Relationship between incidence of gastric dilatation-volvulus and biometeorologic events in a population of military working dogs

OBJECTIVE: To calculate the monthly incidence of gastric dilatation-volvulus (GDV) in a population of military working dogs during a 5-year period and determine whether there was an association with synoptic climatologic indices. SAMPLE POPULATION: Medical records of all military working dogs housed at Lackland Air Force Base,Tex, from Jan 1, 1993 to Dec 31, 1997. PROCEDURE: Confirmed cases of GDV were identified from evaluation of medical records and used to calculate incidence of GDV. Factor analysis of local climatologic data was used to classify each day into 1 of 8 meteorologically homogeneous types of days for this location. Occurrence of GDV was compared with frequency of occurrence of synoptic climatologic days. RESULTS: 48 cases of GDV were identified from January 1993 through December 1997 Mean monthly incidence was 2.5 cases/1,000 dogs at risk (range, 0 to 18.5 cases/1,000 dogs; median, 2.5 cases/1,000 dogs). A seasonal increase in incidence of GDV was detected, because half of the episodes were during November, December, and January. An association with a specific synoptic climatologic day was not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Seasonal fluctuations in incidence of GDV may be associated with external factors that precipitate physiologic changes resulting in GDV. Although a specific cause-effect relationship was not documented, clinicians must be alert for the potential of seasonal variation in incidence of GDV and accordingly heighten their index of suspicion for the condition, particularly in populations of dogs that are predisposed to development of GDV.     

Simulation study of the competitive ability of erect, semi-erect and prostrate cowpea (Vigna unguiculata) genotypes

Ecophysiological simulation models provide a quantitative method to predict the effects of management practices, plant characteristics and environmental factors on crop and weed growth and competition. The INTERCOM interplant competition model was parameterised, calibrated by monoculture data for three cowpea (Vigna unguiculata) genotypes that differed in growth habit, common sunflower (Helianthus annuus) and common purslane (Portulaca oleracea), and used to simulate competition of cowpea cover crops with sunflower or purslane. The simulation results were compared with observations from field competition experiments in 2003 and 2004. INTERCOM more accurately simulated actual field data for the competition of cowpea genotypes and sunflower than companion field experiments for the competition of cowpea and purslane. The validated simulation model of cowpea and sunflower at two densities was used to study the effects of cowpea growth habit on final biomass production of cowpea and sunflower. The model suggested that erect growth habit was more competitive than semi‐erect and prostrate growth habit, when cowpea genotypes were grown with sunflower. Cowpea leaf area distribution was important to higher cowpea biomass production, while cowpea height growth was important to reduce sunflower biomass. Our simulation approach is suggested as a method for crop breeders to gauge the likely success of selection for competitive crops before undertaking expensive long‐term breeding experiments.     

rep-PCR-Mediated Genomic Fingerprinting: A Rapid and Effective Method to Identify Clavibacter michiganensis

ABSTRACT The genomic DNA fingerprinting technique known as repetitive-sequence-based polymerase chain reaction (rep-PCR) was evaluated as a tool to differentiate subspecies of Clavibacter michiganensis, with special emphasis on C. michiganensis subsp. michiganensis, the pathogen responsible for bacterial canker of tomato. DNA primers (REP, ERIC, and BOX), corresponding to conserved repetitive element motifs in the genomes of diverse bacterial species, were used to generate genomic fingerprints of C. michiganensis subsp. michiganensis, C. michiganensis subsp. sepedonicus, C. michiganensis subsp. nebraskensis, C. michiganensis subsp. tessellarius, and C. michiganensis subsp. insidiosum. The rep-PCR-generated patterns of DNA fragments observed after agarose gel electrophoresis support the current division of C. michiganensis into five subspecies. In addition, the rep-PCR fingerprints identified at least four types (A, B, C, and D) within C. michiganensis subsp. michiganensis based on limited DNA polymorphisms; the ability to differentiate individual strains may be of potential use in studies on the epidemiology and host-pathogen interactions of this organism. In addition, we have recovered from diseased tomato plants a relatively large number of naturally occurring avirulent C. michiganensis subsp. michiganensis strains with rep-PCR fingerprints identical to those of virulent C. michiganensis subsp. michiganensis strains.     

A controlled vaccination trial for Newcastle disease under village conditions

All the poultry in each of four distinct Moroccan villages were vaccinated against Newcastle disease using Hitchner B1 and inactivated vaccines. Poultry in a fifth village were monitored as controls. Mortality in the poultry was followed for 20 weeks after the first vaccination and blood samples were taken every 4 weeks from chickens for estimation of antibodies against Newcastle disease virus. Sixty-three percent of the chicken population and 60% of the turkey population in the control village died during the 20 weeks of observation. Necropsied birds showed lesions consistent with Newcastle disease. Mortality did not exceed 22% in the vaccinated villages.     

Reproductive failure in mink and ferrets after intravenous or oral inoculation of Campylobacter jejuni.

Four pregnant mink and seven pregnant ferrets, including five with previous exposure and specific antibody, were injected intravenously with 10(8)-10(10) colony-forming units of Campylobacter jejuni. All 11 pregnancies failed 1-16 days after infection, with results ranging from fetal resorption to expulsion of dead or premature living kits. In every case, uterine contents (placenta, uterine fluid and/or kits) were culture-positive for C. jejuni. Three pregnant mink and nine pregnant ferrets, including four with previous exposure and antibody, were fed 10(9)-10(11) C. jejuni. Two of the mink aborted; kits of all three were culture-positive, but those of one female survived. Seven of the nine ferrets aborted, with two having culture-positive uterine contents. None of 28 uninfected ferret control pregnancies ended in abortion. The most prominent histological feature observed was severe placentitis, which appears to be a more likely cause of Campylobacter-induced abortion than direct pathogenic effects on infected kits. These results suggest that infection of mink or ferrets with C. jejuni during pregnancy poses a serious risk of reproductive failure, even for previously exposed females.     

Comparison of artificial light sources and lighting programmes for laying hens on long ahemeral light cycles

Three lighting treatments were given to laying hens, for which the bright and dim light of 28-h ahemeral light cycles was provided by incandescent (tungsten filament) lamps only or by combinations of tubular fluorescent or compact gas-discharge lamps with incandescent lamps. There were no differences in entrainment (the proportion of eggs laid in 4, 6 or 8 h modal periods) between the three bright:dim treatments. A fourth ahemeral lighting treatment in which the dim lights were extinguished except during a designated work period (09.00 h to 12.00 h daily) was termed bright:dim:dark. Hens given the bright:dim:dark treatment showed an increased entrainment compared with the three bright:dim light treatments. There were no differences (P greater than 0.05) in egg numbers or mean egg weight between all 4 lighting treatments. Birds given the bright:dim:dark treatment tended to have a lower (P greater than 0.05) food intake compared to the three bright:dim treatments.     

Red cell population distributions in healthy dogs

Red blood cells population distributions were studied in puppies and in mature beagle dogs using the Coulter Channelyzer C-1000. Weekly measurements over a period of six months indicated that only minor fluctuations in population distribution indices occurred. Normal range studies showed that although mean cell volume was similar in young and older dogs, young dogs showed an approximately 12.5 per cent greater volume range due to an increased presence of both larger and smaller cells. The red cell population distributions conformed to a single log normal distribution. A mild anaemia was induced in mature dogs. Compensation for this led to transient changes from the usual log normal shape of the red cell population distribution.