Adrenal teratoma in an ox     

PW LADDS  P. RUSSELL†  RA FOSTER 《Australian veterinary journal》1990,67(12):464-465

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BOOK REVIEW     

RA Read 《Australian veterinary journal》1990,67(11):424-424

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Influence of alternative treatment strategies on the output of strongyle eggs in the faeces of horses     

ER HUNT  RA WOODWARD  CG MORRISON 《Australian veterinary journal》1996,74(2):159-161

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Chronic cervical compressive myelopathy in horses: clinical correlations with spinal cord alterations     

JV YOVICH  RA LeCOUTEUR†  DH GOULD† 《Australian veterinary journal》1991,68(10):326-334

Histological examination was performed on the cervical spinal cord from 13 horses with chronic cervical compressive myelopathy of 4 to 29 months duration. Structural alterations were correlated with clinical features. At the level of compression, the spinal cord was grossly deformed. Histological alterations included nerve fibre swelling and degeneration, occasional spheroids, astrocytic gliosis, increased macrophage activity and increased perivascular collagen. Myelin degeneration or loss at the level of the compressive lesion was greatest in the ventral and lateral funiculi and less consistently present in the dorsal funiculi. Asymmetry of lesions in the dorsal funiculi was associated with asymmetry of clinical signs in 5 horses. Histological alterations in areas of Wallerian degeneration were similar to that at the level of spinal cord compression, except that perivascular collagen was not increased. Wallerian degeneration was present cranial to the compressed site in the superficial portions of the lateral funiculi and in the middle of the dorsal funiculi. Caudal to the compressed site it was present in the ventral funiculi adjacent to the ventral median fissure and in the middle of the lateral funiculi. Deformation of the spinal cord did not correlate with the severity or duration of clinical signs but was positively correlated with the amount of perivascular collagen increase. The amount of nerve fibre swelling was not correlated with the severity of clinical signs but was negatively correlated with their duration. A rapid loss of nerve fibres apparently occurred early in the course of compression, since there was a marked decrease in the amount of nerve fibre swelling and Marchi stained degenerating myelin with increasing clinical duration.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Influence of landscape structure on local and regional climate   总被引：21，自引：1，他引：20  

R. A. Pielke  R. Avissar 《Landscape Ecology》1990,4(2-3):133-155

This paper discusses the physical linkage between the surface and the atmosphere, and demonstrates how even slight changes in surface conditions can have a pronounced effect on weather and climate. Observational and modeling evidence are presented to demonstrate the influence of landscape type on the overlying atmospheric conditions. The albedo, and the fractional partitioning of atmospheric turbulent heat flux into sensible and latent fluxes is shown to be particularly important in directly affecting local and regional weather and climate. It is concluded that adequate assessment of global climate and climate change cannot be achieved unless mesoscale landscape characteristics and their changes over time can be accurately determined.  相似文献   

Evaluating baseline data for trace elements,pH, organic matter content,and bulk density in agricultural soils in Nigeria     

Chrysanthus Chukwuma Sr. 《Water, air, and soil pollution》1996,86(1-4):13-34

Agricultural soil samples were collected about 1 km apart over 21 km from 32 tilled/cultivated plots of yam, rice, and cassava in urban, rural, and the derelict Enyibga lead-zinc mine (EM) in the Abakaliki area, Nigeria during the rainy season in September, 1992. In the derelict mine, mean elemental contents increased in the order Cd < Ni < Cu < Mn < Pb < Zn; while in the urban, rural, and all soils combined, the order increased as follows: Cd < Cu < Ni < Pb < Zn < Mn. The overall mean distribution of all soils shows Mn and Zn to approach and exceed toxic levels, respectively. In all soils, the total mean concentrations of Cu and Ni are well below toxic levels. The Abakaliki area is less likely to be subjected to Cd-contaminated soils. Pb was excessively high at EM and, moderately high at Mgbowo Street in the urban area, but very less so in the rural areas. The rural agricultural areas of Agbaja, Nkwaegu, and Amaegu, including the isolated Ezza Road as well as the peripheral Expressway had relatively lower levels of heavy metals, pH and organic matter content than the urban conglomeration of Mile 50, Mgbowo Street, and Azuiyiokwu including the derelict mining village of Enyigba and EM; except that Ezza Road had pH and organic matter as high as the densely populated urban cultivated areas. The relationship between bulk density and organic matter was highly dependent on pH.  相似文献   

An outbreak of avian malaria in captive yellowheads/mohua (Mohoua ochrocephala)     

MR Alley  RA Fairley  DG Martin  L Howe  T Atkinson 《New Zealand veterinary journal》2013,61(5):247-251

CASE HISTORY: Eight mohua, or yellowheads (Mohoua ochrocephala), were held in a large open aviary over the summer months of 2003–2004, following their capture for captivebreeding purposes. Two birds died of transportation trauma shortly after arrival, one became ill and died a month later, and another four died within a 2-week period in February 2004. The eighth bird also became ill at this time but survived for a year following treatment with chloroquine and doxycycline.

