle.

=Diagnosis.= The condition is often confused with meningitis, and the mistake is not serious, because meningitis and encephalitis frequently accompany one another.

=Prognosis.= The prognosis must be regarded as fatal. The patients very seldom recover, and there is no reason for keeping them alive.

=Treatment.= Here, again, blisters may be applied to the upper extremity of the neck, or setons may be passed. Cooling applications to the cranial region have also been suggested. None of these methods produces more than a temporary palliative effect.

CEREBRAL TUMOURS.

The brain may be injured and compressed by various tumours of other than parasitic origin. Such tumours may originate in the bones, the meninges or the choroid plexus, or they may simply be due to generalisation of a previously existing tumour. Whilst of very varied origin and nature, all tumours of the cranial cavity have one common effect, viz., to compress the brain. This continuous compression causes progressive atrophy of the brain, but its existence is not always suspected, because the lesions may not give rise to any marked symptoms.

The hind portions of the hemispheres and the white substance are generally very tolerant. The front portions, on the other hand—the frontal lobes and the grey substance—resent compression, which provokes various symptoms in consequence.

=The symptoms= of compression and atrophy of the brain differ greatly, a fact which is easily understood, inasmuch as the seat of the change may vary, and therefore it is possible only to trace the chief manifestations, which suggest the existence of a cerebral tumour.

The general changes are indicated by signs precisely similar to those so common in horses with dropsy of the ventricles (general depression, inability to back, long intervals between the prehension of successive mouthfuls of food, sudden cessation of mastication, etc.), by an impulsive or automatic gait, and by the assumption of strange attitudes (kneeling down in front, etc.). When at rest the animals appear to be in a state of continual torpor.

Special symptoms sometimes occur, which enable the seat of the injury to be localised in more or less exact fashion. These symptoms affect the vision (amblyopia, amaurosis, strabismus, nystagmus), general sensibility (hyperæsthesia, anæsthesia, etc.), and the power of movement (total, partial or crossed hemiplegia, want of co-ordination of movements, etc.).

Trifling stimuli almost always lead to marked and even epileptiform attacks.

=The diagnosis= of cerebral tumours is very difficult, particularly when attempts are made to indicate their exact seat, but that of other cerebral lesions is somewhat easier.

=The prognosis= is very grave, and in the case of domestic animals nothing can be done. In the ox intra-cranial operations are difficult, by reason of the presence of the sinuses which obstruct the approach to the brain cavity; economically surgical treatment is seldom advisable.

INSOLATION.

Insolation is an exceptional accident in animals of the bovine, ovine, or porcine species. If at liberty these animals move about, and always seek shelter when the sun is fierce. If, on the contrary, they are harnessed and kept standing for long, exposed to the full midday sun during June, July or August, they may suffer from insolation.

During the International Cattle Show attached to the Exhibition of 1900 in Paris, a considerable number of cases of insolation occurred in animals of one class, exposed to the full midday sun, in an ill-ventilated spot. The other classes only received sunlight from the sides, and in them not a single case occurred.

Death may follow in a few hours; it is difficult to say precisely how it is brought about, but it is always accompanied by congestion of the cerebro-spinal centres and general blood stasis.

=The symptoms= of the development of insolation occur very rapidly. In animals of the bovine species there is accelerated respiration, which soon amounts to dyspnœa. The mucous membranes then become cyanotic. The animals attacked seem anxious, although not agitated, and soon afterwards the eyes water, the mucous membrane and the lips of the vulva display œdematus infiltration and congestion, and areas of cutaneous congestion, closely resembling mud fever in the horse, appear over the mammæ. At this stage the animals move with difficulty, and show all the symptoms seen at the outset of gangrenous coryza.

All these symptoms develop in one, two, or three hours, and death may follow if nothing is done. They disappear, however, as rapidly as they appear. In an hour or less we have seen in some cases a complete return to the normal condition. Given the facts, the =diagnosis= is extremely easy.

=Treatment.= Treatment should be commenced by immediately removing the animal to a cool, airy, shady place. It may then be bled, and the head and neck should be freely drenched with cold water. The symptoms generally disappear as though by magic.

