CHAPTER IV.. Lungs and Pleuræ.

LUNGS AND PLEURÆ.

PULMONARY CONGESTION.

Besides passive congestions of the lung, which it is unnecessary to describe here, and which result from cardiac or pericardiac affections or the compression of important vessels, there sometimes occur, particularly among young animals, cases of active congestion of the lung. Such cases are produced by over-exertion on the part of animals which have escaped from control or have been chased by dogs.

They are most common in animals usually kept in stables, but which have accidentally escaped, or in very fat animals.

Dyspnœa and cough are the chief =symptoms=. The animals stop as though exhausted, extend their neck and head, dilate their nostrils and thrust their limbs out on either side of the body, while at the same time they appear in a condition of terrible distress.

The respiration is rapid and short, the patient can scarcely breathe, and asphyxia seems imminent. On auscultation it seems that the respiratory murmur has disappeared over almost the entire extent of the lung.

Death may occur very quickly.

=The diagnosis= is extremely easy, provided that the history is known.

=The prognosis= is grave.

One of the most successful methods of =treatment= consists in free bleeding. In a great majority of cases this causes the symptoms to abate as though by enchantment. Cutaneous stimulation by mustard and similar irritants, as well as ablutions of cold water, are useful. The animal should be placed in a very airy spot.

SIMPLE PNEUMONIA.

=History.= Veterinary surgeons have long been divided in opinion on the question whether simple pneumonia occurs in animals of the bovine species. Whilst some affirm it, others think that all lesions of the lung in the ox, apart from pneumonia due to foreign bodies, should be regarded as of the nature of peripneumonia.

Some ten years ago two veterinary surgeons of the department of the Aisne, Coulon and Ollivier, practising in a district where peripneumonia rages, made some extremely interesting observations on pneumonia in the ox. Their object was to distinguish between contagious peripneumonia and simple pneumonia during life, simple pneumonia having formerly been regarded as a non-contagious peripneumonia. Despite the rather unfavourable conditions in which ordinary practitioners are frequently placed, these gentlemen performed a work of great value. The facts which point to the occurrence of simple pneumonia are as follows:—

=The disease= is not contagious. One may allow affected animals to mix with normal subjects without the disease being communicated. Pulmonary exudate from cases of simple pneumonia can be injected into the dewlap and hind quarters of young and adult animals, without pathological results.

=The lesions= and =course= of simple pneumonia entirely differ from those of peripneumonia.

=Causation.= Simple pneumonia is not common, and only occurs quite exceptionally in fat stock, or in milch cows kept in stables at a regular temperature, as in the north of France and near Paris.

It occurs most commonly in working animals, which are exposed to variations in temperature and to chills. By causing vascular disturbance, chill favours microbic infection and visceral inflammation. Trasbot has described the case of an ox which, after having worked hard, and whilst freely sweating, was left exposed to the wind under a shed for about three hours. This animal contracted unilateral pneumonia the following day.

Coulon and Ollivier have seen the disease in animals living in damp, low-lying valleys, or valleys exposed to the north wind, which are exposed in consequence to great variations in temperature.

=The symptoms= follow almost the same course as in the horse, and one may distinguish three periods:—

=I. Period of onset.= The symptoms which mark the onset of the disease are moderate fever, which progressively increases, and acceleration of respiration and of circulation. The number of the respiratory movements rises to twenty or twenty-five per minute, those of the pulse to fifty, sixty, or eighty. The conjunctiva becomes injected, and then of a yellow tint. At this period the appetite never disappears completely, rumination is regular, and there is neither tympanites nor colic.

These general symptoms, which are not of special significance, are supplemented by more precise local symptoms—an abortive, difficult and painful, cough which is easily induced, and a whitish discharge. The rusty expectoration which is characteristic of simple pneumonia in the horse and in man has never been observed.

Percussion discloses partial dulness, usually on one side, in the lower region of the chest: the respiratory murmur in this region is ascertained by auscultation to have diminished, whilst in the upper part and also on the opposite side the respiratory murmur is increased.

=II. Period of exacerbation.= This period is characterised by accentuation of all the symptoms: the temperature rises, and may attain 104° Fahr.; the submaxillary artery is tense; the dulness becomes more marked, whilst crepitant and mucous râles are heard. In the portions still unattacked the function of the lung is exaggerated in order to make up for the defect of the diseased parts, and the respiration becomes juvenile.

The appetite, which previously had been maintained, diminishes considerably, without, however, entirely disappearing, and intense thirst sets in, as a consequence of the fever.

=III. Period of crisis.= The general symptoms remain stationary for four or five days; the respiration, which is always affected, sometimes becomes as rapid as thirty to forty per minute; the tubal souffle which invariably occurs in pneumonia of the horse is not always clearly audible.

=Terminations.= (1.) Resolution.—This is indicated by the attenuation of all the symptoms and the disappearance of fever, which gradually sinks from 105° to 101° Fahr. The respiratory movements become fuller and fewer in number, the pulse slower, and the artery softer and more compressible. The cough changes its character, is stronger, more sonorous and prolonged, and is accompanied by the free discharge of muco-pus. The dulness descends, and the tubal souffle, if previously existing, is replaced by the returning crepitant râle. In general the disease runs its course in eight to ten days in young and in fourteen to fifteen days in aged subjects.

(2.) Death by asphyxia is almost the only fatal termination of pneumonia in the ox. It occurs in one-third to one-fourth of the subjects attacked. Its approach is announced by a deep mahogany-red coloration of the conjunctiva. The pulse becomes very rapid, 100 to 110 per minute, thready, small, and almost imperceptible, whilst the beating of the heart is strong and tumultuous. Respiration is rapid and very laboured (50 to 70 per minute). The animal’s attitude is typical; it stands with its limbs thrust out, its head extended, its nostrils dilated, and its mouth half open, discharging foamy and viscous saliva. Throughout the greater portion of the lung gurgling sounds and crepitant mucous râles can then be detected.

(3.) Cases ending in gangrene and suppuration are excessively rare, and others resulting in chronic pneumonia have not been authoritatively described.

Pneumonia is distinguished from broncho-pneumonia by the existence of dulness at the period of crisis, whilst in the case of broncho-pneumonia this period is only marked by partial dulness, which is even then sometimes slight. Moreover, broncho-pneumonia usually develops much more slowly.

The disease, then, is distinguished from peripneumonia by the following points:—

(a) By the character of the temperature curve, which is regular in pneumonia, only attaining its highest point at the period of crisis, whilst in peripneumonia it ascends suddenly, and presents sudden oscillations.

(b) The appetite remains, although diminished.

(c) Sensitiveness in the region of the ribs is but feebly marked, or is entirely absent, simple pneumonia not being accompanied by pleurisy.

