98 DISEASES OP SWINE AND OTHER ANIMALS. 



-DR. LAW'S SUPPLESIENTAL REPORT. 



■ As an addendum to ray former report, I would respectfully submit the follorring 

 further oIi'^ota ntions on tlio fever of swine, commonly known ms hog cholera: 



r.XPKIIIMENTS IN FEEDING THE VIRTTIJENT BIATTEH. 



A healthy pig was f'dtho substance of an intestinal ulcer and a little nianni'e from 

 the same bowol, bu,t sliovved no evil results for fovirteen days, when it was put to 

 other uses. It should be added that the nicer fed to this pig was partially putrid, 

 and was inocailateel on two other SAvine without success. 



A second i>ig Avas fed a port ion of di'ied intestine and its contents, both of which had 

 remained packed in wheat-brau for a mouth. Notwithstanding this, the animal re- 

 tained good health for seventeen days, when it, too, was put to other uses. The 

 material fed to this pig acted with fatal effect on two other pigs on wbich it was in- 

 oculated. 



These experiments can only bo taken as shov/ing thqt a small quantity of poison 

 may pass through the intestinal canal with impunity, but they would not warrant 

 the conclusion that similar materials would be equally barmless when taken in larger 

 quantities and with every meal, as invariably ha])pens when sAvine are fed in the ordi- 

 nary manner and plunge their filthy feet and noses fresh Irom the pestiferous manure 

 into the feeding-trougii. Dr. Osier has succeeded in developing the disease by feeding 

 the diseased intestine, but as the feeding was accomplished by force there is just the 

 possibility of abrasion and direct inoculation. Abrasions are indeed so common in the 

 mouth from .injuries by the teeth and by hard objects masticated and derangements of 

 the epithelial covering of the mucou.s membrane of the stomach and intestines, are 

 so frequent in connection Avith slight gastro-intestinal disorders, that it is needless to 

 calculate on an immunity which can only be secitred by the entire absence of such 

 lesions. If to scctu'c immunity in feeding we must proA'ide that not even a worm shall 

 bite the mucous membrane of the stomach or intestine, any guarantee rests on an ex- 

 ceedingly slender basis and had best be rejected at once. 



SUCCESSFUL INOCULATION WITH FKOZEN PKOBUCTS OF THE DISEASE. 



In two cases I have successfully inoculated virulent i^roducts which had been frozen 

 hard for one and two days respectively. In both instances the resulting disease was 

 of a very violent type, and would assuredly hav'e proved fatal if left to run its course. 

 The freezing had certainly failed to impair the virulence ; it had rather sealed it up to 

 be opened and given free coni'se on the occtuTcnce of a thaw; for, once it is frozen, 

 it is manifest that no further change could take place until it was again thawed" out, 

 and if it was preserved for one night unchanged in its potency, it would be equally 

 nnatfected after the lapse of many months, provided its liquids had remained in the 

 same crystalline condition throughout. In this way undoubtedly the vu'us is often 

 preserved through the winter in pens and yards, as well as in cars and other convey- 

 ances, to break forth ancAV with returning spring. This is precisely what avo find to 

 be the case w"ith the other fatal animal plagues, the A^kus of rinderpest, lung fever, 

 anthrax, and aphthous fever, being often bound up through the winter Avith frozen 

 manure to reapi^ear with undiminished power on the access of warmer weather. This 

 is a matter of no small moment inasmuch as the long-continued frosts of our Northern 

 States proA'ent any such destruction of the jioisou as takes place so readily in summer 

 in coimection with, the alternate wetting and drying and the resulting putrefaction. 



I have had instances brought under my notice in which, after the })revalence of the 

 icYL'T in a herd in early smmuer, new swine were introduced into the open yard a 

 month or tAVO after all trace of the disease had disappeared and had continued to pre- 

 serve the most perfect health. This is qirite in keeping, too, Avith my failure in the 

 attempts tQ convey the disease by feeding and inoculating Avith a semi-putrid intestine. 

 It serves, moreover, to explain "my faillu'o, as the exposure and Avct at a moderately 

 higli temperature avouUI lead in both cases alike to decomposition and destruction. 



The bearing of this upon the prevention of the disease is self-evident. Infected yards 

 and other opeii and uncovered jilaces may bo considered safe after tAvo months' vaca- 

 tion in summer, provided that sulhcicnt rain has fallen in the interval to insure the 

 soaking and ])ulrid decomposition of all organic matter near the surface, and that 

 there are no great accuimxlations of manure, straAV, hay, or oilier material in whicli 

 the A'U'us may be preserved dry and infecting. In Avinter, on the other hand, ihe yard 

 or other open infected iilaco may prove non-infecting for weeks and mouths, and yet 

 retain the A^rus in readiness for a now and deadly career as soon as a thaw sets in. 

 Safety in such circumstawces is contingent on a disuse of the ])remises so long as tlie 

 Irost continues and for at least one niontli thereafter. Even during iho eou-tinuauee 

 of frostj such places arc daoigca-Qus, as the heat of the anionala' bodies or of the rays of 





