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21.
Dawson A Harvey RE Thevasagayam SJ Sherington J Peters AR 《The Veterinary record》2002,151(18):535-538
The field efficacy and safety of a single-dose Mycoplasma hyopneumoniae vaccine were evaluated in three-to five-week-old pigs. Two field efficacy studies were conducted, one in England with 673 pigs, and one in Germany with 719 pigs. The pigs were injected intramuscularly with either the vaccine or saline (control) at a ratio of 2:1 and reared under commercial conditions to slaughter weight. The efficacy of the vaccine was evaluated by comparing the lung lesions associated with infection with M. hyopneumoniae in the control and vaccinated animals postmortem. In both countries the vaccinated pigs had a significantly lower percentage of lung lesion scores, in England 5.7 v 10.2 per cent (P = 0.0022) and in Germany 3.9 v 7.7 per cent (P = 0.0056). In Germany the average daily weight gain (ADG) of the vaccinated pigs was significantly higher (639 g v 616 g) (P = 0.0205). In both countries and in both the treated and control animals there was a significant negative correlation between the ADG and the lung lesion score (P = 0.0001). Two safety trials were conducted, one in England and one in Germany, each with 75 pigs, and in each case 50 pigs were given the maximum batch release antigen titre of the vaccine and 25 were given saline. The safety of the vaccine was evaluated by observation for local and systemic reactions and any increases in rectal temperature. No abnormal reactions were observed in the vaccinated pigs and there was no significant difference between the mean peak rectal temperatures of the vaccinated and control pigs in either trial. 相似文献
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D A Dzanis L Krook H J Harvey F A Kallfelz 《American journal of veterinary research》1990,51(4):682-687
The feasibility of renal arterial infusion of nonbiodegradable microspheres as a model of chronic renal disease in dogs was evaluated. Resin-coated, styrene-divinyl benzene copolymer microspheres were infused into the kidneys of healthy adult Beagles by direct injections of both renal arteries in a single surgical procedure. Injections of 25-microns diameter microspheres had minimal effect on either the clinical status or serum values of the dogs. Histologic examination revealed the majority of the microspheres lodged within the capillary beds of the glomeruli, and little change to the kidneys. However, injections of 50-microns diameter microspheres caused significant increases in serum concentrations of urea nitrogen and creatinine. Histologically, the larger microspheres obstructed afferent arterioles and small arteries, which caused diffuse glomerular necrosis and nephron damage. With doses ranging from 1 to 3 million microspheres/dog, a correlation between the quantity of microspheres injected and severity of renal damage was observed. The optimal dose for producing a model of moderate renal disease was determined to be 1.8 million microspheres/dog (0.9 million microspheres/kidney). During long-term studies, microsphere-injected dogs fed a moderately restricted protein ration remained relatively azotemic, compared with control dogs on the identical ration. During the 5-month postsurgical period, the serum urea nitrogen concentration averaged 18.41 +/- 1.59 mg/dl (mean +/- SE) for the microsphere-injected dogs vs 9.31 +/- 0.38 for the control dogs (P less than 0.001). Similarly, the mean serum creatinine value was significantly higher (P = 0.020) for the microsphere-injected dogs, compared with the controls (1.23 +/- 0.12 mg/dl vs 0.94 +/- 0.03).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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- 1. River lamprey (Lampetra fluviatilis) and sea lamprey (Petromyzon marinus) are designated features of the River Derwent Special Area of Conservation (SAC) and the Humber Estuary (a possible SAC). This study determined the condition of lamprey populations in the Yorkshire Ouse catchment by assessing the species composition, distribution, abundance and size‐structure of larval (ammocoete) populations in five major tributary rivers (Derwent, Swale, Ure, Nidd and Wharfe).
- 2. According to EU condition assessment criteria, Lampetra populations (assumed to be mostly river lamprey) are at present in favourable condition, with site mean (±SE) densities ranging from 2.7 (±1.2) to 160.3 (±50.5) individuals m?2 (all river means >2 individuals m?2), and at least two size (≈age) classes present in optimal microhabitats. By contrast, no sea lamprey larvae were recorded, suggesting that populations of this species are in unfavourable condition.
- 3. Actions to protect and enhance nationally or internationally important stocks must be implemented from at least a catchment perspective, because many of the issues affecting such species are not localized. With respect to lampreys, particular attention should be given to protecting spawning and nursery habitats, improving water quality, reducing impingement at abstraction points, preventing exploitation at spawning grounds and increasing passage at potential physical obstructions.
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