POST-PARTUM PARALYSIS—MILK FEVER—MAMMARY TOXÆMIA—PARTURIENT APOPLEXY—DROPPING AFTER CALVING.

For a great part of the following short account we are indebted to an excellent report by J. J. Repp, V.M.D., in the Journal of Comp. Medicine and Veterinary Archives, September, 1901:—

The word “fever” in connection with the terminology of this disease is not very appropriate, because in the majority of cases fever is not present, but the animal has a subnormal temperature. The term milk fever is very misleading and indefinite, as it is also used by the laity to designate other diseases, such as parturient septicæmia and the various forms of mammitis. Parturient paralysis must be clearly differentiated from parturient septicæmia, which is a disease of an entirely different character and which may occur in any of the domestic species, whereas parturient paralysis occurs only in the cow.

=Distribution.= Parturient paralysis occurs wherever milch cows are kept. It is more prevalent in dairy districts, because it is the heavy milking strains of cows that are most subject to the disease.

=Cause.= No definite cause can be assigned for this disease. Schmidt’s theory is that parturient paralysis is caused by the evolution in the mammary gland of a poisonous substance through the over-activity of the epithelial cells of this gland excited by the determination to the udder after birth of large quantities of blood which was supplied to the uterus and the fœtus before birth, but which now goes to the udder because of the natural demand for milk secretion. This poisonous substance being carried in the circulation to various parts of the body, brings on the symptoms which characterise the disease. It is well recognised that living cells may, under certain circumstances, produce poisonous substances. Schmidt’s theory, therefore, is in accord with an established principle.

=Pathogenesis, or generation, of the disease.= Parturient paralysis, as a rule, occurs in cows which give a heavy flow of milk and which are in a high state of nutrition. It may develop at any age, but is extremely rare in cows before they have reached adult age and have given birth to several calves. It is also rare in old cows. It occurs, then, in cows which are of middle age and in the full height of their activity as milk producers. The disease attacks the cow after she has given birth to a calf, usually within twenty-four hours thereafter, but in some cases not until a week or even a month after parturition. In a few cases the disease has its inception a short time before parturition. Cows which are stabled and deprived of exercise are said to be more prone to the disease than those which are permitted to exercise at will. There are many exceptions to this statement, although it is the usual teaching. Further observation may show that it is not correct. In Iowa more cows take this disease while at pasture than in any other circumstance. This doubtless arises from the fact that in Iowa cows are given more freedom than is customary in older dairy States. The disease may arise at any time in the year, but, on account of the fact that spring-time is pre-eminently the calving season, most cases originate at this season.

=Morbid anatomy.= The morbid alterations are limited and variable, and offer nothing characteristic. The blood is irregularly distributed, a condition which probably indicates marked vaso-motor disturbance resulting from the profound interference with the nervous functions which accompanies the disease. The abdominal organs are usually filled with blood. The brain may be anæmic, œdematous, easily torn, and yellowish in colour. In other cases it shows hyperæmia of the meninges and of the brain substance.

=Symptoms.= The disease usually appears within twenty-four to forty-eight hours after parturition. In extreme cases it may not occur until two months or even six months after parturition. It may rarely occur before birth. It usually follows an easy birth. At the onset of the disease the cow manifests some uneasiness; it moves about in a restless manner, stamps, strikes the abdomen with its hind legs, perhaps bellows, grinds the teeth, and may have spasms of groups of muscles or even a general convulsion. After this period, which may be unnoticed, the symptoms of paralysis come on. The cow shows weakness, staggers, and at last falls. As the paralysis advances it stretches on the ground, lying on its side usually with the neck bent to one side so as to bring the nose into the flank or the costal region. This is the characteristic position in parturient paralysis. If the head is brought into the normal position, it at once returns to the unnatural position in which it was found. The animal is in a state of partial or complete unconsciousness, does not respond to blows or calls, and takes no note of its surroundings. The eye is dull and not sensitive to the finger touch, sunken, pupil dilated, and the upper lid is drooping; the tongue is paralysed, saliva runs from the mouth, the pharynx and œsophagus have lost the power of motion, so that the animal is unable to swallow; the peristalsis of the stomachs and intestines is in abeyance, and as a result digestion is arrested, fermentation sets in, and the animal becomes tympanitic; the contents of the rectum and colon are hard and dry, and may be covered with mucus or blood, urination is suspended; the os uteri is almost invariably dilated if the disease occurs within a day of parturition; pulse small, often imperceptible, 60 to 120 per minute; temperature, usually normal or below normal, may be as low as 95° Fahr., in some cases may be as high as 105° Fahr. Such a high temperature probably does not occur in a case of pure parturient paralysis, but only when there is a complication of parturient septicæmia. The extremities are cold. The after-birth is sometimes retained. There may be accompanying prolapse of the uterus.

