The principles and practice of veterinary medicine / by William Williams.

  • William Williams
Date:
1909
Catalogue details

Licence: In copyright

Credit: The principles and practice of veterinary medicine / by William Williams. Source: Wellcome Collection.

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    agents which, operating on the body, especially when predis- posed, may excite disease; amongst them are included those specific causes, or elements of disease, which stamp their in- dividuality on the morbid processes which ensue in the animal body when the germs of such diseases happen to become implanted therein (as in glanders, rabies, rinderpest, scabies, &c.), and are divided into the cognizable and non-cognizable. The first includes all the physical and other agents of whose existence we can take cognizance, independently of their opera- tion in producing disease; but these so-called non-cognizable causes are now found to consist of certain organisms, the majority of which have been demonstrated to be living matters having specific effects. The predisposing and exciting causes of disease, when ex- isting within the system, are called intrinsic, endopathic, or internal; but when they arise without the system, they are denominated extrinsic, exopathic, or external causes of disease. Predisposing causes of diseases.—The most important and generally recognised predisposing causes of disease are— (1.) The influence of age.—This is not so striking in the lower animals as in man, but still it plays an important part. In the dog, for example, the period of dentition renders the animal liable to fits of convulsion, paralysis, disturbances of the digestive process, with vomition, irregularity of the fascal discharges, weakness, and even inflammation of the eyes, and attendant unthriftiness. Kickets is also a disease which is only seen during the early period of life, and is witnessed in all our domesticated animals, but more particularly in the dog. Canine distemper may be manifested during any period of life: as a great rule, it is only seen during the first few weeks or months of the animal’s existence. Again, the strangles of the horse is generally a disease of adolescence. It is also well known that the invasion of parasites is much more common during the earlier period of an animal’s life ; thus we find the Coenurus cercbralis developed in the brains of sheep and cattle during the first months of life. The Strongylus fllaria] of the lamb, and its analogue, the Strongylus micrurus of the calf, as a general rule induce disease in these animals in early life. The Trichonema arcuata,1 witnessed by me in Icelandic ponies, and referred to in the latter part of this work, are rarely found in horses above two years old. 1 Trichonema arcuata is the larval form of Schlcrostomum tctracanthum.
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