Chapter LX: Section X: Infectious Diseases (2)

Tuberculous lesions develop in the vaginal sheath of the male genital organs exactly in the same way as in an ordinary closed serous cavity; tubercles may also develop on the surface or in the substance of the testicle. They become aggregated, undergo softening, spread towards the interior, and may break down, thus forming abscesses. In the female genital passages the disease invades the thickness of the walls, but shows a marked tendency to ulceration, as in the intestine or trachea.

In the udder tuberculosis is generally diffuse, shows a tendency to hypertrophy and the free formation of fibrous or sclerous tissue; only tubercles in the glandular layer of the acini become ulcerated. In time the whole of the secreting structure undergoes diffuse tuberculous suppuration, fibro-caseous masses form in the depths of the tissue and may soften, producing deep-seated tuberculous “cold abscesses.” The mammary lymphatic glands are affected in the same way as other lymphatic glands.

In the joints tubercles appear either on the synovial membrane or in the thickness of the bony epiphyses, very often at both points simultaneously. The synovial membrane is covered with vegetations and villous growths, the ends of the bones are attacked by a destructive ostitis, tubercles or tuberculous centres form in the thickness of the spongy tissue, the articular cartilages are destroyed, the ends of the bones become deformed, and in the last stages fungoid arthritis in various forms may be produced.

In bones the tubercles originate in the depths of the spongy tissue. They produce destructive hypertrophic ostitis, in which the bony tissue is replaced by tuberculous centres or masses divided by fibrous partitions. On section, these lesions exhibit the same yellowish caseated or calcified appearance as the lesions of other affected organs. The compact layer may sometimes be perforated at several points before being destroyed.

In tuberculosis of the brain the primary lesions develop at the expense of the serous layers of the arachnoid and on the pia mater, towards the base of the brain and the fissure of Sylvius, or at the expense of the small vessels which penetrate the depths of the nerve substance itself. Some tubercles remain isolated, become confluent or are collected in masses of different sizes, and provoke symptoms which vary with the locality attacked.

=Symptoms.= Tuberculosis is the most protean of all diseases, and at first sight it often seems impossible to assign to one group, clinical conditions presenting such essentially different appearances. All the tissues may be attacked, from the bones to the most delicate of the viscera, a fact which explains why all aspects of tuberculosis cannot be described. Certain forms, however, occur very frequently, and may be regarded as classic; these will be considered in the order of their frequency.

TUBERCULOSIS OF THE RESPIRATORY APPARATUS.

Without doubt this form of tuberculosis is by far the most frequent. It assumes the form either of bronchitis, laryngo-bronchitis, or pulmonary tuberculosis.

=Tuberculous Bronchitis.=—The symptoms of tuberculous bronchitis do not essentially differ from those of ordinary bronchitis, though the disease develops more insidiously and slowly, and is seldom accompanied by fever. At first the cough is dry and suppressed; later it becomes paroxysmal, and at a still more advanced period liquid and rough. The least irritation brings on these attacks of coughing; changes from the warmth of the stable to the coldness of the outer air or _vice versâ_, the presence of dust or the action of liquids when drinking, etc., etc. During the first stage coughing is not followed by expectoration, but later yellowish-grey, glairy mucus may be discharged: more frequently it is coughed into the pharynx and swallowed.

These symptoms continue for weeks or months without showing any tendency to abate. If the larynx is attacked inspiration becomes rattling and difficult, while the neck and head are held extended, and the least pressure over the larynx produces coughing.

Tuberculosis of the larynx, trachea, and bronchi is usually accompanied by disease of the lung, but may occur by itself.

When there is a discharge it consists of thick, viscous, sticky mucus of a peculiar greyish-yellow colour. Microscopical examination shows it to contain tuberculous bacilli.

=Pulmonary Tuberculosis= usually assumes the chronic form, and is almost always preceded by specific bronchitis. The patients retain their appearance and condition for a longer or shorter time, and, without the experience resulting from continued observation, it would be difficult to believe them to be suffering from the slow development of a serious disease.

Frequent coughing without any apparent reason is the only symptom likely to arouse suspicion.

At a later stage these animals lose condition, feed less eagerly or exhibit capricious appetite, and sometimes well-marked and repeated digestive disturbance, such as slight tympanites with constipation or diarrhœa, moderate impaction of the rumen, relative atony and slackening of peristaltic movements. The wasting gradually becomes more marked or, in the case of pregnant or milch cows, makes intermittent progress, until the animals become anæmic and finally cachectic. The cough is more frequent and more severe, and is followed by discharge from the nose or by swallowing movements. From this time phthisis, properly so called, exists.

The course of the disease is not invariable. Certain animals may appear ill for years without clinically showing the least apparent aggravation; others on the contrary, though living under similar conditions, are rapidly attacked, and in six to twelve months exhibit all the signs of advanced phthisis. Pregnancy, suckling, and prolonged lactation favour the development of the disease by taxing the physical resources of the animal.

Animals suffering from phthisis exhibit a peculiar appearance. They are extremely thin, all their soft tissues are wasted, the limbs are dragged in moving, respiration is rapid and sometimes jerky, the mucous membranes are pale and discoloured, and the skin is tight and adherent to the subjacent tissues.

These general signs, however, would not warrant a diagnosis, for, apart from the cough, certain other diseases present all the external appearances of the last period of tuberculosis (chronic diarrhœa, chronic forms of poisoning—bacterial or otherwise—dyspepsia, etc.).

In cases of doubt it is essential to discover by percussion and auscultation that the external signs are really the result of lesions of the lung, and that the lung disease has developed gradually in accordance with the signs shown by simple external inspection.

The symptoms presented during the development of the pulmonary lesions may be divided into three phases.

In the =first phase= percussion gives no information, though auscultation reveals rough respiration, inspiration and expiration being also unequal. Expiration, which, in the healthy subject, is silent, becomes clearly perceptible, not over the whole lung, but usually over the anterior lobes, particularly the cardiac lobes. This sign is the result of tuberculous infiltration and of the neighbouring pulmonary tissue having lost its elasticity.

