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The Etiology of Pneumonia in the Pig
THE
JOURNAL OF
COMPARATIVE PATHOLOGY AND
THERAPEUTICS. VOL. X.-No.
I.
MARCH 31, 1897.
PRICE 2S.
6d.
THE ETIOLOGY OF PNEUMONIA IN THE PIG. By
J.
M'FADYEAN, Royal Veterinary College, London.
IN an article which appeared in this Journal for September last, reference was made to the discrepant views held by different veterinary surgeons regarding the etiology and diagnostic value of pneumonic lesions encountered in pigs suspected of swine-fever, and readers of the Journal were requested to forward for examination pig's lungs showing the lesions of pulmonary inflammation. During the last three months of 1896 less than a dozen sets of diseased lungs were received at the Research Laboratory, and the fact may be adduced as evidence of the comparative rarity of pneumonia in pigs affected with swine-fever. Although the number of specimens received was thus small, it was not found possible to carry out the projected experiments and observations with each of them, for, as the following account will show, the investigation of even one such case involves the expenditure of a good deal of time and trouble. A few of the cases were selected for examination, and the results will be described in the following pages. 1 CASE No. I. The parts received for examination in this case were a piece of large intestine showing the characteristic swine-fever ulceration, and a piece of lung with an area of firm hepatisation the size of a hen's egg. The 1 This opportunity is taken to return cordial thanks to the following gentlemen for their kindness in forwarding specimens of the nature alluded to :-Messrs J. D. Armfield, Oldham; G. E. King, Abingdon; G. W. 1\1. Haydon, 1\lidsomer Norton; T. B. Bindloss, Long Sutton; T. M. M'Connell, Wigtown; H. Kidd, Melton Mowbray; W. Anderson, MayboIe; H. Edgar, ""anstead; J. Edwards, Kingston·on-Thames; J. ]<'. Simpson, Maidenhead.
'v.
A
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pig had been killed on the morning of the day on which the parts were received at the laboratory. A cover-glass preparation made from the hepatised area, and stained with methyl blue, showed fairly numerous short bacteria, and slanting agar tubes inoculated from the lesion yielded, after twenty-four hours' incubation at 37° C, numerous circular, flat, transparent colonies, which on microscopic examination were found to be composed of short ovoid bacteria resembling those of fowl cholera. When re-inoculated into bouillon the organism grew in that medium as a fluffy growth at the bottom of the tube, the liquid remaining clear. In hanging-drop preparations the organism was found to be non-motile, and in gelatine-agar medium it formed spherical colonies, easily distinguished from those of the swine-fever bacillus. No growth took place on potato. Two rabbits (A and B) were subcutaneously inoculated on the abdomen with a scraping taken from the centre of the hepatised area in the pig's lung. The scraping was suspended in bouillon, and the experiment was made with the customary precautions. One of the rabbits (A) was found dead forty-eight hours after inoculation. The post-mortem examination showed a very slight inflammatory reaction at the seat of inoculatIOn. A cover-glass preparation made from the blood of the ear showed fairly numerous short bacteria. Slanting agar tubes inoculated from the heart yielded an apparently pure culture of short bacteria with the characters above described. The second rabbit (B) was found dead on the fourth day after inoculation. The subcutaneous tissue over almost the entire abdominal wall was the seat of inflammatory congestion and cedema, with some blanching of the tissues from incipient necrosis. The peritoneum was intensely inflamed, and covered with flakes of fibrinous lymph. A preparation from the ear blood showed a few short or ovoid bacteria, and slanting agar tubes inoculated from the heart yielded these in apparently pure culture. Inoculated a rabbit (C) subcutaneously on the abdomen with ICC. bouillon culture, being the first generation from the above rabbit B. The culture had been incubated for forty-eight hours at 37°, after which it had remained for five days at the room temperature. The bouillon was very slightly turbid, and a fluffy growth was present at the bottom of the tube. The rabbit was found dead on the fourth day after inoculation. At the seat of inoculation, and spreading over the greater part of the abdominal wall, there was an inflammatory lesion. The peritoneum was the seat of dry inflammation, and the intestinal loops in contact with the abdominal wall were matted together with fibrinous lymph. A cover-glass preparation made from the ear blood showed only a small number of short ovoid bacteria, and from the heart these were recovered in apparently pure culture on slanting agar. A rabbit CD) was inoculated subcutaneously on the abdomen with a culture which was the second generation from the last-named rabbit CC), and at the same time a pigeon was inoculated into the pectoral muscles. The rabbit was found dead on the third day after inoculation. A cover-glass preparation from the blood of the ear showed great numbers of short bacteria. At the seat of injection on the abdominal wall there was a lesion about 2k inches in diameter; the tissues here were
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swollen and cedematous. The peritoneum was inflamed, and the intestines were matted together with fibrinous lymph. The pleura was also inflamed on both sides, and entirely covered with a thin greyish layer of lyn;tph. The pericardium was in a similar condition. Cover-glass preparations made from the fibrinous lymph showed immense numbers of short bacteria. The organism was recovered in apparently pure culture on slanting agar and boullion tubes inoculated from the pleural lymph, and from the heart blood. The pigeon was found dead on the fifth day after inoculation. At the seat of inoculation in the right pectoral muscle there was a blanched area of necrosis larger than a hazel nut. Cover-glass preparations made from the blood showed only a small number of ovoid bacteria, free and included in leucocytes. The organism was recovered in apparently pure culture on slanting agar and in bouillon inoculated from the heart, and from the local lesion in the pectoral muscle. Inoculated a rabbit (E) subcutaneously on the abdomen with a culture which was the first generation from the pectoral muscle of the above-mentioned pigeon. The rabbit was found dead on the fourth day after inoculation, with an extensive lesion at the seat of inoculation and peritonitis with a dry fibrinous exudate. Slanting agar and bouillon tubes inoculated from the heart blood and from the local lesion yielded abundant apparently pure growth. The carcase of the rabbit (E) of the last experiment was skinned and decapitated; it was then cut into pieces and given along with the viscera to a pig (A) about six months old. The pig had been starved for some time previously, and the whole of the flesh and the greater part of the viscera were consumed. This pig was killed on the seventh day of the experiment. During the interval it had not shown any symptom of ill-health. The only abnormalities discovered at the post-mortem examination were the presence of some spots of congestion on the mucous membrane of the colon, and intense general congestion of the mucous membrane of the ileum. In neither large nor small intestine was there any trace of ulceration or diphtheritic deposit. Slanting agar tubes inoculated from the mesenteric glands remained sterile. Inoculated a pig (B) subcutaneously in the right thigh with It cc. of sterile water holding in suspension part of a slanting agar culture, which was the second generation from the last-mentioned rabbit (E). At the same time 4 cc. of the same liquid were injected through the left chest wall of another pig (C) of the same lot (about six months old). The pig inoculated subcutaneously (B) was killed on the tenth day of the experiment. At the seat of inoculation in the right thigh there was a suhcutaneous nodule as large as a horse bean. Several of the mesenteric glands were enlarged, and on section one of them was found .to be caseating. 1 No other lesions were discovered. Two slanting agar tubes from the right thigh yielded an abundant apparently pure growth of the organism used for inoculation. The pig (C) inoculated through the chest wall was also killed on 1 This and the other pigs in which tuberculous lesions were found in thE) mesenteric glands belonged to the same litter. They had apparently been infected with tuberculosis before they were purchased for experiment.
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the tenth day of the experiment. The seat of inoculation was not discoverable either in the textures of the thoracic wall, in the pleura, or if). the lung. Several of the mesenteric glands were found to be indurated and caseating. No other lesion was discovered. CASE
No. II.
