Survey of equine castration techniques,preferences and outcomes among Australian veterinarians

Objectives

(1) To collect the perceptions of veterinarians performing equine castrations in Australia on techniques, preferences and outcomes, (2) to investigate veterinarian use and experience with the Henderson castrating instrument and (3) to investigate potential associations between demographics, castration methods and techniques, and complications.

Design

Online survey of members of the Australian Veterinary Association’s Special Interest Group, Equine Veterinarians Australia (EVA).

Methods

A link to the survey was included in the EVA e‐newsletter and practices on the EVA website were contacted by telephone and follow‐up email. Fisher’s exact test was used to determine associations between ligation and complications. A generalised linear model with a negative binomial family was used to determine associations between count response variables and categorical independent variables.

Results

Responses were obtained from 138 veterinarians (response rate, 13.1%) who performed 5330 castrations over 12 months. Castrations were most commonly performed in the field, on anaesthetised horses, using emasculators, via an open approach and without ligation of the spermatic cord. Estimated complications after use of emasculators were swelling (25%), haemorrhage (5%) and infection (5%). The Henderson instrument was used by approximately 10% of respondents and its use for castration was associated with fewer reports of postoperative swelling compared with emasculators (P = 0.002). Rates of evisceration with the Henderson and emasculator methods were comparable (0.43% and 0.9%, respectively).

Conclusion

Castration preferences varied widely among survey participants. Reported complication types and rates were comparable to those reported previously in other countries. Perceptions that the Henderson instrument was associated with less swelling should be investigated further via a prospective controlled investigation.     

Mites of the genus Carabodes (Acari,Oribatida) in Norwegian coniferous forests: occurrence in different soils,vegetation types and polypore hosts

Oribatid mites (Acari) represent a considerable part of the biodiversity in Fennoscandian forests, but our knowledge about their habitat requirements is limited. We studied 10 Carabodes species in the forest floor of seven coniferous forest types, and in dead fruiting bodies (sporocarps) of 6 species of wood-living polypore fungi in southern Norway. The most common Carabodes species in soil were rare in sporocarps, and vice versa. The density of several ground-living species was significantly influenced by vegetation type and soil type. Carabodes willmanni and C. subarcticus were considered as lichen feeders on the ground, and occurred abundantly in Cladonia-rich pine forests. Three species, C. femoralis, C. areolatus and C. reticulatus, seem to be sporocarp specialists. Their relative numbers were rather similar in dead sporocarps of five different fungal species, including annual and perennial sporocarps, soft and hard. This was in contrast to beetles from the same sporocarps, which in a previous study proved to be strongly host-specific. Although being tolerant to different fungal species, the association of certain Carabodes species to dead sporocarps could make them vulnerable in forests with little dead wood and few sporocarps.     

Characterisation of the microbiota associated with intestine of Atlantic cod (Gadus morhua L.): The effect of fish meal, standard soybean meal and a bioprocessed soybean meal

Populations of aerobic heterotrophic bacteria present in the gastrointestinal (GI) tract of healthy Atlantic cod (Gadus morhua L.) fed three different diets, fish meal, standard or a bioprocessed soybean meal (BPSBM), were estimated using the dilution plate technique. A total of 944 isolates were characterised by biochemical and physiological properties and 425 isolates were identified further by sequencing the 16S rRNA genes. Our results showed that gut microbiota were affected by dietary manipulation. The GI tract of fish fed fish meal was dominated by Gram-positive bacteria of the genera Brochothrix and Carnobacterium. The Gram-negative bacteria Chryseobacterium spp. and Psychrobacter glacincola, and Gram-positive bacteria belonging to Carnobacterium, dominated in the digestive tract of fish fed soybean meal. In contrast to these results, genus Psychrobacter dominated in the GI tract when fish were fed BPSBM.Until recently, it was generally suggested that the gut microbiota of fish were less diverse than in homoeothermic animals. However, the present study identified several “new” bacterial species isolated from the alimentary tract of Atlantic cod. These “new” bacterial species are not normally isolated from the GI tract of fish. Based on our finding we suggest that the GI tract microbiota of fish might not be as simple as believed.Antagonistic activity of carnobacteria regarding inhibition of growth of two fish pathogens (Aeromonas salmonicida ssp. salmonicida and Vibrio anguillarum) was observed. However, some difference in the antibacterial activity of Carnobacterium spp. was observed. Whether this antagonistic activity has any effect in challenge studies will be discussed, especially in relation to the finding that the digestive tract is one of the major infection routes in fish.     