Inspiration is rough and rasping, and sometimes occurs in several stages, the act being interrupted or jerky; expiration lasts longer than inspiration, is rough and prolonged, but never blowing in character. These peculiarities are only found in one other condition of the lung, viz., emphysema.

The patients appear little affected in this, the first, stage of tuberculosis. But for the cough they may seem perfectly healthy.

In the =second phase= the tuberculous infiltration extends and ends in the massing, by fusion or centrifugal growth, of the tuberculous masses.

Percussion may now indicate localised dulness, but this is not invariable, because the diseased anterior and middle lobes of the lung are concealed beneath the muscles of the shoulder. When dulness is noted, it is usually over the lower part of the posterior lobes, very rarely at any higher point on the side of the chest. Frequently the dulness is only partial.

On auscultation the signs met with during the first stage become much more marked. Inspiration is always rough, rasping, painful and difficult at certain points, particularly in the anterior zones. In this region expiration is rough, prolonged and sometimes of a clearly marked blowing character. This is particularly the case in the subscapular zone and the auscultation zones 2 and 3 (Fig. 166). In the dorsal region and in zone No. 1, respiration may appear normal. Nevertheless, the sounds are propagated to a distance, the infiltrated lung steadily loses its elastic qualities, the vesicular murmur entirely disappears from the affected regions, and the sounds noted are of bronchial origin.

Like the first, the second phase may vary in intensity, extent, and in the diffusion or localisation of the tuberculous lesions. Blowing respiration may be noted over different areas, accompanied by sibilant, snoring and migratory mucous _râles_. The vesicular murmur is exaggerated in the healthy parts, coughing, accompanied by expectoration or followed by swallowing movements, is frequent, the appetite becomes capricious, and the general condition suffers. In this second phase almost the whole of one lung may be diseased and exhibit the signs described.

The =third phase= corresponds to the softening of the tuberculous masses, and the formation of ulcers and caverns. The zones of dulness or partial dulness may be more extensive, though cavern formation is usually confined to the anterior or middle lobes. Percussion still affords no precise information.

As the tuberculous masses undergo softening and ulceration, their contents are gradually passed into the bronchi, and auscultation reveals signs indicative of the existence of caverns, which signs vary with the dimensions of the caverns themselves. On auscultation the respiration is always found to have at certain points a blowing character, and it may even develop into a true tubal souffle. In other areas, where the caverns are merely in course of formation, gurgling sounds are all that are heard, but where true caverns exist there is an incessant cavernous souffle.

The lesions peculiar to the third phase are seldom seen in practice; because the animals become anæmic, exhausted and cachectic, they are usually slaughtered early. Nevertheless, the third stage occasionally develops in an astonishingly short time, six to eight months at most.

Very frequently the patients, although cachectic and even phthisical, do not yield on auscultation the sounds described as peculiar to the third stage, because the tendency to softening is not very marked in bovine animals. The lungs exhibit massive infiltration, and, whilst pulmonary consumption is not uncommon, the development of caverns is comparatively rare.

The expectoration or discharge in this third form is puriform, glairy, viscous, and of a dirty-yellow or even greenish-yellow colour. Bacteriological examination reveals the presence of tubercle bacilli and adventitious organisms.

These conditions are always associated with various complications, and the second and third stages of chronic tuberculosis are frequently accompanied by lesions of the pleura, of the mediastinal lymphatic glands, of the liver, etc.

Digestive disturbances often occur; the appetite is capricious or in abeyance, there is atony of the rumen and chronic dyspeptic tympanites. These disturbances are easily understood where there are lesions of the liver, intestine, and mesenteric lymphatic glands, but not when the lung alone appears the seat of the disease. In this condition the patients probably suffer from permanent complex intoxication, due to toxins elaborated by the tubercle bacillus and other microbes which multiply on or in the lesions, and this chronic intoxication reacts on the vital functions (innervation, secretion, digestion and nutrition). Nor are the effects limited to these appearances; the heart’s action is also accelerated, and the temperature rises. During the first and part of the second phase there is comparatively little fever, but afterwards this is continuous or of a peculiar intermittent character. In the morning the patient’s temperature may be normal; in the evening it has risen from 1·5 to as much as 9° Fahr. (1·1 to 5·2° C.) above normal, and this recurs day by day. These attacks coincide with softening of the lesions, and when suppurating caverns exist they are more marked and more nearly continuous, assuming the characters of the hectic fever shown in consumption.

Often during the febrile periods the urine is albuminous.

In chronic tuberculosis of bovine animals bleeding from the lung is rare even when caverns exist, and Moussu, in spite of extensive experience, has seen only two cases. This is in striking contrast with the condition in human sufferers from pulmonary tuberculosis, two-thirds of whom bleed at the lungs.

TUBERCULOSIS OF SEROUS MEMBRANES.

After pulmonary tuberculosis, tuberculosis of the pleural and peritoneal serous membranes is the most frequent clinical form of this disease. Sometimes both forms exist, and although the pleural and peritoneal lesions predominate or alone attract attention, there are also lesions in the lung or mediastinal lymphatic glands.

It is difficult to explain how the pleural and peritoneal serous membranes can be seriously invaded without the lung becoming affected, though in point of fact such a state of things frequently exists.

Tuberculosis of the pleura without pulmonary lesions is suggested by very obscure symptoms. The general signs consist in diminution of appetite, loss of condition, tachycardia, elevation of temperature, and progressive organic wasting. These are always present, though in themselves they have no specific significance.

The local symptoms are still more vague. Percussion causes pain, and the practitioner might at first suspect peripneumonia. The patient edges away, and tries to avoid the application of the pleximeter hammer. Firm pressure over the intercostal spaces sometimes causes struggling, and produces indications of abnormal sensitiveness. There is generally extensive partial dulness, sometimes complete dulness towards the lower regions of the chest.

