Ulcerative enterocolitis in two goats associated with enterotoxin- and beta2 toxin-positive Clostridium perfringens type D

Enterotoxemia caused by Clostridium perfringens type D in sheep is believed to result from the action of epsilon toxin (ETX). However, the sole role of ETX in the intestinal changes of the acute and chronic forms of enterotoxemia in goats remains controversial, and the synergistic action of other C. perfringens toxins has been suggested previously. The current study examined 2 goats that were found dead without premonitory clinical signs. Gross lesions at necropsy consisted of multifocal fibrinonecrotic enterocolitis, edematous lungs, and excess pleural fluid. Histologically, there were multifocal fibrinonecrotic and ulcerative ileitis and colitis, edema of the colonic serosa, and proteinaceous interstitial edema of the lungs. Clostridium perfringens type D carrying the genes for enterotoxin (CPE) and beta2 toxin (CPB2) was cultured from intestinal content and feces of 1 of 2 goats, while C. perfringens type D CPB2-positive was isolated from the other animal. When multiple colonies of the primary isolations from both animals were tested by Western blot, most of the isolates expressed CPB2, and only a few isolates from the first case expressed CPE. Alpha toxin and ETX were detected in ileal and colonic contents and feces of both animals by antigen capture enzyme-linked immunosorbent assay. CPB2, but not CPE, was identified in the small and large intestines of both goats by immunohistochemistry. These findings indicate that CPB2 may have contributed to the necrotic changes observed in the intestine, possibly assisting ETX transit across the intestinal mucosa.     

Target-controlled infusion of propofol combined with variable rate infusion of remifentanil for anaesthesia of a dog with patent ductus arteriosus

An 18-month-old Lurcher was anaesthetized for surgical ligation of a patent ductus arteriosus using a target-controlled infusion (TCI) of propofol and a variable rate infusion of remifentanil. Before anaesthesia, radiographic and echocardiographic examination indicated that the dog had left-sided congestive heart failure and impaired left ventricular systolic function. Ramipril and furosemide were administered pre-operatively. Following pre-anaesthetic medication with morphine, 0.5 mg kg(-1), by intramuscular injection, and pre-oxygenation, remifentanil was infused for 5 minutes at 0.2 microg kg(-1) minute(-1), followed by induction of anaesthesia using intravenous propofol administered by TCI, set at a target concentration of 3.5 microg mL(-1) of propofol in blood. Tracheal intubation was performed and 100% oxygen delivered through a non-rebreathing (Bain) system and then a circle system in the operating theatre. Anaesthesia was maintained with propofol and remifentanil, adjusted according to clinical requirements. Peri-operative analgesia consisted of intercostal bupivacaine nerve block, with meloxicam, morphine and remifentanil.     

DEVELOPMENT OF REFERENCE INTERVALS FOR THE LARGE INTESTINAL TRANSIT OF RADIOPAQUE MARKERS IN DOGS

Ten healthy dogs were fed 30 1.5 mm and 10 5 mm radiopaque markers (BIPS, MedID, Grand Rapids) mixed with sufficient quantities of a high fibre diet to meet 25% of their estimated daily caloric requirements. Abdominal radiographs were made at two hour intervals until 90% of the small and large markers had left the colon. The mean residence times (MRT) of each size of marker in the proximal, distal and total colon were calculated using kinetic analysis. The MRT's of the small markers were 4.9 hours (SD 4.4), 7.1 hours (SD 3.3) and 12.0 hours (SD 7.1) respectively. The MRT's of the large markers were not significantly different from the small markers except in the proximal colon where they were significantly shorter (3.2 hours, SD 2.3). Reference colonic filling and colonic transit curves for both sizes of markers were constructed. These may be useful to detect abnormal colonic transit in dogs.     

Ecosystem structure and functioning of Lake Taihu (China) and the impacts of fishing

Lake Taihu is the third largest freshwater lake in China and has provided local communities with valuable fisheries for centuries. However, we have only a limited knowledge of its ecosystem. In this study, a trophic model was constructed for the Lake Taihu ecosystem. This model was used to evaluate and analyze the food web structure and other properties of this ecosystem using data covering the period from 1991 to 1995. Using the model, we evaluated the impacts on local fisheries of various management scenarios comprising two basic management regimes: (1) setting fishing mortality for the top predator (large culters, Erythroculter mongolicus and Erythroculter ilishaeformis) to 0, 0.3, 0.6, 0.9 and 1.2, and (2) adjusting overall fishing effort to 0.25, 0.5, 0.75 and 1.25 times the current level. For both scenarios, fishery profit and cost were evaluated to provide an understanding of how components of the ecosystem interact. We identified possible causes of fishery overexploitation in the lake ecosystem and described the necessity of developing ecosystem-based management. The results showed that Lake Taihu had six theoretical trophic levels (TLs), with the trophic flows primarily occurring through the first five TLs. System properties such as transfer efficiency, Finn's index, Finn's mean length, connectance index, system omnivory index, primary production/respiration ratio, and net primary production all indicated that Lake Taihu was an immature, fairly simple ecosystem in which a relatively low fraction of total primary production was utilized. At the same time, the ecosystem was also experiencing high fishing pressure. Yet despite this, the low ascendency index (25.9%) and high system overhead ratio (74.1%) indicated that the system was highly developed and relatively stable, a condition that might result from the high degree of recycling in the system. Among the harvesting strategies considered, a strategy of either decreasing the fishing mortality of the top predator (large culters) to 0.3 or, alternatively, reducing the overall effort on the system by a factor of 0.75 appeared to be most effective at increasing the efficiency of the fisheries.     

Examining horizontal and vertical social ties to achieve social–ecological fit in an emerging marine reserve network

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