=Course.= Without treatment, and, indeed, with most kinds of treatment which have been applied in the past, the disease usually runs rapidly to a fatal issue. It lasts two to three days, and in some cases longer, the condition gradually becoming more and more aggravated. Death results from sudden failure of the heart or brain, and is often preceded by profuse diarrhœa. In milder cases the cow may linger as long as two to four weeks and then die of pneumonia, which results from the inhalation, or introduction through attempts at medication, of foreign substances into the lungs during the period of paralysis of the pharynx and œsophagus. If recovery occurs, the animal is entirely well in two to five days. In rare cases paralysis of the hind parts may persist for a long while.

=Diagnosis.= This is made by a study of the history and symptoms. It is comparatively easy.

=Differential diagnosis.= It must be distinguished from ante-partum paralysis, broken-back, parturient septicæmia; but one familiar with the character of these diseases will find no difficulty in making this differentiation.

=Treatment.= This may be considered under two distinct subdivisions, viz., preventive treatment and curative treatment.

(a) Preventive treatment.—By considering what has been said under the head of “generation of the disease,” one can easily infer what measures should be adopted to prevent the disease. Cows in the later stage of gestation should be fed moderately, grain especially being given sparingly or entirely withheld; the animals should be given an opportunity to take plenty of exercise; the bowels should be kept in good condition by the administration of such salines as magnesium sulphate, sodium chloride, and sodium bicarbonate. The after-birth should be removed soon after parturition and several uterine douches administered.

(b) Curative treatment.—The older methods of treatment comprised: warmth and friction to the mammary gland; the administration of sedatives, such as opium, chloral and bromide of potassium; stimulants, including ammonia, ether, turpentine and alcohol; washing out the uterus with water or disinfectant solutions; the relief of tympany by the use of the trocar and canula (by which instrument medicines may also be injected directly into the rumen); the removal of fæces from the rectum; warm clothing of the body and general attention to the animal’s comfort, and to the teachings of hygiene. For all these widely diversified methods good results have been claimed, and, we may add, bad ones at times recorded. F. T. Harvey (Cornwall) estimates the average mortality at from 40 to 66 per cent., though he claims for his more recent practice a lessened mortality of only 20 per cent.

Schmidt does not claim that his method of treatment disposes bodily of the morbid condition, but that it does measurably assist Nature in her efforts to restore the animal to the normal physiological state. It is well known that after the beginning of the attack the animal, if left to itself, rapidly grows worse until the crisis of the disease is reached, at which time death occurs or convalescence begins, usually the former. It has been observed, however, that if the treatment is applied within a few hours after the inception of the disease its progress is modified in such a way that convalescence at once begins, as a rule, and the animal hastily recovers its health, usually within twelve hours, although in extreme cases it may be as late as forty-eight hours. The following is an outline of the plan of treatment of parturient paralysis suggested by Schmidt. The operator should disinfect his hands and the udder and teats of the cow by washing with a 5 per cent. solution of carbolic acid or creolin, or a 1½ per cent. solution of lysol or trikresol. The apparatus needed for the treatment consists of a small glass funnel, a rubber hose three feet long and one-eighth inch in calibre into which the funnel fits, and an ordinary milking tube over which the rubber hose fits. This apparatus should be sterilised immediately before it is used by boiling or soaking in such a solution as recommended for washing the udder. Dissolve from 2 to 2½ drachms of potassium iodide—the size of the dose depending upon the size of the cow and the character of the attack—in about one quart of clean water previously boiled to sterilise it, and allow the solution to cool to a little above body temperature, or 40° C. or 104° Fahr. The temperature may be determined with the clinical thermometer. Withdraw all the colostrum or milk from the udder. Then insert the milking tube, with hose and funnel attached, into one of the teats, elevate the funnel about two feet above the teat and slowly pour in one-fourth of the solution, allowing the funnel and hose to become empty several times during the process in order to permit the entrance of a liberal quantity of air. Repeat this infusion with the other three quarters of the udder. After all is introduced, knead the udder carefully so as to cause the solution to permeate the ducts and acini as much as possible.