On auscultation the lung may reveal the different indications of chronic pulmonary tuberculosis, or simply diminution of the respiratory murmur at points, accompanied by crepitant, sibilant râles, and moist, crackling sounds. As the anterior portions of the pleural sacs are most commonly invaded, the anterior vena cava is compressed, causing some difficulty in the return circulation, and producing venous pulse, which may extend as high as the parotid gland; there is, however, no swelling of the dewlap.

Respiration is frequent and difficult in consequence of adhesions between the pleura and lungs, which are connected by bands of fibrous tissue of varying extent. Coughing is rarely absent, and if the lung is diseased may be followed by discharge containing numerous bacilli. Otherwise the cough exhibits the pleuritic character, that is, it remains slight, dry, paroxysmal, and painful. The pericardium may be affected as well as the pleura; if the conditions occur simultaneously the venous pulse in the jugulars will be particularly apparent.

The symptoms of tuberculous pericarditis are similar to those of ordinary pericarditis, except that the exudation is less abundant; in a word, the symptoms are those of rather trifling exudative pericarditis.

Tuberculosis of the peritoneum is frequently accompanied by that of the pleura or the abdominal viscera. The lesions are localised on the parietal peritoneum and epiploon, producing in time adhesions between the viscera and walls of the peritoneal cavity, which affect the action of the digestive organs, gradually causing interference with the peristaltic movement both of the rumen and the intestines. The stagnation of alimentary matter favours fermentation, so that the rumen becomes permanently distended. The right flank also is swollen, and the abdomen exhibits a change in shape similar to that in peritonism, which is a constant symptom of tuberculous peritonitis.

As in the thorax, the tuberculous lesions seldom produce extensive liquid exudation, so that ascites does not occur, but on palpation the abdominal walls appear to have entirely lost their pliability and to be unyielding and greatly thickened, a point which is the more remarkable as the animals are thinner.

The wall of the abdomen is stiff, incapable of being depressed as in ordinary subjects, and gives to the fingers the sensation of a thick hard covering, through which the subjacent organs and their contents, that is, the rumen, intestine and alimentary material, can no longer be felt. This rigidity is always most marked in the lower abdominal region. The digestive peristaltic movement can no longer be detected, and on auscultation the normal sounds are manifestly much slower than usual.

TUBERCULOSIS OF LYMPHATIC GLANDS.

It might perhaps have seemed more logical to place tuberculosis of the lymphatic glands at the commencement of these clinical divisions of tuberculosis, as when tuberculous lesions, of whatever kind, occur in the lung, pleura, abdomen, etc., the lymphatic glands in the neighbourhood are invariably invaded. In such cases, however, the lesions in question are not the dominant features.

Under this heading must be classed tuberculous lesions which, on the contrary, affect the lymphatic glands in so marked a manner that lesions in other organs may be regarded as secondary. This occurs somewhat frequently, because at the present day there is a tendency to believe that inoculation takes place mainly through the mucous membrane of the pharynx, and thence extends towards the neighbouring lymphatic glands. At any rate, it is unquestionable that tuberculosis of the lymphatic glands may exist quite apart from any other lesion visible to the naked eye.

Two forms are very common, tuberculosis of the retro-pharyngeal region and of the neck, and tuberculosis of the mediastinal lymphatic glands.

=Tuberculosis of the Retro-pharyngeal Glands.=—In addition to the retro-pharyngeal glands the cervical chain of lymphatic glands, the subglossal, subatloid, preparotid, and even the prescapular lymphatic glands and those at the entrance to the chest, may also be invaded more or less.

This form of tuberculosis may remain latent for a long time, attention being attracted to it only when deglutition is impeded and local deformity becomes apparent.

Swelling of lymphatic glands resulting from tuberculous infection is slow and progressive, differing entirely from that which accompanies suppurative adenitis. The neighbouring connective tissue is certainly somewhat thickened or infiltrated, but the glands themselves can always be detected. The region of the gullet is enlarged, the depression marginating the lower jaw is filled up, the subatloid space disappears, the subglossal glands occupy the space beneath the tongue, and in cases where the lesions are very pronounced the œsophagus and larynx may even be pushed downwards.

Swallowing is difficult, in consequence of compression of the upper part of the œsophagus, and, as the laryngeal nerves may be included in the swelling, dyspnœa or roaring not uncommonly results.

By palpation with one or both hands it is easy to identify the glands and detect enlargement, hardness and sensitiveness. In exceptional instances the caseous masses they contain undergo softening and conversion into purulent material.

When the cervical lymphatic glands are attacked the jugular furrows disappear, and the whole of the pretracheal and lateral regions of the neck exhibit doughy swellings.

These swellings are rarely symmetrical, a fact which admits of this condition being distinguished from lesions due to lymphadenitis, without examining the blood.

The prescapular glands are rarely attacked, but those at the entrance to the chest, which may be found on either side of the trachea by passing the fingers between the two first ribs, are frequently enlarged to the size of a fowl’s egg.

=Tuberculosis of the Mediastinum.=—Whenever the lungs are much involved, the bronchial glands are also invaded, though the glands of the anterior and posterior mediastina may escape. On the other hand, the mediastinal glands are sometimes much involved, whilst the lung remains intact.

The lymphatic glands, particularly those of the mediastinum, may be enormously enlarged, and the various accidents which result are due as much to mechanical interference with the functions of adjacent organs as to the lesions themselves.

When the glands of the anterior mediastinum are affected, they cause compression of the anterior vena cava, with stasis of blood in the jugular vein and venous pulse, then compression of the œsophagus and trachea, and of the nerves at the entrance to the chest, producing difficulty in swallowing, respiration and circulation.

