Relating plant and pathogen development to optimise fungicide control of phoma stem canker (<Emphasis Type="Italic">Leptosphaeria maculans</Emphasis>) on winter oilseed rape (<Emphasis Type="Italic">Brassica</Emphasis><Emphasis Type="Italic">napus</Emphasis>)

In winter oilseed rape experiments at Rothamsted in 2000/01 to 2002/03 growing seasons, the severity of phoma stem canker epidemics in summer depended on the timing of phoma leaf spot epidemics in the previous autumn, and hence on the timing of Leptosphaeria maculans ascospore release. The first major release of L. maculans ascospores was earlier in 2000 (26 September) and 2001 (18 September) than in 2002 (21 October). Consequently, the autumn phoma leaf spot epidemic was also earlier in 2000 and 2001 than in 2002. The resulting stem canker epidemics were severe by harvest (July) in 2001 and 2002 but not in 2003. No correlation was found between the severity or duration of phoma leaf spotting (lesion days or lesion °C-days) and the subsequent severity of phoma stem canker epidemics. Rates of leaf production and loss were similar in the three growing seasons. Out of ca. 25 leaves produced on plants during each season, leaf numbers 10–14 generally remained on plants for the longest. Treatment with flusilazole + carbendazim in autumn decreased the severity of phoma leaf spotting for several weeks after treatment, decreased the severity of stem canker the following summer and increased yield significantly in 2001 and 2002 but not in 2003. The most effective timings for flusilazole + carbendazim application were when leaves 7–11 were present on most plants and at least 10% of plants were affected by phoma leaf spot. Two half-dose applications of fungicide reduced phoma stem canker and increased yield more than a single full dose application when phoma leaf spot epidemics were early (<800 °C-days after sowing).     

Integrated disease management of ascochyta blight in pulse crops

Ascochyta blight causes significant yield loss in pulse crops worldwide. Integrated disease management is essential to take advantage of cultivars with partial resistance to this disease. The most effective practices, established by decades of research, use a combination of disease-free seed, destruction or avoidance of inoculum sources, manipulation of sowing dates, seed and foliar fungicides, and cultivars with improved resistance. An understanding of the pathosystems and the inter-relationship between host, pathogen and the environment is essential to be able to make correct decisions for disease control without compromising the agronomic or economic ideal. For individual pathosystems, some components of the integrated management principles may need to be given greater consideration than others. For instance, destruction of infested residue may be incompatible with no or minimum tillage practices, or rotation intervals may need to be extended in environments that slow the speed of residue decomposition. For ascochyta-susceptible chickpeas the use of disease-free seed, or seed treatments, is crucial as seed-borne infection is highly effective as primary inoculum and epidemics develop rapidly from foci in favourable conditions. Implemented fungicide strategies differ according to cultivar resistance and the control efficacy of fungicides, and the effectiveness of genetic resistance varies according to seasonal conditions. Studies are being undertaken to develop advanced decision support tools to assist growers in making more informed decisions regarding fungicide and agronomic practices for disease control.     

Multiple ligamentous injuries of the canine stifle joint: a study of 12 cases

Multiple ligamentous injuries of the canine stifle are uncommon. In this study, they affected mainly adult, male, working or sporting dogs and occurred secondary to severe trauma, or where chronic joint infection had weakened the supporting structures. Rupture of the cranial cruciate, caudal cruciate and lateral collateral ligaments was the most common injury observed and this occurred after catching the limb in a fence or gate. Reconstruction of the collateral and cranial cruciate ligaments, and careful repair of damaged menisci and joint capsule, was an effective method of treatment for medium- and large-size dogs. Reconstruction of the caudal cruciate ligament and postoperative limb support was not found to be essential. All dogs with subluxated stifles had good to excellent limb function with minimal loss of mid-thigh circumference or stifle joint range of motion at follow-up. Less favourable results were achieved where there was stifle joint luxation with extensive disruption to secondary joint restraints.     