The parts received for examination in this instance were a piece of large intestine with typical swine-fever ulcers, and the left lung of the same pig. The apex of the lung and part of the lower edge of its main lobe behind the heart were hepatised. The hepatised part had a mottled surface-greyish pink with streaks of opaque yellowishwhite suggestive of necrosis. The pig had died on the morning of the day previous to that on which the parts were received at the laboratory. A cover-glass preparation made from the hepatised part showed only a sparing number of short or ovoid bacteria. Two rabbits (A and B) were inoculated subcutaneously on the abdomen with a scraping from the hepatised' part suspended in bouillon. One rabbit (A) was found dead on the seventh day after inoculation. Spreading from the seat of inoculation over almost the entire abdominal wall there was an inflammatory lesion associated with a good deal of necrosis. At its maximum the abdominal wall was four or five times its normal thickness, and on its peritoneal side it was covered with yellow fibrinous lymph. A cover-glass preparation made from the blood of the ear showed no free bacteria, but very numerous purple granules in the leucocytes (methyl-blue staining). Two slanting agar tubes inoculated from the heart blood yielded each about twenty discrete colonies, and a similar but more abundant growth was obtained on two slanting agar tubes inoculated from the lesion of the abdominal wall. The second rabbit (B) was found dead on the eleventh day after inoculation. As in the previous case, there was a very extensive lesion of the abdominal wall associated with some necrosis of the tissues. No peritonitis. No free bacteria in the blood of the ear, but numerous violet granules in the leucocytes (methyl-blue staining). A slanting agar tube inoculated from the abdominal wall yielded an almost continuous transparent growth, and two slanting agar tubes inoculated from the heart blood yielded each about a dozen colonies. These colonies were flat, circular, and translucent, and on examination they were found to be composed of bacteria of the fowl cholera type. The organism was non-motile, and not distinguishable, morphologically, or by its mode of growth, from the bacterium isolated from Case I. A rabbit (C) was inoculated subcutaneously on the abdomen with a culture which was the second generation from the above-mentioned rabbit (A), and with the same culture a pigeon was inoculated at the same time into the pectoral muscle. The rabbit was found dead on the eleventh day after inoculation. A cover-glass preparation made from the blood of the ear showed no bacteria. At the seat of inoculation and extending over nearly the whole of the right half of the abdominal wall there was an inflam-
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matory lesion associated with much thickening of the textures of the abdominal wall, and a good deal of necrosis. At some places the textures of the - abdominal wall had been broken down so as to resemble thick tenacious pus. A slanting agar tube inoculated with a loopful of blood from the heart remained sterile, but two slanting agar tubes inoculated from the local lesion yielded each an abundant growth in the form of flat, circular, transparent colonies. The above pigeon was alive and apparently healthy two months after inoculation. Inoculated a rabbit (D) subcutaneously in the groin with 5 cc.1 mixed bouillon and slanting agar cultures, each being the first generation from the last-mentioned rabbit. The rabbit was found dead on the third day after inoculation. The post-mortem examination showed an extensive inflammatory lesion starting from the seat of inoculation, as well as pleurisy and pericarditis with flakes of fibrinous lymph, but no liquid exudate. The organism was recovered in apparently pure culture on slanting agar tubes inoculated from the blood, inoculation lesion, and pleural lymph. The rabbit used in the last experiment CD), after skinning and decapitation, was cut into pieces and given together with the viscera to a pig (A) about six months old. The pig had been starved for 'some time previously, and the whole was greedily consumed by it. The pig was killed on the seventh day after the beginning of the experiment. The mucous membrane of the ileum showed intense general congestion, and some spots of congestion were also present in the large intestine. No trace of ulceration or diphtheritic deposit was present in any part of the alimentary canal, and no lesion except the above-mentioned congestion was found in any of the organs. Slanting agar tubes inoculated from the mesenteric glands remained sterile. By the aid of a platinum needle a culture on slanting agar (second generation from the blood of rabbit D) was detached into 10 cc. of sterile bouillon, and I k cc. of this liquid was used to inoculate a pig (B) subcutaneously in the right thigh, while about 4 cc. of the same liquid were injected into another pig eei through the left chest wall. Both pigs were about six months old. On the morning of the day after inoculation, the pig inoculated in the thigh (B) was found to be very ill, and it died twenty-two hours after inoculation. The post-mortem examination revealed the following lesions : At the seat of inoculation there was a lesion about the size of a hazel nut; this was firm and on section rather dry, and reddishyellow in colour. There was general peritonitis with abundant fibrinous lymph matting the intestines and causing easily separated adhesions between the organs and the parietal peritoneum. No appreciable liquid in the peritoneum. Pleurisy and pericarditis without liquid, but with the same fibrinous lymph. Throughout both large and small intestines there were irregular areas of congested mucous membrane, and the large Peyer's patches below the ileo c;:ecal valve had a livid colour. The lungs, stomach, spleen, liver, kidneys, tongue, and throat were normal. 1 A large dose was here intentionally used with the object of killing the rabbit with the septicremic type of the disease.
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No organisms were discoverable in cover-glass preparations made from the inflammatory exudate. Slanting agar tubes inoculated from pleural lymph, peritoneal lymph, pericardial lymph, and spleen pulp all remained sterile. A bouillon tube inoculated with a loopful of blood from the heart also remained sterile. Slanting agar tubes inoculated from the lesion in the right thigh yielded an abundant apparently pure growth of the organism used for inoculation. The cause of this pig's illness, and of the peritonitis, pleurisy, and pericarditis of which it was the subject, remains obscure. It was at first thought that these lesions were ascribable to the organism used for inoculation, but that conclusion does not seem admissible in face of the failure to find these organisms on microscopic examination of the inflammatory lymph, or to demonstrate their presence by culture. The conclusion is also negatived by the result of the post-mortem examination of the other pig. The pig inoculated through the chest wall (C) was killed on the ninth day of the experiment. In the interval it had not shown any symptom of ill health. Post-mortem examination showed along the line of the ninth rib on the left side a firm adhesion between the lung and the parietal pleura, but there was no consolidation of the lung at this point or elsewhere. Other organs normal. CASE
No. II I.
The parts received for examination in this case were both lungs and the ca::cum. The pig was said to have been the subject of swine fever, but no distinct lesions were present in the piece of bowel sent. In the right lung there was a large area of hepatisation opposite the heart; on section the solid part showed a pale pink ground surface beset with yellowish-white tubercle-like points, varying in size from a pin's head to a barley grain. The bronchi in this part contained a thin muco-purulent liquid. The bronchial and tracheal glands were much enlarged, but on section showed no caseation. Tubercle bacilli could not be found either in scrapings from the lung lesion or from the glands. N early the whole of the left lung, with the exception of the large lobe, was hepatised, and on section the solid part showed the appearances above described. ' Two rabbits were inoculated, one (A) subcutaneously and the other (B) intraperitoneally, with bouillon holding in suspension a scraping from the lung lesion of the above pig. Both rabbits were found dead the following day, less than twenty-four hours after inoculation. In the rabbit (A) there was an inflammatory swelling 2 inches in diameter at the seat of inoculation in the abdominal wall. All the internal organs appeared normal, with the exception of the liver, which contained some spots of psorospermosis. Cover-glass preparations from the blood of the ear showed great numbers of short or ovoid bacteria. Two slanting agar tubes inoculated from the heart yielded, after twenty-four hours' incubation at 37° c., an abundant crop of flat, transparent, circular colonies composed of bacteria of the fowl cholera type. Two bouillon tubes inoculated each with a loopful of blood were slightly turbid after twenty-four hours with numerous coarse flocculi suspended in the liquid; with continued incubation the
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bouillon soon became clear, and deposited a coarse, flocculent precipitate. In rabbit (B) the peritoneum was not inflamed, but at the point where the needle had been inserted there was a small cyst-like structure under the peritoneum, as if the fluid had been injected there and not into the peritoneal Gavity. All the organs appeared to be normal, with the exception of the liver, which contained some spots of psorospermosis. An organism apparently identical with that above described was obtained on slanting agar and in bouillon tubes from the heart. The organism cultivated from these two rabbits was found to have characters similar to the bacteria isolated from Cases I. and II. It was non-motile and did not grow on potato. On slanting agar it grew in the form of circular, flat, transparent colonies. In gelatineagar the discrete colonies were spherical or oval, with a well-defined periphery. Bouillon cultures remained almost clear, with coarse suspended particles, which subsequently settled as a bottom growth. Inoculated a rabbit (C) subcutaneously on the abdomen with t cc. of mixed bouillon and slanting agar cultures, each being the second generation from one of the above-mentioned rabbits. At the same time a pigeon was inoculated into the pectoral muscle with icc. of the same liquid. Both the rabbit and the pigeon were found dead on the following day, less than twenty-four hours after inoculation. At the seat of inoculation in the rabbit there was an area of inflammation, with injection of the vessels and (edema of the tissues. Cover-glass preparations from the blood of the ear showed immense numbers of short and ovoid bacteria. No visceral lesions. Around the seat of inoculation in the pectoral muscle of the pigeon there was considerable blood extravasation. No visceral lesions. Bacteria numerous in the blood. From heart blood of both pigeon and rabbit the organism was recovered in apparently pure culture on slanting agar and in bouillon. Inoculated a rabbit (D) subcutaneously on the abdomen with ICC. of bouillon culture, which was the fourth generation from the heart of rabbit A. The rabbit was found dead on the following day, eighteen hours after inoculation. A cover-glass preparation from the blood of the ear showed enormous numbers of short bacteria. After having been skinned and decapitated the carcase of the above rabbit was cut up into pieces, and given together with the viscera to a pig (A) about six months old. Over the pieces of carcase and viscera 48 cc. of a bouillon culture, which had been incubated for forty hours at 37° c., were sprinkled. This bouillon culture was the fourth generation from the heart of rabbit (A). The pig had been starved for some time previously, and the whole was greedily consumed by it. On the second day of the experiment this pig had profuse diarrhcea ; on the third day the f