If, as often happens, the glands of the posterior mediastinum are affected and greatly enlarged, they may involve the œsophagus and the œsophageal nerves, interfere with deglutition and rumination, and thus produce marked disturbance. The animals only swallow with difficulty, and later rumination becomes impossible, the antiperistaltic movement not being powerful enough to overcome the resistance. Soon after eating, the patients exhibit tympanites, certainly only to a moderate extent, but the swelling is long in disappearing. This tympanites is due to the difficulty in eructation and to the impossibility of rumination. The contents of the rumen pass slowly towards the intestine until the onset of a fresh attack.

On account of digestive difficulties, the animals rapidly lose flesh, just as though they were suffering from extensive visceral lesions.

TUBERCULOSIS OF THE DIGESTIVE TRACT.

Tuberculosis of the digestive tract is rarer than tuberculosis of the lungs or lymphatic glands, and occurs in two well-differentiated clinical forms, that is to say, tuberculosis of the buccal and pharyngeal membrane and tuberculosis of the intestines. Tuberculosis of the liver, which is less easily recognised, is indicated by signs of dyspepsia.

=Bucco-Pharyngeal Tuberculosis.=—This may be primary or secondary, and occurs in the form of local or general glossitis or superficial ulcerative stomatitis.

In the former case the glossitis may be regarded as due to actinomycosis; in the latter it can only be mistaken for simple ulcerative stomatitis.

It is accompanied by difficulty in mastication, and still more, where the pharynx is invaded, in deglutition; abundant frothy salivation in feeding; sometimes by true spasm of the pharynx and rejection of masticated balls of food.

Locally the buccal mucous membrane (cheeks, tongue, pillars of the fauces, etc.) exhibit ulcerations, with festooned borders, in size something between a florin and a five-shilling piece, covered with a greyish-yellow, earthy-coloured exudation adhering firmly to the subjacent parts. The margin of the ulceration is but slightly indurated, and the tongue preserves its mobility, except in cases of general deep-seated glossitis.

The condition may continue for weeks and months without improvement.

=Intestinal Tuberculosis.=—Tuberculous enteritis is always accompanied by tuberculosis of the mesenteric glands and of the sublumbar lymphatic chain. It is indicated at first by chronic tympanites and peritonism, unaccompanied, however, by atony of the rumen; at a later period by intermittent diarrhœa, which attains a maximum and is followed by constipation. Finally, when there exist numerous intestinal ulcers, the diarrhœa is profuse and intractable, the animals rapidly grow exhausted, and the disease spreads to other organs with startling rapidity.

The food is ill-digested and the fæces have a repulsive odour, as has also the gas which escapes from the rumen when it is punctured.

TUBERCULOSIS OF THE GENITAL ORGANS.

In males, tuberculosis may attack the testicle and neighbouring organs and tissues; in females, the ovary, uterus, vagina, or udder.

Tuberculosis of the testicle is rare. Moussu appears only to have seen one case, namely, in the boar. The disease produces specific vaginitis and specific orchitis, the serous surfaces of the vaginal tunic becoming adherent, and tubercles forming in the depths of the testicle, whilst in time the testicle becomes the seat of fungoid growths.

Tuberculosis of neighbouring glands has only been observed in the case of the prostate. Clinically it is distinguished by symptoms which suggest difficulty in urination, and comprise frequent straining, efforts to micturate, dysuria, etc. Examination by the rectum reveals changes in the prostate, but affords no exact information as to their nature.

Tuberculosis of the genital tract in the female is usually a delayed complication of a preceding visceral tuberculosis, though it may occur as a primary disease, in which case the lesions are localised about the vulva or the vagina. Tuberculosis of the ovaries, Fallopian tubes, and uterus is much more common than that of the two organs just mentioned. It seems certain that the disease may be transmitted directly from the male to the female by copulation, in cases where the male animal has a lesion on the penis.

Tuberculosis of the vulva is rarer, and is indicated by swelling, sclerotic changes, and the presence of tuberculous nodules, varying in size between a lentil and a hazel-nut; after ulceration of these growths, a thick yellowish pus containing the specific bacilli is discharged.

Tuberculosis of the vagina is also indicated by hardening of the walls, sclerous infiltration, and the presence of deep-seated tuberculous nodules, which may or may not become ulcerated. It may follow uterine tuberculosis, the discharge from the uterus continually soiling and at length infecting the floor of the vagina. In such cases the lower wall of the vagina is thickened and infiltrated to a greater extent than the roof, and is sometimes intersected by transverse ulcerated suppurating folds. Bacteriological examination reveals the presence of bacilli.

Tuberculous invasion of the ovaries, Fallopian tubes, and uterus is externally indicated by signs of chronic metritis accompanied by a purulent discharge, which may or may not be fœtid, but always possesses special characteristics. The neck of the uterus is half open, and the discharge is continuous. The pus is of a greyish-yellow colour, ill-formed, grumous, or more frequently granular, and it sometimes accumulates in large quantities in the depressions of the vagina. Examination by means of the speculum is of great value in diagnosing such lesions. On examining the parts through the rectum, the walls of the uterus are found to be greatly thickened, sometimes indurated, bosselated or totally deformed.

The Fallopian tubes and ovaries may have attained enormous dimensions, and the normal anatomy of the parts is greatly altered both as regards dimensions and relations.

The almost inevitable consequences of tuberculosis of the genital organs are hypertrophy, induration or caseation of the subsacral and sublumbar lymphatic glands.

=Udder.=—Tuberculosis of the udder may be primary or secondary. When the infection is slight the results may escape notice for weeks or even months, the patients appearing to suffer only from subacute or chronic mammitis, while at the same time the milk preserves its ordinary appearance. In time, however, the mammitis becomes aggravated, the infected regions are enlarged, and the secretion becomes grumous, serous, curdled, and of a yellowish colour, afterwards ceasing altogether. In some cases one quarter only is attacked, though total mammitis is more common.

