Evaluation of sodium percarbonate as a bath treatment for amoebic gill disease in Atlantic salmon

Amoebic gill disease (AGD), caused by Neoparamoeba perurans, is a major health challenge for Atlantic salmon aquaculture globally. While freshwater bathing for 2 hr is effective in reducing infection severity, there is need for more rapid and lower cost alternatives. To this end, a combination of sodium percarbonate (SPC) in freshwater was examined for its treatment efficacy. Initial in vitro studies showed a reduction in amoeba viability when exposed for 30 min to freshwater containing >500 mg/L SPC. Subsequently, AGD‐affected salmon were bathed for 30 min in 16°C freshwater containing 100, 500 or 1,000 mg/L SPC, or for 2 hr in 16°C freshwater to mimic industry practice. Treatment at the highest SPC concentration caused extensive gill damage and substantial mortality. Neither occurred to a significant extent at lower SPC concentrations. Gill pathology of surviving fish 10 days post‐treatment (dpt) was comparable to or more severe than pre‐treatment, and significantly (p < .001) more severe than in 2 hr freshwater bathed fish. N. perurans DNA was confirmed by qPCR in all treatment groups at 10 dpt. The data indicate that a 30‐min exposure to SPC in freshwater is not a suitable alternative to existing freshwater treatment of AGD.     

Effect of Two Novel Experimental Microdiet Types on Growth,Survival, and Pigmentation during the Weaning Period of the Fine Flounder,Paralichthys adspersus,Larvae

The aim of this study was to evaluate two new types of experimental weaning microdiets for fish larvae, using the same formulation, but with different manufacturing processes, microextrusion marumerization (MEM) and particle‐assisted rotational agglomeration (PARA). Both microdiets were compared to a commercial microdiet, Otohime? (OTO), during the weaning of the fine flounder, Paralichthys adspersus . Weaning was achieved by cofeeding with live food from 40 to 50 d after hatch (d.a.h.). Thereafter, only the microdiets were fed to the end of the study (60 d.a.h.), where the total length, dry weight, and survival rates were 15.9 ± 3.20, 14.3 ± 1.72, and 14.4 ± 2.28 mm; 8.83 ± 3.40, 5.53 ± 2.85, and 7.10 ± 3.56 mg; 18.1, 16.3, and 15.2%, for OTO, MEM, and PARA, respectively. The dry weight and total length were significantly higher (P < 0.05) for larvae fed OTO compared with those fed MEM. There were no differences between the other comparisons. Based on these results, any of the two experimental microdiets can be used for future investigations. However, we recommend the PARA microdiets because the manufacturing process produces less‐dense and smaller particle size diets, reducing sinking rates and increasing the probability of the larvae in detecting and ingesting the diet.     

The role of metabolic enzymes in insecticide-resistant colorado potato beetles

Several metabolic enzymes were assayed in susceptible and insecticide-resistant (R-mfo and R-AchE) strains of the Colorado potato beetle (Leptinotarsa decemlineata Say). We compared the activities of esterases, glutathione transferases and mixed function oxidases, and measured in-vivo metabolism of carbofuran to determine the contributions of metabolic factors to the observed resistance. There were no substantial differences between strains in α- or β-naphthylacetate hydrolysis, or in glutathione transferase activity. Compared to the susceptible strain, the R-mfo strain showed 4-fold higher activity in both ethoxyresorufin-O-dealkylase, and pentoxyresorufin-O-dealkylase activity. The R-AChE strain had a 1.5-fold higher level of ethoxyresorufin-O-dealkylase activity. Correspondingly, the in-vivo metabolism of carbofuran was highest in the R-mfo strain, and the R-AChE strain was slightly higher than the susceptible strain. These results are discussed in relation to other resistance mechanisms which we have examined in these strains.     