As the condition of the cow is usually such as to call for additional treatment, the veterinarian should not be content with injecting the potassium iodide solution, but should resort to any and all other measures which promise assistance.

As the cow is usually unable to urinate, the bladder will be found filled with urine. This should be removed with the catheter, and its removal accomplished at intervals until the recovery of the cow renders this procedure no longer needful.

It may be advisable that catharsis be brought about. As the cow is usually unable to swallow, it is dangerous to attempt to give medicines by the mouth. This may be done if assurance that the cow can swallow is obtained. Some have given medicines successfully through a probang inserted into the stomach. The plan is feasible. Schmidt says that he usually resorted to an aloe powder. If this is done 1 ounce to 1½ ounces of aloes may be given. It would seem preferable to give the aloes in a bolus, capsule, or drench. Some have given linseed oil or Epsom salts. If the animal cannot swallow and a probang is not at hand, one may administer 1½ to 2 grains of physostigmine salicylate subcutaneously, repeating the dose in about three hours if purgation is not produced. Rectal injections should be given at short intervals in order to get rid of the accumulation of hard, dry fæces in the rectum. These injections may be of linseed oil, cotton-seed oil, or warm soap solution. Schmidt recommends, also, enemata of sodium chloride solution. Meanwhile the cow should be kept propped up on the sternum by means of bags of straw or pieces of wood. If the temperature is below normal, as it usually is, the cow should be thickly clothed with blankets and straw heaped up about it. Schmidt used powdered digitalis given by the mouth when the heart was rapid and weak. It would seem much better in every way to give the tincture of digitalis subcutaneously. He has also resorted to subcutaneous injections of camphor and caffeine. This is good treatment. If the cow does not show marked improvement within eight hours the potassium iodide infusion may be repeated. Schmidt has found that as much as 6 drachms may be injected into the udder without harm to the cow. Schmidt, in his first report, made in 1898, recorded 50 cases treated for parturient paralysis by this method with but two deaths from the disease. There were, however, only 46 recoveries, as two cows were slaughtered for beef during the first day of convalescence. A short time later a report was made by Jensen showing that in Denmark up to that time sixty-five veterinarians of that country had treated 412 cases by the Schmidt method, 90 per cent. of which recovered. Such results seem to indicate this as the treatment par excellence for parturient paralysis. It still remained to secure the introduction of this treatment into the United States and to determine what results could be obtained. In all 166 cases were reported; of these 166, 119 resulted in recovery, while 47 were fatal. Of the fatal cases, in eight of the cows death may be traced to some complication, such as prolapse of the uterus, foreign-body pneumonia, etc. In these cases the Schmidt treatment cannot be said to have failed, for it is not in any way intended that it shall be able to overcome such accidental conditions. If the cow has recovered from its condition of paralysis as a result of the Schmidt treatment far enough to be out of danger from that source and to promise recovery, but later falls a victim to some complication that is in no measure a part of parturient paralysis, but only a result of that disease, it may with justice be said that the Schmidt treatment was a success so far as the malady against which it was directed is concerned. Looking at the reports from this generous point of view, in 127 cases out of 166, or 76·5 per cent., the Schmidt treatment was successful so far as the parturient paralysis was concerned.

In a paper published in the Berliner Thierärztliche Wochenschrift in August, 1902, Schmidt reviews the results of his treatment as evinced by 914 patients treated by thirty-one different practitioners: 884, or 96·7 per cent., recovered, twelve died and six were slaughtered during the course of the disease. Twelve others were slaughtered at a later period in consequence of complications. Jensen reported the results of 1,744 cases.

