1968 Onderstepoort Journal of Veterinary Research, Volume 35, 1968

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Contentes Pages: Onderstepoort Journal of Veterinary Research, Vol 35, 1968

CONTENTS

*Volume 35: Number 1*

New concepts on the epidemiological features of bovine besnoitiosis as determined by laboratory and field investigations	Bigalke, RD	3

Electron microscopic study of the information of bluetongue virus	Lecatsas, G	139

Electron microscopic studies on reovirus type 1 in BHK 21 cells	Lecatsas, G	151

The epizootiology of helminth infestation in sheep in the south-western districts of the Cape	Muller, GL	159

The pathological physiology of helminth infestation. lll. Trichostrongylus colubriformis	Horak, IG, Clark, R & Gray, RS	195

Studies on Filaroides osleri infestation in dogs	Dorrington, JE	225

An anthelmintic test for larval stages of sheep nematodes	Reinecke, RK	287


*Volume 35: Number 2*

Ovarian function, follicular oestradiol-17ß, and luteal progesterone and 20a-hydroxy-pregn-4-en-3-one in cycling and pregnant equines	Van Rensburg, SJ & Van Niekerk, CH	301

Biochemical studies on geeldikkop and enzootic icterus	Brown, JMM	319

Author index		577

Subject index		578

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Now showing 1 - 11 of 11

Biochemical studies on geeldikkop and enzootic icterus
(Pretoria : Government Printer, 1968) Brown, J.M.M.; Jansen, B.C.
The haematology, chemical pathology, disturbed biochemistry, general enzymology and histopathology of geeldikkop, enzootic icterus and icterogenin intoxication in sheep are presented in full for the first time. The relationship of geeldikkop to enzootic icterus is demonstrated and both diseases are shown to be the result of sudden catastrophic failures of membrane permeability in various tissues of the body. The conditions are thought to be two different manifestations of a single disease entity, possibly low grade selenium intoxication. The acute manifestations are precipitated by various forms of non-specific stress the effects of which, on sheep from the areas where the diseases are enzootic, are described. One of the most important factors in this regard is thought to be a virus infection similar in nature to bluetongue. The chemical pathology and haematology of mild bluetongue infections in sheep are thus described in detail. The chemical nature of the ovine bile pigments is described and methods are given for their isolation and identification, as well as for the isolation of bromsulphalein conjugates formed by the ovine liver. Methods are given for the determination of copper in body fluids and tissues, the various copper fractions in blood, and iron and selenium in body tissues. The diagnosis of ovine liver, renal and adrenal dysfunction and myopathy by means of clinical laboratory tests is fully dealt with. Intermediary metabolism in the ovine red cell is discussed and activity levels of numerous metabolic enzymes in these cells are presented for consideration. Carbohydrate metabolism in the sheep as it is revealed by a study of the disturbances seen in geeldikkop forms an important theme of this thesis.
Subject index
(Pretoria : Government Printer, 1968)
Author index
(Pretoria : Government Printer, 1968)
Ovarian function, follicular oestradiol-17β, and luteal progesterone and 20α-hydroxy-pregn-4-en-3-one in cycling and pregnant equines
(Pretoria : Government Printer, 1968) Van Rensburg, S.J.; Van Niekerk, C.H.; Jansen, B.C.
Reproductive patterns were studied in the majority of 46 mares before obtaining the ovaries for examination at slaughter. Steroids identified and determined were progesterone and 20∝-hydroxypregn-4-en-3-one in the corpora lutea and oestradiol- 17 β in the follicular fluid. A study of ovarian morphology revealed no significant cyclical variations of the ovarian weight and number of follicles, but the total volume of follicular fluid increased in the latter half of the cycle. Consistent and marked follicular growth was present at about the 25th day of gestation. Mares 16 to 28 days pregnant had significantly more follicles than cycling mares, and the ovarian weight and volume of follicular fluid were also increased at this time. Peak total oestradiol values at 25 days and maximal progesterone concentrations at 27 days preceded implantation on the 28th day. Oestradiol was present before puberty and the amount in anoestrous animals seems to increase gradually as the breeding season approaches. In cycling mares, total follicular fluid oestradiol values are variable for up to five days after ovulation, but oestradiol is virtually absent during the mid-luteal period. From the 