MOTION-CORRECTION TECHNIQUES FOR STANDING EQUINE MRI

Magnetic resonance imaging (MRI) of the distal extremities of the standing, sedated horse would be desirable if diagnostic quality images could be obtained. With the availability of extremity and special purpose magnet designs on the market, a system to safely accommodate the standing horse may gain increasing popularity. This paper considers the issue of motion that will need to be addressed to achieve successful, diagnostic quality images. The motion of the carpus and tarsus of five standing, sedated horses was quantified. The obtained motion records were then used to induce motion in cadaveric joint specimens during several MRI scans. The measured dorsal-palmar/plantar, medial-lateral, and proximal-distal random wobbling motions in the standing sedated horse were several centimeters in magnitude and generated severe motion-artifacts during axial MRI of the cadaveric specimens. Two retrospective motion-correction techniques (autocorrection and navigator-based adaptive correction) were used to correct the corrupted images. The motion artifacts were nearly eliminated with the use of both techniques in series. Although significant hurdles remain, these results suggest promise for allowing diagnostic quality MRI of the carpus and tarsus in the standing horse.     

Effects of long-term administration of enalapril on clinical indicators of renal function in dogs with compensated mitral regurgitation

OBJECTIVE: To determine the effect of long-term administration of enalapril on renal function in dogs with severe, compensated mitral regurgitation. DESIGN: Randomized controlled trial. ANIMALS: 139 dogs with mitral regurgitation but without overt signs of heart failure. PROCEDURE: Dogs were randomly assigned to be treated with enalapril (0.5 mg/kg [0.23 mg/lb], PO, q 24 h) or placebo, and serum creatinine and urea nitrogen concentrations were measured at regular intervals for up to 26 months. RESULTS: Adequate information on renal function was obtained from 132 dogs; follow-up time ranged from 0.5 to 26 months (median, 12 months). Mean serum creatinine and urea nitrogen concentrations were not significantly different between dogs receiving enalapril and dogs receiving the placebo at any time, nor were concentrations significantly different from baseline concentrations. Proportions of dogs that developed azotemia or that had a +/- 35% increase in serum creatinine or urea nitrogen concentration were also not significantly different between groups. Conclusions: And Clinical Relevance: Results suggest that administration of enalapril for up to 2 years did not have any demonstrable adverse effects on renal function in dogs with severe, compensated mitral regurgitation.     

Prospective clinical evaluation of serum cardiac troponin T in dogs admitted to a veterinary teaching hospital

The purpose of this study was to measure serum cardiac troponin T (cTnT) with a commercially available human enzyme-linked immunoassay (ELISA) test in various groups of dogs, including those undergoing doxorubicin chemotherapy. Serum samples were obtained from 6 groups of dogs: (1) normal adult dogs (n = 15); (2) dogs with asymptomatic dilated cardiomyopathy (n = 5); (3) dogs with congestive heart failure (n = 10); (4) dogs with untreated neoplasia (n = 20); (5) dogs with skeletal muscle trauma (n = 10); and (6) dogs with neoplasia receiving doxorubicin chemotherapy (n = 4). One serum sample was obtained from each of the normal dogs, those with asymptomatic cardiomyopathy, those with congestive heart failure, and those with untreated neoplasia. Serum samples were obtained serially from the dogs that were undergoing doxorubicin chemotherapy; samples were collected before doxorubicin (30 mg/m2) administration and then 1, 5, 7, and 14 days after administration throughout 6 cycles for a cumulative total dose of 180 mg/m2. All normal dogs, dogs with untreated neoplasia, and dogs with asymptomatic dilated cardiomyopathy had cTnT concentrations below the lower limits of detection for the assay used (<0.05 ng/mL). Detectable concentrations of cTnT were found in 3 dogs with congestive heart failure and in 2 dogs with skeletal muscle trauma. Detectable concentrations also were found in both dogs that had received 180 mg/m2 of doxorubicin. We conclude that dogs with congestive heart failure and those with skeletal muscle trauma and dogs with neoplasia receiving high-dose doxorubicin chemotherapy may have increased serum cTnT concentration, which may be suggestive of myocardial damage.     

