1944 Onderstepoort Journal of Veterinary Science and Animal Industry, Volume 20, Number 1, 1944

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Contentes Pages: Onderstepoort Journal of Veterinary Research, Vol ??, 19??

CONTENTS

*Volume 20: Number 1*

Section I: Virus Diseases

Rinderpest in game : a description of an outbreak and an attempt at limiting its spread by means of a bush fence	Thomas, AD & Reid, NR	7

The susceptibility of the springbuck (Antidorcas marsupialis) to heartwater	Neitz, WO	25

The influence of solar radiation on the course of bluetongue	Neitz, WO & Riemerschmid, G	29

Section II: Bacteriology

A case of swine erysipelas in the Union of South Africa	Haig, DA & Adelaar, TF	57

Section III: Toxicology and Poisonous Plants

Dicrotaline : the toxic alkaloid from Crotalaria dura (Wood and Evans) and Crotalaria globifera (E. Mey)	Marais, JSC	61

Monofluoroacetic acid, the toxic principle of "gifblaar", Dichapetalum cymosum (Hook) Engl.	Marais, JSC	67

Recent investigations into the toxicity of plants, etc., in the Union of South Africa	Van der Walt, SJ	75

Section IV: Nutrition

The nutritive value of South African feeding stuffs. II. Digestible nutrients and metabolizable energy of lucerne hay at different planes of intake for sheep	Louw, JG	85

