(466) Pneumo-Enteritis of the Pig.

This disease has been exhaustively investigated in a series of researches by Dr. Klein, see the 7th Annual Report of the Local Government Board (Supplement to Rep. of Medical Officer for 1877). It has been called a great variety of names, such as pig typhoid, hog cholera, malignant erysipelas, red soldier, purples, blue disease, and others. It has also been confused with splenic fever or anthrax. It is an infectious malady caused by special micro-organisms having considerable resemblance to the bacillus anthracis.

The disease is somewhat common in England, and causes when prevalent great losses to swine farmers.

In mild cases the skin is normal, but the inguinal glands are enlarged and red. The lymphatic glands of the pelvis are distinctly enlarged. So are also the mesenteric glands and the glands in the ligamentum gastro-hepaticum. Greater or smaller portions of these masses of lymph glands show redness of their cortical part, a redness due to hæmorrhage in the cortex of the gland.

The peritoneum is but slightly inflamed, but in the peritoneal cavity is a small quantity of fluid or solid lymph. The serous covering of the small and large intestine is hyperæmic.

In the mucous membranes of the intestines are very evident changes; that of the duodenum is intensely red, and on the crests of the folds are small hæmorrhages. The ilio-cæcal valve, the cæcum and colon, are also more or less congested, and very often there are minute hæmorrhages. There are always small ulcers on the iliocæcal valve, and a few also on the colon. Plate VIII. represents a portion of the mucous membrane of the ileum of a pig which had died of pig typhoid (Royal College of Surgeons' Museum). In the mild forms the colon and rectum are filled with normal fæcal matter. The lungs are usually congested, and many lobules in a more or less advanced stage of pneumonia. The bronchial glands are red and enlarged.

The muscular structure of the heart shows in most cases minute hæmorrhages, the same is to be said of the endocardium.

In the front part of the tongue on both upper and lower surfaces there are occasionally hæmorrhages.

In the severer cases all these pathological signs are much accentuated, and there are often patches of redness of the skin.

In the general muscular system no naked eye changes are to be seen, hence a single joint of pork derived from a pig, which has suffered or died from pneumo-enteritis, might be passed as good by any observer who had had no opportunity of investigating the internal organs.

In severe cases Klein states that the muscular tissue appears pale, soft, and moist, and on microscopic examination the muscular fibres are seen to be in a state of fatty degeneration. He further states that his assistants consumed without injury salt pork derived from carcases of pigs used in his experiments which had suffered from the mild attacks produced by inoculation.

In examining a pig's carcase for signs of pneumo-enteritis the most constant changes are the diseased condition of the lungs, the intestinal glands, and the congestion and ulceration of the lining membrane of the gut. If these are healthy the animal cannot have suffered from pneumo-enteritis. The liver, spleen, and kidneys in the milder forms are healthy, hence the normal condition of these organs must not be taken as evidence of previous good health. The bacillus associated with the disease is two to three μ long (but it is capable of growing to a great length), it is actively motile, which distinguishes it from anthrax. Spore formation has been observed. The bacilli can be cultivated in broth or hydrocele fluid. From artificial cultures the disease may produced in pigs, mice and rabbits. The bacilli are not to be found in the blood or spleen, but may be found in the lung, in the sanguineous fluid of the trachea, in the peritoneal exudation, and in any purulent collection, such as abscesses at the seat of inoculation. So far as is known the disease is not transmissible to man.

(467) Swine Plague.

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This is an affection of the digestive organs of which the large intestine is principally involved. The latter is as a rule the seat of diphtheria. At the same time the lymphatic glands are affected, and there may be observed traces of a general slight infection. The disease may be accompanied by slight lung affections.

(468) St. Anthony's Fire.

In this disease the symptoms cannot be differentiated from pyæmia or anthrax. The most important changes are bright

patchy redness of the skin, enlargement of the spleen, inflammation with minute hæmorrhages of the stomach and intestines, infiltration and congestion of the kidneys; there may also be purulent foci in the liver, but save in the worst cases the muscular system will show little if any alteration.

(469) Foot and Mouth Disease.

This is a disease often epizootic among cattle and sheep. The milk of affected cows will produce the same malady in man, and such milk should be destroyed. The essential features of the disease are the formation of blebs or blisters on the tongue, the lining membrane of the mouth, the udder of cows, and between the claws of the hoof; the blisters soon break and leave ulcers. The changes in the internal organs are of too general a nature or too slight in character to be pathognomic, so that unless the mouth, feet, and mucous membranes be inspected there will be but little chance of ascertaining whether a given animal has suffered from foot and mouth disease or not. A special micro-organism, a streptococcus, is associated with the disease, and has been found in the fluid of the vesicles and in the milk. The cocci occur singly, in dumb-bell, and in curved chains. They can be readily cultivated in the ordinary nutrient media, and do not liquefy the gelatin. The flesh of animals suffering from foot and mouth disease is said to be innocuous, but there have been few exact experiments, and it is safest to consider all animals affected with general diseases unfit for use as food.

(470) Pleuro-Pneumonia.

The pleuro-pneumonia of cattle is a very fatal and contagious disease; the post-mortem characters are confined to the organs of the chest, the lungs are deeply congested and enormously increased in weight, they sink in water, have lost their crepitant feel, are more or less cedematous, and when cut in two they have a marbled appearance, the pleura or lining membrane is adherent, being covered with a fibrinous layer, and there is more or less effusion. The cellular tissue between the chest wall and the pleura is seldom affected, and the butcher by removing the lungs and stripping off the pleura removes all traces of disease. The flesh, once the lungs