Part 8

In the slightest cases there may be only a capricious or irregular appetite, drooping tail, enlarged inguinal glands, and a progressive emaciation, with loss of life and strength and occasional irregularity of the bowels. The greasy exudation on the skin and black scaly encrustation is not uncommon. Such patients usually survive but they are liable to prove unthrifty and unprofitable.

In other cases the pig becomes dull and listless, leaves its fellows, creeps and lies much under the litter, has impaired or irregular appetite, some costiveness followed by a fœtid diarrhœa, abdominal tenderness, enlarged inguinal glands, progressive emaciation, arched loins, hollow flanks, skin exudation, and oftentimes in the end erythematous eruption with petechiæ and black scaly exudate on the skin. It is in these protracted cases especially that the formation and detachment of the necrotic intestinal sloughs take place and these may pass in the fæces as flattened rounded masses or more extensive plaques. Necrotic ulcers are also liable to show on the buccal mucous membrane or skin. The patient may finally die of colliquative diarrhœa, of exhaustion and marasmus, in a state of coma as in the more acute cases. The mortality may be high and the survivors are liable to prove unthrifty and unprofitable.

Diagnosis. With a group of plagues in swine bearing a strong family resemblance, and maintained by microörganisms, which, though maintaining distinct characters, yet show so much in common that it seems not impossible that they may have been originally derived from a common ancestor, and in face of the not infrequent complication of two of these microbes in one patient, it becomes a task of great difficulty to diagnose at once the particular outbreak that is met with in the field. In some outbreaks, however, the differential features are clear enough to allow the veterinarian to pronounce at once on the true nature of the disease. In others he must withhold his diagnosis until he can put it to the test of microscopic examination, bacteriological culture, the Widal test, or inoculation.

Hog Cholera may be decided upon, when upon wholesome food, in healthy environment, without any change of food, and in six to fourteen days after the introduction of pigs from outside, or the arrival of strange pigs in the near vicinity, or higher up on the watershed, sickness appears tardily, taking one or two daily, with or without a sudden hyperthermia, petechiæ on nose, eyes, belly, axilla, or groin, a general soreness of the skin and abdomen, stiffness or weakness, hiding much under the litter, enlargement of the lymph glands, costiveness with dark red rectum and glazed dung, followed by a profuse, watery, fœtid, bloody, black or yellow diarrhœa, and death mostly after one or two weeks or more. The absence of cough, and the presence of ulcers bearing necrotic sloughs on the lips, mouth or skin, and above all the presence of the button-like necrotic ulcers on the mucosæ of the cæcum, colon or ileum may be accepted as conclusive evidence on this point. So also its prompt fatality to rodents, but not to pigeons.

Swine erysipelas has a much shorter incubation, more rapid and violent onset, deeper, darker congestion of visible mucosæ, more extensive petechiæ of skin, mucosæ, serosæ, and tissues generally, a comparative absence of inflammatory and necrotic lesions of bowels, a very early and high mortality in swine, rabbits and pigeons, and a harmlessness toward the inoculated Guinea pig.

Swine plague also shows a shorter incubation, a speedy elevation of temperature, more mucous congestion, less indication of abdominal tenderness or of diarrhœa, more cough, dyspnœa, wheezing and objective symptoms of pulmonary consolidation, less congestion or engorgement of the spleen, or ulceration of the bowels, and finally is very much more fatal to pigeons, and spares neither rabbits nor Guinea pigs.

Widal test. The cessation of movements and the agglutination of the bacilli of hog cholera, noted by Dawson, is a valuable test, but as in the case of typhoid fever in man is not to be implicitly relied on in all cases. Some of the forms of bacillus coli commune and other allied microbes act in a similar way. It necessitates the maintenance of fresh (24 hours) active, artificial, agar cultures of the hog cholera bacillus and is thus virtually reserved for the bacteriological laboratory. A drop of blood is drawn from the suspected pig smeared very thinly on the cover glass and about 10 times the amount of sterile water added. Then the smallest possible addition of the agar culture of the bacillus is made. Immediately, or in ½ hour the bacilli cease their active motility and mass together in clumps in which they can be seen individually clear and distinct but absolutely still and crossing each other in all directions forming a kind of network. A few isolated bacilli remaining in the intervals between the clumps and even showing a slight motility are not to be considered as invalidating the reaction.

The table on the next page will serve to place in contrast the differential phenomena of the diseases caused by bacilli of hog cholera, swine plague and swine erysipelas in uncomplicated infections.

Prevention. As in all other contagious diseases, effective preventive measures imply the destruction of the pathogenic germ and all sanitary measures should aim at the early and final extinction of this organism and its subsequent exclusion from the country. This, however, entails an outlay and governmental control which it seems idle to expect in the very near future so that palliative measures, and those looking toward success over limited areas must still be resorted to. It should be here distinctly stated, however, that the extinction of a plague, though often the most expensive at the start, is in the end by far the most economical resort.

Removal of accessory causes. The health and vigor of the animal exposed is not without its influence in case of attempted invasion by a virus of diminished potency.

DIFFERENTIAL SYMPTOMS AND PHENOMENA.

=Hog Cholera.= =Swine Plague.= =Rouget.=

Incubation 6 days + Incubation 1 day to + Incubation 1 day

Mucosæ not necessarily Mucosæ congested Mucosæ deeply congested congested, dark red, violet

Petechiæ on snout, Petechiæ on snout, Petechiæ extensive eyes, mouth, etc. eyes, mouth, etc.

Necrotic ulcers on Necrotic ulcers rare Necrotic ulcers less snout, mouth, skin, frequent etc.

Furred tongue, vomiting Vomiting less likely Vomiting not uncommon common

Temperature high in Temperature high in Temperature very high, acute cases (104° to acute cases 107° to 109° 108°)

Lies on belly mostly, May lie on side May lie on side abdomen hot, tender

Moves stiffly, feebly, Stiff but less so, Stiff, weak, paraplegic unsteadily with Paretic. grunting, may be paraplegic

Bowels 1st costive, Diarrhœa less marked, Diarrhœa usually sets fæces molded, glazed; may be entirely in 2d or 3d day, or absent before death, diarrhœa, profuse, watery, fœtid, bloody, black on slops,—yellow on corn (maize)

Everted anus dark red Anus may not be deep Anus may be less red, red, less everted less everted

Cough often present, Cough, hard, frequent; Cough absent, save in hurried breathing wheezing breathing. latter stages with Auscultation and pulmonary percussion may show consolidation lung consolidation toward lower border. May bleed from nose

Spleen slightly Spleen usually little Spleen enlarged, soft, enlarged altered grumous

When death is deferred Necrotic, button-like Necrotic ulcers on 1 to 2 weeks, ulcers on cæcum bowels rare necrotic button-like rarely marked ulcers on ilio-cæcal valve, cæcum, colon, or ileum

Lobar pneumonia Lobar or lobular Pulmonary and enteric uncommon pneumonia a marked inflammation rare lesion

Kills rabbits (5 to 7 Kills rabbits (1 to 12 Kills pigeon (3 to 8 days) and Guinea pigs days), Guinea pigs (1 days), rabbit (4 to 8 (7 to 12 days). to 4 days), pigeon days), Guinea pig Pigeons sicken but (48 hours) resists survive

Blood serum of hog cholera patient causes agglutination of bacilli in cultures; (not constant, occurs with other bacilli)