Schmidt also found that the simple injection of air was in many cases sufficient to produce recovery, and subsequent observation tends to show that the fluid injected is of less importance than was first anticipated. A large number of unirritating solutions may be employed. Schmidt, however, still counsels the use of a quart of 1 per cent. solution of iodide of potassium, in which can be dissolved 5 grammes of caffein sodio-salicylate if the heart’s action is weak. About 10 ounces of this solution are injected into each quarter, and are followed by a liberal injection of air. The parts should afterwards be freely massaged.

CŒNUROSIS (GID, STURDY, TURN-SICK).

Cœnurosis is a disease due to invasion of the animal body by embryos of larvæ of the Tænia cœnurus of dogs and wolves. These embryos only develop freely in the brain substance (Cœnurus cerebralis) and medulla oblongata. The hosts of the larvæ include the calf, sheep, goat, roedeer, reindeer and horse.

The disease was formerly erroneously called “turn-sick,” for the turning is only a manifestation, and even a tardy manifestation, of the disease, while in addition it is not invariably present.

Cœnurosis principally attacks lambs of from three to six months, although it occurs up to eighteen months, and sometimes even two years. It is exceptional, however, in adults. Similarly in the bovine species it usually affects young animals up to the fourth or fifth year.

Cœnurosis with diffuse parasitic encephalitis often remains unrecognised, the animals being regarded as affected with epizootic meningitis of unknown cause or septic intoxication, and when they die the owners are ignorant as to the cause of death. The stage corresponding to turn-sick, which is an advanced phase of the disease, is only seen in animals which have been infested to a slight extent, and in which three or four parasites only, sometimes only one, have attained the brain and developed there. Such cases exhibit all the classic symptoms of turn-sick, viz., turning movements, heaviness, vertigo, etc.

=Causation.= Cœnurosis is due solely to one cause, viz., the ingestion of eggs or embryos in feeding or drinking.

The Tænia cœnurus lives in the dog, and fertilised segments are passed with the fæces in yards, pastures and fields, and on the margins of roads, ditches and ponds. Amongst damp grass or in water the eggs, which contain more or less well-developed embryos, may retain their vitality for several weeks, and when swallowed the embryos are set at liberty in the intestine.

The six-hooked embryos perforate the walls of the intestine, pass into the blood stream or chyle ducts, and from these points are carried in all directions. Those which gain the nervous centres, the brain or spinal cord, continue to develop; the others, dispersed through different tissues, degenerate and disappear.

Experimental infection with these parasites shows that the brain is invaded after about a week’s time. From the twentieth day the presence of embryos can easily be detected in the superficial layers of the convolutions. They make their way through the grey substance, leaving behind them greenish-yellow sinuous tracts with caseous contents.

The cyst or finn undergoing development can be found at the end of one of these tracts in the form of a little transparent bladder, of a size varying between that of a pin’s head and that of a lentil or a small hazel-nut.

Later the tracts, with their caseous contents, disappear, and the development of many of the vesicles proves abortive. At the end of a month the vesicles, continuing to develop regularly, attain to about the size of a pea. Between the fiftieth and sixtieth days heads or scolices appear in the interior of the vesicle, which then reaches the dimensions of a hazel-nut. From this time the vesicles continue to increase in size until the death of the patient. Usually they become as large as a walnut, or even larger, and the interior contains hundreds of scolices, each showing a head.

The cystic phase only develops completely in animals whose brains contain a limited number of cysts, and in such the signs of turn-sick are well developed. In others, where the numbers are large (ten to fifteen embryos or more), death occurs during the primary stage, usually towards the end of the first month, in consequence of acute encephalitis and without any of the symptoms of turn-sick.

The number of animals attacked is sometimes enormous. Moussu has recorded cases where fifty, one hundred, and even four hundred lambs of one flock were affected. The enormous mortality in such cases is very apt to cause errors in diagnosis. Cœnurosis occurs most frequently during rainy seasons, moisture favouring the preservation of the eggs. Young animals become infected, particularly during the spring and autumn, more rarely in the summer, as prolonged desiccation, say for a period of twelve to fifteen days, destroys the vitality of the eggs, but animals may become infested at any time through drinking contaminated water. Moussu has seen cœnurosis (acute encephalitis) from the last-named cause in the middle of January.

