Control and monitoring: control strategies for Plum pox virus in Canada

In 2000, Plum pox virus (PPV) was discovered in Canada in the provinces of Ontario and Nova Scotia. Delimitation surveys were used to define quarantine areas. An eradication strategy was developed based on a threshold value for virus incidence which triggered removal of the entire orchard block. Each year the threshold value is being lowered until reaching a zero tolerance level. Growers are compensated financially for their losses. A two-tiered certification programme was designed to provide clean replacement trees. Initially, growers planted PPV-tested trees as an interim measure until fully virus-tested stock became available. It is hoped that this eradication programme will eliminate PPV from Canada by 2010.     

Acute cortisol responses of calves to scoop dehorning using local anaesthesia and/or cautery of the wound

Objective To measure plasma cortisol responses in calves dehorned using a scoop after administration of local anaesthesia and/or cautery of the wounds.
Design A physiological study with controls.
Procedure There were six treatments: control handling with and without local anaesthesia, dehorning, dehorning after local anaesthesia, dehorning followed by wound cautery, and dehorning after local anaesthesia followed by wound cautery. Blood samples were taken before and after dehorning.
Results Dehorning caused an increase in plasma cortisol concentrations, which decreased a little to plateau values and then declined to pretreatment values 3 to 4 h after dehorning. The peak was smaller after local anaesthesia was administered but when its effects wore off, cortisol concentrations increased and thereafter were similar to those in the dehorned animals. The combination of local anaesthesia and cautery resulted in a plasma cortisol response similar to those in control calves with or without local anaesthesia.
Conclusions If plasma cortisol concentrations reflect the distress being experienced by the calves, then local anaesthesia reduces the acute distress for about 3 h after dehorning but not during the subsequent 3 to 4 h. Combining local anaesthetic and cautery prevented the significant increase in plasma cortisol following dehorning and may eliminate the acute distress caused by scoop dehorning.     

Prevalence and genotypic characterisation of Giardia in dairy calves from Western Australia and Western Canada

In this study, the prevalence of Giardia duodenalis infections was determined in Western Canadian and Western Australian dairy calves. Faecal samples were collected from Holstein calves located on a commercial dairy near Lethbridge, Alta., Canada (N=28) and from calves located on two commercial dairies located near Perth, WA, Australia (N=36). Faecal samples were examined for the presence of Giardia cysts using sucrose gradient centrifugation, followed by immunofluoresence microscopy. DNA was then extracted from Giardia isolates obtained from positive samples. A PCR based method was employed to amplify and sequence a 292bp region of the 16S-rRNA gene. Genetic sequences obtained from Giardia isolates were compared to each other and to previously sequenced isolates. Following a single faecal sample, 58% of Western Australian calves and 57% of Western Canadian calves were positive for Giardia. Geometric mean cyst counts/g of faeces were 839 for Western Australian calves and 3475 for Western Canadian calves, but these values did not differ significantly. Genetic sequences were obtained from 10 calves from Western Canada, while six sequences were obtained from Western Australian calves. Of the Western Canadian isolates, eight aligned with the proposed 'Hoofed livestock' genotype. Of the five isolates obtained from Western Australian calves, four sequences were identical to the 'Hoofed livestock' genotype. Two isolates from the Western Canadian calves and one isolate from the Western Australian calves had the identical genetic sequence to the Genotype (Assemblage) A sequence, a common human genotype. The results of this study demonstrate, for the first time, that Giardia infections occur in Western Australian calves. Also, calves from different geographical locations appear to be primarily infected with a Giardia genotype unique to hoofed livestock. However, calves can shed Giardia cysts potentially infective for humans. Thus, Giardia infections should be considered important to Australian dairy producers, and infections in calves may pose a risk to public health regardless of geographical location.     

COMPARISON OF AQUACULTURE EXTENSION IMPACTS IN BANGLADESH

ABSTRACT

Production from small scale pond aquaculture in Bangladesh trebled in the decade to 1999 under the influence of extension projects of the Department of Fisheries. The impacts of completed aquaculture extension projects and practices of former participants have rarely been investigated so this was done for four past projects. The different extension approaches were: extension with credit and intensive or little supervision; demonstrations; group extension and informal extension by fry traders; and adaptive research-development. Generally extension recipients and non-participants had similar sized landholdings, but demonstration farmers had larger farms and ponds. Extension recipients mainly received information from project-related sources and rated its utility highly. Neighbours and control farmers mainly obtained information from mass media and other farmers, over 90% of these households also cultivated fish. Extension recipients generally followed better practices: for example stocking fewer fingerlings and achieving higher production than non-participants, but with wide variations. Training of fry traders appeared to reduce overstocking in general probably due to the advice of fry traders. Overall, 2–6 years after extension the recipients have continued to farm fish, have a fair understanding of good practice and achieve reasonable yields. Limited demonstration effects occurred. Extension through group approaches and informal agents seem to be cost effective for the many pond owners in Bangladesh.     

