Investigation into the disease of sheep called "scrapie" (Traberkrankheit, la tremblante) : with especial reference to its association with sarcosporidiosis / by J.P. M'Gowan ; with an appendix on a case of Johne's disease in the sheep.

M'Gowan, J. P. (John Pool)

Date:: 1914

Credit: Investigation into the disease of sheep called "scrapie" (Traberkrankheit, la tremblante) : with especial reference to its association with sarcosporidiosis / by J.P. M'Gowan ; with an appendix on a case of Johne's disease in the sheep. Source: Wellcome Collection.

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$the animals under quite abnormal conditions. However, on several occasions it seemed that the shyness and fear of the animals was actually increased as compared to normal control animals. . The death of the animal usually takes place, without complicating diseases, as a result of marked lowering of the nutrition. In one case there was a pneumonia as a cause of death; in the four other cases the sectto gave us no clue to the cause of death. Jf we try to get a picture of the nature and seat of the disease from the clinical examination only, we hardly get any further than that we can exclude certain parts of the nervous system (to an affection of this system without doubt most of the symptoms point). The nature of the dts- turbance of movement points to the motor protoneuron not being the seat of the disease. Against such a stte everything speaks. Local muscular atrophy wis absent, qualitative changes in the electrical re- actions are absent, and the tendon phenomena are all retained. Also for an affection of the peripheral sensory nerves there is no indication ; therefore only the central nervous system remains, as also a primary muscular affection cannot be considered. A closer localisation in this region from a clinical standpoint seems to be futile. [Italics mine.— J.P. M‘G.] Only one more point may be brought forward. The assump- tion that one has to deal with a disease which is similar to Locomotor ataxia of man has no clinical support; for although the disturbance of movement suggests a disturbance of co-ordination, yet the re- tention of the tendon phenomena speaks quite definitely against Locomotor ataxia. As regards finding the key to the disease from an anatomical ex- amination of the nervous system, we have not obtained it even by a very exhaustive exact microscopic examination of the whole nervous system. For the result was, as could be concluded from the very beginning, for all practical purposes negative. The following further extract from Cassirer’s article, page 99, has an important bearing on the subject. It is as follows :— Fig. 4 shows a piece of the gluteal muscle from “trotting” sheep I. The cross section of the muscle has a normal appearance, and on longitudinal section one sees very well the cross striation. Between the muscle bundles one sees lying in the figure given very numerous (eight in one field) round figures (in other sections these are less numerous) which, stained deep yellow, consist of refractile coccidia like balls, which, as the longitudinal section also shows, are lying in such a way in the muscle fibre that they sometimes bulge out this slightly, but yet leave the substance wholly intact. There can be no doubt that we have to do in these bodies with psorosperm corpuscles which have been called Rainey or Miescher’s corpuscles,! and which largely present in different animals are considered as moderately harmless inclusions which we in no way can bring into relation with the 1 Sarcosporidial cysts.—[J. P. M‘G. ]$