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diffusely congested, and its surface appeared slightly eroded, but there was no trace of diphtheritic deposit. The c;ecum and the rest of the alimentary canal were normal, as were also all the other organs of the abdomen and thorax. Two slanting agar tubes inoculated from the mesenteric glands remained sterile. Took a slanting atar culture, which was the third generation from the heart blood of the before-mentioned pigeon, and had been incubated for five days at 38° c.; poured into this about 8 cc. of sterile water and detached the surface growth by means of a platinum needle. Inoculated a pig (B) subcutaneously in the right thigh with It cc.-of this liquid, and at the s,ame time injected 4 cc. of the liquid through the left chest wall of another pig (C). Both pigs were about six months old. Pig (B) was killed on the ninth day of the experiment. In the interval it had not shown any symptom of ill health. At the seat of inoculation in the right thigh there was a swelling about the size of a pigeon's egg; centrally this was found to contain thick pus and broken down tissue. Some of the mesenteric lymphatic glands were enlarged, indurated, and commencing to caseate (tuberculous). No other lesions. Two slanting agar tubes inoculated from the lesion in the thigh yielded each an abundant apparently pure growth. Pig (C) (inoculated through the chest wall) was also killed on the ninth day of the experiment; it had appeared to be quite well during the interval. The post-11lortem examination showed that the left lung was partially adherent to the chest wall, and where the lung was free the left pleural sac contained a quantity of reddish turbid liquid. The free surface of the pleura was covered with a thick layer of yellow fibrinous lymph. There was also an adhesion between the lower edge of the right lung and the chest wall. The left lung was partly collapsed from pressure, but there was no pneumonic lesion in either lung. A small crater-like (tuberculous) ulcer was present in the small intestine, and two of the mesenteric lymphatic glands were enlarged and caseating. Three slanting agar tubes inoculated from the pleural fluid yielded each an abundant apparently pure growth of the organism used for infection. CASE
No. IV.
The parts received for examination in this case were a piece of large intestine showing characteristic swine-fever ulcers, and both lungs. A large part of the right lung was hepatised; the hepatised area was moderately firm, and on section it showed marked swelling of the interlobular septa. The parenchyma was mottled with a lighter and a darker shade of red. A cover-glass preparation made from the lesion showed great numbers of short ovoid bacteria. The left lung was normal, and a cover-glass preparation made from its parenchyma showed no bacteria. The pig had been found dead on the morning of the day on which the parts had been brought to the laboratory. Inoculated a rabbit (A) on the right side of the abdominal wall with a scraping from the lung lesion suspended in bouillon. The rabbit was found dead on the fifth day after inoculation. Around the seat of inoculation there was an inflammatory swelling as large as the palm of the hand; on section.this showed inflammatory
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congestion, <:edema, and blanching of the tissues from necrosis. A cover-glass preparation from the blood of the ear showed no free bacteria, but many violet granules in the leucocytes (with methylblue staining). Slanting agar tubes inoculated from the heart blood yielded an abundant growth of flat, circular, transparent colonies. A bouillon tube inoculated with a loopful of blood from the heart was slightly turbid after twenty-four hours' incubation at 37° c., and subsequently became almost clear, depositing a somewhat ropy deposit at the bottom of the tube. On microscopic examination these cultures were found to be composed of non-motile bacteria of the fowl cholera type. As regards its mode of growth on the surface of agar and in gelatine-agar it was not distinguishable from the organism isolated from the three preceding cases. It formed no visible growth on potato. The hepatised part in the right lung of the before-mentioned pig after having been immersed for half-a-minute in boiling water,! was cut into small pieces with a sterile knife, and given mixed with food to three adult sows (A, B, and C). One day after the experiment was begun, sow A farrowed eleven pigs. On the twelfth day of the experiment this sow, which had hitherto appeared to be quite well, refused her food; on the following day she appeared to be very weak, and food was still refused. On the fourteenth day of the experiment the sow took some food and appeared to be rather better. The improvement was continued during the next three days, but on the twentieth day the animal was found to be very ill, and death took place during the evening. The following are the notes of the post-JIlortem examination, which was made fifteen minutes after death. The right lung contains near its base a hepatised area about the size of a hen's egg. On section a turbid juice exudes from this. The cut surface is partly pink flesh-coloured (this is the firmest portion), and the rest is greyish pink. The cut surface of the firm portion is distinctly granular, and at one place ha:morrhagic in appearance. At one end the solid part shades gradually into the surrounding lung, but elsewhere it is well defined. A cover-glass preparation shows very numerous short bacteria. Left lung normal. Bronchial glands normal. Mesenteric glands normal in size; some of them congested. The ileo-ca:cal projection is swollen, livid in colour, and <:edematous, and on it there are several spots of necrosis. The large bowel contains no food materials, but about 6 oz. of blood, partly coagulated. The colon is intensely inflamed throughout, being generally of a livid colour, with here and there dark spots of extravasation. Jejunum much congested; no diphtheritic deposit and no ulceration. Stomach moderately filled with food materials. The cuticular portion has some adherent yellowish friable material. The fundus of the stomach is deeply inflamed. Spleen, liver, kidneys, and uterus normal. The right tonsil contains a dark-coloured ha:morrhagic-Iooking area about as big as a pea. Slanting agar tubes inoculated from the lung lesion yielded an abundant growth of an organism which grew in the form of large, glistening, opaque white colonies, and a few colonies with a similar appearance were obtained on slanting agar tubes inoculated from the 1
To destroy any swine-fever bacilli accidentally present on the surface.
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mesenteric glands. In both cases the colonies were found to be composed of a short motile bacterium, easily distinguished by its mode of growth from the swine-fever bacillus and from the organism cultivated from rabbit A. It coagulated milk, and formed a white growth on potato. No inoculation experiments have been made with this organism. Sows Band C were killed on the twenty-first day after they had been fed with the diseased lung. In the interval they had appeared to be quite well, and the post-mortem examination did not reveal any lesion in the organs of the thorax or abdomen. Detached a slanting agar culture, which was the second generation from the heart blood of the before-mentioned rabbit (A), into about IO cc. of a bouillon culture, which was also the second generation from the same source. Injected! cc. of the mixed cultures under the skin of the abdominal wall of a rabbit (B), and the same quantity into the pectoral muscle of a pigeon. The rabbit was found dead on the eleventh day after inoculation. Around the seat of inoculation, and occupying nearly the whole of the right half of the abdominal wall, the subcutaneous and deeper textures were much swollen, and dissection showed that at this point the tissues of the abdominal wall were largely necrotic. A coverglass preparation made from the blood of the ear showed no bacteria, and tubes inoculated from the heart blood remained sterile. An agar tube inoculated from the lesion of the abdominal wall yielded an abundant apparently pure growth of flat transparent colonies. A bouillon tube inoculated from the same source also yielded an apparently pure growth. The above pigeon was alive and apparently healthy two months after inoculation. Inoculated a rabbit (C) subcutaneously in the right groin with 5 cc. of a bouillon culture holrling in suspension a culture on slanting agar; both cultures were the first generation from the abdominal wall of rabbit B. The rabbit was found dead on the third day after inoculation. Around the seat of inoculation there was much inflammatory congestion and some hccmorrhage. No visceral lesions. Slanting agar tubes inoculated from the heart and from the local lesion yielded abundant apparently pure cultures. Skinned and decapitated the above rabbit and then cut it into pieces, and gave the whole, together with the viscera, to a pig (A) about six months old. The whole was greedily consumed. The pig was killed on the seventh day of the experiment; during the interval it had not shown any symptom of ill health. Throughout the whole of the small intestine the mucous membrane was more or less congested, and there was also some cOllgestion of the gastric mucous membrane. The large intestine was normal throughout. The other abdominal organs and those of the thorax, as well as the tongue and throat, were normal. Of two slanting agar tubes inoculated from a mesenteric gland, one remained sterile, and the other developed two large opaque white colonies. Took a culture on slanting agar, the second generation from rabbit C ; poured into the tube about 6 cc. of sterile water, and detached the surface growth into this by the aid of a platinum needle. Injected
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I! cc. of this liquid under the skin of the right thigh of a pig (B), and 4 cc. of the same liquid through the left chest wall of another pig (both about six months old). Pig B was killed on the thirteenth day of the experiment. At the seat of inoculation in the right thigh there was a pea-sized induration of the subcutaneous tissue. Several of the mesenteric glands were found to contain tuberculous lesions, and there was a small area of collapse near the edge of the left lung. All the other viscera were normal. Two slanting agar tubes inoculated from the centre of the nodule at the seat of inoculation remained sterile. Pig C (inoculated through the chest wall) was also killed on the thirteenth day of the experiment. The post-mortem examination showed an adhesion between the parietal pleura and the left lung opposite the eighth and ninth ribs; at the point of adhesion there was a solid area of lung nearly as large as a walnut, and on section this was found to contain centrally a piece of necrotic tissue. Several mesenteric glands were enlarged and tuberculous. The organism was recovered in apparently pure culture from the necrotic lung tissue, but a slanting agar tube inoculated from the pleural lesion remained sterile. CASE
No. V.
