Experimental infection of Artibeus intermedius with a vampire bat rabies virus

Experimental infection of Artibeus intermedius, the great fruit-eating bat, was performed with vampire bat rabies isolates. Bats (n = 35) were captured in the wild and quarantined prior to experimental infection. No rabies antibodies were detected by rapid fluorescent focus inhibition test (RFFIT) prior to infection. Three doses of rabies virus (RV) and three different routes of infection were used. One out of 35 bats died without showing any clinical signs at day 14 and was positive for rabies. None of the 34 other bats showed clinical signs for rabies, but high antibody titers were detected post-inoculation, suggesting either innate immune response to the vampire bat rabies virus or possible pre-exposure to RV and inoculation leading to a booster effect. Rabies virus was detected by hemi-nested RT-PCR (hnRT-PCR) in the brain (n = 3), stomach (n = 1) of bats that were negative by immunofluorescence and that survived rabies infection. The bat that died on day 14 was positive by hnRT-PCR on the brain, heart and liver. These results suggest that either previous non-lethal exposure to RV or natural low susceptibility to vampire bat viruses somehow protected Artibeus intermedius from clinical rabies infection leading to a marginal lethality effect on this bats species population in the wild.     

Radial strain and strain rate by two-dimensional speckle tracking echocardiography and the tissue velocity based technique in the dog

ObjectivesTwo-dimensional (2D) speckle tracking echocardiography (STE) is a new angle-independent ultrasound technique based on tracking of speckles within the myocardium on 2D grayscale images. The aims of this prospective study were as follows: (1) to assess the variability of left ventricular peak systolic radial strain (St) and strain rate (SR) in awake dogs using STE (Protocol 1); and (2) to quantify these variables in a healthy canine population and compare them with tissue Doppler imaging (TDI)-based St and SR values (Protocol 2).BackgroundSt and SR may be assessed using TDI, which is limited by angle dependency.Animals, materials and methodsThirty-six STE examinations were performed on 6 healthy dogs for Protocol 1 and 37 healthy dogs were recruited for Protocol 2. In both studies, STE measurements were obtained offline from the right parasternal short-axis view by the same trained observer using automatic frame-to-frame tracking of grayscale speckle patterns.ResultsAll within- and between-day coefficients of variation were <10% (Protocol 1). In Protocol 2, St (46.7 ± 12.2%) and SR (2.7 ± 0.6 s⁻¹) measured by STE were correlated with heart rate (p < 0.01), but not with the ratio of early mitral inflow velocity to early mitral annular velocity. There was a good correlation between STE and TDI for both St and SR values (p < 0.001).ConclusionsSTE is a repeatable and reproducible non-Doppler method for assessing radial St and SR. The combination of these indices with conventional echo-Doppler variables could provide a new approach for accurately quantifying canine systolic function.     

Immune responses of orange-spotted grouper,Epinephelus coioides,against virus-like particles of betanodavirus produced in Escherichia coli

Betanodaviruses are the causative agents of viral nervous necrosis (VNN), a serious disease of cultured marine fish worldwide. Virus-like particles (VLPs) are one of the good novel vaccine candidates to control this disease. Until now, betanodavirus vaccine studies mainly focused on the humoral immune response and mortality after virus challenge. However, little is known about the activation of genes responsible for cellular and innate immunity by vaccines. In the present study, VLPs of orange-spotted grouper nervous necrosis virus (OGNNV) were produced in prokaryotes and their ability to enter Asian sea bass cells was the same as native virus, suggesting that they possess a similar structure to OGNNV. VLPs immunogenicity was then determined by intramuscularly vaccinating Epinephelus coioides at different concentrations (1.5 or 15 μg g^?1 fish body weight, FBW) and immunizing frequencies (administration once, twice and thrice). A single vaccination with the dosage of 1.5 μg g^?1 FBW is enough to provoke high titer antibodies (average 3 fold higher than that of negative control) with strong neutralizing antibody titer as early as 1 week post immunization. Furthermore, quantitative PCR analysis revealed that eleven genes associated with humoral, cellular and innate immunities were up-regulated in the liver, spleen and head kidney at 12 h post immunization, correlating with the early antibody response. In conclusion, we demonstrated that VLP vaccination induced humoral immune responses and activated genes associated with cellular and innate immunity against betanodavirus infection in orange-spotted grouper.     

