DISEASES OF CATTLE.

From a work by the well-known veterinarian, Prof. John Gamgee, on the selection, diseases and produce of dairy stock, published in Edinburgh, in 1861, some extracts are here inserted. They refer chiefly to diseases either common in this country, or to those from the introduction of which danger is apprehended. Of the latter character is the

PLEURO-PNEUMONIA EPIZOOTICA,

or the Epizootic Lung-Disease of Cattle, which within a few years has made its appearance in some of our Eastern States, where its ravages have already occasioned serious loss, and justly created much alarm in reference to other sections of the country. As Prof. Gamgee's opportunities for studying this disease have been extensive, his remarks cannot fail to be read with interest by all owners of cattle. He says:

No malady can be more terrible and ruinous than this amongst dairy stock, and its spread all over the country; its continuance, with scarcely any abatement, must be attributed to the combination of various causes. The chief are, firstly, the very contagious or infectious nature of the disorder; secondly, inattention on the part of the government to the importation and subsequent sale of diseased animals; thirdly, the recklessness of purchasers of dairy or feeding cattle.

The disease may be defined an acute inflammation of the organs of the chest, with the development of a peculiar and characteristic poison, which is the active element of infection or contagion. It is a disease peculiar to the cattle tribe, notwithstanding occasional assertions regarding observations of the disease amongst horses, sheep, and other animals, and which have not been well attested.

The contagious nature of this virulent malady is incontestibly proved by an overwhelming amount of evidence, which I cannot adduce at full length here, but which may be classified under the following heads: Firstly. The constant spread of the disease from countries in which it rages to others which, previously to the importation of diseased animals, have been perfectly free. This may be proved with regard to England, where it was carried in 1842 by affected animals from Holland. Twelve months after, it spread from England to Scotland by some cattle sold at All-Hallow Fair, and it was only twelve months after, that cattle imported as far north as Inverness took the disease there Lately, a cow taken to Australia, from England, was observed to be diseased on landing, and the evil results were limited to her owner's stock, who gave the alarm, and insured the effectual check to further spread. Lastly, the recent importations of pleuro-pneumonia into the United States from Holland, seems to have awakened members of the agricultural press here, and convinced them of the stubborn fact that our cattle have been decimated by a fearfully contagious and probably preventable plague. In a letter from America, we find on this subject: "Its contagious character seems to be confirmed beyond a doubt, though some of the veterinary practitioners deny it, which is almost as reasonable as it would be to deny any other well authenticated historic fact. Every case of the disease is traceable to one of two sources—either to Mr. Chenery's stock in Belmont, into which the disease was introduced by his importation of four Dutch cows from Holland, which arrived here the 23d of last May, [1859], or else to one of the three calves which he sold to a farmer in North Bloomfield, last June."

Secondly. Apart from the importation into countries, we have the certain proof, to which I drew special attention several years back, that cattle dealers' farms and public markets constitute the busy centres of infection. Most anxious and careful inquiries have proved to me, that in breeding districts, where the proprietors of extensive dairies, as in some parts of Dum

fries, etc., abstain from buying, except from their neighbors who have never had the lung disease amongst their stock, pleuro-pneumonia has not been seen. There is a wide district in the vicinity of Abington, and in the parish of Crawford, which has not been visited by this plague, with the exception of two farms, to which market cattle have been imported and carried the disease.