In this instance only the lungs were sent for examination. At the base of the left lung, and constituting about one-fourth of the organ, there was an area of hepatisation; on section the ground colour was greyish-pink, with hcemorrhagic-Iooking specks and streaks. The bronchi in this part contained a turbid mucus. A cover-glass preparation from the hepatised part showed an immense number of short bacteria, while a similar preparation from the normal lung tissue showed only an occasional organism (the lung was not quite fresh). Slanting agar tubes inoculated from the depth of the lung lesion yielded, after twenty-four hours' incubation at 37 9 c., an apparently pure growth composed of small, circular, flat, transparent colonies, which, on microscopic examination, were found to be composed of short bacteria of the fowl cholera type. Two rabbits (A and B) were subcutaneously inoculated on the abdomen with a scraping from the hepatised part. One of the rabbits (A) was found dead on the third day after inoculation. A cover-glass preparation made from the blood of the ear showed only a few short bacteria. Around the seat of inoculation on the abdominal wall there was a lesion about 2~ inches in diameter; the textures of the abdominal wall were here infiltrated and partly necrotic. The peritoneum was inflamed, with intense injection of the vessels, particularly of the large bowel. Other organs normal. An agar tube inoculated from the blood of the heart yielded a culture similar to that obtained from the original lesion in the lung; a bouillon tube inoculated from the same source remained almost clear, while a growth formed at the bottom of the liquid. The second rabbit (B) was also found dead on the third day after inoculation. The result of the post-mortem examination of it was almost identical with the foregoing, that is to say, very few bacteria were discoverable in the blood, and there was a comparatively large
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lesion at the seat of inoculation, and peritonitis. The organism was recovered on agar and in bouillon in apparently pure culture from the blood of the heart. The organism cultivated from the hepatised area in the abovementioned pig's lung, and from the blood of the two rabbits inoculated from that lesion, is morphologically identical with the organisms isolated from the preceding four pigs, and it also resembles these in respect of its mode of growth in artificial media. A rabbit (C) was inoculated subcutaneously on the abdomen with I cc. of a bouillon culture, which was the second generation from the above-mentioned pig's lung. The rabbit was found dead on the fourth day after inoculation. A cover-glass preparation from the ear showed only a few short bacteria. Around the seat of inoculation there was a lesion 3 inches in diameter. The peritoneum was inflamed, with coarse coagula of fibrinous lymph between the intestines. The organism was recovered in apparently pure culture from the heart blood and the lesion in the abdominal wall. A rabbit (D) was subcutaneously inoculated on the abdomen with I:t cc. of bouillon culture, which was the third generation from the before-mentioned pig's lung; this formed part of a flask of 40 cc. which had been incubated for twelve days at 37° C. The remainder of the flask (38~ cc.) was mixed with food and given to a six months' old pig (A). The whole was consumed. The pig was killed on the seventh day of the experiment; in the interval it had appeared to be quite well, except for slight diarrhcea on the second day of the experiment. The post-mortem examination revealed no lesions in any part of the body, and two agar tubes inoculated from the mesenteric glands remained sterile. In the above-mentioned rabbit (D) a swelling formed slowly at the seat of inoculation, and at the end of the third week it had attained the size of a hen's egg; after that it gradually declined. The general health of the rabbit did not appear to be seriously affected. The rabbit was killed forty-nine days after inoculation. It then had at the seat of inoculation a nodule about the size of a horse bean; centrally this was found to contain thick pus, and a cover-glass preparation made from that showed fairly numerous short bacteria, which were recovered in pure culture on slanting agar. Took a culture on slanting agar, which was the seventh generation from the lesion in the original pig's lung, and detached it into about 6 cc. of sterile water. The culture had been incubated for five days at 37° C. Injected I k cc. of this liquid under the skin of the right thigh of a pig (B), and 4 cc. through the left chest wall of another pig (C) ; both pigs were about six months old. Pig B was killed on the thirteenth day of the experiment; in the interval it had not shown any symptom of ill health. The seat of inoculation in the right thigh was not discoverable, even by dissection, and no lesion was discovered in any of the internal organs. Pig C (inoculated through the chest wall) was also killed on the thirteenth day of the experiment. The seat of inoculation was not apparent in the tissues of the chest wall, or by any adhesion between the lung and the parietal pleura. Near the seat of inoculation the left lung contained, immediately under the pleura, a nodule about
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13
half the size of a pea; the centre of this was firm, dry, and yellowishwhite in colour. Otherwise both lungs were normal, and no lesion was discovered in any of the other organs. A slanting agar tube inoculated from the centre of the lung lesion remained sterile. (To be continued.)
PNEUMONIA AND PLEURISY IN THE HORSE. By Veterinary-Major F. SMITH, F.R.C.V.S., Army Remount Department, Woolwich. REGIONAL ANATOMY OF THE LUNGS.
AN accurate conception of the regional anatomy of the chest will be found of considerable service in diagnosis. On this subject I propose to say a few words. It is usual to divide the chest of the horse into three regions, superior, middle, and inferior, and this division will clinically be found most useful. The extent of the chest is considerable; a large region lies concealed under the fore legs, a part we may term the scapular region; while posterior to this a considerable surface is presented by what may be termed the available region. This term if adopted would simply indicate that portion of the chest which can be subjected to examination, it being obvious that the scapular region is not so available. In Fig. I (p. I4) the extent and area of the chest is shown with a considerable degree of accuracy. I have termed it a diagram because my method failed to obtain a completely accurate representation of the chest for the purpose of this communication. But in spite of this it is prepared from photographs which were specially taken, and it may be accepted as quite accurate for all clinical purposes. The points I wish to bring out in the figure are the extent of the scapular region B, D, E, C, and the considerable area of the available chest A, B, C, F. The line A F represents the last rib. B C is a line running parallel with the posterior edge of the triceps muscle; A B is one parallel to the lower edge of the longissimus dorsi muscle; F C is a line running along the costal ridge, but the lungs do not reach to within a hand-breadth of the bottom of the false ribs. In the scapular region D is the head of the first rib and E its sternal insertion; the line B D runs close to the bodies of the dorsal vertebr;:e, while C E cuts through the cartilages of the sternum. Anteriorly the cavity of the chest is narrow from side to side and from top to bottom, while in the available region of the chest it is both wide and deep. The lungs are higher in the body at A than they are at D, they are lower at C than they are at E. As the chest is wider transversely, say through the sixteenth rib, than it is through the sixth, a greater bulk of lung should be situated
JOURNAL OF
COMPARATIVE PATHOLOGY AND
THERAPEUTICS. VOL. X.-No.
I.
