A decision-support system for Salmonella in broiler-chicken flocks

We built a decision-support system to assess the risk of contamination of chicken-broiler flocks by Salmonella at the end of the rearing period. This system was developed from the survey data from 85 chicken-broiler flocks located in western France. First, we estimated the probability of contamination of the house by Salmonella before placement of day-old chicks via a cleansing inspection using a visual-inspection grid, a decontamination evaluation using count-plates, and risk factors for Salmonella persistence in the barn after cleansing and disinfection. Second, we estimated (using a logistic model) the probability of prevalent contamination of the flock by Salmonella at the end of the rearing period. Validation was carried out on 60 flocks selected from seven production companies in western France. The risk estimated by the model was compared to the Salmonella status of the flock (gold standard) assessed by samples taken from the environment of the broilers and analysed with classical bacteriological methods. The sensitivity was 97.8% and the specificity 64.3%.     

Recombinant equine growth hormone administration: effects on synovial fluid biomarkers and cartilage metabolism in horses

REASONS FOR PERFORMING STUDY: Recombinant equine growth hormone (reGH) has recently been evaluated for effects on body condition and wound healing. It has the potential to influence articular cartilage via stimulation of IGF-1. OBJECTIVES: To investigate effects of administration on synovial joint metabolism. METHODS: Six mature horses were given 20 microg/kg bwt reGH daily for 8 weeks by i.m. injection. Three control horses were injected with sterile water. Serum and synovial fluid samples were collected at 6, 8, 11 and 16 weeks for GH and IGF-1 assays. Articular cartilage harvested at week 16 was evaluated by Western analysis using monoclonal antibodies BC-13, BC-4, 8-A-4 and CH-3. RESULTS: Concentrations of IGF-1 in serum and synovial fluid were significantly elevated (P < 0.05) at 6 and 8 weeks in the reGH group. Glycosaminoglycan concentrations in synovial fluid were significantly less than controls at these time points, suggesting that reGH may modulate proteoglycan metabolism in articular cartilage. In the reGH group, there were not any alterations in synovial fluid content of 3B3(-) epitope or aggrecan metabolite, or in aggrecan or link protein catabolites retained within cartilage, that might be expected with development of osteoarthritis. CONCLUSIONS: Intramuscular administration of reGH may be a more efficient means of delivery of IGF-1 to joints for cartilage resurfacing initiatives. POTENTIAL RELEVANCE: We found no alterations in cartilage metabolism indicative of development of osteoarthritis.     

Comparison of the cardiopulmonary effects of anesthesia maintained by continuous infusion of romifidine,guaifenesin, and ketamine with anesthesia maintained by inhalation of halothane in horses

OBJECTIVE: To compare cardiopulmonary responses during anesthesia maintained with halothane and responses during anesthesia maintained by use of a total intravenous anesthetic (TIVA) regimen in horses. ANIMALS: 7 healthy adult horses (1 female, 6 geldings). PROCEDURE: Each horse was anesthetized twice. Romifidine was administered IV, and anesthesia was induced by IV administration of ketamine. Anesthesia was maintained for 75 minutes by administration of halothane (HA) or IV infusion of romifidine, guaifenesin, and ketamine (TIVA). The order for TIVA or HA was randomized. Cardiopulmonary variables were measured 40, 60, and 75 minutes after the start of HA orTIVA. RESULTS: Systolic, diastolic, and mean carotid arterial pressures, velocity time integral, and peak acceleration of aortic blood flow were greater, and systolic, diastolic, and mean pulmonary arterial pressure were lower at all time points for TIVA than for HA. Pre-ejection period was shorter and ejection time was longer for TIVA than for HA. Heart rate was greater for HA at 60 minutes. Minute ventilation and alveolar ventilation were greater and inspiratory time was longer for TIVA than for HA at 75 minutes. The PaCO2 was higher at 60 and 75 minutes for HA than forTIVA. CONCLUSIONS AND CLINICAL RELEVANCE: Horses receiving a constant-rate infusion of romifidine, guaifenesin, and ketamine maintained higher arterial blood pressures than when they were administered HA. There was some indication that left ventricular function may be better during TIVA, but influences of preload and afterload on measured variables could account for some of these differences.     