Adrenocortical suppression in the dog given a single intramuscular dose of prednisone or triamcinolone acetonide

Adrenocortical function was assessed in dogs given a single intramuscular dose of either prednisone or triamcinolone acetonide (TCA; or saline solution to controls) to determine the duration of adrenocortical suppression caused by 2 commonly used glucocorticoids. The glucocorticoids were administered at recommended therapeutic doses; therefore, dogs given prednisone received a greater amount of glucocorticoid activity than did in dogs given TCA. Basal and ACTH-stimulated plasma cortisol concentrations, as determined by radioimmunoassay, were obtained once a week. Total intravascular eosinophil concentration and skin responses to intradermally injected histamine phosphate were quantitated. Dogs given TCA showed suppressed basal and ACTH-stimulated plasma cortisol concentrations 1 week after injection; the latter change persisted 2 weeks after injection. Adrenocortical function in 1 of 4 dogs given TCA remained suppressed for 4 weeks. In contrast, prednisone did not significantly alter adrenocortical function. Although intravascular eosinophil concentrations did not vary among groups, skin responses to intradermally injected histamine phosphate were reduced 6 days after prednisone and TCA were given.     

Effect of adrenalectomy in the dog on blood gas tensions and oxygen content.

Arterial and venous blood gas tensions and pH were determined in 8 dogs during a control interval, while adrenal deficient, and following replacement therapy with corticosteroids. Additionally, erythrocyte 2,3-diphosphoglycerate (DPG) values were measured, and oxygen tension (mm of Hg) when hemoglobin is half-saturated with oxygen (P50) values were calculated. Mixed venous oxygen tension (PVO2), but not arterial oxygen tension (Pao2), decreased significantly (P less than 0.001) during adrenal insufficiency. This change was reflected in a significantly decreased (P less than 0.001) venous oxygen content and a significant increase (P less than 0.001) of the arterial-venous oxygen content difference. Other changes during adrenal insufficiency were nonsignificant decreases in DPG and P50 values. Treatment with corticosteroids for 2 to 3 days resulted in a significant (P less than 0.001) increase in DPG concentrations, a significant (P less than 0.025) increase in P50, and a reduction in the arterial-venous oxygen content difference compared with those values found in the adrenal-deficient dog.     

Idiopathic hepatic veno-occlusive disease causing Budd-Chiari-like syndrome in a cat

Budd-Chiari-like syndrome (BCLS) is a rare clinical entity characterised by portal hypertension and ascites. This report describes a case of BCLS in a cat due to obstruction at the level of the hepatic veins. The diagnosis was based on the clinical findings and a histopathological assessment of the liver demonstrating perivenular fibrosis around the central and sublobular veins. Although these lesions are similar to those observed in man with BCLS, the aetiology in this case remains unknown.     

Ectopic hepatocellular carcinoma in a dog

CASE HISTORY: A 14-year-old neutered male Bearded Collie was presented with a history of recurrent, intermittent urinary incontinence of 7 years duration. CLINICAL FINDINGS: A large, firm, non-painful mass was found in the mid-abdominal region on palpation. Ultrasonography of the mass revealed a compartmentalised structure with mixed echogenicity, and which did not appear to be associated with any of the abdominal organs. Ultrasound-guided fine needle aspirates contained several clusters of epithelial cells with cytological features of hepatocytes. At exploratory laparotomy, the mass was found in the gastrosplenic ligament within the greater omentum. PATHOLOGICAL FINDINGS AND DIAGNOSIS: Histopathologically, the mass consisted of sheets of hepatocytes, but without the characteristic hepatic architecture. The cells showed moderate variation in nuclear size and were sometimes binucleate. A diagnosis of hepatocellular carcinoma (HCC) in the mesentery was made. CLINICAL RELEVANCE: The presence of ectopic hepatic tissue has been reported rarely in man and cats, but not in the dog. Neoplastic transformation of ectopic hepatic tissue is seen in man. This is the first report of the presentation, clinical findings and treatment of a dog with ectopic HCC.