MARCH 31, 1897.
PRICE 2S.
6d.
THE ETIOLOGY OF PNEUMONIA IN THE PIG. By
J.
M'FADYEAN, Royal Veterinary College, London.
IN an article which appeared in this Journal for September last, reference was made to the discrepant views held by different veterinary surgeons regarding the etiology and diagnostic value of pneumonic lesions encountered in pigs suspected of swine-fever, and readers of the Journal were requested to forward for examination pig's lungs showing the lesions of pulmonary inflammation. During the last three months of 1896 less than a dozen sets of diseased lungs were received at the Research Laboratory, and the fact may be adduced as evidence of the comparative rarity of pneumonia in pigs affected with swine-fever. Although the number of specimens received was thus small, it was not found possible to carry out the projected experiments and observations with each of them, for, as the following account will show, the investigation of even one such case involves the expenditure of a good deal of time and trouble. A few of the cases were selected for examination, and the results will be described in the following pages. 1 CASE No. I. The parts received for examination in this case were a piece of large intestine showing the characteristic swine-fever ulceration, and a piece of lung with an area of firm hepatisation the size of a hen's egg. The 1 This opportunity is taken to return cordial thanks to the following gentlemen for their kindness in forwarding specimens of the nature alluded to :-Messrs J. D. Armfield, Oldham; G. E. King, Abingdon; G. W. 1\1. Haydon, 1\lidsomer Norton; T. B. Bindloss, Long Sutton; T. M. M'Connell, Wigtown; H. Kidd, Melton Mowbray; W. Anderson, MayboIe; H. Edgar, ""anstead; J. Edwards, Kingston·on-Thames; J. ]<'. Simpson, Maidenhead.
'v.
A
2
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pig had been killed on the morning of the day on which the parts were received at the laboratory. A cover-glass preparation made from the hepatised area, and stained with methyl blue, showed fairly numerous short bacteria, and slanting agar tubes inoculated from the lesion yielded, after twenty-four hours' incubation at 37° C, numerous circular, flat, transparent colonies, which on microscopic examination were found to be composed of short ovoid bacteria resembling those of fowl cholera. When re-inoculated into bouillon the organism grew in that medium as a fluffy growth at the bottom of the tube, the liquid remaining clear. In hanging-drop preparations the organism was found to be non-motile, and in gelatine-agar medium it formed spherical colonies, easily distinguished from those of the swine-fever bacillus. No growth took place on potato. Two rabbits (A and B) were subcutaneously inoculated on the abdomen with a scraping taken from the centre of the hepatised area in the pig's lung. The scraping was suspended in bouillon, and the experiment was made with the customary precautions. One of the rabbits (A) was found dead forty-eight hours after inoculation. The post-mortem examination showed a very slight inflammatory reaction at the seat of inoculatIOn. A cover-glass preparation made from the blood of the ear showed fairly numerous short bacteria. Slanting agar tubes inoculated from the heart yielded an apparently pure culture of short bacteria with the characters above described. The second rabbit (B) was found dead on the fourth day after inoculation. The subcutaneous tissue over almost the entire abdominal wall was the seat of inflammatory congestion and cedema, with some blanching of the tissues from incipient necrosis. The peritoneum was intensely inflamed, and covered with flakes of fibrinous lymph. A preparation from the ear blood showed a few short or ovoid bacteria, and slanting agar tubes inoculated from the heart yielded these in apparently pure culture. Inoculated a rabbit (C) subcutaneously on the abdomen with ICC. bouillon culture, being the first generation from the above rabbit B. The culture had been incubated for forty-eight hours at 37°, after which it had remained for five days at the room temperature. The bouillon was very slightly turbid, and a fluffy growth was present at the bottom of the tube. The rabbit was found dead on the fourth day after inoculation. At the seat of inoculation, and spreading over the greater part of the abdominal wall, there was an inflammatory lesion. The peritoneum was the seat of dry inflammation, and the intestinal loops in contact with the abdominal wall were matted together with fibrinous lymph. A cover-glass preparation made from the ear blood showed only a small number of short ovoid bacteria, and from the heart these were recovered in apparently pure culture on slanting agar. A rabbit CD) was inoculated subcutaneously on the abdomen with a culture which was the second generation from the last-named rabbit CC), and at the same time a pigeon was inoculated into the pectoral muscles. The rabbit was found dead on the third day after inoculation. A cover-glass preparation from the blood of the ear showed great numbers of short bacteria. At the seat of injection on the abdominal wall there was a lesion about 2k inches in diameter; the tissues here were
GENERAL ARTICLES.
3
swollen and cedematous. The peritoneum was inflamed, and the intestines were matted together with fibrinous lymph. The pleura was also inflamed on both sides, and entirely covered with a thin greyish layer of lyn;tph. The pericardium was in a similar condition. Cover-glass preparations made from the fibrinous lymph showed immense numbers of short bacteria. The organism was recovered in apparently pure culture on slanting agar and boullion tubes inoculated from the pleural lymph, and from the heart blood. The pigeon was found dead on the fifth day after inoculation. At the seat of inoculation in the right pectoral muscle there was a blanched area of necrosis larger than a hazel nut. Cover-glass preparations made from the blood showed only a small number of ovoid bacteria, free and included in leucocytes. The organism was recovered in apparently pure culture on slanting agar and in bouillon inoculated from the heart, and from the local lesion in the pectoral muscle. Inoculated a rabbit (E) subcutaneously on the abdomen with a culture which was the first generation from the pectoral muscle of the above-mentioned pigeon. The rabbit was found dead on the fourth day after inoculation, with an extensive lesion at the seat of inoculation and peritonitis with a dry fibrinous exudate. Slanting agar and bouillon tubes inoculated from the heart blood and from the local lesion yielded abundant apparently pure growth. The carcase of the rabbit (E) of the last experiment was skinned and decapitated; it was then cut into pieces and given along with the viscera to a pig (A) about six months old. The pig had been starved for some time previously, and the whole of the flesh and the greater part of the viscera were consumed. This pig was killed on the seventh day of the experiment. During the interval it had not shown any symptom of ill-health. The only abnormalities discovered at the post-mortem examination were the presence of some spots of congestion on the mucous membrane of the colon, and intense general congestion of the mucous membrane of the ileum. In neither large nor small intestine was there any trace of ulceration or diphtheritic deposit. Slanting agar tubes inoculated from the mesenteric glands remained sterile. Inoculated a pig (B) subcutaneously in the right thigh with It cc. of sterile water holding in suspension part of a slanting agar culture, which was the second generation from the last-mentioned rabbit (E). At the same time 4 cc. of the same liquid were injected through the left chest wall of another pig (C) of the same lot (about six months old). The pig inoculated subcutaneously (B) was killed on the tenth day of the experiment. At the seat of inoculation in the right thigh there was a suhcutaneous nodule as large as a horse bean. Several of the mesenteric glands were enlarged, and on section one of them was found .to be caseating. 1 No other lesions were discovered. Two slanting agar tubes from the right thigh yielded an abundant apparently pure growth of the organism used for inoculation. The pig (C) inoculated through the chest wall was also killed on 1 This and the other pigs in which tuberculous lesions were found in thE) mesenteric glands belonged to the same litter. They had apparently been infected with tuberculosis before they were purchased for experiment.
4
GENERAL ARTICLES.
the tenth day of the experiment. The seat of inoculation was not discoverable either in the textures of the thoracic wall, in the pleura, or if). the lung. Several of the mesenteric glands were found to be indurated and caseating. No other lesion was discovered. CASE
No. II.