12th day there is a rapid increase to maximal values immediately prior to oestrus. Limited evidence suggests that ovarian oestradiol decreases from the commencement of oestrus. Pregnant animals exhibit an indistinguishable pro-oestrual rise, but drop suddenly when oestrus would be expected on the 17th day. When more than one corpus luteum was present and after two months gestation, no oestradiol was detected. Waves of follicular growth and oestradiol synthesis commence at 2, 12, 22 and 32 days after ovulation, suggesting a cyclical release of pituitary gonadotrophin every 10 days, irrespective of whether an active corpus luteum is present or not. Maximal follicular growth during pregnancy was encountered at 25 days, before the appearance of PMSG. Actual ovulation was only encountered soon after the– expected appearance of PMSG, suggesting a synergistic effect between PMSG and pituitary gonadotrophin. When steroidal inhibition of pituitary gonadotrophin increased and PMSG levels were maximal, the ovaries were relatively quiescent. Many active luteinized follicles were encountered as PMSG levels waned. Luteal progesterone concentrations rose linearly for 14 days; in cycling mares, regression took place on the 14th or 15th day. In pregnant animals the concentration continued to rise, reaching a peak at 27 days. Secondary corpora lutea, resulting from ovulations during the second month of gestation, had an initial concentration resembling cycling animals, but marked increases were found during the third month of gestation. The primary corpus luteum does not regress with the occurrence of secondary ovulations as is generally believed, but remains active for at least three months. 20∝-Hydroxypregn-4- en- 3- one was always present in the corpora lutea of cycling animals and increases were associated with luteal regression. This steroid was never detected in animals more than 18 days pregnant, including fresh secondary corpora lutea. The ovaries of mules contained similar amounts of steroids as found in horses. However, the occurrence of ovulation in the presence of functional corpora lutea suggests failure of the luteal regression mechanism, or alternatively an inability of the hypothalamus to regulate gonadotrophin secretion in the usual manner. The theoretical implications of these findings on sterility work are discussed.
An anthelmintic test for larval stages of sheep nematodes
(Pretoria : Government Printer, 1968) Reinecke, R.K.; Jansen, B.C.
A test for the evaluation of anthelmintics against the larval stages of nematodes is described. Worm-free lambs are given doses of infective larvae of several species of nematode in such a way as to ensure that all the developmental Stages are present on the day of treatment. The drug under test is administered by intraruminal injection on day 0 and controls are slaughtered on day 0 or day 1 and day 3 to ascertain the numbers of worms present at the time of dosing. The treated sheep are killed from days 1 to 3 after dosing. The worms are recovered by Shone's water bath method and counted. Details are given of all the techniques used in the test.
Studies on Filaroides osleri infestation in dogs
(Pretoria : Government Printer, 1968) Dorrington, J.E.; Jansen, B.C.
1. The early history of F. osleri together with its world-wide distribution is discussed. 2. The various breeds of dogs affected are listed showing that most breeds have been affected at some stage. 3. The South African history is traced showing how some breeds and studs were infested. 4. The various symptoms found with infestation by F. osleri are enumerated. 5. The factors influencing the pathogenesis are mentioned and discussed. 6. All breeds of dogs of all ages are equally susceptible. Reasons for the seemingly greater susceptibility of the newly born puppies are advanced. 7. Both the macroscopic and microscopic lesions of F. osleri infestation are described. Mention is also made of the morphology of the parasite. 8. Diagnostic methods are dealt with and only the reliability of examination with a bronchoscope advocated. 9. The differential diagnosis of the condition and possible pitfalls in diagnosis are discussed. 10. Observations on the life cycle indicates this to be direct with no evidence of intra-uterine transmission. 11. Both sexes of the host animal are equally susceptible. 12. Infestation of the host is acquired at a very early age under natural conditions, the larvae being transported to the predilection site via the lymphatic system. Migration experiments are discussed in detail as is the morphology of the migrating larvae. 13. Histopathological changes observed in the lymph nodes, liver and lungs are described, the absence of eosinophiles especially being noteworthy. 14. Various chemotherapeutic agents are evaluated together with a description of a surgical technique for the removal of nodules. 15. A completely successful treatment consisting of a course of caparsolate sodium followed by intratracheal surgery is described and discussed. 16. The need for the possible re-classification of F. osleri in the light of the evidence advanced is suggested. 17. Prophylactic measures are listed.
