A morphological study of the lesions of African horsesickness

Gross, histological and ultrastructural findings are described in 6 natural cases and in 2 experimental cases of African horsesickness. From the gross lesions the cases were divisible into 2 groups which represented the previously described pulmonary and mixed forms of the disease. Histologically, abundance of fibrin and inflammatory cells in oedematous lung suggests that the pulmonary lesion is an exudative pneumonia. Lymphoid depletion and necrosis in germinal centres were consistently present. Electron microscopy failed to demonstrate virus particles or virus-associated structures in the tissues. Ultrastructural evidence of vascular injury was not apparent in oedematous tissues. Possible mechanisms in the development of the lung oedema are considered and a comparison is made with oedema induced by alpha-naphthyl-thiourea. Lack of structural evidence of vascular injury revealed by this study extends some hope for therapy in African horsesickness.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Resistance of sheep to poisoning by the plant, Matricaria nigellifolia DC

The plant, Matricaria nigellifolia, was dosed to 2 sheep to reinvestigate whether or not sheep are susceptible to pushing disease ("stootsiekte"). Each sheep received a total dose of 370 g/kg of the milled, dried plant from a batch that had caused pushing disease in cattle when given at doses as low as 10 g/kg. Neither of the sheep developed clinical disease over the trial period of 60 days, and necropsies revealed no macro- or microscopical lesions. Sheep are apparently resistant to pushing disease, which supports previous findings.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.am201

Mycose cerebral£ chez un chien, causee par Cladosporium trichoides Emmons 1952

The fungus, Cladosporium trichoides, was isolated and cultured from a lesion in the cerebellum and from smaller lesions in the liver, kidney and spleen of a dog which had a history of behavioural changes, ataxia and collapse. Histopathological examination showed the cerebellar lesion to be a purulent granuloma which contained brown, septate hyphae and structures resembling conidia. The source of infection was not traced and no predisposing factors were apparent. As far as is known,this is the first record of the condition in animals in southern Africa and the first report anywhere of this condition in the dog.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

A suspected lipofuscin storage disease of sheep associated with ingestion of the plant, Trachyandra divaricata (Jacq.) Kunth

Paresis afflicted 85 out of a flock of 770 young Merino ewes kept on old wheat lands in the western Cape during a period of drought. Many of the paretic ewes died. The vegetation was sparse and was dominated by Trachyandra divaricata. At necropsy, yellowish-brown discoloration of the grey matter throughout the brain and spinal cord and mild brown discoloration of the liver, renal cortex and lymph nodes were consistently seen. Light microscopical examination revealed abundant, yellowish-brown pigment granules in the cytoplasm of most of the larger neurons. Similar pigment also occurred in some non-nervous tissues. Shrinkage and loss of a few randomly scattered axons were observed in the white matter of the spinal cord in 2 sheep. Histochemical and ultrastructural features of the pigment were consistent with those of lipofuscin. T. divaricata failed to reproduce the condition when dosed to a sheep, but the paresis and pigmentation shown to be caused by the closely related plant, T. laxa, are strikingly similar. Trachyandra poisoning appears to be the first documented example in farm animals of an acquired lipofuscin storage disease involving nervous and non-nervous tissues for which a specific plant has been causally implicated.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Bovine skin lesions of possible filarial origin associated with heavy hornfly infestations (Haematobia meridiana)

Circumscribed, ulcerative skin lesions, usually situated caudal to the scapula, affected cattle in the Republic of Venda during the summer of 1981-82. The occurrence of the lesions was associated with heavy infestations of the hornfly, Haematobia meridiana. Microscopically the lesions were characterized by intense eosinophilic dermatitis. Microfilariae were seen in histological sections of one lesion, but a species identification could not be made. The possible cause of the lesions is discussed.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Pathology of a nervous disorder (pushing disease or "stootsiekte") in cattle caused by the plant Matricaria nigellifolia DC. (Asteraceae)