The parts received for examination in this instance were a piece of large intestine with typical swine-fever ulcers, and the left lung of the same pig. The apex of the lung and part of the lower edge of its main lobe behind the heart were hepatised. The hepatised part had a mottled surface-greyish pink with streaks of opaque yellowishwhite suggestive of necrosis. The pig had died on the morning of the day previous to that on which the parts were received at the laboratory. A cover-glass preparation made from the hepatised part showed only a sparing number of short or ovoid bacteria. Two rabbits (A and B) were inoculated subcutaneously on the abdomen with a scraping from the hepatised' part suspended in bouillon. One rabbit (A) was found dead on the seventh day after inoculation. Spreading from the seat of inoculation over almost the entire abdominal wall there was an inflammatory lesion associated with a good deal of necrosis. At its maximum the abdominal wall was four or five times its normal thickness, and on its peritoneal side it was covered with yellow fibrinous lymph. A cover-glass preparation made from the blood of the ear showed no free bacteria, but very numerous purple granules in the leucocytes (methyl-blue staining). Two slanting agar tubes inoculated from the heart blood yielded each about twenty discrete colonies, and a similar but more abundant growth was obtained on two slanting agar tubes inoculated from the lesion of the abdominal wall. The second rabbit (B) was found dead on the eleventh day after inoculation. As in the previous case, there was a very extensive lesion of the abdominal wall associated with some necrosis of the tissues. No peritonitis. No free bacteria in the blood of the ear, but numerous violet granules in the leucocytes (methyl-blue staining). A slanting agar tube inoculated from the abdominal wall yielded an almost continuous transparent growth, and two slanting agar tubes inoculated from the heart blood yielded each about a dozen colonies. These colonies were flat, circular, and translucent, and on examination they were found to be composed of bacteria of the fowl cholera type. The organism was non-motile, and not distinguishable, morphologically, or by its mode of growth, from the bacterium isolated from Case I. A rabbit (C) was inoculated subcutaneously on the abdomen with a culture which was the second generation from the above-mentioned rabbit (A), and with the same culture a pigeon was inoculated at the same time into the pectoral muscle. The rabbit was found dead on the eleventh day after inoculation. A cover-glass preparation made from the blood of the ear showed no bacteria. At the seat of inoculation and extending over nearly the whole of the right half of the abdominal wall there was an inflam-
GENERAL ARTICLES.
5
matory lesion associated with much thickening of the textures of the abdominal wall, and a good deal of necrosis. At some places the textures of the - abdominal wall had been broken down so as to resemble thick tenacious pus. A slanting agar tube inoculated with a loopful of blood from the heart remained sterile, but two slanting agar tubes inoculated from the local lesion yielded each an abundant growth in the form of flat, circular, transparent colonies. The above pigeon was alive and apparently healthy two months after inoculation. Inoculated a rabbit (D) subcutaneously in the groin with 5 cc.1 mixed bouillon and slanting agar cultures, each being the first generation from the last-mentioned rabbit. The rabbit was found dead on the third day after inoculation. The post-mortem examination showed an extensive inflammatory lesion starting from the seat of inoculation, as well as pleurisy and pericarditis with flakes of fibrinous lymph, but no liquid exudate. The organism was recovered in apparently pure culture on slanting agar tubes inoculated from the blood, inoculation lesion, and pleural lymph. The rabbit used in the last experiment CD), after skinning and decapitation, was cut into pieces and given together with the viscera to a pig (A) about six months old. The pig had been starved for 'some time previously, and the whole was greedily consumed by it. The pig was killed on the seventh day after the beginning of the experiment. The mucous membrane of the ileum showed intense general congestion, and some spots of congestion were also present in the large intestine. No trace of ulceration or diphtheritic deposit was present in any part of the alimentary canal, and no lesion except the above-mentioned congestion was found in any of the organs. Slanting agar tubes inoculated from the mesenteric glands remained sterile. By the aid of a platinum needle a culture on slanting agar (second generation from the blood of rabbit D) was detached into 10 cc. of sterile bouillon, and I k cc. of this liquid was used to inoculate a pig (B) subcutaneously in the right thigh, while about 4 cc. of the same liquid were injected into another pig eei through the left chest wall. Both pigs were about six months old. On the morning of the day after inoculation, the pig inoculated in the thigh (B) was found to be very ill, and it died twenty-two hours after inoculation. The post-mortem examination revealed the following lesions : At the seat of inoculation there was a lesion about the size of a hazel nut; this was firm and on section rather dry, and reddishyellow in colour. There was general peritonitis with abundant fibrinous lymph matting the intestines and causing easily separated adhesions between the organs and the parietal peritoneum. No appreciable liquid in the peritoneum. Pleurisy and pericarditis without liquid, but with the same fibrinous lymph. Throughout both large and small intestines there were irregular areas of congested mucous membrane, and the large Peyer's patches below the ileo c;:ecal valve had a livid colour. The lungs, stomach, spleen, liver, kidneys, tongue, and throat were normal. 1 A large dose was here intentionally used with the object of killing the rabbit with the septicremic type of the disease.
6
GENERAL ARTICLES.
No organisms were discoverable in cover-glass preparations made from the inflammatory exudate. Slanting agar tubes inoculated from pleural lymph, peritoneal lymph, pericardial lymph, and spleen pulp all remained sterile. A bouillon tube inoculated with a loopful of blood from the heart also remained sterile. Slanting agar tubes inoculated from the lesion in the right thigh yielded an abundant apparently pure growth of the organism used for inoculation. The cause of this pig's illness, and of the peritonitis, pleurisy, and pericarditis of which it was the subject, remains obscure. It was at first thought that these lesions were ascribable to the organism used for inoculation, but that conclusion does not seem admissible in face of the failure to find these organisms on microscopic examination of the inflammatory lymph, or to demonstrate their presence by culture. The conclusion is also negatived by the result of the post-mortem examination of the other pig. The pig inoculated through the chest wall (C) was killed on the ninth day of the experiment. In the interval it had not shown any symptom of ill health. Post-mortem examination showed along the line of the ninth rib on the left side a firm adhesion between the lung and the parietal pleura, but there was no consolidation of the lung at this point or elsewhere. Other organs normal. CASE
No. II I.
The parts received for examination in this case were both lungs and the ca::cum. The pig was said to have been the subject of swine fever, but no distinct lesions were present in the piece of bowel sent. In the right lung there was a large area of hepatisation opposite the heart; on section the solid part showed a pale pink ground surface beset with yellowish-white tubercle-like points, varying in size from a pin's head to a barley grain. The bronchi in this part contained a thin muco-purulent liquid. The bronchial and tracheal glands were much enlarged, but on section showed no caseation. Tubercle bacilli could not be found either in scrapings from the lung lesion or from the glands. N early the whole of the left lung, with the exception of the large lobe, was hepatised, and on section the solid part showed the appearances above described. ' Two rabbits were inoculated, one (A) subcutaneously and the other (B) intraperitoneally, with bouillon holding in suspension a scraping from the lung lesion of the above pig. Both rabbits were found dead the following day, less than twenty-four hours after inoculation. In the rabbit (A) there was an inflammatory swelling 2 inches in diameter at the seat of inoculation in the abdominal wall. All the internal organs appeared normal, with the exception of the liver, which contained some spots of psorospermosis. Cover-glass preparations from the blood of the ear showed great numbers of short or ovoid bacteria. Two slanting agar tubes inoculated from the heart yielded, after twenty-four hours' incubation at 37° c., an abundant crop of flat, transparent, circular colonies composed of bacteria of the fowl cholera type. Two bouillon tubes inoculated each with a loopful of blood were slightly turbid after twenty-four hours with numerous coarse flocculi suspended in the liquid; with continued incubation the
GENERAL ARTICLES.
7
bouillon soon became clear, and deposited a coarse, flocculent precipitate. In rabbit (B) the peritoneum was not inflamed, but at the point where the needle had been inserted there was a small cyst-like structure under the peritoneum, as if the fluid had been injected there and not into the peritoneal Gavity. All the organs appeared to be normal, with the exception of the liver, which contained some spots of psorospermosis. An organism apparently identical with that above described was obtained on slanting agar and in bouillon tubes from the heart. The organism cultivated from these two rabbits was found to have characters similar to the bacteria isolated from Cases I. and II. It was non-motile and did not grow on potato. On slanting agar it grew in the form of circular, flat, transparent colonies. In gelatineagar the discrete colonies were spherical or oval, with a well-defined periphery. Bouillon cultures remained almost clear, with coarse suspended particles, which subsequently settled as a bottom growth. Inoculated a rabbit (C) subcutaneously on the abdomen with t cc. of mixed bouillon and slanting agar cultures, each being the second generation from one of the above-mentioned rabbits. At the same time a pigeon was inoculated into the pectoral muscle with icc. of the same liquid. Both the rabbit and the pigeon were found dead on the following day, less than twenty-four hours after inoculation. At the seat of inoculation in the rabbit there was an area of inflammation, with injection of the vessels and (edema of the tissues. Cover-glass preparations from the blood of the ear showed immense numbers of short and ovoid bacteria. No visceral lesions. Around the seat of inoculation in the pectoral muscle of the pigeon there was considerable blood extravasation. No visceral lesions. Bacteria numerous in the blood. From heart blood of both pigeon and rabbit the organism was recovered in apparently pure culture on slanting agar and in bouillon. Inoculated a rabbit (D) subcutaneously on the abdomen with ICC. of bouillon culture, which was the fourth generation from the heart of rabbit A. The rabbit was found dead on the following day, eighteen hours after inoculation. A cover-glass preparation from the blood of the ear showed enormous numbers of short bacteria. After having been skinned and decapitated the carcase of the above rabbit was cut up into pieces, and given together with the viscera to a pig (A) about six months old. Over the pieces of carcase and viscera 48 cc. of a bouillon culture, which had been incubated for forty hours at 37° c., were sprinkled. This bouillon culture was the fourth generation from the heart of rabbit (A). The pig had been starved for some time previously, and the whole was greedily consumed by it. On the second day of the experiment this pig had profuse diarrhcea ; on the third day the f
8
GENERAL ARTICLES.