The pathological physiology of helminth infestation. lll. Trichostrongylus colubriformis
(Pretoria : Government Printer, 1968) Clark, R.; Gray, R.S.; Jansen, B.C.; Horak, Ivan Gerard
Trials are described in which the reactions of 11 sheep infested with T. colubriformis and 11 uninfected controls were studied in detail. The main findings in the acute disease were anorexia, retention of ingesta in the rumen and abomasum, diarrhoea, a severe hypo-albuminaemia and death 16 to 17 days after infestation. In the chronic disease there was a progressive decrease in feed intake and loss of body weight. Plasma albumin concentration decreased with a rise in plasma gamma globulin concentration later in the disease. A drop in packed red cell volume, haemoglobin concentration, red cell count, total volume of circulating erythrocytes and plasma inorganic phosphate was noted. There was a decrease in protein, phosphate and possibly selenium uptake leading to emaciation, muscular and myocardial atrophy and degeneration and eventually death.
The epizootiology of helminth infestation in sheep in the south-western districts of the Cape
(Pretoria : Government Printer, 1968) Muller, G.L.; Jansen, B.C.
1. The epizootiology of nematode parasites of sheep was investigated at the Outeniqua Experimental Farm, George, Cape Province. 2. There was a negative correlation between temperature and the availability of infective larvae on the pasture. During spring and summer when the mean average mean temperatures exceeded 20° C, low recoveries were recorded; whereas maximum recoveries were made when the mean temperature varied between 14° and 17° C in autumn and winter. 3. The major parasites at Outeniqua were Trichostrongylus spp., Ostertagia spp. and to a lesser degree H. contortus, Cooperia spp. and Nematodirus spp. 4. Flocks acquired massive worm burdens during the cooler months of the year, from autumn to spring. 5. The massive build-up of retarded fourth stage larvae and immature adults is a physiological process in the life-cycle, whereby the parasite ensures itself of optimal circumstances for survival against adverse climatic conditions.
Electron microscopic studies on reovirus type 1 in BHK 21 cells
(Pretoria : Government Printer, 1968) Lecatsas, G.; Jansen, B.C.
BHK 21 cells infected with reovirus Type 1 were sampled at various stages during a single cycle of virus replication, sectioned and studied with the electron microscope. Attention is drawn to cytopathic characteristics shown by the infected cell which are absent from uninfected cells. On the basis of similarities with bluetongue virus it is suggested that the nucleic acid moiety of the virus particles may be incompletely inserted in the capsid. This may be due to incomplete coiling up of the nucleic acid before condensation of the capsid around the nucleic acid or incomplete packing in of the nucleic acid into a preformed capsid or possible leaking out of the nucleic acid from the formed virus particle.
Electron microscopic study of the information of bluetongue virus
(Pretoria : Government Printer, 1968) Lecatsas, G.; Jansen, B.C.
BHK 21 cells infected with bluetongue virus were sampled at various stages during a single cycle of viral replication, sectioned and studied with the electron microscope. Stages in development of the virus have been recorded including initial penetration into the cell and eventual exit from the cell of mature particles. This study indicates that bluetongue virus essentially has no envelope. Successive characteristics shown by the cells include: (1) appearance of dense inclusion bodies; (2) swelling of the endoplasmic reticulum; (3) the appearance of masses of fine filaments m the cytoplasm; (4) the presence of mitochondria containing dense inclusion bodies; (5) the appearance of bundles of tubular elements; (6) the presence of irregular, dense bodies containing virus particles and (7) incipient and mature virus particles.
New concepts on the epidemiological features of bovine besnoitiosis as determined by laboratory and field investigations
(Pretoria : Government Printer, 1968) Bigalke, R.D.; Jansen, B.C.