(d) The dewlap never shows œdema, a symptom which usually accompanies the period of crisis in peripneumonia, when the jugular veins and the anterior vena cava are compressed.

(e) These signs alone are almost sufficient on which to base the =diagnosis=, but they are often supplemented by two others, of some what less importance (for in exceptional cases they may also be observed in simple pneumonia), viz.—the absence in most instances of a membranous sound, and of a well-marked souffle.

=Prognosis.= Two-thirds of the cases recover. This proportion might be increased if the veterinary surgeon were called in at the beginning.

=Lesions.= Post-mortem examination reveals neither pleural exudate nor pleural lesions. The lung is large and of increased weight, hepatised along its lower borders, and congested in its upper part.

The sero-hæmorrhagic infiltration of the interlobular spaces varies, according to the region examined: the upper regions are engorged and black, owing to capillary hæmorrhages and blood clots, which completely surround the pulmonary lobule, the latter being violet or brownish-red in colour. In the hepatised portions the lobules are of a washed-out reddish tint, and the interspaces of a whitish colour.

The bronchi are filled with frothy, whitish mucus; the small bronchi sometimes contain fibrous concretions and the mucous membrane is injected, and may be destroyed in places. The bronchial lymphatic glands are enlarged, congested, and contain small hæmorrhages.

It is important in making a post-mortem examination to be able to distinguish pneumonia from peripneumonia. This is comparatively easy if one bears in mind that in the latter pleurisy always exists, that the interlobular connective tissue spaces are always greatly distended with a citrine-coloured serosity, that on section the peripneumonic lung resembles a mosaic; and that, finally, the course of hepatisation is centripetal, the inflammation commencing at the periphery of the lobule, and progressively extending towards the centre. In pneumonia, on the contrary, pleurisy is always absent; the interlobular connective spaces are only distended slightly, if at all, and always contain a brownish-red serosity: the course of hepatisation is centrifugal; it commences in the pulmonary alveoli, and extends towards the periphery and the interlobular divisions. The following table gives a résumé of the other differences between the two diseases:—

Peripneumonia. │ Pneumonia. │ Œdema of the dewlap. │No œdema of the dewlap. Pleural exudate. │No pleural exudate. Centripetal lobular hepatisation. │Ascending centrifugal lobar │ hepatisation. Extreme infiltration of the │Moderate infiltration of the interlobular connective tissue │ interlobular connective tissue spaces (primary yellow │ spaces (secondary reddish-brown infiltration). │ infiltration).

=Treatment.= Good hygiene, regular ventilation, moderate warmth, and the administration of tepid drinks facilitate recovery.

Certain German authors recommend cold compresses to the thorax, douches, and cold enemata in pneumonia. We do not think that such treatment has proved very successful, although it has been well tried.

The classic treatment commences with moderate bleeding, the free application of mustard to the sides, the application of moxas, frictions with antimonial or blister ointment, and the administration of draughts containing 2 to 2½ drachms of tartar emetic per day, or considerable doses of alcohol; and this treatment seems to have given the best results. Antithermic agents, like acetanilide, phenacetin and quinine sulphate, are too costly to be greatly used in bovine medicine. Salicylate of soda is preferable.

In order to assist circulation, support the tone of the heart and avoid engorgement of the lung and asphyxia; digitalis should be given in doses of ¾ to 1 drachm per day, or digitalin in subcutaneous injections of 5 to 6 milligrammes, continued for five or six days. Finally, iodide of potassium may be given in doses of 1 to 1½ drachms, to reduce inflammation and as an expectorant.

PNEUMONIA DUE TO FOREIGN BODIES—MECHANICAL PNEUMONIA.

It may happen that in examining a patient pneumonia is diagnosed under circumstances which seem to forbid its being regarded as simple or primary. This may be explained by the fact that ruminants are very apt to suffer from pneumonia produced by foreign bodies. The lung may be penetrated either by some sharp object making its way forwards from the rumen or reticulum or by liquid or solid material passing into the trachea. These are two common methods by which this form of pneumonia is produced.

PNEUMONIA DUE TO THE MIGRATION OF FOREIGN BODIES FROM THE RETICULUM.

=Causation.= The conditions under which food is swallowed by ruminants after preliminary mastication permit indigestible objects, such as stones, fragments of wood, nails, needles, bits of iron wire, etc., to enter the rumen, whence they reach the reticulum in consequence of peristaltic movements. Sharp, perforating objects, like needles or fragments of iron wire, penetrate the walls of the gastric compartments, and, impelled by the movements of these organs, pass through the intervening tissues, usually in the direction of the heart. Under conditions which cannot precisely be defined, these foreign bodies make their way towards the pleural cavity (usually the right, in consequence of the situation of the reticulum), traverse the diaphragm, and directly penetrate the base of the lung.

As the migrating object is usually infected, its passage through the diaphragm always produces a localised patch of diaphragmatic pleurisy. Although possible, it is only rarely that the pleural sac becomes generally infected, or that rapidly fatal septic pleurisy is set up. Usually the localised pleurisy causes the base of the lung to become adherent to the anterior surface of the diaphragm. The foreign body continuing its movements, passes into the lung, and there sets up pneumonia.

=Symptoms.= When the practitioner is first consulted he often finds only indications of the crisis period of a localised pneumonia at the base of the affected lung. The symptoms include fever, accelerated breathing, moaning, loss of appetite, cough without discharge, dulness over the base of the lung on percussion, disappearance of the respiratory murmur in the dull area, souffle opposite the inferior bronchi, and normal or juvenile respiration towards the front, i.e., in the anterior lobe, and sometimes in the cardiac lobe.

The temptation under such circumstances is to deliver a diagnosis of simple pneumonia with prognosis of probable recovery. It should be remembered, however, that in all cases of basilar pneumonia without affection of the anterior lobes there is a considerable chance of the condition being due to the presence of a foreign body. On more careful examination it is found that the intercostal spaces opposite the affected region are very sensitive, and that the circle of the hypochondrium is correspondingly sensitive. The owner, moreover, almost always informs the practitioner that for several weeks his animal has coughed, shown tympanites, diminished appetite, etc.

Compression of the roots of the corresponding diaphragmatic nerve at the base of the neck always produces coughing.

These symptoms rarely accompany the development of simple pneumonia. Furthermore, the =course= of this accidental pneumonia is entirely different. Instead of developing regularly according to the above-described cycle, pneumonia due to foreign bodies develops slowly, and only becomes well defined after several weeks, whilst its tendency is to grow more and more aggravated. The zone of dulness extends both in a forward and upward direction. The souffle extends forwards. Auscultation and palpation sometimes reveal the formation of an abscess or local gangrene; while there is slight œdema of the wall of the chest, as well as a gurgling sound at the moment when the lung is displaced, high fever, intensely coloured urine, and very marked leucocytosis, etc. Death is inevitable, and when gangrene exists it sometimes occurs suddenly.