These forms of tuberculous mammitis tend towards hypertrophy, local hardening, and the formation of deeply-seated cavities containing pus, the gland itself sometimes acquiring enormous dimensions. The retro-mammary lymphatic glands are invaded even before the gland itself is seriously attacked. For a longer or shorter time the udder may externally appear healthy, although on manual examination these lymphatic glands are found to be indurated and bosselated.

TUBERCULOSIS OF BONES AND ARTICULATIONS.

Tuberculosis of the bones is seen only in young animals, and chiefly affects the vertebral column and the bones of the head. The limb bones are attacked as a rule only in the vicinity of diseased articulations.

The vertebral lesions corresponding to those in Pott’s disease in human beings are very difficult to discover before they produce complications, such as depression of the spine, compression of the spinal cord, paralysis, etc.

Lesions of the bones of the head or of the limbs are characterised by local deformity, destruction of osseous tissue, invasion of surrounding tissues, and by local symptoms peculiar to tumours originating in the periosteum.

Tuberculosis of joints produces special symptoms resembling those seen in the “white swellings” of man, that is, diffuse, œdematous, warm and moderately painful swelling of adjacent parts, accompanied by lameness of varying intensity. According to Guillebeau and Hess, many conditions described as strain or rheumatic arthritis are really tuberculous in character. They may remain stationary for a long time, or even recede under treatment. As a rule, however, these forms of tuberculous arthritis assume the fungoid type and prove incurable.

They are clinically distinguished from ordinary arthritis by the enormous swelling, which involves the extremities and a portion of the shafts of the bones. The adjacent muscles are chronically contracted, and the diseased joint is held semi-flexed. In course of time, if the patients are kept alive, abscess formation may occur, but this is seldom seen in practice, because the animals are slaughtered.

TUBERCULOSIS OF THE BRAIN.

Tuberculosis of the nervous centres, localised either in the meninges or the brain proper, may attack both young and old animals, not as a primary condition, but as a sequel to visceral disease, which, however, may have produced no outward indications, a fact that renders the diagnosis extremely difficult.

When localised in the meninges, the disease produces the symptoms of ordinary meningitis, general weakness, vacillating, staggering or irregular gait, disturbed vision, variation in the size of the pupils, difficulty in swallowing, muscular twitching, cramp of the muscles along the upper margin of the neck, etc.

Tuberculosis of the brain proper seems more commonly to affect the anterior convolutions and the depths of the frontal and temporal lobes. It produces some of the symptoms of meningitis or symptoms suggestive of the existence of cœnurosis, as, for instance, walking in circles, lameness of central origin, without appreciable lesions of the limbs, prolonged kneeling, disturbed vision, generalised attacks of epilepsy or of Jackson’s epilepsy, spasm of the pharynx, general signs of compression of the brain or cerebral dropsy, dulness, coma, etc.

In the absence of pulmonary lesions it is extremely difficult to arrive at an exact diagnosis except after injection of tuberculin, for the above symptoms very closely resemble those of cœnurosis, brain tumours, and even tumours in the frontal sinuses.

TUBERCULOSIS OF THE SKIN.

Cutaneous tuberculosis is one of the rarest forms of the disease. It is distinguished by the formation beneath the skin of little hardened swellings varying in size between a hazel-nut and a walnut, and containing caseous or calcareous material. These swellings have no connection with the superficial lymphatic glands. They may be found grouped together within certain areas, or distributed irregularly over the whole body, particularly towards the base of the tail.

The condition may be mistaken for generalised sarcomatosis, from which, however, it is readily distinguished by microscopic examination of the contents of the swellings.

ACUTE TUBERCULOSIS—TUBERCULOUS SEPTICÆMIA.

However rapidly the above-described forms of tuberculosis may develop, the disease as a whole is always of long duration, and continues for months, or even for years. The development of these chronic forms may, however, be interrupted by various influences which cause it to assume an acute character, either for a time or continuously. Each intermittent attack aggravates the condition of the patient, but gradually subsides, with or without treatment. Continued attacks, however, rapidly lead to death; they may be seen in animals previously unsuspected of any grave disorder.

The dominant symptom is continuous fever, accompanied by signs of disturbance of any or all of the chief bodily functions.

The temperature rises to 102° Fahr. (39° C.), or even to 104° or 105° Fahr. (40° or 41° C.), with morning and evening remissions of some hours. The respiration is accelerated. On auscultation it is often difficult to discover signs of chronic tuberculosis. The lung is the site of repeated congestive changes, resembling those of broncho-pneumonia or contagious pleuro-pneumonia. The pleura and walls of the chest become extremely sensitive, as in the last-named disease, and the abdomen may exhibit signs of peritonism, as at the beginning of acute peritonitis. The pulse rises to 80, 90, 100, or even 120 beats per minute, and the urine contains albumen in notable quantities. This condition continues for weeks without apparent diminution, the patients refuse food, lose flesh with startling rapidity, and finally die of exhaustion.

It would be impossible from these peculiarities alone to identify the nature of the disease which causes such progressive organic wasting, as the continued presence of fever prevents the use of tuberculin, but fortunately the preliminary changes in the lungs, lymphatic glands, genital tract, etc., are sufficient in most cases for the purposes of diagnosis.

=Sheep, Goats, and Pigs.=—In the other domestic animals tuberculosis is only of secondary importance to the practitioner.

It has been seen in the sheep and goat, but almost exclusively as the result of experiment. It must be understood, however, that prolonged cohabitation with diseased oxen or lengthened sojourn in contaminated places may easily produce tuberculosis in the goat, though the sheep continues to resist for a somewhat longer period.

Clinically such tuberculosis presents little interest on account of its rarity.

The same remark applies to pigs; nevertheless, an entire herd may become infected, and it may be necessary, after making a preliminary post-mortem, to examine the other patients. All forms of the disease occur in pigs, the lung being most frequently affected, but tuberculosis also attacks the intestine, udder, lymphatic glands, joints, etc. The pig, in fact, is extremely susceptible to this disease, whilst the sheep is only subject to it in a comparatively trifling degree.