=Symptoms. First phase.=—Disseminated encephalitis.—The symptoms vary with the phases of evolution of the parasite and of the disease which it causes. After the six-hooked embryos have penetrated to the brain, the animals affected lose appetite and show a certain degree of dulness, which is all the more marked inasmuch as the animals usually affected are young, and therefore should appear bright and alert. Then follow wasting and depression; the animals remain stationary for whole hours together, the head being carried low or inclined to one side. At this stage disturbance in vision and irregularities in movement may appear.

The eyesight is almost always affected, but the symptoms may vary widely. In some cases the patients seem to be absolutely blind, and strike against any obstacle in their way; in others the power of vision seems to be lost only on one side. All that can be discerned objectively is an inequality in the pupils, together with retraction or dilatation, convergent or divergent strabismus, nystagmus, etc. The humours of the eye appear infected, but examination with the ophthalmoscope reveals lesions of more or less extensive neuro-retinitis.

The visual disturbance is of central origin. The powers of movement may be affected in numerous ways, which at times are extremely difficult to estimate with accuracy. Sometimes the gait is uncertain, inco-ordinated, and hesitant; at others the animal shows lameness or loss of control over a front or hind limb, or over two limbs simultaneously (either the two front or hind limbs or the diagonal limbs), or it may be absolutely unable to stand.

It walks obliquely, or the front or hind limbs collapse; or again, it may persistently lie down, a fact which makes the shepherd think it is suffering from paralysis. On examination, however, no true indications of paralysis can be found; sensation and motor power are both preserved in a modified form.

Death is very frequent at this stage of the disease; the animals eat little or nothing, refuse drink, and die of exhaustion.

All this general disturbance is of central origin, and is due to disseminated parasitic encephalitis, but up to this point the seat of the disease is not yet clearly apparent.

=Second phase.=—Turn-sick.—The central symptoms are slow of development, and are due to the progressive growth of one or two, more rarely three or four, fertile vesicles. These are the true symptoms of turn-sick, and it is only after this phase of the disease has developed that the term becomes appropriate.

Left at liberty, the patient usually walks in a circle towards the right or left in an impulsive and irresponsible fashion. Sometimes it describes a circle, always of the same size. In other cases, on the contrary, it travels along a spiral track, getting further from or nearer to the centre as the case may be. The turning movement may become so accentuated that the animal appears to revolve as on a pivot, and if it is confined in a field or straw-yard its legs become caught in the litter and it falls to the ground.

Attempts have been made under these circumstances to discover the exact point of compression, i.e., the point at which the cyst exists, by noting the direction of the turning movement. The diagnosis, however arrived at in this way is frequently illusory, because it is not uncommon to find two or three vesicles, and in any case the most important information in regard to diagnosis is to be derived from the ocular symptoms.

When only one vesicle exists, the turning movement usually occurs towards the side on which it is situated, and the eye of the opposite side is affected with amaurosis.

If the cyst is situated near the olfactory lobes, the animal marches with a high-stepping movement and the head drawn back towards the body. If the cyst is in the cerebellum the animal is incapable of moving, because it can no longer co-ordinate its movements. Finally, if the cyst develops in the occipital region, animals turn towards the wind, with the neck raised and the head extended.

At the moment when they fall to the ground they sometimes have epileptiform convulsions, grind their teeth, and salivate profusely. In a severe attack even death may supervene at this point.

=Cœnurosis of the Medulla.= The embryos may develop in the medulla oblongata as well as on the brain itself. Compression and atrophy of the medulla then give rise to true paralysis.

The animals exhibit paralysis of the hind quarters, unilateral paralysis only, or still less marked signs. Everything depends on the degree of development of the cysts.

=Bovine Animals.= Cœnurosis in oxen is less important than in sheep. Moreover, it very rarely affects a large number of young animals belonging to one farm. Loss of appetite, dulness and depression are the earliest indications, as in sheep. The gaze seems fixed, the neck is held stiffly and almost rigidly, the animal shows a tendency to vertigo, pushes its head against a wall, or leans the head or neck on the manger or trough.