Evidence for occurrence of an organophosphate-resistant type of acetylcholinesterase in strains of sea lice (Lepeophtheirus salmonis Krøyer)

Acetylcholinesterase (AChE) is the target of a major pesticide family, the organophosphates, which were extensively used as control agents of sea lice on farmed salmonids in the early 1990s. From the mid‐1990s the organophosphates dichlorvos and azamethiphos were seriously compromised by the development of resistance. AChE insensitive to organophosphate chemotherapeutants has been identified as a major resistance mechanism in numerous arthropod species, and in this study, target‐site resistance was confirmed in the crustacean Lepeophtheirus salmonis Krøyer isolated from several fish‐farming areas in Norway and Canada. A bimolecular rate assay demonstrated the presence of two AChE enzymes with different sensitivities towards azamethiphos, one that was rapidly inactivated and one that was very slowly inactivated. To our knowledge this is the first report of target‐site resistance towards organophosphates in a third class of arthropods, the Crustacea. Copyright © 2004 Society of Chemical Industry     

Low-voltage organic transistors on plastic comprising high-dielectric constant gate insulators

The gate bias dependence of the field-effect mobility in pentacene-based insulated gate field-effect transistors (IGFETs) was interpreted on the basis of the interaction of charge carriers with localized trap levels in the band gap. This understanding was used to design and fabricate IGFETs with mobility of more than 0.3 square centimeter per volt per second and current modulation of 10(5), with the use of amorphous metal oxide gate insulators. These values were obtained at operating voltage ranges as low as 5 volts, which are much smaller than previously reported results. An all-room-temperature fabrication process sequence was used, which enabled the demonstration of high-performance organic IGFETs on transparent plastic substrates, at low operating voltages for organic devices.     

Use of tilmicosin in a severe outbreak of respiratory disease in weaned beef calves

Severe respiratory disease, associated with seroconversion to bovine respiratory syncitial virus (BRSV), caused the death of two cattle and necessitated antibiotic treatment of 70 calves (rectal temperature of 39.6°C or greater) from a group of 96 (73%) during an 8-day period. Tilmicosin injection resulted in a reduction in median rectal temperature from 40.3°C to 39.2°C and 39.0°C for the first and second days after treatment. The rectal temperature was 39.5°C or lower in 72% (48 of 67) and 96% (64 of 67) of cattle 1 and 2 days after tilmicosin treatment, respectively. Ten cattle were re-treated with tilmicosin 6 to 16 days after the first treatment. Our study demonstrated that bovine respiratory syncytial virus infection could cause severe respiratory disease in a beef herd that had no previous history of BRSV-related disease. Secondary bacterial invasion after BRSV infection was controlled effectively by tilmicosin treatment but repeat antibiotic treatments were occasionally necessary due to bacterial re-infection of the respiratory tract.     

Analysis and management of resistance to chemotherapeutants in salmon lice,Lepeophtheirus salmonis (Copepoda: Caligidae)

In Northern Europe and Canada, the salmon louse, Lepeophtheirus salmonis (Kr?yer), seriously affects the marine phase of salmon production. Although the problem is long-standing, the development of sustainable methods of pest management has been unable to keep pace with the intensification of production, leading to large-scale reliance on very few chemotherapeutants. This runs the risk of selecting for genetically determined resistance in target organisms. There are many examples of similar evolutionary adaptations in arthropod pests of arable crops, livestock and human health. Several hundred pest species are now documented as being resistant to one or more chemical classes of insecticides and acaricides. Many of these compounds are identical or closely related to ones currently employed against salmon lice. It is, therefore, opportune to consider what lessons have been learnt from contending with resistance in terrestrial organisms, the implications for sustainable use of chemotherapeutants in aquaculture, and the potential for developing effective resistance management strategies. An EU-funded project named SEARCH (QLK2-CT-2000-00809) has been initiated to explore in more detail the diagnosis, incidence, dynamics and management of resistance to chemotherapeutants in L salmonis.     