=Diagnosis.= The clinical manifestations of tuberculosis are so numerous and so various that it is often an extremely hard task to form a diagnosis. Without doubt detection is relatively easy in well-marked forms, such as tuberculosis of the lungs, lymphatic glands and genital apparatus, but even in such cases the symptoms must be reasonably well-marked.

At first, unless the lesions produce externally visible signs, diagnosis is impossible, and in the case of hidden forms, such as tuberculosis of the serous membranes, mediastinum, intestine, testicle, etc., all that can be done is to take into account the probabilities.

Clinical diagnosis is therefore possible, but only in exceptional cases can it be absolutely relied upon. Fortunately, methods of investigation increase and become more exact every day, so that the points which clinical examination is incapable of deciding are often cleared up in the laboratory. Bacteriological examination of morbid products, such as the nasal discharge, the products of suppuration, the milk or the diseased tissues, is a valuable means in many cases of determining the presence of the organism which causes the disturbance. In all cases, in fact, the tubercle bacillus should be sought for in order to confirm the diagnosis.

If this method cannot be employed, as for example in tuberculosis of the liver, brain, etc., and the diagnosis is uncertain, the use of tuberculin constitutes the surest and easiest method of coming to a conclusion. Nocard’s researches have shown the precautions to be observed. A minimum febrile reaction of 2° Fahr. (1·5° C.) is, however, necessary before the existence of the disease can be affirmed.

Lastly, there remains a less rapid method, which aims at transmitting the disease to specially susceptible animals by inoculating with suspected materials, such as the nasal discharge, pus, milk or pulp of internal organs. This method is most valuable when bacteriological examination has failed and tuberculin has produced only doubtful results. The guinea-pig is the subject usually chosen, but some weeks, or even months, may elapse before definite results are obtained.

In those forms where ordinary methods of investigation prove sufficient it is well to bear in mind the symptoms which differentiate this disease from others closely resembling it.

Pulmonary tuberculosis, for example, should always be suspected whenever there exists frequent coughing, nasal discharge and poor bodily condition; if in addition to this respiration is found on auscultation to be rough, inspiration interrupted or rasping, expiration prolonged or blowing and the vesicular murmur non-existent, suspicion becomes almost a certainty. The diagnosis is even more assured if the respiration is of a blowing character at certain points, accompanied by snoring and sibilant _râles_ and gurgling or cavernous souffles.

The distinction between pulmonary tuberculosis and chronic bronchitis or simple pulmonary emphysema is based on the increased resonance revealed by percussion in the latter case; the different character of expiration; the existence of a double breathing movement; the external appearance of the animal; the absence of bacilli from the nasal discharge, and the failure to react to tuberculin.

The condition cannot be mistaken for verminous broncho-pneumonia if the information furnished by auscultation and the results of microscopical examination of the discharge are taken into account, the eggs or embryos of strongyles being extremely easy to detect.

Tuberculosis of the pleura may be mistaken for peripneumonia if the observer trusts to percussion alone, but the auscultation sounds are then different, and an injection of tuberculin will remove any doubt.

Tuberculosis of the peritoneum is often suggested by the indications afforded by careful palpation (thickening of the walls of the abdomen, rigidity and sensitiveness), and is distinguished from ordinary acute peritonitis by the difference in the appearance of the animals and the absence of much fluid. Chronic exudative peritonitis and ascites also exhibit sufficiently well-marked characteristics to enable them to be differentiated from tuberculosis of the peritoneum, but this is certainly not true of adhesive peritonitis, and in cases of the latter kind tuberculin is the only means of confirming the diagnosis.

External tuberculosis of the retro-pharyngeal and cervical lymphatic glands resembles, at a first glance, simple inflammation of lymphatic glands, but in the last-mentioned disease the lesions are symmetrical and the glands still retain a certain amount of elasticity, whilst in tuberculosis they are bosselated, hard, and sometimes fluctuating.

Tuberculosis of the mediastinum is suggested by difficulty in swallowing, especially if tympanites follows soon after eating, eructation is absent, and rumination is arrested.

A careful study of the development of the ulcerations will also in most instances make clear the difference between tuberculous stomatitis and simple stomatitis or stomatitis due to actinomycosis. Intestinal tuberculosis and tuberculous enteritis are sufficiently characterised by persistent intractable diarrhœa accompanied by tympanites, by the fœtid character of the fæces, and by moderate but continued fever. Chronic diarrhœa, which alone presents some analogy with this condition, is never accompanied by permanent tympanites.

Tuberculosis of the genital organs in male animals is always liable to be mistaken for simple orchitis and the development of tumours in the testicle; an injection of tuberculin will, however, indicate the nature of the lesion.

When the symptoms of genital disease or chronic mammitis in female animals suggest that the disease is of a specific character, the diagnosis can frequently be confirmed by a microscopical examination of the pus or milk.

Finally, should the practitioner hesitate as to the nature of the lesions which are the cause of arthritis, deformity of bones, cerebral symptoms, etc., tuberculin again will in most cases settle the question.

=The prognosis= in cases of tuberculosis is extremely unfavourable, whatever the form of the disease or its manifestations. Clinically the disease should be regarded as incurable in the strict sense of the word, however limited may be the lesions. The affected animals are not all doomed to immediate death: some may be kept alive, and may even serve an economic purpose without necessarily endangering others; it is sometimes possible to fatten them, though the risks probably far outweigh the advantages, but one can never rely on recovery in any particular case.

The gravity of this disease is the greater inasmuch as it assumes so many forms, any one of which may result in the infection of other animals.

All those forms of the disease, such as tuberculosis of the respiratory, digestive and genital tracts, in which virulent material containing bacilli is discharged realise these conditions. The patient becomes a source of infection to others of its kind, a fact which more than anything else renders the disease so dangerous to the farmer and breeder.