(1) The central theme of this investigation was the part played by the chronically infected beast in the epidemiology of bovine besnoitiosis. The incentive was provided by the discovery that cyst organisms of B. besnoiti were transmissible to rabbits and cattle by inoculation. It brought the long-neglected, indomitable chronic case into the picture as a life-long reservoir. (2) Transmission was observed to occur if susceptible cattle were allowed to cohabit with chronic cases in open paddocks. All the animals contracted a clinically in apparent form of the disease. About 50 per cent developed relatively small numbers of SC cysts, and in one-fifth of them cysts were detected in skin sections. In the other half immunity to challenge was the only evidence of infection. Transmission was almost exclusively confined to cattle that were in direct contact with the carriers, indicating a mode of transmission that operated over relatively short distances only. Venereal transmission could be excluded because infection occurred irrespective of whether or not bulls were present. (3) These results, together with the well-known summer seasonal incidence, implied that mechanical transfer of the disease by a blood-sucking arthropod was a very likely mode of transmission. The feasibility of mechanical transmission was therefore investigated in rabbits using G. brevipalpis as tool and chronically infected cattle as donors. The majority became infected and developed typical reactions. The experiments were extended to cattle. They all contracted a rather mild form of the disease with no anasarca or scleroderma. Tsetse flies were no longer infective when tested three hours after potentially infective feeds, and there was no indication of cyclical development of the parasite within them. They also transmitted proliferative forms mechanically from rabbit to rabbit. (4) The study was extended to flies that inhabit enzootic regions. Tabanid flies were also capable of transmitting cyst forms mechanically. Even a single fly could infect a rabbit. Cattle developed mild to fairly severe reactions but again no anasarca and scleroderma were evident. Tabanids remained infective by bite for 24 hours and were shown by rabbit inoculation with triturated flies to harbour viable organisms in their bodies for 29 hours after feeding; there was no sign of cyclical development in the three species tested. Gut smears of newly caught horse flies revealed the presence of flagellates, the "barleycorn" (choanomastigote) forms of which were remarkably similar to B. besnoiti at a cursory glance. Morphological, cultural and infectivity studies on rabbits and cattle indicated that they bore no relationship to B. besnoiti. The flagellates were apparently developmental stages of Crithidia and Blastocrithidia or Trypanosoma spp. Attempts to relate them to T. theileri were inconclusive. (5) S. calcitrans also transmitted cyst organisms mechanically to rabbits and an ox. Subinoculation of small numbers of triturated flies into rabbits revealed that they had no difficulty in penetrating cysts and imbibing organisms, but large numbers of flies were required to transmit the disease mechanically. After ingestion organisms remained infective for an hour only and no biological development occurred. Three of the twelve attempts to isolate B. besnoiti from recently engorged stable flies that had been caught in an open paddock containing some chronically infected cattle were successful, which indicated that they also penetrated cysts when feeding naturally. (6) Even C. simpsoni and unidentified Culex spp. penetrated cysts and ingested organisms, which retained their infectivity for up to 50 hours. (7) Successful transmission in the experiment where cattle were exposed to conditions of cohabitation indicated that the transmissibility of B. besnoiti by various natural openings should be reinvestigated. Hamsters were susceptible to infection by ingestion of, as well as by inoculation with, tissues harbouring proliferative forms and cysts. Proliferation was enhanced, and symptoms of paralysis were seen in hamsters injected with cortisone. Rabbits could be infected quite readily by intranasal instillation of cyst organisms, but the conjunctival sac was a less reliable route. Cattle were susceptible to proliferative but not to cyst forms administered by mouth. Cyst organisms were, however, infective if dosed via the nostrils. Cattle developed fairly mild but quite distinct reactions with no anasarca or scleroderma. It is, however, difficult to envisage how cattle could be exposed to infection by these routes in nature.

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