Section V: Pathology

The cytology of the contagious (venereal) tumour of the dog	Jackson, C	97

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The cytology of the contagious (venereal) tumour of the dog
(Pretoria : The Government Printer, 1944) Jackson, Cecil; Du Toit, P.J.
1. The contagious venereal tumour of dogs has been examined for the first time by modern cytological technical methods and the cytoplasmic structure revealed. 2. Adequate technique, controlled by observations on the living cells, shows that these tumour cells are exceedingly rich in lipide globules, the presence of which has been overlooked (a) because they are dissolved out from paraffin sections and (b) because in frozen sections they are refractory to the customary methods for the demonstration of fatty substances. To stain these globules, the use of a specially devised acetic-carbol-sudan method is recommended. 3. Previously employed methods of studying the tumour cells have been misleading - as indeed they were doomed to be - not merely because of failure to demonstrate the lipides, but still more because of the extensive artefacts which result from failure to take precautions against shrinkage of the cells which follows dissolution of this constituent, which occupies so large a part of the cytoplasm. Current views - that the contagious venereal tumour is composed of round cells or of stellate cells (reticulum cells) - depend entirely on the examination of material showing such fixation or rather post-fixation artefacts. 4. The cell membrane is highly developed and the cells are polygonal in shape and closely aggregated together as in an epithelium. 5. The granules (mitochondria?) are distributed throughout the cytoplasm and are less constantly stained by the classical mitochondrial techniques than are the mitochondria of most other cells. Technique suitable for their demonstration is described. 6. The Golgi apparatus is well developed and has the form of a spiked wreath, one-third to one-half the size of the nucleus. 7. The centrosome and the achromatic spindle have been demonstrated and described. Measurements of the spindle angle reveal a mean value of 114°, contrasting with the angle of cells of the lymphoid series as measured by Ellermann. 8. Routine diagnosis of the contagious venereal tumour is more rapidly and certainly accomplished by means of teased preparations than by the usual sections. Pitfalls in the differential histopathological diagnosis have been explained, especially from mastocytoma and endothelioma. 9. According to present conceptions of the structure and habitus of large lymphocytes (lymphoblasts) it would be difficult to identify the tumour cells with these elements. 10. Accordingly, further support is provided for the author's alternative theory that the contagious venereal tumour may be an apolar neuroblastoma.
Monofluoroacetic acid, the toxic principle of "gifblaar", Dichapetalum cymosum (Hook) Engl.
(Pretoria : The Government Printer, 1944) Marais, J.S.C.; Du Toit, P.J.
The identity of the toxic substance of "Gifblaar", Dichapetalum cymosum, has been established to be monofluoroacetic acid. The potassium and calcium salts as well as the p-nitrobenzyl and p-bromophenacyl esters of monofluoroacetic acid have been described.
Rinderpest in game : a description of an outbreak and an attempt at limiting its spread by means of a bush fence
(Pretoria : The Government Printer, 1944) Thomas, A.D.; Reid, N.R.; Du Toit, P.J.
1. The history of rinderpest and of measures taken to check its spread in Central East Africa is briefly reviewed. 2. A description is given of a disease, believed to be rinderpest, affecting buffalo, eland and kudu in the Lake Rukwa trough. 3. Attention is drawn to some of the habits of game and the close association often existing between cattle and game in the dry season. 4. Subinoculations from affected buffalo and eland into susceptible young cattle and goats show that these animals suffered from rinderpest. 5. While defensive measures for cattle, namely immunization and control of movement are eminently successful, game still remains the greatest source of danger for spreading and for maintaining rinderpest. Segregation of game on a large scale, possibly with selective destruction in certain restricted areas, is the only weapon we possess at present to counter this danger. The type of bush fencing described is an attempt at evolving a practical, effective and relatively cheap means of achieving this. 6. The need for further research into the diseases of game animals and the necessity for revision of the prevalent attitude toward the game problem in Africa is emphasized.
The nutritive value of South African feeding stuffs. II. Digestible nutrients and metabolizable energy of lucerne hay at different planes of intake for sheep
(Pretoria : The Government Printer, 1944) Louw, J.G.; Du Toit, P.J.
In an experiment consisting of three periods the digestibility and metabolizable energy content of lucerne hay were determined with each of five mature Merino wethers at the following daily levels of intake, corresponding to the three periods of the experiment: I. 600 grams, II. 800 grams, and III. 1,000 grams. Whilst the differences in the coefficients of digestibility and metabolizable energy content of the lucerne hay fed in periods I and III, respectively, were, in general, found to be insignificant, the hay fed in period II was digested significantly better and contained significantly more metabolizable energy than the hay fed in either of the other two periods. These variations in digestibility and metabolizable energy content are considered to have been caused chiefly by the observed differences in chemical composition - protein, cellulose, and lignin contents - of the lucerne hays consumed in the several periods.
Recent investigations into the toxicity of plants, etc., in the Union of South Africa
(Pretoria : The Government Printer, 1944) Van der Walt, S.J.; Du Toit, P.J.
The toxicity of 16 plants was investigated. Of these the following four were, according to the literature available to the author, for the first time proved to be poisonous: Encephalartos horrridus Lehm., Royena decidua Burch., Eucomis undulata Ait., Scilla rigidifolia Kunth. The toxicity of Dowicide P was determined.
Dicrotaline : the toxic alkaloid from Crotalaria dura (Wood and Evans) and Crotalaria globifera (E. Mey)
(Pretoria : The Government Printer, 1944) Marais, J.S.C.; Du Toit, P.J.
The isolation of the alkaloid dicrotaline from Crotalaria dura and Crotalaria globifera has been described. On alkaline hydrolysis dicrotaline yields retronecine and an unknown dibasic acid, dicrotalic acid.
A case of swine erysipelas in the Union of South Africa
(Pretoria : The Government Printer, 1944) Haig, D.A.; Adelaar, T.F.; Du Toit, P.J.
1. A case of swine erysipelas was encountered for the first time in South Africa. 2. A description of the post-mortem lesions is given. 3. The bacteriological and biological properties of the bacillus isolated in pure culture from the valvular lesions of the heart are given.
The influence of solar radiation on the course of bluetongue
(Pretoria : The Government Printer, 1944) Neitz, W.O.; Riemerschmid, G.; Du Toit, P.J.
1. Experiments which clearly indicate the detrimental influence of solar radiation on the course of bluetongue are described. 2. Preliminary experiments were carried out during different seasons of the year in a limited number of sheep. Some of them were photosensitized against light with methyleneblue. During the course of the disease the sheep were exposed to solar radiation daily for several hours. 3. The result was, that the exposed sheep showed distinctly severer reactions than those kept in the stable. The strongest and most fatal reactions (6 out of 10 sheep died) were observed during a test conducted in February, when the solar radiation was very intense. Exposure during winter (June) had practically no influence on the course of the disease. 4. In order to verify these observations, two experiments on a large scale (60 sheep each) were undertaken on sheep subjected to the immunization process. Half the sheep were kept in the stable and the other half freely exposed to solar radiation. In each locality half of the sheep were shorn, the others remained unshorn. 5. The body temperatures and the nature of the clinical symptoms showed that the reactions were much more pronounced in the camp than in the stable. The symptoms of bluetongue were most pronounced in the shorn animals in the sun. 6. Since a distinct influence on the severity of bluetongue reactions was noticed in sheep photosensitized with methyleneblue, it is believed that sheep in the field may react very severely to this disease if they become photosensitized naturally. 7. Bronchopneumonia in sheep photosensitized with methyleneblue occurred on several occasions and developed sometimes very rapidly. This observation suggests that natural photosensitization in the field may partly be responsible for the bronchopneumonia which is frequently observed in sheep m the field reacting to bluetongue. 8. During the course of the above investigations, multiple haemorrhages and muscular degeneration, a lesion which had not been previously associated with bluetongue, were observed in the stabled as well as in the exposed sheep. This observation gives an explanation to the general weakness, torticollis and stiffness of the sheep reacting to bluetongue. 9. The unthriftiness frequently observed in sheep after immunization or natural infection can also be attributed to the muscular degeneration. 10. Since the influence of solar radiation on the course of bluetongue has definitely been established, particular attention should be paid to the time of the year when the immunization is carried out. On account of the fact that the severest reactions were observed in shorn sheep, immunization should preferably be undertaken on unshorn sheep. 11. The provision of shade for sheep which have been vaccinated or which contracted the disease naturally should be promoted wherever possible in order to exclude the harmful influence of solar radiation on the course of bluetongue.
The susceptibility of the springbuck (Antidorcas marsupialis) to heartwater
(Pretoria : The Government Printer, 1944) Neitz, W.O.; Du Toit, P.J.
1. Observations on the association of heartwater with springbuck are recorded. 2. The significance of this association is discussed briefly.

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