diffusely congested, and its surface appeared slightly eroded, but there was no trace of diphtheritic deposit. The c;ecum and the rest of the alimentary canal were normal, as were also all the other organs of the abdomen and thorax. Two slanting agar tubes inoculated from the mesenteric glands remained sterile. Took a slanting atar culture, which was the third generation from the heart blood of the before-mentioned pigeon, and had been incubated for five days at 38° c.; poured into this about 8 cc. of sterile water and detached the surface growth by means of a platinum needle. Inoculated a pig (B) subcutaneously in the right thigh with It cc.-of this liquid, and at the s,ame time injected 4 cc. of the liquid through the left chest wall of another pig (C). Both pigs were about six months old. Pig (B) was killed on the ninth day of the experiment. In the interval it had not shown any symptom of ill health. At the seat of inoculation in the right thigh there was a swelling about the size of a pigeon's egg; centrally this was found to contain thick pus and broken down tissue. Some of the mesenteric lymphatic glands were enlarged, indurated, and commencing to caseate (tuberculous). No other lesions. Two slanting agar tubes inoculated from the lesion in the thigh yielded each an abundant apparently pure growth. Pig (C) (inoculated through the chest wall) was also killed on the ninth day of the experiment; it had appeared to be quite well during the interval. The post-11lortem examination showed that the left lung was partially adherent to the chest wall, and where the lung was free the left pleural sac contained a quantity of reddish turbid liquid. The free surface of the pleura was covered with a thick layer of yellow fibrinous lymph. There was also an adhesion between the lower edge of the right lung and the chest wall. The left lung was partly collapsed from pressure, but there was no pneumonic lesion in either lung. A small crater-like (tuberculous) ulcer was present in the small intestine, and two of the mesenteric lymphatic glands were enlarged and caseating. Three slanting agar tubes inoculated from the pleural fluid yielded each an abundant apparently pure growth of the organism used for infection. CASE
No. IV.
The parts received for examination in this case were a piece of large intestine showing characteristic swine-fever ulcers, and both lungs. A large part of the right lung was hepatised; the hepatised area was moderately firm, and on section it showed marked swelling of the interlobular septa. The parenchyma was mottled with a lighter and a darker shade of red. A cover-glass preparation made from the lesion showed great numbers of short ovoid bacteria. The left lung was normal, and a cover-glass preparation made from its parenchyma showed no bacteria. The pig had been found dead on the morning of the day on which the parts had been brought to the laboratory. Inoculated a rabbit (A) on the right side of the abdominal wall with a scraping from the lung lesion suspended in bouillon. The rabbit was found dead on the fifth day after inoculation. Around the seat of inoculation there was an inflammatory swelling as large as the palm of the hand; on section.this showed inflammatory
GENERAL ARTICLES.
9
congestion, <:edema, and blanching of the tissues from necrosis. A cover-glass preparation from the blood of the ear showed no free bacteria, but many violet granules in the leucocytes (with methylblue staining). Slanting agar tubes inoculated from the heart blood yielded an abundant growth of flat, circular, transparent colonies. A bouillon tube inoculated with a loopful of blood from the heart was slightly turbid after twenty-four hours' incubation at 37° c., and subsequently became almost clear, depositing a somewhat ropy deposit at the bottom of the tube. On microscopic examination these cultures were found to be composed of non-motile bacteria of the fowl cholera type. As regards its mode of growth on the surface of agar and in gelatine-agar it was not distinguishable from the organism isolated from the three preceding cases. It formed no visible growth on potato. The hepatised part in the right lung of the before-mentioned pig after having been immersed for half-a-minute in boiling water,! was cut into small pieces with a sterile knife, and given mixed with food to three adult sows (A, B, and C). One day after the experiment was begun, sow A farrowed eleven pigs. On the twelfth day of the experiment this sow, which had hitherto appeared to be quite well, refused her food; on the following day she appeared to be very weak, and food was still refused. On the fourteenth day of the experiment the sow took some food and appeared to be rather better. The improvement was continued during the next three days, but on the twentieth day the animal was found to be very ill, and death took place during the evening. The following are the notes of the post-JIlortem examination, which was made fifteen minutes after death. The right lung contains near its base a hepatised area about the size of a hen's egg. On section a turbid juice exudes from this. The cut surface is partly pink flesh-coloured (this is the firmest portion), and the rest is greyish pink. The cut surface of the firm portion is distinctly granular, and at one place ha:morrhagic in appearance. At one end the solid part shades gradually into the surrounding lung, but elsewhere it is well defined. A cover-glass preparation shows very numerous short bacteria. Left lung normal. Bronchial glands normal. Mesenteric glands normal in size; some of them congested. The ileo-ca:cal projection is swollen, livid in colour, and <:edematous, and on it there are several spots of necrosis. The large bowel contains no food materials, but about 6 oz. of blood, partly coagulated. The colon is intensely inflamed throughout, being generally of a livid colour, with here and there dark spots of extravasation. Jejunum much congested; no diphtheritic deposit and no ulceration. Stomach moderately filled with food materials. The cuticular portion has some adherent yellowish friable material. The fundus of the stomach is deeply inflamed. Spleen, liver, kidneys, and uterus normal. The right tonsil contains a dark-coloured ha:morrhagic-Iooking area about as big as a pea. Slanting agar tubes inoculated from the lung lesion yielded an abundant growth of an organism which grew in the form of large, glistening, opaque white colonies, and a few colonies with a similar appearance were obtained on slanting agar tubes inoculated from the 1
To destroy any swine-fever bacilli accidentally present on the surface.
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GENERAL ARTICLES.
mesenteric glands. In both cases the colonies were found to be composed of a short motile bacterium, easily distinguished by its mode of growth from the swine-fever bacillus and from the organism cultivated from rabbit A. It coagulated milk, and formed a white growth on potato. No inoculation experiments have been made with this organism. Sows Band C were killed on the twenty-first day after they had been fed with the diseased lung. In the interval they had appeared to be quite well, and the post-mortem examination did not reveal any lesion in the organs of the thorax or abdomen. Detached a slanting agar culture, which was the second generation from the heart blood of the before-mentioned rabbit (A), into about IO cc. of a bouillon culture, which was also the second generation from the same source. Injected! cc. of the mixed cultures under the skin of the abdominal wall of a rabbit (B), and the same quantity into the pectoral muscle of a pigeon. The rabbit was found dead on the eleventh day after inoculation. Around the seat of inoculation, and occupying nearly the whole of the right half of the abdominal wall, the subcutaneous and deeper textures were much swollen, and dissection showed that at this point the tissues of the abdominal wall were largely necrotic. A coverglass preparation made from the blood of the ear showed no bacteria, and tubes inoculated from the heart blood remained sterile. An agar tube inoculated from the lesion of the abdominal wall yielded an abundant apparently pure growth of flat transparent colonies. A bouillon tube inoculated from the same source also yielded an apparently pure growth. The above pigeon was alive and apparently healthy two months after inoculation. Inoculated a rabbit (C) subcutaneously in the right groin with 5 cc. of a bouillon culture holrling in suspension a culture on slanting agar; both cultures were the first generation from the abdominal wall of rabbit B. The rabbit was found dead on the third day after inoculation. Around the seat of inoculation there was much inflammatory congestion and some hccmorrhage. No visceral lesions. Slanting agar tubes inoculated from the heart and from the local lesion yielded abundant apparently pure cultures. Skinned and decapitated the above rabbit and then cut it into pieces, and gave the whole, together with the viscera, to a pig (A) about six months old. The whole was greedily consumed. The pig was killed on the seventh day of the experiment; during the interval it had not shown any symptom of ill health. Throughout the whole of the small intestine the mucous membrane was more or less congested, and there was also some cOllgestion of the gastric mucous membrane. The large intestine was normal throughout. The other abdominal organs and those of the thorax, as well as the tongue and throat, were normal. Of two slanting agar tubes inoculated from a mesenteric gland, one remained sterile, and the other developed two large opaque white colonies. Took a culture on slanting agar, the second generation from rabbit C ; poured into the tube about 6 cc. of sterile water, and detached the surface growth into this by the aid of a platinum needle. Injected
GENERAL ARTICLES.