Insecticidal activity of N-arylalkylbenzhydrolpiperidines

Benzhydrolpiperidine (BZP) insecticides represent a novel class of chemistry. Their specificity and efficacy as well as their low mammalian toxicity give them excellent potential for commercialization. Several N-arylalkylbenzhydrolpiperidines were tested for activity against a variety of insects in the laboratory and greenhouse. These tests were used to select compounds for field trials and determine rates of application for field tests. The BZP compounds have good activity against Lepidoptera, with modest Coleoptera activity. They are toxic by oral administration and have about 100-fold lower activity by topical exposure. A methyl carbamate BZP, F4265, was the most active compound, with LC50 values of 6 mg litre(-1) or less for most Lepidopteran species tested. F4265 was active in a variety of field trials at 112-224gAI ha(-1). Whole-plant testing methods conducted in the greenhouse were effective in determining field test rates.     

Spatial and temporal patterns of exotic shrub invasion in an Australian tropical grassland

We used aerial photography from 1960, 1974 and 1994 to quantify meso-scale spatial and temporal invasion patterns of an exotic, leguminous shrub, Acacia nilotica, in a northern Australia grassland. The invasion was episodic, the population remained relatively stable from 1960 to 1974, then exhibited a large increase from 1974 to 1994. This episodic increase did not appear to be regulated by climate or changes in landscape attributes, but rather, paralleled a shift to cattle (a more effective dispersal vector) as the dominant domestic livestock species, implicating more effective dispersal as the proximate cause. We also measured much greater A. nilotica densities adjacent to water courses than in upland areas, suggesting either better quality habitat or greater numbers of seeds deposited there by cattle. We infer that habitat quality rather than seed availability regulates shrub density as density remained constant from 1974 to 1994 in areas that were occupied in the 1960 to 1974 period. There was a significant effect of landscape position on population dynamics of the invasion. A. nilotica increased in both extent and density in riparian areas but remained static in upland areas during 1960–1974. There were significant increases in extent and density in both riparian and upland areas in 1974–1994. Thus, it is likely that landscapes with fewer or smaller riparian areas would be less susceptable to the invasion of A. nilotica. However, the ability of domestic stock to transport seeds across distances that exceed the distance between riparian areas renders this argument less relevant.The transition from open grassland to shrubland may be irreversible in a practical sense, so control programs should emphasize containment of the invasion to existing levels as well as restoration of invaded areas. This will require strategies, tactics and operations to 1) control cattle movement, 2) exclude cattle from seed producing A. nilotica populations, 3) detect new populations early in the life cycle and implement broadscale, low-cost control techniques and 4) prioritize eradication efforts on populations that act as a seed source to uninfested areas.     

Prolactin stimulates the internalization of Staphylococcus aureus and modulates the expression of inflammatory response genes in bovine mammary epithelial cells

The incidence of mastitis in dairy cattle is highest at the drying off period and parturition, which are characterized by high levels of the lactogenic hormone prolactin (PRL). One of the most frequently isolated contagious pathogens causing mastitis is Staphylococcus aureus. However, the role of PRL on S. aureus infection in mammary epithelium has not been studied. In this work we evaluated the effect of bovine PRL (bPRL) on S. aureus internalization in a primary culture of bovine mammary epithelial cells (bMEC) and on the expression of cytokine and innate immune response genes. Our data show that 5ng/mL bPRL enhances approximately 3-fold the internalization of S. aureus (ATCC 27543) into bMEC. By RT-PCR analysis, we showed that bPRL is able to up-regulate the expression of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and inducible nitric oxide synthase (iNOS) mRNAs. However, bPRL together with S. aureus did not modify the expression of TNF-alpha and iNOS mRNAs, while it down-regulated the expression of beta-defensin and IL-1beta mRNAs, as well as nitric oxide production, suggesting that infection and bPRL together can inhibit elements of the host immune response. To our knowledge, this is the first report that shows a role of bPRL during the internalization of S. aureus into bMEC.