CLINICAL AND PATHOLOGICAL FINDINGS: The affected birds were depressed, lethargic and dyspnoeic. Necropsy of three birds showed a slightly pale and swollen liver and spleen. Impression smears of the liver of one bird revealed schizonts resembling Plasmodium spp. within the cytoplasm of many hepatocytes, which was confirmed histopathologically. Similar protozoal organisms were seen within splenic histiocytes and pulmonary endothelial cells of 5/6 birds. Electron microscopy identified these as protozoal schizonts containing merozoites of similar size and structure to those of Plasmodium spp.

DIAGNOSIS: The birds were infected with a protozoal haemoparasite resembling Plasmodium spp.; asexual stages within hepatocytes and endothelial cells of the lung and spleen were typical of this organism.

CONCLUSIONS AND CLINICAL RELEVANCE: The mohua captured from west Otago were highly susceptible to avian malaria as they came from an isolated population that was likely to be naïve and have had no previous contact with this organism. The birds were probably infected by bites from mosquitoes feeding off local populations of blackbirds subsequently found to be infected with Plasmodium spp.  相似文献   

Failure of zinc supplementation to prevent severe facial eczema in cattle fed excess copper     

C Dawson  RA Laven 《New Zealand veterinary journal》2013,61(6):353-355

CASE HISTORY: A 400-cow dairy unit in the Waikato suffered a severe outbreak of facial eczema (FE) despite consistent zinc supplementation and significantly elevated serum zinc concentrations.

CLINICAL FINDINGS: FE prevention had begun in mid-January 2006, via zinc sulphate supplementation in the water. Photosensitisation was reported on 06 April, contemporaneous with a marked increase in the number of Pithomyces chartarum spores in pasture samples. Within 10 days of this first clinical case, 100 affected cows had been dried off, eight of which subsequently died or were culled. Blood samples were collected from ten affected cows; all had serum zinc concentrations >17 µmol/L, and eight had gamma-glutamyl transferase (GGT) activities >200 U/ml, indicating that the photosensitisation was secondary to liver damage, i.e. probably FE. Further investigation identified that this herd had been receiving excess copper supplementation; 4/6 culled cows had liver copper concentrations within or above the marginal range for copper toxicity.

DIAGNOSIS: Severe FE despite zinc supplementation that increased serum zinc concentrations above recommended levels

CLINICAL RELEVANCE: As zinc supplementation significantly reduces apparent copper status, copper supplementation is often used to counteract this. Previous excess copper intake may reduce the efficacy of zinc in preventing FE, thus copper intake should be assessed prior to the start of zinc supplementation.  相似文献   

Lesions in the brains of three cattle resembling the lesions of enterotoxaemia in lambs     

RA Fairley 《New Zealand veterinary journal》2013,61(5):356-358

CASE HISTORY: A 3-month-old female Angus calf was found dead, and two adult Friesian dairy cows died soon after developing nervous signs.

PATHOLOGICAL FINDINGS: Grossly, bilateral and mostly symmetrical areas of haemorrhage were evident that mainly involved areas of grey matter in the brainstem from the level of the caudal colliculi to the thalamus and, in one, the internal capsule and caudate nucleus. In the occipital and caudal parietal cortex, there was extensive oedema of white matter. Histologically, in addition to haemorrhage, there was protein-rich oedema around arterioles and venules in the cerebrum, hippocampus, internal capsule, thalamus, midbrain, dorsal medulla, and central cerebellar and cerebellar folial white matter. The calf's brain had bilateral and symmetrical oedema and necrosis affecting several brainstem nuclei and the occipital grey matter overlying areas of oedema of the corona radiata.

DIAGNOSIS: Although the cause was not established, the perivascular lesions resembled those produced in calves by the intravenous administration of epsilon toxin.

CLINICAL RELEVANCE: It is possible that epsilon toxin-induced enterotoxaemia occurs naturally in cattle, and where bilateral haemorrhage is recognised in the brains of cattle, small intestinal contents should be collected for analysis of epsilon toxin.  相似文献   

Drenching adult ewes: Implications of anthelmintic treatments pre- and post-lambing on the development of anthelmintic resistance     

DM Leathwick  CM Miller  DS Atkinson  NA Haack  RA Alexander  A-M Oliver 《New Zealand veterinary journal》2013,61(6):297-304

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