=Diagnosis.= The diagnosis is based on the information furnished with regard to the course of the disease, the localisation of the hepatised zone, and the progressive character of the affection.

The diagnosis, nevertheless, is always a little doubtful, but may be so far assured as to attain the position of a quasi-certainty.

=Prognosis.= The prognosis is unequivocal.

=Treatment.= No practical treatment, either to extract the foreign body or to combat the special pneumonia which it has produced, can be attempted. All the interlobular connective layers and the lobules themselves are invaded by various microorganisms carried by the foreign body. Numerous fragments of tissue serve as centres of suppuration and gangrene, and the only chance would lie in attempting resection of the lung. Such intervention has no practical interest in veterinary surgery. It is true that when the existence of an abscess is suspected, an aseptic exploratory puncture may be made, and, in the event of the diagnosis being so far confirmed, the abscess might be opened through an intercostal space. Under such circumstances, however deep the point of penetration of the foreign body, the development of the resulting abscess causes local pleurisy and adherence between the pleura and lung, so that there is no immediate danger of producing purulent pleurisy and pneumo-thorax. If small the foreign body might possibly be discharged through the passage thus afforded.

In practice the best plan is to recommend slaughter as soon as the diagnosis becomes certain, provided that the meat can still be utilised.

PNEUMO-MYCOSIS DUE TO ASPERGILLI.

The term pneumo-mycosis, or pulmonary aspergillosis, is used to denote a condition due to the growth in the respiratory apparatus of a fungus of the order aspergillus (family, Perisporiæ; sub-order, Perisporiaceæ; order, Ascomycetes).

In ruminants, as in all other animals, pulmonary aspergillosis occurs accidentally, and may often pass unperceived, in spite of the indications given by Lucet and Bournay regarding its development and symptoms.

It seems most frequently to be caused by Aspergillus niger and Aspergillus fumigatus, particularly by the latter, which, according to Rénon’s work, also appears to be the most pathogenic. It only develops in animals whose respiratory apparatus is injured and is the seat of such lesions as those of chronic bronchitis, bronchi-ectasis, and of parasitic lesions or those containing cavernous spaces resulting from abscess formation, etc., etc.

The fungi, or more properly the spores, which have accidentally penetrated into the respiratory channels germinate and develop in the pathological dilatations, causing disseminated areas of pneumonia and some mechanical disturbance, but not producing intoxication by liberating toxins.

=Causation.= Infection occurs through the air passages, in consequence of the inspiratory current carrying spores of the fungi into the ramifications of the bronchi, where they develop if the soil is favourable. Development is favoured if the animals exposed to contamination are in bad condition, or if, as sometimes happens, the walls of the stables are not kept clean, and are covered with various forms of fungi.

Prolonged feeding on musty fodder may also favour respiratory infection; but it seems highly improbable that under ordinary conditions infection can occur through the digestive tract. Infection of the lung must also be regarded as exceptional, if one bears in mind the frequency with which oxen are fed on musty or mildewed fodder and the small number of accidents recorded.

=Symptoms.= The symptoms are obscure, and pulmonary aspergillosis is often only discovered on post-mortem examination. A cough is the chief symptom. It is dry at first. Afterwards it becomes spasmodic and frequent.

Respiration is difficult, dyspnœic, effected only with effort, and sometimes even discordant. Expiration is sighing.

Percussion reveals zones of partial or complete dulness when the lesions are near the surface of the lung, which, however, is rare. Bournay has noted the occurrence of a musical sound resembling that obtained by tapping a small crystal or glass bell.

Auscultation is said to reveal rough or sibilant râles, but as the lesions occur only in animals whose respiratory apparatus has already been impaired, it is difficult to offer an opinion on the subject.

These signs are invariably accompanied by a certain amount of general ill-health, wasting, and irregularity of appetite and of rumination.

On post-mortem examination the lung of the affected animal appears strewn with nodules, varying in size between a hazel-nut and a walnut. On section, Bournay claims to have found a wall or fibrous shell covering a greenish cryptogamic growth, in the centre of which was a yellowish, sharply defined kernel formed of masses of fungi (Mycelium, sterigmata and spores). In cases of rapid development, the pulmonary tissue around the parasitic lesion is completely hepatised.

=Diagnosis.= Diagnosis is impossible without recourse to microscopic examination of the discharge. This examination, which, however, is somewhat difficult, may, after staining, result in the detection of débris of the mycelial filaments and of spores, with or without bacilli of tuberculosis. The diagnosis as regards fungi can only be assured by preparing cultures.

=Prognosis.= The prognosis is grave, because the disease is always superadded to lesions, which of themselves would justify a sombre view.

=Treatment.= In consequence of the small number of observations published and the difficulty in diagnosis, no rational treatment has hitherto been laid down. From a purely theoretical standpoint, fumigations with tar and essence of turpentine and the inhalation of carbolic spray have been recommended. Life in the open air would, without doubt, be equally or more efficacious. Preventive treatment consists in withholding musty fodder and keeping the stables clean.

GANGRENOUS BRONCHO-PNEUMONIA DUE TO FOREIGN BODIES.

Foreign bodies which find their way into the trachea instead of the œsophagus provoke in most cases broncho-pneumonia, which very rapidly terminates in gangrene and death.

=Causation.= Forced feeding of sick animals which have lost their appetite is one of the principal causes of this grave condition. In order to administer food such as mashes, gruel, hay tea, etc., the oxherds have a bad habit of lifting the entire head and drawing forward the tongue whilst they pour the concoctions into the animal’s mouth. The liquid cannot then be divided into portions, deglutition in the pharynx is badly effected, and the substances administered find their way partly into the larynx and partly into the œsophagus. In the case of astringent, bitter, or highly stimulating drugs, a similar accident may be caused by spasm of the pharynx or œsophagus, where the tongue has not been left free and excessive quantities have been given.

Again, during the course of diseases complicated with paralysis of the pharynx (cow-pox, parturient apoplexy), obstruction of the pharynx and œsophagus (tympanitic indigestion), intense pharyngeal dysphagia (foot-and-mouth disease), etc., the risk of broncho-pneumonia due to foreign bodies is much greater still. It may even occur spontaneously in animals in the enjoyment of complete freedom (foot-and-mouth disease).

Lastly, cases of broncho-pneumonia have been described as a consequence of inhaling foreign bodies, when the animals are fed, for example, with meal made from undecorticated cotton-seed. Under such circumstances the lesions produced are similar to those of pneumoconiosis in man (the chronic forms of pneumonia of miners, charcoal-burners, quarrymen, stonemasons, etc.).