Only in cases where the lesions are closed (as in tuberculosis of the lymphatic glands, serous membranes, joints, etc.) can the sufferers be regarded as innocuous, and—as these lesions are exceptional or at least, as animals suffering from them are very frequently afflicted with open lesions from which bacilli are continually being discharged—every tuberculous animal must be regarded from a clinical standpoint as a constant danger to its neighbours.

This, however, must not be understood to mean that there are not different degrees of danger. It is quite certain that a patient with pulmonary caverns which are constantly throwing off enormous quantities of material full of bacilli is much more dangerous than another suffering only from slight bronchial or tracheal lesions, though the danger in the latter case is none the less always present.

=Treatment.= There is no really curative treatment of tuberculosis.

It must not be thought, however, that we are completely helpless and that the present condition of affairs must be allowed to continue indefinitely. Nocard and Leclainche have minutely laid down the lines to be followed as regards prophylaxis, though unfortunately the measures recommended cannot always be carried out.

Tuberculin having been proved an exact means of detecting tuberculous lesions in animals even where none were suspected, it is desirable, firstly, to test all the animals in a given establishment with tuberculin; and, secondly, to separate into classes (1) all animals which have reacted, and (2) those which have resisted.

The stables, etc., should then be completely disinfected by sweeping, washing first with hot water, then with strong antiseptic solutions, brushing over the walls with quick-lime solution and fumigating with sulphurous acid or formic aldehyde. The healthy animals should then be placed in one shed and the diseased animals in another. In order to render this system of isolation really efficacious the isolated animals and the healthy animals should have nothing in common, and the persons tending the two classes of animals, the buckets and other utensils, the watering places, etc., should be kept rigorously apart.

The animals known to be tuberculous should as rapidly as possible be prepared for slaughter, and if pregnant cows are included in the number the calves should be removed to the healthy stable immediately after birth and brought up either on boiled milk or by a healthy mother, experience having shown that congenital tuberculosis is of rare occurrence.

After the tuberculous animals have left the shed, this should again be thoroughly disinfected, in order to make it fit for the reception of healthy subjects.

Unfortunately such precautions can only be observed in model establishments. They necessitate expenses and immediate sacrifices of a very serious character, and breeders too often view only the sacrifice without regard to the after benefits. For this reason the above system has only been practised in certain of the best known and best managed farms.

To ensure the full benefit of these precautions, and to prevent a fresh introduction of tuberculosis into the herd, every new animal introduced should be subjected to the tuberculin test. Unless this precaution is taken, there is always a risk of introducing a tuberculous subject, thus nullifying all the precautions previously taken.

The problem is therefore still very complex, and the system can only give good results when rigorously observed and followed out.

As, however, in spite of all precautions, animals regarded as healthy are always, under normal conditions of existence, more or less exposed to accidental infection, it is desirable to subject the entire herd to the tuberculin test annually. This would cause the immediate detection of any animals with latent infection, so that they could be removed from the herd.

These wise precautions might, if understood and observed, eliminate the disease from the country, but they depend on individual initiative, and have not as yet been grasped by the mass of small breeders, farmers, etc. This class only see the difficulties in the way of realising the idea, without appreciating the constant benefit which they would derive from it.

SWINE FEVER—VERRUCOUS ENDOCARDITIS AND PNEUMONIA OF THE PIG.

Although it is not contemplated in this work to deal with those disorders which, on account of their highly contagious or infectious character, can only be dealt with by legislative action and by processes of “stamping-out,” it may be permissible to make certain exceptions. While we have made no reference to contagious pleuro-pneumonia of cattle, foot-and-mouth disease, rinderpest, anthrax and black-quarter we have devoted some space to Texas fever and tuberculosis, and give herewith a summary of the present state of knowledge regarding swine fever or hog cholera and a hæmorrhagic septicæmia of cattle known under various names in different countries and of very wide distribution.

SWINE FEVER.[9]

Footnote 9:

Report of the Departmental Committee _re_ Swine Fever. (Annual Report
of Board of Agriculture, 1896.)

Swine fever may assume two distinct forms, viz., the acute and fatal and the non-acute or slowly progressive.

=Symptoms.= In the acute form all those symptoms which are indicative of a severe febrile affection are present. The animals are disinclined to feed; they present evidence of great prostration and lie about their dwellings in a listless manner sheltering themselves from cold; their skins are hot, their eyes partially closed, and they are obviously suffering from some severe constitutional disturbance. Within a very few hours after these premonitory symptoms have set in the pigs become rapidly worse; they may or may not have a deep-red blush on the skin, which is more particularly noticeable on those parts of the body where there is an absence of hair, such as the inside of the thighs, the point of the axilla, and over the abdomen. Choleraic evacuations, having a most offensive odour, succeeding upon constipation, follow later on, and the animals die perhaps as early as the third or fourth day after the symptoms have first been observed.

In some instances the disease proceeds with great rapidity through a herd, the symptoms being of a most aggravated and pronounced character, and the outbreak attended with great fatality.

Generally speaking, the above description depicts the symptoms of swine fever in the acute form, more especially when it breaks out in a herd of young pigs.

In the non-acute form the disease progresses slowly, the clinical evidence is extremely obscure, the reddening of the skin, formerly regarded as being invariably present in swine fever, is absent, and beyond the fact that the animal is unthrifty, develops slowly, and perhaps has a constantly relaxed condition of the bowels, it may be asserted that there are no symptoms which could be regarded as absolutely indicative of swine fever, and nothing short of a post-mortem examination will enable even an expert to satisfy himself that the animal was affected with the disease.

As a general rule swine fever assumes this non-acute and slowly progressive form in pigs which have arrived at an age when their powers of resistance to disease are materially increased, _i.e._, in animals of eight or more months old; on post-mortem examination they are found to have been extensively diseased, more particularly in the large intestine, a portion of the digestive apparatus which does not appear to perform any very important function in connection with the nutrition of the animal, and so long as the stomach and small intestines remain healthy, pigs with a considerable amount of disease in the large intestine may still keep up their condition for a considerable time.