Severity and persistence of footrot in Merino sheep experimentally infected with a protease thermostable strain of Dichelobacter nodosus at five sites

Objective To test the hypothesis that ovine footrot associated with a thermostable protease strain of Dichelobacter nodosus undergoes self cure or is sustained as an annually recurring disease, depending on the environment.
Design and procedure Forty Merino sheep from a single blood line were infected with a protease thermostable strain of D nodosus a t each of five sites in Western Australia. Footrot lesions and microscopic evidence of D nodosus were recorded every fortnight for 2.5 years, supplemented by laboratory culture. Rainfall, soil and air temperature, pasture quantity and composition and soil types were also recorded. Flocks that apparently self cured were relocated to a more favourable site for footrot in the final spring season.
Results The maximum prevalence of feet with clinical footrot lesions was 80.6, 1.3, 14.4, 3.8 and 88.1% at the five sites. Severe footrot occurred for three consecutive spring seasons at one site that had clay loam soil and at least 3500 kg/ha total pasture dry matter annually. However, the infection was asymptomatic for up to 10 weeks between outbreaks. D nodosus was isolated from flocks for 2.5 years at only two sites, although there was microscopic evidence of the organism at other sites in the final year. A thermolabile variant (strain U6) of D nodosus was isolated from the two sites where footrot persisted.
Conclusion Depending on time and location, ovine footrot induced by a protease thermostable strain of D nodosus either self cured or persisted as annual outbreaks interspersed with periods of asymptomatic infection.     

Use of 16S rRNA gene sequencing analysis to characterize culturable intestinal bacteria in Atlantic salmon (Salmo salar) fed diets with cellulose or non-starch polysaccharides from soy

Duplicate groups of Atlantic salmon (Salmo salar L.), kept in seawater, were fed fish meal‐based cold‐pelleted diets. Diets with non‐starch polysaccharides (NSP), either cellulose, purified soybean NSP or extruded purified soybean NSP at a dietary level of 100 g kg^?1, were compared with a diet without supplemental NSP and a diet with soybean meal in a 28‐day feeding trial. Isolation and characterizations were limited to culturable bacteria and population levels of aerobic and facultative aerobic heterotrophic autochthonous (adherent) and allochthonous (transient) bacteria present in the mid and distal intestines of Atlantic salmon fed the five different diets estimated using traditional bacteriological techniques. The presence of an autochthonous microbiota was demonstrated using transmission electron microscopy. No significant effects of diet composition were observed on total population levels of culturable bacteria present in the digestive tract, but the study showed that the composition of the gut microbiota (autochthonous or allochthonous) was sensitive to dietary changes. A total of 752 culturable isolates from the intestines were characterized by biochemical and physiological properties. Of these, 188 isolates were further characterized by partial sequencing the 16S rRNA genes. Among these, 146 isolates belonged to 31 phylotypes that were >94% identical to previously described species. However, 42 isolates showed similarity <94% to species available at the National Center of Biotechnology Information. Several of the phylotypes identified in the present study have not been reported previously in the gastrointestinal (GI) tract of fish, including the Gram‐negative bacteria Gelidibacter salicanalis, Pseudoalteromonas elyakovii, Psychrobacter aquimaris, Psychrobacter cibarius, Psychrobacter fozii, Psychrobacter maritimus, Psychrobacter okhotskensis and Psychrobacter psychrophilus. Among the Gram‐positive bacteria identified were Arthrobacter bergeri, Arthrobacter psychrolactophilus, Arthrobacter rhombi, Bacillus pumilus, Bacillus subtilis, Exiguobacterium spp., Microbacterium oxydans, Planococcus maritimus, Sporosarcina ginsengisoli and several bacteria that have been described as unculturable previously. In addition, we identified Carnobacterium inhibens, a lactic acid bacterium that is not frequently isolated from the GI tract of fish. Psychrobacter cibarius was the dominant bacterial species and was isolated from the digestive tract of all fish investigated.