A Syndrome Resembling Idiopathic Noncirrhotic Portal Hypertension in 4 Young Doberman Pinschers

We describe 4 young male Doberman Pinschers (3 littermates and 1 unrelated dog) with a syndrome resembling idiopathic or noncirrhotic portal hypertension of humans. Each dog was evaluated for a hepatopathy resulting in portal hypertension, development of portosystemic collateral vessels, and hepatic encephalopathy. These dogs differ from previous reports of young dogs with hepatic insufficiency associated with portal hypertension and acquired portal systemic shunting by their lack of intrahepatic arteriovenous fistulae, portal vein atresia, or intrahepatic fibrosis. Clinicopathologic features included erythrocyte microcytosis, normal to mildly increased liver enzyme activities, increased concentrations of serum bile acids, reduced plasma indocyanine green clearance, and normal total bilirubin concentration. Abdominal ultrasonography disclosed a small liver and portosystemic collateral vessels. Radiographic imaging studies confirmed hepatofugal portal circulation and discounted hepatic arteriovenous fistulae. Histopathologic features in liver tissue from each dog were similar and consistent in all sections examined. Common findings included increased cross-sectional views of hepatic arterioles; hepatic lobular atrophy; scanty increase in connective tissue around some large portal triads; and absence of inflammation, disturbed lobular architecture, bile duct proliferation, or intrahepatic cholestasis.     

Feline ocular toxoplasmosis

Ocular infection with Toxoplasma gondii is a well-recognized and important clinical entity in many animal species. In the cat, ocular toxoplasmosis is commonly associated with systemic infection, yet its role in causing anterior uveitis in an otherwise healthy cat is unclear. The purpose of this article is to review the salient epidemiological, clinical, and histopathologic features of systemic and ocular toxoplasmosis in the cat. Additionally, pathogenesis and possible immunopathogenic mechanisms of ocular toxoplasmosis, which may account for the higher prevalence of anterior uveitis in cats seropositive for T. gondii , are discussed. Finally, diagnosis, treatment and prevention of feline toxoplasmosis are reviewed.     

Growth rates and survival of western rock lobster (Panulirus cygnus) at two temperatures (ambient and 23 °C) and two feeding frequencies

Wild caught post-pueruli, year one and year two post settlement juvenile western rock lobster, Panulirus cygnus, were held at ambient temperatures (15.6 °C to 23.1 °C; mean 19.0 ± 0.07 °C) or at 23 °C, and fed the same ration of a formulated pellet diet either once per night, or 3 times per night, over 12 months, to determine whether elevated temperatures and multiple feeds per night would stimulate growth through increased metabolism and feed utilisation without significant negative impacts on survival. Survival of post-pueruli (mean 63%) did not differ between ambient and 23 °C. Survival of year 1 and 2 juveniles was higher at ambient temperatures (p < 0.01 ambient: year 1 juveniles, 68%; year 2 juveniles, 88%; 23 °C: 57% and 74%, respectively). Feeding frequency did not affect survival of post-pueruli and year 2 juveniles (mean 63%, 81% respectively), but survival was 9% higher for year 1 juveniles fed three times per night (58% versus 67%; p < 0.01). All lobsters grew faster at 23 °C than at ambient temperatures (p < 0.05), with the growth of post-pueruli almost doubled at 23 °C (weight gain at 23 °C versus ambient: post-pueruli, 18 438 % versus 9 915 %; year 1 juveniles 259% versus 165%; year 2 juveniles 23% versus 21%). Feed frequency did not influence the growth of year 1 and 2 juveniles. However, there was an interaction effect of temperature and feed frequency on post-pueruli where weight and carapace length were significantly higher at ambient temperatures when post-pueruli were fed three times a day, whereas at 23 °C weight and carapace length were significantly greater when fed once per day (p < 0.05). Feed intake (g pellet dry matter lobster^− 1 day^− 1) of pellet was higher at 23 °C for all lobsters (p < 0.05), but was the same between lobsters fed 3 times per night versus once per night. This study has shown that increasing temperatures to 23 °C significantly improved the growth of P. cygnus post-pueruli without any adverse effects on survival. The faster growth rates exhibited by year 1 and 2 juveniles at 23 °C may potentially offset their lower survival by significantly reducing culture period. There is no benefit of feeding P. cygnus multiple times at night in terms of growth and survival. The implications for P. cygnus culture are that temperatures should be maintained close to 23 °C during the entire growout period, with due care taken to minimise mortalities through adequate provision of food and shelter. Feeding P. cygnus once daily to excess just prior to dusk to co-incide with nocturnal feeding behaviour is recommended.     