Localization of Transmissible and Nontransmissible Viruses in the Vector Nematode Xiphinema americanum

ABSTRACT The inner lining of the food canal of nematodes that transmit plantinfecting viruses is regarded as the retention region of viruses. To characterize the location of transmissible and nontransmissible viruses in the vector nematode Xiphinema americanum, three nepoviruses, Tobacco ringspot virus (TRSV), Tomato ringspot virus(TomRSV), and Cherry leaf roll virus(CLRV), and one non-nematode-transmissible virus, Squash mosaic virus (SqMV), were evaluated for transmission efficiency and localization sites in the nematode. Transmission trials showed highest transmission efficiency for TomRSV (38% with 1 and 100% with 10 nematodes, respectively), intermediate efficiency for TRSV (27% with 1 and 65% with 10 nematodes, respectively), and no transmission for CLRV and SqMV. Electron microscopy and immunofluorescent labeling revealed that TRSV was primarily localized to the lining of the lumen of the stylet extension and the anterior esophagus, but only rarely in the triradiate lumen. Within a nematode population, particles of TRSV were no longer observed in these three regions 10 weeks after acquisition, and it is assumed that there was gradual and random loss of the virus from these areas. The percentage of nematodes that were labeled by virus-specific immunofluorescent labeling in a population of viruliferous nematodes decreased gradually after TRSV acquisition when the nematodes were placed on a nonhost of the virus, and the loss of immunofluorescent labeling paralleled the decrease in the ability of the nematode population to transmit the virus. TomRSV was localized only in the triradiate lumen based on thin-section electron microscopy. No virus-like particles were observed in any part of the food canal of nematodes that had fed on CLRV-infected plants. Virus-like particles that appeared to be partially degraded were observed only in the triradiate lumen of nematodes that had fed on SqMV-infected plants. These results clarified the status of localization of two nontransmissible viruses in X. americanum and presented evidence that two nematode-transmissible viruses, TRSV and TomRSV, are localized in different regions of the food canal of X. americanum.     

Some safety aspects of salmonella vaccines for poultry: distribution and persistence of three Salmonella typhimurium live vaccines

The purpose of this study was to analyze the safety characteristics of three commercially available live Salmonella vaccine strains (vacT, Zoosaloral, and X3985) in relation to their persistence in individual animals but also within a flock and in the environment. In a first experiment, the digestive and systemic distributions in chickens were followed for 10 days in individually reared chickens that were orally inoculated at 1 day of age. Strain X3985 quickly disappeared from the digestive tract but remained in the liver until the end of this experiment, whereas strains vacT and Zoosaloral colonized the liver as well as the gut for 10 days. In the second trial, behavior of the vaccine strains was studied in groups of 20 chickens during 10 wk after a single oral administration to individual birds. Strain vacT remained in the environment of inoculated animals for 4-5 wk. Six weeks after the inoculation, vacT was not recovered from internal organs such as liver and spleen, and vacT disappeared from the digestive tract between the sixth and the 10th weeks. Comparatively, both Zoosaloral and X3985 vaccine strains persisted longer in the environment (8 wk at least). Of the vaccine strains, X3985 showed the greatest colonization of both systemic and digestive organs.     

Issues associated with the application to veterinarians of a mailed questionnaire regarding lower respiratory-tract disease in racehorses

This study evaluated a questionnaire investigating the attitudes and behaviours of veterinarians regarding the cause, diagnosis and treatment of lower respiratory-tract disease in racehorses. The questionnaire was sent to all non-student members (648) of the Australian Equine Veterinary Association: two mailings and a single telephone contact (each separated by four weeks). Subsequent phases were only administered to those who had not responded to earlier phases. In total, 467 (72.1%) of the 648 mailed questionnaires were returned. Of these, 354 were usable. The remaining 113 respondents gave various reasons for not completing the questionnaire; the most common (68%) was that horses were not a component of their practice. Those respondents working primarily with horses required fewer phases to return the questionnaire. Although deviating from previously described questionnaire designs, the described protocol provided a reasonable response rate.     

Acute onset of pulmonary necrotising arteritis in a dog with a left-to-right patent ductus arteriosus

A 12-week-old, clinically normal Chihuahua was referred for investigation for a continuous heart murmur. Cardiac evaluation revealed an anatomically and haemodynamically typical left-to-right shunting patent ductus arteriosus. The continuous wave Doppler measurement of peak ductal jet velocity of 5.6 m/s was suggestive of a normal pulmonary to systemic arterial pressure ratio. The dog returned 16 days later with right heart failure and severe pulmonary hypertension. Marked reduction in left-to-right shunting was demonstrated and the ductal jet velocity had decreased to 2.5 m/s. Immediate ductus ligation, oxygen therapy before and after the operation, and administration of hydralazine failed to reduce pulmonary hypertension, and the dog was euthanased. Histopathological examination of the lung showed pulmonary necrotising arteritis with acute and chronic arterial lesions. Chronic pulmonary vascular changes related to high flow have been associated with altered nitric oxide and endothelin responses. These changes may be responsible for the acute onset of pulmonary hypertension due to relatively minor vascular insults in some human and veterinary patients with left-to-right shunts. The potential for acute progression supports the recommendations for early ductus ligation and the prognostic importance of detecting pulmonary hypertension presurgically in patent ductus arteriosus patients.