=Symptoms.= The symptoms of gangrenous broncho-pneumonia become apparent immediately after the foreign body has entered the trachea. They commence with a violent, spasmodic cough, produced by reflex action, which in its turn is due to the laryngeal mucous membrane having been touched. But this cough is now too late to be of use, for the food, drug or liquid has passed into the depths of the trachea, and cannot be ejected. The cough soon ceases, and the animals may even return to their food. These appearances, however, are deceptive, for twelve, twenty-four or forty-eight hours later the cough reappears, whilst appetite diminishes. The attacks of coughing are succeeded by the discharge of a greyish or reddish-grey offensively smelling material; respiration becomes more rapid, the heart’s action violent, and the temperature rises to 103° or even 105° Fahr. (39·5 to 40·5° C.).

The patients soon refuse all solid food, and if the chest is then examined by percussion one finds partial dulness, rarely simple dulness, over the cardiac lobes opposite the point where the girth passes. The partial dulness may rise to a varying height on both sides; sometimes it is confined to one side.

On auscultation the respiratory murmur in the upper two-thirds of the lung appears exaggerated on both sides, and is found to have greatly diminished, or disappeared altogether in the inferior zone.

Auscultation through the scapula almost always shows that the anterior lobes are affected; but, at all events, in the examinations we have made, checked by post-mortem examination, the cardiac lobes have always proved to be most affected, a fact attributable to the direction of the principal bronchi. The lower portion of the posterior lobes may also be affected, but this is rarer. All the lower zone is irregularly hepatised, and on auscultation one hears large moist râles, whilst respiration sometimes appears of a blowing character, and divided by a pause, but there is no tubal souffle. If the patient survive for a certain time, the sounds heard on auscultation undergo change; gurgling noises and sometimes true cavernous souffles are heard, as a result of suppuration in the bronchi and gangrene of one or more areas in the lung. Diffuse gangrene is rare, and the inferior zone is usually the only portion affected.

During this phase the expired air has an absolutely characteristic gangrenous odour.

Death occurs by asphyxia and intoxication, but some animals hold out for a fortnight and more.

=Lesions.= Post-mortem examination reveals a suppurative but secondary inflammation of the mucous membrane of the nasal cavities, pharynx, larynx, and trachea.

In the bronchi, sometimes very deeply placed, remains of foreign bodies are found in cases where some solid material has been inhaled. The mucous membrane of the bronchi is violet in colour, in places appears to be sloughing, and is covered by gangrenous patches immersed in a reddish-grey putrid fluid of offensive odour. In places the pulmonary tissue has undergone gangrene; and incision of the diseased centres discovers irregular cavities, filled with a pultaceous, greyish material, which often makes its way into the bronchi. These are the irregular cavities which give rise to the gurgling sounds. The walls of these cavities are formed of disintegrating pulmonary tissue, which again is surrounded by a zone of grey hepatisation. The gangrenous areas may unite, forming vast caverns. If near the surface they cause adhesive or septic pleurisy.

=Diagnosis.= The diagnosis is not very difficult, provided that an exact account can be obtained of the circumstances which preceded the appearance of the disease. The signs furnished by the discharge, the expired air, percussion and auscultation are sufficiently significant to remove any doubt.

=Prognosis.= The prognosis is extremely grave, and in the great majority of cases fatal.

=Treatment.= There is very little chance of recovery, no matter what treatment may be employed. The most favourable termination consists in the gangrene remaining limited to the bronchi and to a small fragment of the lung, so that the damaged tissues, being gradually delimited and sloughed off, may finally be discharged by coughing.

This is an exceptional termination, but attempts may be made to assist its evolution by giving alcohol in doses of 8 to 10 ounces per day, and salicylate of soda in doses of 4 to 5 drachms. When the condition can be early diagnosed before intense and continued fever has set in, and when the animal’s condition is good, it is often preferable to slaughter the patient.

INFECTIOUS BRONCHO-PNEUMONIA.

The ox’s lung is liable to so many and such extremely varied diseases that it seems desirable to add to the above descriptions some remarks on infectious broncho-pneumonia of external or internal origin.

Anatomically these forms of broncho-pneumonia are characterised by the occurrence of “islands” of pulmonary hepatisation, more rarely by extensive (massive) hepatisation; in all cases the hepatisation is irregular, and in no way resembles that of simple pneumonia.

=Causation.= The internal causes are numerous and varied. They are due to primary infection of an organ whence arises a general infection, sometimes even true septicæmia. Some form of broncho-pneumonia, such as simple broncho-pneumonia, purulent broncho-pneumonia, gangrenous broncho-pneumonia, etc., then follows as a complication. These broncho-pneumonias are therefore only manifestations of purulent infection or septicæmia. They frequently follow post-partum infections, vaginitis, metritis, and suppurative mammitis.

=Symptoms.= The general symptoms first attract attention, and are extremely acute. They comprise high fever, loss of appetite, cessation of rumination and of milk secretion, breathlessness, blowing, etc.—all signs of grave and rapidly progressive infection.

Sometimes at this period nothing more than the primary lesion, such as metritis or mammitis, can be detected. It may even happen that the uterus seems little affected, and, despite the accelerated respiration, neither partial nor complete dulness of the lung is discovered.

Hepatisation only occurs some days afterwards, and with it irregular partial dulness localised in the lower zones, disappearance of the respiratory murmur in the corresponding regions, exaggeration in the infected regions, an expiratory sound which is barely perceptible or may be of a blowing character, or, again, after several days may be transformed into a tubal souffle.

The cough then becomes frequent, generally difficult, paroxysmal, feeble, and easily provoked. The appetite suffers, the patients seem to prefer fluid nourishment and lose flesh very rapidly.

If the broncho-pneumonia is about to terminate in suppuration or gangrene, the respiration becomes sighing, the breath fœtid, and the cough is accompanied by a greyish muco-purulent or gangrenous discharge.

When the abscesses are deep-seated, the alarming symptoms retain their primary degree of intensity for weeks, until the animals are completely exhausted. Abscesses, originating in deep-seated parts, may even extend towards the surface of the lung, and produce either adhesive pleurisy that can be detected by palpation, or exudative pleurisy, easily recognised on percussion.

When the infective microbes are not pyogenic the general condition appears less grave, the animals exhibit only moderate fever, appetite is diminished but not lost, wasting is slower, and may continue for months, but the affected portions of lung become converted into fibrous masses or a material resembling spleen pulp.