=Etiology.= As regards the etiology of the form of swine fever prevalent in England no question now exists. It has been proved to demonstration by the bacteriological inquiry conducted by Professor McFadyean that it is due to a special pathogenic organism, a bacillus, which, after cultivation in artificial media, will produce in the healthy pig fed with the pure cultures the typical ulcerations which are found in the intestines of pigs affected with swine fever contracted in the ordinary way.

The observations made by the veterinary officers of the Board of Agriculture caused them to doubt whether there was any disease of the lungs of pigs which, in the absence of lesions in the intestinal tract, could be accepted as evidence of swine fever.

The bacillus which produced swine fever when introduced in the healthy pig did not induce any special disease of the lungs.

=Pathology and morbid anatomy.= Swine fever, like typhoid fever in man, is essentially a disease of the digestive system, its chief characteristic being certain morbid changes of a well-marked nature which are found upon the surface of the mucous membrane in some part of the alimentary canal.

The changes referred to consist of what have been commonly described as the formation of a series of ulcers, single or confluent, distributed upon some part of the intestinal tract, varying in size and shape, of a yellowish-grey to black colour, and assuming as a rule a circular form. In some instances the lesions consist of diphtheritic exudations with necrosis of the lining membrane of the bowels.

These ulcers or necrotic patches may be found upon the tongue, tonsils, epiglottis, stomach, and small intestines, but they are more constant in the large intestines, especially the cæcum and colon. The lesions may involve the whole thickness of the mucous membrane, but seldom penetrate the other coats of the intestine; in fact, perforation of the peritoneal covering of the bowel is very rare in even prolonged cases of swine fever.

In cases where swine fever assumes the more acute form and death supervenes rapidly, it is usual to find that the small intestines are largely involved.

In the non-acute or slowly progressing form the lesions are more abundant in the large intestines, and in some instances the walls of the intestines become so thick as a result of infiltration into their structure and the excessively thick deposits upon the lining membrane, that it becomes a matter of surprise that the passage of the ingesta has been possible and that the animal has lived so long.

Next to the intestinal lesions the congested condition of the lymphatic glands, especially those of the mesentery, may be considered as most prominent among the pathological changes which occur in swine fever. Occasionally centres of necrosis are observed in the liver, and some writers refer to changes in or upon the spleen and kidneys.

The only lesions which can be characterised as absolutely typical of swine fever are those present in the bowels, the absence of which will justify any observer in declining to accept the case as one of swine fever without some further evidence or inquiry. It must, however, be distinctly understood that in the case of very young pigs which have died shortly after infection, there is often an entire absence of the lesions described, the only changes present being inflammation of the stomach or some part of the intestines.

Further, there are instances where older pigs have been slaughtered in the early stage of the disease in which no definite lesions have been found, and in such cases inquiry into the condition of the rest of the herd becomes necessary.

One most important feature in connection with the morbid anatomy of swine fever is the disposition which many animals have to recover from the disease; evidence of the reparatory process having often been detected in the intestines after they had been carefully washed.

Dr. Klein also maintained that many pigs took the disease in the mild form, and recovered without presenting any of the marked symptoms of swine fever.

It was found that, whether infected in the ordinary way or by direct inoculation, in some pigs killed only a few days after being infected the ulcers were occasionally seen gradually detaching from the surface of the intestines, and cicatrisation had already commenced.

VERRUCOUS ENDOCARDITIS OF THE PIG.

In the report of the Board of Agriculture for 1894 reference was made to the numerous instances in which the heart of the pig had been found affected with verrucous endocarditis.

This form of disease of the heart was known to veterinarians in Great Britain as far back as the year 1847. For reasons given in that report it became obvious that this diseased condition of the valves of the heart was not produced by swine fever. The question arose whether in addition to swine fever another disease existed, known on the Continent under the name of swine erysipelas. The importance of this question will be appreciated when it is explained that on the Continent swine erysipelas is classed among the contagious diseases of the pig.

The clinical evidence of the disease called swine erysipelas on the Continent appears to be more or less discoloration of the skin, similar to that which is frequently observed in swine fever, together with the occasional presence within the warty growths upon the valves of the heart of a bacillus which is regarded by Continental authorities as the cause of the disease.

Early in the inquiry it was ascertained that a bacillus identical with that found in swine erysipelas was also present in the diseased portion of the valves of the heart of the pigs in this country.

But the inquiries made did not corroborate or favour the suggestion that the disease which produced these morbid growths was in any way infectious or contagious. Such inquiries as could be made led to the opposite conclusion, since in every instance where the cases could be followed up it was ascertained that the deaths had been quite sudden, were limited to a single animal, and that those in contact remained in perfect health.

At this stage the all-important point to determine was whether the disease which existed in this country, “verrucous endocarditis,” was communicable from pig to pig, and with this object numerous experiments have been conducted to discover whether the bacilli found within the hearts of diseased pigs were pathogenic to healthy swine.

A large number of healthy pigs have been fed or inoculated with the blood, the diseased portions taken from the valves of the heart, and with artificial cultures of the bacilli obtained from the heart, but in no instance has the attempt to produce this disease been successful.

PNEUMONIA OF THE PIG.

The occasional association of pneumonia with or without pleurisy in cases of swine fever has led many veterinarians in England to regard lung complications as one of the lesions produced by that disease.

In the Board of Agriculture’s report for the year 1894 a description was given of the various diseases in the lungs of swine which had come under notice, and it was therein stated that the Board had been unable to discover any special lesion of the lung which would warrant them in stating that it was indicative of swine fever or due to contagion.

It is an indisputable fact that pigs are extremely liable to pneumonia and pleurisy. But as the clinical appearances present in the lungs examined in no wise differed from those which take place in the lungs of other animals which have been exposed to cold or septicæmia and other causes, the Board’s officers have never accepted these lesions as being specific.