Physiological Responses of Rainbow Trout Oncorhynchus mykiss to Crowding and Anesthesia with AQUI-S™

Abstract.— Following exposure to the anesthetic AQUI-S™, plasma cortisol concentration in immature rainbow trout was measured as (mean) 293 ± 48 ng/ mL, which was significantly ( P > 0.05) higher than the mean concentration in resting fish. Cortisol concentrations remained significantly ( P > 0.05) elevated for at least 24 h after treatment. This was accompanied by a significant increase and decrease in hematocrit and plasma potassium, respectively. These perturbations continued for at least 48 h following recovery from anesthesia. Plasma concentrations of total protein and sodium remained unchanged following anesthesia with AQUI-S™. Crowding stress is commonly encountered by fish during manipulation in aquaculture situations. Anesthetising fish prior to, and during, manipulation may reduce the associated stress. Changes in cortisol values resulting from crowding (30 min; 0.1 kg/L) during anesthesia with AQUI-S™ were not appreciably different from those in fish crowded without anesthesia. Thus, anesthesia with AQUI-S™ at the recommended dose of 17 mg/L did not appear to be effective for alleviating the stress of crowding under the conditions of our experiments.     

In vitro effects of malathion and O,O,S-trimethyl phosphorothioate on cytotoxic T-lymphocyte responses

Oral administration of O,O,S-trimethyl phosphorothioate (OOS), an impurity present in technical formulations of malathion, has been shown to be associated with a high incidence of pneumonia in rats and to be highly immunosuppressive in mice. Based on these findings, an in vitro model was established to study the effect of this and other organophosphorus compounds on murine cytotoxic T-lymphocyte (CTL) responses. The organophosphorus compounds were tested for their ability to block in vitro generation of CTL responses to alloantigen and/or the expression of these cytotoxic responses. Responses were generated in C57Bl/6 (H-2^b) spleen cells to mitomycin C-blocked P815 (H-2^d) tumor cells. The cytotoxicity of the cultured splenocytes to P815 target was measured using a 4-hr chromium release assay. These data demonstrated that malathion was able to block the ability of splenocytes to sensitize to P815 at concentrations as low as 25 μg/ml, but was not able to block the expression of cytotoxicity by mature killer T cells. The same was true for OOS which had been activated by preincubation with rat liver postmitochondrial supernatant (PMS). Activated OOS blocked the generation of CTL responses at concentrations as low as 75 μg/ml while having no effect on mature cytotoxic cells. In fact, both malathion and activated OOS were no longer able to suppress CTL responses if treatment was performed as early as 24 hr after exposure to antigen. Additionally, it was demonstrated that when malathion was preincubated with PMS it was no longer suppressive and that OOS without activation failed to suppress CTL responses.     

Acute Reactions in Dogs Treated with Doxorubicin: Increased Frequency with the Use of a Generic Formulation

During a 4-month period, 34 dogs with tumors received a total of 60 doses of a single generic formulation of doxorubicin; 13 acute drug reactions were observed in these 34 dogs, and no acute reactions were observed after replacing the product with the proprietary brand. These reactions were characterized by one or more of the following signs: pruritus; head-shaking; urticaria; erythema of the pinnal, axillary, or inguinal regions; vocalization; vomiting; hyperemic or pale mucous membranes; high heart rate; and high respiratory rate. We propose that a component unique to generic doxorubicin was responsible for the unusually high number of acute drug reactions observed.