The duration of infectious broncho-pneumonia, therefore, varies with the nature of the infecting organism. In cases which terminate in gangrene, the animals may survive for three or four weeks; in those where suppuration occurs, for several months. In short, recovery is the rule in simple broncho-pneumonia; but from an economic standpoint there is little reason for keeping the animals alive.

=Diagnosis.= The diagnosis is not generally very difficult; for if at first the case may be mistaken for one of simple pneumonia, the persistence or prolonged aggravation of the symptoms and the irregularity in position of the lesions revealed by percussion and auscultation enable the condition to be distinguished at an early period from simple pneumonia.

Confusion with acute or chronic pleuro-pneumonia may easily be avoided by noting the absence of pleural effusion, and of the soft pleuritic souffle of peripneumonia, etc.

Where auscultation is chiefly relied upon it is more difficult to differentiate between this disease and acute tuberculosis, and between it and broncho-pneumonia produced by foreign bodies, although the latter disease develops differently.

=Prognosis.= The prognosis is always extremely grave and, in cases where there is gangrene or abscess formation, fatal. From the economic standpoint the chronic form is also very grave.

=Treatment.= As broncho-pneumonia is frequently of a secondary character, treatment should at first be particularly directed against the primary condition, whether in the mammary gland, uterus or elsewhere. Early treatment of suppurative mammitis, metritis, etc., is therefore necessary.

Broncho-pneumonia is treated by free vesication of the walls of the chest, the administration of tonics and antiseptics, alcohol in small doses, acetate of ammonia in doses of 1 to 2 drachms, salicylate of soda in doses of 5 to 8 drachms per day, salicylic acid in doses of 1 drachm, and creosote in doses of 1½ to 5 drachms, given in electuary, etc.

Diuretics, farinaceous gruels, etc., may be used freely, and are of value.

If the symptoms persist or become aggravated, and suggest the development of an abscess or gangrene, it is better to slaughter the animal.

BRONCHO-PNEUMONIA OF SUCKING CALVES.

Young animals still with the mother, particularly calves during the first few weeks of life, are liable to broncho-pneumonia of a specialised character, as regards not only its causes, but its development and duration.

=Causation.= The causes may be grouped under two principal heads:—

(a) In slow or difficult cases of parturition, the fœtus may be injured whilst being delivered, as a consequence of direct compression of the great blood-vessels, etc. (particularly of compression of the umbilical cord, compression of the thorax in the cardiac region, or partial premature separation of the envelopes), and may thus by reflex action make automatic inspiratory movements.

Respiration being impossible, inasmuch as the thorax has not yet passed the posterior passages, such inspiratory efforts made during the passage through the pelvis may cause amniotic liquid to pass into the bronchi. This accident is particularly liable to occur during deliveries with breech presentation. If, as happens frequently, the amniotic liquid has become infected either prior to or as a consequence of obstetrical manipulation, the result is fatal; for the passage of infected amniotic fluid into the bronchi develops a broncho-pneumonia of a degree of gravity depending on the character of infection.

(b) By an entirely different mechanism broncho-pneumonia may occur in sucking calves during the first few weeks of life, even in the case of animals born in a vigorous condition, and kept in warm and well-arranged stables. This form follows diarrhœa, and constitutes a final complication which is always of very marked gravity, and in most cases fatal.

Such secondary broncho-pneumonia only occurs when the diarrhœa has resisted treatment, and it is important to note that the pectoral lesions appear at a time when the intestinal mischief seems to have diminished, the diarrhœa having lessened or disappeared. This variety of broncho-pneumonia of young animals is by far the most frequent. It has been termed broncho-pneumonia of intestinal origin, and exactly resembles, so far as its development and gravity are concerned, the broncho-pneumonia in young infants described by Sevestre and Lesage.

The term broncho-pneumonia, moreover, is not strictly correct, or at least is not exclusive; for the rapid forms often exhibit lesions other than those of broncho-pneumonia. Post-mortem examination reveals pleurisy and pericarditis.

=Pathogeny.= At the outset of these attacks of broncho-pulmonary disease, a careful bacteriological examination of the organisms to be found in the discharge of bronchial mucus leads to the discovery of bacilli which do not stain with Gram, and which resemble varieties of the colon bacillus; in other cases of streptococci. At a later stage, when the animal has become weak, microorganisms are present in much greater variety. Nocard found in lung abscesses the bacillus of epizootic lymphangitis. It seems that the development of various lesions in the thoracic cavity may be due to auto-infection, i.e., to the penetration from the intestine of germs which, after passing through the circulation, establish themselves at some point in the lung. The pleura is attacked at a later period as a consequence of continuity and contiguity of tissue.

In a similar way pericarditis and even valvular endocarditis may be produced.

=Symptoms.= The symptoms are similar to those of all forms of broncho-pneumonia. Where diarrhœa has been neglected, the conditions may apparently improve without evident cause, whilst the respiration becomes more frequent. The patient soon suffers from cough, and in a few hours the existence of broncho-pneumonia is clearly apparent. Acceleration of breathing is the dominant symptom. The respirations may rise to fifty to sixty per minute, at which they continue, while fever sets in. On percussion the thorax may appear of normal resonance throughout; but when pleural lesions and exudates exist, resonance gives place to partial or complete dulness. Should pericarditis or small cardio-pericardial adhesions exist, they may escape observation, but if the exudate is abundant or the adhesions multiple or of large size the usual symptoms of pericarditis develop progressively.

On auscultation the respiratory murmur is always found to be greatly exaggerated in the healthy parts, usually the upper portions of the lung. On the contrary, it is attenuated or suppressed in the affected regions. The other signs vary greatly, according to the extent, intensity, and more or less advanced condition of the lesions. Crepitant and bronchial râles, blowing respiration and tubal souffles, etc., are among the symptoms.

The duration of the disease varies; some patients may be carried off in five or six days, while others survive for one or two months, or even longer. A few recover, but they remain thin, puny, and atrophied, and are not worth keeping alive.

=Lesions.= The lesions extend to the bronchi, the pulmonary tissue, and sometimes the pleura and pericardium. They consist in lesions of diffuse broncho-pneumonia, pleurisy with false membranes and parietopulmonary adherences, and pericarditis with partial cardio-pericardial adhesions.

In rare cases abscesses caused by pyogenic streptococci may be found.

The anterior lobes, cardiac lobes, and lower part of the posterior lobes are those singled out for attack.

=Diagnosis.= The diagnosis is not difficult, provided that the circumstances preceding the appearance of the pulmonary lesions are known.

=Prognosis.= The prognosis is very grave.

=Treatment.= Treatment very often proves useless, because the patients have little resisting power and are exhausted, and also because they are suffering from a slowly progressive septicæmia. It may, however, be worth while in the early stages to apply blisters to the chest and administer general stimulants: alcohol in doses of 8 to 12 drachms per day, divided into two parts and mixed with milk; acetate of ammonia in doses of ½ to 1 ounce; and tinctura digitalis 5 to 6 drops.