Thirdly. In 1854, appeared a Report of the Researches on Pleuro-pneumonia, by a scientific commission, instituted by the Minister of Agriculture in France. This very able pamphlet was edited by our esteemed friend, Professor Bonby, of Alfort. The members of the commission belong to the most eminent veterinarians and agriculturists in France. Magendie was President; Regnal Secretary; besides Rayer, the renowned comparative pathologist; Yvart, the Inspector General of the Imperial Veterinary Schools; Renault Inspector of the Imperial Veterinary Schools; Delafond, Director of Alfort College; Bonby, Lassaigne, Baudemont, Doyère, Mauny de Morny, and a few more representing the public. *

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The conclusions arrived at by this commission are two important to be overlooked here. I must refer the reader to the Report itself, if he needs to satisfy himself as to the care taken in conducting the investigations; but the foregoing names sufficiently attest the indisputable nature of the facts alluded to In instituting its experiments, the commission had in view to solve the following questions:

1. Is the epizootic pleuro-pneumonia of cattle susceptible of being transmitted from diseased to healthy animals by cohabitation?

2. In the event of such contagion existing, would all animals become afflicted, or what proportion would resist the disease? 3. Amongst the animals attacked by the disease, how many, and under what circumstances? How many succumb?

4. Are there animals of the ox species decidedly free from any susceptibility to be affected from the contagion of pleuropneumonia ?

5. Do the animals which have been once affected by a mild form of the disease, enjoy immunity from subsequent attacks?

6. Do the animals which have been once affected by the disease in its active form, enjoy such immunity?

To determine these questions, the commission submitted at different times to the influence of cohabitation with diseased animals forty-six perfectly healthy ones, chosen from districts where they had never been exposed to a similar influence. Of these forty-six animals, twenty were experimented on at Pomeraye, two at Charentonneau, thirteen at Alfort, and eleven in the fourth experiment at Charentonneau.

Of this number, 21 animals resisted the disease when first submitted to the influence of cohabitation, 10 suffered slightly, and 15 took the disease. Of the 15 affected, 4 died and 11 recovered. Consequently the animals which apparently escaped the disease at the first trial, amounted to 45.65 per cent., and those affected to 21.73 per cent. Of these, 23.91 per cent. recovered, and 8.69 per cent. died. But the external appearances in some instances proved deceptive, and 6 of the 11 animals of the last experiment, which were regarded as having escaped free, were found, on being destroyed, to bear distinct evidence of having been affected. This, therefore, modifies the foregoing calculation, and the numbers should stand thus:

Of the 42 animals which were exposed in the first experiments at Pomeraye and Charentonneau, and which escaped either without becoming affected, or recovering, 18 were submittted to a second trial, and of these 18, four were submitted to a third.

Of the 18 animals, five had, in the first experiment, suffered from the disease and had recovered, five had never become af

fected, and four had been indisposed. The four animals submitted to the influence of contagion a third time, had been affected on the occasion of their first trial. None of the 18 animals contracted the disease during their renewed exposures to the influence of contagion.

From the results of these experiments, the commission has drawn the following conclusions:

1. The epizootic pleuro-pneumonia is susceptible of being transmitted from diseased to healthy animals, by cohabitation.

2. All the animals exposed do not take the disease-some rather slightly, others not at all.

3. Of the affected animals, some recover, and others die.

4. The animals, whether slightly or severely affected, possess an immunity against subsequent attacks.

These are the general conclusions which the commission has deemed itself authorized to draw, from their experiments. The absolute proportion of animals which become affected, or escape the disease, or of those which die and those which recover, as a general rule, cannot be deduced from the foregoing experiments, which, for such a purpose, are too limited. The commission simply states the numbers resulting from their experiments. From these, it transpires that 45 per cent. of the animals became affected with pleuro-pneumonia, and 21 per cent. took the disease slightly, making in the whole 66 per cent. which were more or less severely attacked; 34 per cent. remained free from any malady. The proportion of animals which re-acquired their wonted appearance of health amounted to 83 per cent., whereas 17 per cent. died.

Many minor points might be insisted on, but it will suffice for me to say, that the most careful analysis of all facts have proved to practical veterinarians, to experienced agriculturists, and must prove to all who will calmly and dispassionately consider the point, that pleuro-pneumonia is pre-eminently a contagious malady.

Symptoms. From the time that an animal is exposed to the contagion to the first manifestation of symptoms, a certain pe