Inequality in the size of the pupils, amaurosis, hesitating and inco-ordinated movements may also be seen developed in different degrees. The animals have the appearance of horses suffering from “immobilité”—that is, the very peculiar general condition produced by dropsy of the brain ventricles, or from encephalitis. They forget to eat or do not attempt to chew unless handfuls of food are thrust between the molars; they plunge the muzzle into a bucketful of water and do not drink, etc. They take little notice of what passes around them, although they may become greatly excited if an attempt is made to move them, to give them medicine from a bottle, or to set them at liberty, etc. Such attacks of excitement often end in vertigo and in the animals falling to the ground and showing epileptiform movements. All these symptoms may occur with extraordinary variations, due in reality to the peculiar position which the cœnurus occupies.

=Second phase.= If set at liberty during the first phase of the disease, the animal’s gait appears only slightly disordered, but when a single vesicle has become well developed in one of the hemispheres (and this is usually the case with oxen), the symptoms of turn-sick appear as in sheep, and are equally varied. The patients seem impelled to move in a given direction, whatever obstacles may be in their way. It is not at all uncommon to see them thrusting their heads against walls or trees, falling into ponds or ditches, or attempting to force their way through blind alleys between hay or straw stacks.

After the cyst develops in the cerebellum, the animals are soon unable to move. They may be able to stand in one position, but on any attempt to move they fall.

=Lesions.= The lesions develop successively from the moment the embryos arrive in the mass of the brain. At first the six-hooked embryos only excite a slight disseminated encephalitis. Their course through the brain is marked by short, greyish-green caseous tracts, the thickness of a needle, which are readily discoverable in the superficial layers. Later these caseous deposits become absorbed, the lesions of disseminated encephalitis diminish and disappear, while a certain number of vesicles after partial development undergo atrophy and disappear. Before long nothing remains but local atrophic encephalitis caused by the development of the vesicles, and from this time the central symptoms begin to appear.

=Diagnosis.= When the turning movement has developed the diagnosis is generally easy, but it is more difficult during the first period, when encephalitis alone exists; or at least, it is very difficult at this period to discover whether the symptoms are attributable to encephalitis, meningoencephalitis, cœnurosis, tuberculosis, or to some injury.

=Prognosis.= The prognosis is grave, and very few animals recover. Zürn estimated the cases of recovery in flocks at 2 per cent. In these cases the cysts degenerate and disappear.

=Treatment.= At the present moment there is no really practical curative treatment.

The best plan appears to be to trephine the skull and remove the cyst, provided its exact position can previously be determined. That, however, is the great difficulty. Its solution presupposes a perfect knowledge of the central nervous system and of the real purport of any apparent symptoms.

On the other hand, in sheep at least, the position of the cyst must always remain somewhat uncertain, because there are generally several, and the symptoms are of a mixed character.

The only treatment, therefore, which would be likely to succeed is difficult to carry out, and more difficult in the ox than in the sheep because of the great development of the frontal sinuses.

It has been mentioned that under exceptional circumstances the cœnurus, if very superficially placed, may cause atrophy of the cranial wall in the sheep by the outward pressure it exerts, and that the points of least resistance may be detected by the touch. In such cases intervention is necessary and is greatly facilitated; but they must be extremely rare, and Moussu declares he has never seen one.

Hartenstein has suggested continuous cooling of the cranium by irrigation or by applications of ice, the local lowering of temperature serving to impede the development of the cœnurus. This method should be tried in animals of high value, and, if the symptoms have not yet become too alarming, recovery is possible. On the other hand, when the symptoms indicate the presence of an old-standing cyst, there is little chance of success. Moreover, the treatment could not be applied where a large number of animals are affected.

It is much better to send the animals to the butcher if they are in good condition. In Scotland, however—particularly in Caithness—operation is said to be frequently practised with success.

=Prophylaxis.= In well-managed establishments it is easy to avoid the appearance of cœnurosis.

The development of this condition being due to the Tænia cœnurus of the dog, which passes ripe segments containing eggs with its fæces in the pastures, the first indication is to prevent the development of this tænia in sheep dogs, sporting dogs and house dogs, and the sole precaution required is to avoid giving them as food sheeps’ heads containing the bladder-worms. But, as despite these precautions they may accidentally contract infection with Tænia cœnurus by eating the offal of slaughtered animals, it is a wise precaution to administer to all farm dogs, twice a year at least, a dose of some tænicide.