The primary disease of the intestine is masked by the pulmonary symptoms, but should not be overlooked. Rice water, subnitrate or salicylate of bismuth may be added to the milk or albuminous solutions constituting the diet. When an epizootic of broncho-pneumonia complicates the diarrhœa it is necessary to take all the preventive measures which have been suggested in connection with white scour and umbilical diseases in calves. These comprise disinfection of the premises and local disinfection of the animals affected.

SCLERO-CASEOUS BRONCHO-PNEUMONIA OF SHEEP.

The sheep suffers from a special form of broncho-pneumonia, which is seldom seen except in isolated cases, but which, under exceptional circumstances, may nevertheless attack a certain number of animals in a particular flock. It was first noticed and described by Liénaux in 1896, and has more recently been studied by Sivori (1899). Moussu has only seen it in flocks in the north of France.

=Causation.= The causes of this disease are still imperfectly understood.

Sivori’s researches show that the disease may be referred to a microorganism, but we do not yet know exactly by what path infection occurs.

The agent of sclero-caseous broncho-pneumonia in the sheep appears similar to that described by Preisz and Guinard in 1891, and identical with the microbe of ulcerative lymphangitis of the horse (Nocard, 1897). It is probable that infection occurs through the respiratory apparatus.

=Symptoms.= The clinical development of the disease is difficult to describe, because its course is slow and unaccompanied by well-marked external signs.

The animals lose flesh, pant for breath when moved, drop to the rear of the flock, cough frequently, feed badly and end by becoming cachectic. Many suffer from the disease and yet remain in fair bodily condition.

On post-mortem examination the lungs are found not to collapse, having lost their elasticity, and are of a yellowish-white colour, which is only seen in this disease. On section the pulmonary tissue appears dense, hard, and of a fibrous and lardaceous character. At various points nodules with fibrous envelopes and caseous, yellowish or greenish contents are found.

When the caseous nodules are near the surface the pleura may be chronically inflamed and thickened. The liver and kidney frequently contain caseous lesions.

=Diagnosis.= The diagnosis becomes easy after the first post-mortem examination, for the lesions discovered cannot be mistaken for those of parasitic broncho-pneumonia, degenerated pulmonary echinococcosis or tuberculosis. In the living animal, on the contrary, the diagnosis is extremely difficult.

=Prognosis.= The prognosis is grave. No special method of treatment is known.

PULMONARY EMPHYSEMA.

Pulmonary emphysema, i.e., exaggerated dilatation of the pulmonary tissue by air, is not uncommon in the bovine species, and occurs under the two classical forms—(1) alveolar or intra-lobular emphysema limited to dilatation of the alveoli; and (2) interlobular emphysema, produced by the entrance and diffusion of air in the interlobular spaces in consequence of rupture of the lobules.

These two forms are very frequently associated:—

(1.) Emphysema by dilatation usually begins in the right pretracheal lobe; also in the cardiac and even in the posterior lobes.

(2.) Interlobular emphysema begins in the same regions, but it spreads readily in a backward direction, remaining interstitial; or, on the other hand, becoming subpleural at the periphery of the lung.

In both cases the pulmonary tissue is pale, the blood-vessels are partially obliterated by compression; circulation and aeration of the blood are impeded—hence the appearance of the disturbance noted.

=Causation.= Emphysema is seen in adult working oxen; also, and to an even greater degree, in aged cows. It is produced by excessive strains in draught, or more often by the paroxysms of coughing so common during simple or parasitic bronchitis, broncho-pneumonia, pneumonia, chronic broncho-pneumonia, etc. Successive gestations also produce it.

All these pathological conditions also interfere with the nutrition of the bronchial mucous membrane, particularly of its deep-seated muscular layer, which is then incapable of regulating the distribution of air in the bronchial channels. The distribution being no longer regulated by reflex action, air accumulates at certain points as a result of the expiratory efforts made during coughing, and dilatation of the vesicles or lobules occurs.

Diseases of the digestive apparatus, acute or chronic tympanites in particular, may play a certain part by compressing the diaphragm, causing expiratory efforts and fits of coughing.

Furthermore, swelling of the lymphatic glands at the entrance to the chest, by compressing the pneumo-gastrics, provokes reflex cough and finally emphysema.

=Symptoms.= Pulmonary emphysema is marked by accelerated respiration due to diminution in the respiratory capacity, which is often very seriously affected; to insufficient absorption of oxygen in consequence of diminution in the space available for exchange of gases in the lung, and to insufficiency of expiration. This acceleration in breathing, though little marked during repose, becomes very pronounced after exercise, or during hot weather; and under these circumstances is accompanied by a paroxysmal, feeble but shrill cough, without discharge. This cough without discharge is frequently followed by swallowing.

Percussion reveals an important point, viz., increase in the normal resonance of the thorax.

On auscultation the vesicular murmur is found to be diminished, the respiration assumes a rough and rasping character, inspiration is difficult, expiration painful, and often divided into two periods, as indicated by a slight double movement of the flank. Expiration is clearly audible. Its duration is generally less than that of inspiration, although in some cases it is equal or even longer. It is accompanied by sibilant and snoring râles, sometimes even mucous râles, of an intermittent character. In rare cases there may be difficulty of respiration, as in broken-winded horses.

=Diagnosis.= The diagnosis may suggest a doubt as to whether emphysema or tuberculosis is present, but in the latter there is fever, the general condition is poor; on percussion the thorax reveals areas of partial dulness; and expiration is rough and prolonged, sometimes of a blowing character, a peculiarity which is exceptional in emphysema.

=Prognosis.= The prognosis is not very grave, except where emphysema is only an accompanying symptom of another disease, such as chronic bronchitis, tuberculosis, etc.

=Treatment.= Little can be done to check the development of the above described pulmonary lesions; but the cough may be relieved, and the pulmonary circulation improved by assisting the heart.

The most prompt and efficacious assistance is given by digitalis in doses of ½ to 1 drachm per day for adults, iodide of potassium in doses of 1 to 1½ drachms, and bromide of potassium in doses of 1 drachm to guard against reflex excitability of the pneumo-gastric. This treatment, however, should not be followed for more than five or six days, and should then be replaced by the administration of arsenious acid in doses of 15 grains per day, ground horse-chestnuts in doses of 3 ounces per day, etc., etc.

DISEASES OF THE PLEURA.

Primary inflammation of the pleura is very rare in animals of the bovine species, but secondary diseases of this membrane, on the other hand, are frequent.

ACUTE PLEURISY.