Brains from 10 bovine field cases of pushing disease, a nervous disorder caused by the plant, Matricaria nigellifolia, were examined by light microscopy. Moderate to marked encephalitis, characterized by predominantly perivascular microgliosis, perivascular lymphocytic infiltrates and reactive changes in astrocytes, was present in all the brains. The lesion was concentrated in the white matter throughout the forebrain and midbrain. Dried, milled M. nigellifolia was dosed to 6 steers. Clinical signs of pushing disease, which included docility, clumsiness and pushing against objects, appeared abruptly in 5 of the steers after a latent period that varied from 16-44 days. The lowest total dose of plant that proved toxic was 10 g/kg. The length of the latent period appeared to be related inversely to the total dose. Encephalitis, which was similar in nature and distribution to those in the field cases, was demonstrated in the 5 affected steers. The lesion was minimal in the brain of the steer that did not develop pushing disease. The cerebral lesion is sufficiently consistent and distinctive to be useful in establishing a diagnosis of pushing disease. The perivascular distribution of microgliosis suggests that the site of the toxic insult is the cerebral vasculature. Botanical information is presented.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.am201

Measurements of mass, length and valve diameters from normal formalin-fixed ovine hearts

Hearts from 60 Merino sheep of known age, sex and live mass and with no known history of disease were collected and fixed in buffered 10% formalin. Systematic light microscopical examination did not indicate any abnormality in hearts of any of the sheep. The mass of various parts of the hearts, the length of the hearts and the diameters of the heart valves were measured to establish a basis for quantitative assessment of possible pathological changes associated with the ingestion of cardiotoxic plants. The mass measurements and, to a lesser degree, the lengths of the hearts varied considerably, but the ratio of the mass of the left ventricle plus ventricular septum divided by the right venticular free wall mass was remarkably stable, and is promising as an indicator of right ventricular hypertrophy.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.am201

Intoxication of cattle on kikuyu grass following army worm (Spodoptera exempta) invasion

Clinical features and pathological and mycological findings in a field outbreak of intoxication in dairy cattle grazing kikuyu grass are reported. The outbreak followed invasion of the grass by the army worm (Spodoptera exempta). Clinical signs included drooling of saliva, depression, apparent inco-ordination, sunken eyes, ruminal distension and atony, recumbency, moderate diarrhoea and ''sham drinking''. Seventy-seven cows (64%) were clinically affected over a period of 12 days. Of these, 37 died. Necropsies performed on 4 affected cattle revealed necrosis of the epithelium of the forestomach, which was consistently more severe in the omasum. Light microscopy showed extensive necrosis of the epithelium of the forestomach with associated fibrinopurulent inflammation. The stratum spinosum and s. granulosum were selectively involved, but the s. basale was generally preserved. Electron microscopical examination of ruminal and omasal epithelium from 2 of these cattle revealed cytopathological features in the s. spinosum and s. granulosum which were consistent with stages in an acute, anoxic type of injury. Mycological examination of the pastures revealed sparse growth of a mixed fungal population, which included Myrothecium verrucaria. There was no evidence of heavy fungal infestation. Previous evidence that M. verrucaria, or other fungi, may be involved in the aetiology of kikuyu grass poisoning of cattle in New Zealand is addressed. It appears improbable that any of the fungi isolated in this investigation could have played an important role in the aetiology of this outbreak.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

A tremorgenic mycotoxicosis of cattle caused by maize sprouts infested with Aspergillus clavatus

An outbreak of disease affecting a herd of 16 dairy cattle which were fed mouldy, sprouted maize is described. Eight of the cattle were affected, 5 of which died. The clinical signs included muscular tremors, hypersensitivity, ataxia, anorexia and salivation. Aspergillus clavatus was the only fungus isolated from the sprouts. Clinical signs that were indistinguishable from those in the field outbreak were reproduced by dosing the mouldy maize sprouts to a steer and a sheep, and by dosing another sheep with maize inoculated with a pure culture of A. clavatus isolated from the mouldy maize on the farm. Light microscopical examination revealed neuronal degeneration and necrosis in the midbrain, medulla oblongata and spinal cord of all 3 of these animals. The disease is clinically and pathologically indistinguishable from the disease caused by the ingestion of sorghum beer residue, and in certain respects it is similar to toxicoses caused by the ingestion of wheat sprouts and malt sprouts infested with A. clavatus.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.am201