They should be starved and kept in for twenty-four hours, and should then receive a full dose of some energetic vermifuge, such as areca nut, kamala, kousso, powdered pomegranate root, extract of male fern, etc., followed by a purgative. The material passed and the fæces should be burned or mixed with quick-lime. By these simple precautions the losses which formerly proved so heavy may entirely be prevented.

“TREMBLING,” OR LUMBAR PRURIGO, IN SHEEP.

The above term is applied to a disease peculiar to sheep, and characterised by neuro-muscular disturbance, which always ends fatally after a longer or shorter period.

=Symptoms.= Clinically the disease occurs in two forms, one termed the convulsive form, the other the pruriginous form. In the convulsive form the patients rapidly lose appetite, soon appear unable to stand, fall on their sides, and exhibit spasmodic contractions of certain groups of muscles. After a time the clonic contractions may give place to persistent rigidity. The patients are carried off rapidly in a week or two without other important symptoms. This disease appears to exhibit certain analogies with louping-ill, but these do not seem to be recognised in France, where it chiefly occurs.

In the pruriginous form the beginning of the attack is obscure, and only the shepherd is able to note anything unusual. The animals move in a jerky way, the hind limbs being lifted at times after the manner of a horse suffering from stringhalt. They are excitable, exhibit trembling movements when touched, with convulsive movements of the head, and present an anxious and vacant appearance. The development of these symptoms, which constitute what may be termed the first phase of the disease, is sometimes prolonged, and in winter may last from one to two months. In summer it rarely lasts longer than a week or two.

At this stage a special pathognomonic symptom develops, viz., intense and permanent pruritus of the hind quarters, which causes the animals to rub the croup against any projecting objects, walls, mangers, etc. They thrust themselves backward against the object, and rub with such violence that the wool is torn away and the skin itself often excoriated, although the irritability appears to be in no wise diminished thereby. In the fold the animals sometimes rub against one another, making their sides raw, and bite themselves on the croup, the quarters, and the tail.

When the affected parts are touched with the hand, peculiar movements of the head and the lips are immediately excited, similar in character to those caused by mange. Up to this time the animals continue to feed, but they progressively lose condition, become weak in the hind quarters, and fail to keep up with the other animals in the flock. Their gait becomes hesitating; they move with a trotting step and appear semi-ataxic.

All these symptoms develop without fever, but become aggravated from day to day, until they end in paraplegia and death. This second phase lasts for a period of from two to four months in winter.

=Lesions.= No lesions can be detected on a simple examination of the dead bodies. Gilbert has mentioned a change in the blood; Trasbot, chronic inflammation of the pia mater and of the lumbo-sacral portion of the spinal cord. German writers have described sclerotic changes in the posterior portions of the cord. Moussu has carried out a large number of examinations, but has never found these lesions, either on anatomical or on histological investigation, and he considers that they are not by any means present in all cases.

Besnoit and Morel, who carried out a very remarkable anatomical and pathological study of the disease, used Nissl’s staining method, but only found very discrete changes in the cord (vacuoles in the motor cells of the anterior horns). They found, however, significant lesions of neuritis in the peripheral nerves.

=Causation.= The cause is as yet little understood, and it is difficult to prove how the forms of neuritis described by Besnoit are brought about.

The disease was not known in France before the introduction of Merinos, and former investigators referred it to heredity, consanguinity, precocity, and even to sexual excitement. German writers declare that it seems more particularly to attack rams and the better-bred varieties. In reality, the disease occurs in all flocks, and in all kinds of sheep indiscriminately; it attacks ewe lambs and young castrated lambs as well as rams. Moussu is absolutely of this opinion, and for want of more precise information agrees with Trasbot, and, he believes, with Besnoit, that the symptoms shown may possibly be referred to a chronic intoxication.

=Diagnosis.= The diagnosis is difficult during the early stages, but when the pruritus becomes manifest there can no longer be room for doubt.

Cases of paraplegia might perhaps be mistaken for paraplegia due to cœnurosis, but in the latter case there is no pruritus.

=Prognosis.= The prognosis is extremely grave, observation having shown that all the patients die after a longer or shorter time.

=Treatment.= Until now treatment has proved absolutely useless, and it would seem the best course to slaughter the animals before wasting becomes marked.