Cruzel, Fabry, and a number of practitioners have described the occurrence in working animals of acute pleurisy à frigore or serofibrinous pleurisy in consequence of severe, sudden variations in temperature, or prolonged chills. At the present day it seems fairly well established that pneumonia, and not pleurisy, is commonest under such conditions, and Moussu disclaims ever having seen primary pleurisy. On the other hand, pleuritic effusions are very common in contagious pleuro-pneumonia, secondary pleurisy due to pericarditis produced by foreign bodies, septic broncho-pneumonia or broncho-pneumonia due to foreign bodies, and the pleurisy which accompanies septicæmia consequent on parturition, etc. These forms of disease, however, are not simple serofibrinous pleurisy, but septic or suppurative pleurisy, still little understood in veterinary surgery.

Tuberculosis of the pleura, although very frequent, is rarely accompanied by marked exudation. Like secondary disseminated pleural carcinoma, it usually assumes the vegetative and adhesive form, with adhesions of greater or less extent between the lung and wall of the chest.

=Symptoms.= In all these morbid conditions the symptoms vary greatly, and it would be difficult to give an accurate general description of them.

In acute pleurisy à frigore shivering attacks, moderate fever, dulness, loss of appetite, interference with rumination, dryness of the skin, rapid wasting and intercostal pain, first indicated by dull colic, constitute the usual symptoms.

The respiration is short and irregular, interrupted when the exudation is abundant. Pressure over the intercostal spaces produces pain, as does strong percussion. Percussion reveals an area of dulness bounded above by a horizontal line.

Auscultation shows the respiratory murmur to have disappeared throughout the zone of dulness, and reveals the presence of a soft pleuritic souffle (a soft tubal souffle quite different from that of contagious pleuro-pneumonia) when pleural exudation is abundant. In septic or suppurative pleurisy fever is higher, loss of appetite more marked, wasting more rapid, and depression extreme, with, however, identical local symptoms.

=Diagnosis.= The diagnosis of pleural exudation presents little difficulty, because of the peculiar characters of the dulness and the pathognomonic indications obtained by auscultation. The exudation is usually unilateral, the mediastinum being very resistant and not perforated in the ox.

By passing the needle of a Pravaz’s syringe with antiseptic precautions through the intercostal space a little fluid may be drawn off and the diagnosis formed, the form and nature of the pleurisy being simultaneously established. The liquid extracted can be examined bacteriologically, and can be grown on nutritive media, or inoculated into experimental animals.

=The prognosis= is grave, because in the ox pleurisy is very often of a secondary character. The outlook varies, however, with the form of the pleurisy and the nature and virulence of the infecting organism.

=Treatment.= Treatment consists firstly in applying an energetic vesicant like antimonial ointment or liquid cantharides blister; internally diuretics such as soda bicarbonate, nitrate of potash, resin, and decoctions of pellitory, dogs’ grass, etc., may be given. If thought desirable the chest may be tapped and the pleural cavity washed out with an antiseptic solution.

CHRONIC PLEURISY.

Chronic pleurisy is frequent in aged animals, but usually assumes the form of local adhesive pleurisy. The adhesions between the lung and pleura are more or less extensive; they result from verminous broncho-pneumonia, echinococcosis, external injuries, etc. Clinically this form is of no importance, and is almost impossible to diagnose. During the development of pleural tuberculosis, on the contrary, adhesive dry pleurisy is frequent, and sometimes becomes so well marked that almost the whole of the opposing pleural surfaces may become united.

PNEUMO-THORAX.

The name pneumo-thorax is given to the condition produced by the entrance of air or gas into one of the pleural cavities.

The accident is usually produced by rupture of the parenchyma of the lung and of the pleura, a rupture which produces a communication between the alveoli or a bronchus and the corresponding pleural cavity. As soon as the rupture occurs air passes from the lung into the pleural cavity, and the lung collapses in consequence of the resilience of its elastic constituents.

Under other, much rarer, circumstances pneumo-thorax occurs in consequence of gas generated in the digestive tract passing into the pleural spaces. The condition then makes rapid progress, and death occurs in a few days.

=Symptoms.= The symptoms are well defined. As soon as the accident occurs the animal exhibits extremely marked and sudden dyspnœa, accompanied by heaving at the flank or general agitation of all the muscles of the body. One of the lungs, in fact, has suddenly been called on to perform the functions of both, and at first it naturally has great difficulty in meeting this demand.

The heaving at the flank and the general agitation of the body muscles is due to the fact that the regularity and rhythm of contraction of the diaphragm are disturbed, and the mechanical conditions have become different on the two sides. From the first, respiration is moaning and expiration becomes rapid, stertorous and deep, while the face is anxious-looking, and the nostrils are dilated as though the animal was on the point of suffocation. On examining the animal from in front or behind, the thorax is easily seen to be wanting in symmetry, the side on which the pneumo-thorax has occurred being immobile as compared with the sound side. The latter, moreover, is dilated in order to compensate for the loss of function of the collapsed lung.

Percussion reveals greatly increased resonance on the side of the pneumo-thorax. On the other hand, the opposite side yields a normal sound.

Auscultation reveals an increase of the respiratory murmur on the side which is still acting and, on the contrary, complete and total suppression of the respiratory murmur on the affected side. On applying the ear to the chest wall, a large soft, amphoric souffle of well-marked metallic character is heard. This is particularly clear on respiration, giving the impression of the existence of a large cavity beneath the ear. The sighing sound heard on auscultation of the chest wall is louder than that heard externally or over the region of the nostrils or larynx; and it seems to be reinforced, as though by the resonance of a large cavity with thin metallic walls. Once or twice per minute, moreover, a sound may be heard like that of dropping water. It is of a very special character, resembling that produced by drops falling to the bottom of a hollow metallic vase, and setting up prolonged vibration.

As secondary symptoms the heart’s action is accelerated, the number of beats rising to 80 or even 120 or 130 beats per minute; appetite is lost; slight tympanites develops as a result of rumination and eructation being suspended; the peristaltic movements of the rumen are interrupted, and constipation develops.

=Diagnosis.= The diagnosis of pneumo-thorax is easy, and the condition can scarcely be mistaken for any other except diaphragmatic hernia; but the indications derived from percussion and auscultation are so different in the two cases that they need not be further emphasised.

The task becomes more difficult, however, when an attempt is made to identify the exact form of pneumo-thorax, for three principal varieties are recognised.

In open pneumo-thorax, the first and most frequent form, air passes from the lung into the pleura at each inspiration, and flows back from the pleural cavity towards the bronchus at each expiration. The intra-pleural pressure is then approximately equal to the intra-bronchial pressure, and undergoes similar oscillations. (It should be noted that the aperture in the lung is seldom sufficiently large to establish an absolute equality of pressure between the bronchus and the pleural cavity. Respiration, therefore, though very seriously impeded, generally continues in a modified form.)