I I
I! cc. of this liquid under the skin of the right thigh of a pig (B), and 4 cc. of the same liquid through the left chest wall of another pig (both about six months old). Pig B was killed on the thirteenth day of the experiment. At the seat of inoculation in the right thigh there was a pea-sized induration of the subcutaneous tissue. Several of the mesenteric glands were found to contain tuberculous lesions, and there was a small area of collapse near the edge of the left lung. All the other viscera were normal. Two slanting agar tubes inoculated from the centre of the nodule at the seat of inoculation remained sterile. Pig C (inoculated through the chest wall) was also killed on the thirteenth day of the experiment. The post-mortem examination showed an adhesion between the parietal pleura and the left lung opposite the eighth and ninth ribs; at the point of adhesion there was a solid area of lung nearly as large as a walnut, and on section this was found to contain centrally a piece of necrotic tissue. Several mesenteric glands were enlarged and tuberculous. The organism was recovered in apparently pure culture from the necrotic lung tissue, but a slanting agar tube inoculated from the pleural lesion remained sterile. CASE
No. V.
In this instance only the lungs were sent for examination. At the base of the left lung, and constituting about one-fourth of the organ, there was an area of hepatisation; on section the ground colour was greyish-pink, with hcemorrhagic-Iooking specks and streaks. The bronchi in this part contained a turbid mucus. A cover-glass preparation from the hepatised part showed an immense number of short bacteria, while a similar preparation from the normal lung tissue showed only an occasional organism (the lung was not quite fresh). Slanting agar tubes inoculated from the depth of the lung lesion yielded, after twenty-four hours' incubation at 37 9 c., an apparently pure growth composed of small, circular, flat, transparent colonies, which, on microscopic examination, were found to be composed of short bacteria of the fowl cholera type. Two rabbits (A and B) were subcutaneously inoculated on the abdomen with a scraping from the hepatised part. One of the rabbits (A) was found dead on the third day after inoculation. A cover-glass preparation made from the blood of the ear showed only a few short bacteria. Around the seat of inoculation on the abdominal wall there was a lesion about 2~ inches in diameter; the textures of the abdominal wall were here infiltrated and partly necrotic. The peritoneum was inflamed, with intense injection of the vessels, particularly of the large bowel. Other organs normal. An agar tube inoculated from the blood of the heart yielded a culture similar to that obtained from the original lesion in the lung; a bouillon tube inoculated from the same source remained almost clear, while a growth formed at the bottom of the liquid. The second rabbit (B) was also found dead on the third day after inoculation. The result of the post-mortem examination of it was almost identical with the foregoing, that is to say, very few bacteria were discoverable in the blood, and there was a comparatively large
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lesion at the seat of inoculation, and peritonitis. The organism was recovered on agar and in bouillon in apparently pure culture from the blood of the heart. The organism cultivated from the hepatised area in the abovementioned pig's lung, and from the blood of the two rabbits inoculated from that lesion, is morphologically identical with the organisms isolated from the preceding four pigs, and it also resembles these in respect of its mode of growth in artificial media. A rabbit (C) was inoculated subcutaneously on the abdomen with I cc. of a bouillon culture, which was the second generation from the above-mentioned pig's lung. The rabbit was found dead on the fourth day after inoculation. A cover-glass preparation from the ear showed only a few short bacteria. Around the seat of inoculation there was a lesion 3 inches in diameter. The peritoneum was inflamed, with coarse coagula of fibrinous lymph between the intestines. The organism was recovered in apparently pure culture from the heart blood and the lesion in the abdominal wall. A rabbit (D) was subcutaneously inoculated on the abdomen with I:t cc. of bouillon culture, which was the third generation from the before-mentioned pig's lung; this formed part of a flask of 40 cc. which had been incubated for twelve days at 37° C. The remainder of the flask (38~ cc.) was mixed with food and given to a six months' old pig (A). The whole was consumed. The pig was killed on the seventh day of the experiment; in the interval it had appeared to be quite well, except for slight diarrhcea on the second day of the experiment. The post-mortem examination revealed no lesions in any part of the body, and two agar tubes inoculated from the mesenteric glands remained sterile. In the above-mentioned rabbit (D) a swelling formed slowly at the seat of inoculation, and at the end of the third week it had attained the size of a hen's egg; after that it gradually declined. The general health of the rabbit did not appear to be seriously affected. The rabbit was killed forty-nine days after inoculation. It then had at the seat of inoculation a nodule about the size of a horse bean; centrally this was found to contain thick pus, and a cover-glass preparation made from that showed fairly numerous short bacteria, which were recovered in pure culture on slanting agar. Took a culture on slanting agar, which was the seventh generation from the lesion in the original pig's lung, and detached it into about 6 cc. of sterile water. The culture had been incubated for five days at 37° C. Injected I k cc. of this liquid under the skin of the right thigh of a pig (B), and 4 cc. through the left chest wall of another pig (C) ; both pigs were about six months old. Pig B was killed on the thirteenth day of the experiment; in the interval it had not shown any symptom of ill health. The seat of inoculation in the right thigh was not discoverable, even by dissection, and no lesion was discovered in any of the internal organs. Pig C (inoculated through the chest wall) was also killed on the thirteenth day of the experiment. The seat of inoculation was not apparent in the tissues of the chest wall, or by any adhesion between the lung and the parietal pleura. Near the seat of inoculation the left lung contained, immediately under the pleura, a nodule about
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half the size of a pea; the centre of this was firm, dry, and yellowishwhite in colour. Otherwise both lungs were normal, and no lesion was discovered in any of the other organs. A slanting agar tube inoculated from the centre of the lung lesion remained sterile. (To be continued.)
PNEUMONIA AND PLEURISY IN THE HORSE. By Veterinary-Major F. SMITH, F.R.C.V.S., Army Remount Department, Woolwich. REGIONAL ANATOMY OF THE LUNGS.
AN accurate conception of the regional anatomy of the chest will be found of considerable service in diagnosis. On this subject I propose to say a few words. It is usual to divide the chest of the horse into three regions, superior, middle, and inferior, and this division will clinically be found most useful. The extent of the chest is considerable; a large region lies concealed under the fore legs, a part we may term the scapular region; while posterior to this a considerable surface is presented by what may be termed the available region. This term if adopted would simply indicate that portion of the chest which can be subjected to examination, it being obvious that the scapular region is not so available. In Fig. I (p. I4) the extent and area of the chest is shown with a considerable degree of accuracy. I have termed it a diagram because my method failed to obtain a completely accurate representation of the chest for the purpose of this communication. But in spite of this it is prepared from photographs which were specially taken, and it may be accepted as quite accurate for all clinical purposes. The points I wish to bring out in the figure are the extent of the scapular region B, D, E, C, and the considerable area of the available chest A, B, C, F. The line A F represents the last rib. B C is a line running parallel with the posterior edge of the triceps muscle; A B is one parallel to the lower edge of the longissimus dorsi muscle; F C is a line running along the costal ridge, but the lungs do not reach to within a hand-breadth of the bottom of the false ribs. In the scapular region D is the head of the first rib and E its sternal insertion; the line B D runs close to the bodies of the dorsal vertebr;:e, while C E cuts through the cartilages of the sternum. Anteriorly the cavity of the chest is narrow from side to side and from top to bottom, while in the available region of the chest it is both wide and deep. The lungs are higher in the body at A than they are at D, they are lower at C than they are at E. As the chest is wider transversely, say through the sixteenth rib, than it is through the sixth, a greater bulk of lung should be situated