"Is chronic pleuro-pneumonia contagious? The farmers believe that it is, and I am partly of their opinion. When an animal falls sick in the pasture, the others, after his removal, go and smell at the grass where he has lain, and which he has covered with his saliva, and, after that, new cases succeed to the first. It is true that this fact is not conclusive, since the disease also appears in a great number of animals that have been widely separated from each other. But I have myself seen three cases in which the cattle of the country, perfectly well before, have fallen ill, and died with the same symptoms, excepting that they have been more acute, after they have been kept with cattle affected with this disease. This circumstance inclines me to think that the disease is contagious; or, at least, that, in the progress of it, the breath infects the cow-house in which there are other animals already predisposed to the same disease. I am induced to believe that most of the serious internal diseases are communicated in this manner, and particularly those which affect the organs of respiration, when the animals are shut up in close, low, and badly-ventilated cow-houses." [_Rec. de Med. Vet. Mai, 1833._] No malady can be more terrible and ruinous than this among dairy-stock; and its spread all over the country, together with its continuance with scarcely any abatement, must be attributed to the combination of various causes. The chief are: _first_, the very contagious or infectious nature of the disorder; _second_, inattention on the part of Government to the importation and subsequent sale of diseased animals; and, _third_, the recklessness of purchasers of dairy or feeding cattle. This disease may be defined as 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 among horses, sheep, and other animals,--which pretended observations have not been well attested.