In a second variety, termed “valvular pneumo-thorax,” air passes freely from the lung into the pleural cavity, but is unable to return from that cavity towards the lung, because a flap of tissue acts as a valve and closes the orifice at the commencement of expiration. As soon as intra-pleural pressure rises above that of the inspiratory effort, the valve remains permanently closed.

In the third variety, called “closed pneumo-thorax,” the orifice of communication is obstructed by some mechanism, and the pleural sac only contains a film of air.

In practice, valvular pneumo-thorax is recognised by the movement of the thoracic wall (which in open and closed pneumo-thorax remains depressed), as well as by extreme intensity of the dyspnœa and attacks of threatened suffocation. Closed pneumo-thorax, which is only a termination and a stage in the cure of open pneumo-thorax and of valvular pneumo-thorax, is suggested by progressive improvement in the symptoms. Scientifically it is very easy to make this diagnosis by putting a manometric apparatus in communication with the pleural cavity by means of a simple hollow needle provided with a thick-walled rubber tube.

In open pneumo-thorax the liquid column in the manometer undergoes rhythmic oscillations corresponding to the respiratory movements; in valvular pneumo-thorax the intra-pleural pressure increases progressively until it becomes higher than the external pressure; and finally, in closed pneumo-thorax, the column of the manometer assumes a certain level at which it rests.

=Prognosis.= The prognosis is very variable, according to the primary cause of the accident. Animals might recover, but economically there is little advantage in preserving them when the diagnosis is assured, except in cases of animals of great value, and when the primary disease admits of it.

=Causation.= Pneumo-thorax may be produced by various causes. The most frequent cause in large animals is pulmonary echinococcosis, during the course of which a peripulmonary vesicle, after having injured several lobules, one of the air passages or even a bronchiole, may break through the pleura, thereby setting up direct communication between the bronchi and the pleural cavity.

To pulmonary tuberculosis, with peripheral softened tubercles, perforating simultaneously into an alveolus or a small bronchus and into the pleura, must be assigned the second place.

Vesicular and interstitial subpleural pulmonary emphysema is also a frequent cause of pneumo-thorax, the pleura being ruptured over the emphysematous points.

Finally, and exceptionally, an abscess of the lung may open into the pleura and form sinuses, which may establish a communication between the digestive reservoirs and pleural sacs; but such accidents produce pyo-pneumo-thorax and septic pleurisy of a rapidly fatal character.

=The diagnosis= of pneumo-thorax, and even of its varieties, does not, however, enable one to form a prognosis; the important point is to ascertain the original cause.

=Treatment.= It may be said of pneumo-thorax that no treatment exists, and that the position is one of expectancy. In fact, we possess no means of directly dealing with such diseases as echinococcosis, tuberculosis, or emphysema. For this reason it is best as a rule to advise slaughter. Nevertheless, when the condition is due simply to pulmonary echinococcosis of a discrete character, there is some chance that after several months the animal may recover spontaneously. The communicating orifice becomes closed by reparative processes (cicatricial contraction, the formation of a false membrane, limited adhesion between the two walls of pleura, etc.); the layer of air imprisoned within the pleural cavity is progressively absorbed, provided that it has not been accidentally infected; the collapsed and partially splenised lung progressively regains its function under the inspiratory efforts, and after some months complete recovery may occur. This termination cannot always be confidently predicted, because complications may arise at any moment; under no circumstances can complete recovery be anticipated when the primary disease is tuberculous.

In cases of valvular pneumo-thorax with extreme oppression, attacks of suffocation threatening death as a consequence of excessive intra-pleural pressure, displacement of the mediastinum towards the opposite side, compression of the heart, and functional disturbance of the sound lung, it may be worth considering whether the attacks of suffocation and threatened asphyxia can be modified or removed by preventing the excess of intra-pleural pressure. By simply passing a stout hollow needle through one of the intercostal spaces, the intra-pleural pressure may be reduced to that of the external atmosphere, and the effects of compression removed. This, however, is a last resort, and has no permanent effect.

HYDRO-PNEUMO-THORAX AND PYO-PNEUMO-THORAX.

When pneumo-thorax is set up, it rarely remains simple. In the great majority of cases the pleura becomes infected, either directly, by the lesion which has determined the pneumo-thorax (tubercle, superficial abscess, actinomycotic lesion, etc.), or secondarily, by the penetration of germs from the air or from the bronchus (echinococcosis, emphysema). Simple pneumo-thorax then becomes converted into hydro-pneumo-thorax or pyo-pneumo-thorax, according to circumstances—that is to say, whether the exudation into the pleural cavity is of a simple character or is of the nature of pus.

=Symptoms.= Hydro-pneumo-thorax is characterised by the signs common to true pneumo-thorax, which constitutes the primary lesion, viz., sudden difficulty in breathing, exaggerated unilateral resonance, amphoric souffle accompanied by a sound like that of drops of water falling into a metallic vessel, and by the signs of secondary exudative pleurisy, viz., moderate fever, dulness over the lower zones of the chest, limited above by a horizontal line, slight splashing sound, and a soft distant pleuritic souffle.

All the secondary symptoms—loss of appetite, suppressed rumination, sighing, accelerated pulse, etc.—are found in a more or less accentuated form.

In pyo-pneumo-thorax fever is more marked, while the signs noted on auscultation and percussion are identical, and are accompanied by digestive disturbance and marked œdema of the wall of the chest, which can be seen or detected by palpation.

=Diagnosis.= The diagnosis is relatively easy when the lesion is secondary; but the difficulty (as in simple pneumo-thorax) is to identify the exact character of the primary affection.

On the other hand, pyo-pneumo-thorax and hydro-pneumo-thorax are not always complete; adhesions of very varying character may exist between the lung and the chest wall; hence it is impossible to group together all the possible symptoms.

Diagnosis is facilitated by aseptically puncturing the chest with a Pravaz’s syringe.

=Prognosis.= The prognosis is extremely grave even in cases of hydro-pneumo-thorax. Treatment is useless, for even allowing that the primary disease might be cured, this process of cure, after reabsorption of the transudate, would be extremely tedious, and the animals would long remain in poor condition.

=Treatment.= In hydro-pneumo-thorax no treatment is advisable. Nothing is gained by thoracentesis, at least at an early stage, or before the lesion causing the pneumo-thorax has closed.

In pyo-pneumo-thorax, on the contrary, the theoretical course is to evacuate the pus and completely wash out the pleural sac with lukewarm non-irritant solutions of antiseptics.