Enhancement of humoral and cellular immunity in mice against Japanese encephalitis virus using a DNA prime–protein boost vaccine strategy

A synthetic multi-epitope gene containing critical epitopes of the Japanese encephalitis virus (JEV) envelope gene was cloned into both prokaryotic and eukaryotic expression vectors. The recombinant plasmid and purified recombinant protein (heterologously expressed in Escherichia coli) were used as immunogens in a mouse model. The results indicate that both the recombinant protein and the DNA vaccine induce humoral and cellular immune responses. Neutralising antibody titres in mice in the pcDNA-TEP plus rEP group increased considerably relative to mice immunised using either pcDNA-TEP or rEP alone (P < 0.05). Furthermore, the highest levels of interleukin (IL)-2, interferon-γ and IL-4 were induced following priming with the DNA vaccine and boosting with the recombinant protein. Together these findings demonstrate that a DNA-recombinant protein prime-boost vaccination strategy can produce high levels of antibody and trigger significant T cell responses in mice, highlighting the potential value of such an approach in the prevention of JEV infection.     

Recurrence of Chlamydia suis infection in pigs after short-term antimicrobial treatment

The effect of short-term antimicrobial treatment on natural excretion of Chlamydia suis in rectal swabs and C. suis and Chlamydophila psittaci in nasal swabs was investigated in 47 clinically normal piglets by quantitative real-time PCR. Pigs were treated IM with 4 mg/kg enrofloxacin for 5 days (n = 22) or 2.5 mg/kg enrofloxacin for 3 days followed by 100 mg/mL tiamulin (n = 25). Antimicrobial treatment reduced the number of pigs positive for chlamydiae and the quantity of chlamydial DNA in positive swabs for a few days, but chlamydial excretion recurred in both groups. Short-term antimicrobial treatment at dosages recommended for treatment of other bacterial infections in pig herds was not effective in eliminating naturally occurring subclinical chlamydial infection in pigs.     

Identification and in vitro screening of avian yeasts for use as probiotic

The objective of this study was to isolate and identify yeast strains from broilers excreta and to evaluate in vitro their potential for probiotic use in animal production.Methods and resultsNine yeast strains were isolated and presumptively pre-identified by biochemical assays. These isolates were grouped in six different molecular profiles using PCR-fingerprinting technique. Each profile was identified by sequencing of the D1/D2 domains of the large subunit of the 26S rRNA gene. These yeasts were identified as: Trichosporon sp. (LV-2), Wickerhamomyces anomalus (LV-6), Pichia kudriavzevii (LV-8), Kodamaea ohmeri (LV-9) and Trichosporon asahii (LV-10). A pre-screening of the strains for probiotic use was based on their ability to agglutinate pathogenic micro-organisms. These yeast strains were characterized for specific growth rate, duplication time, their cell surface hydrophobicity, medium acidification, resistance to low pH (2.0, 2.5 and 3.0) and concentrations of bile salts (0.3% and 0.6%). The isolate of W. anomalus (LV-6) had the highest agglutinating and adherence capacity, a growth rate of 2.07 × 10⁸ cfu/mL in 24 h at 30 °C, decreasing the medium pH from 6.5 to 5.23, a 25% hydrophobicity and an elevated capacity to grow under stress conditions.ConclusionsW. anomalus strain LV-6 showed the best characteristics for use as a probiotic candidate.Significance and impact of the Study:The data from this study helped in choosing a probiotic candidate from yeast to use in broiler production.     

Hypothalamic deafferentation in prepuberal beef heifers: Effects of gonadotropin-releasing hormone and estradiol benzoate on luteinizing hormone secretion

Hypothalamic control of luteinizing hormone (LH) secretion was investigated in crossbred beef heifer calves by comparing anterior (AHD), posterior (PHD), and complete (CHD) hypothalamic deafferentation with sham operated controls (SOC). Heifers (n = 16) were fitted with an indwelling jugular catheter for 6 days before cranial surgery, and assigned randomly to treatments. Blood for radioimmunoassay of LH was collected sequentially at 15-min intervals during an 8-h period on days ? 1 before and day 6 after hypothalamic deafferentation or sham operation. On the day of surgery, blood samples were collected sequentially at 15-min intervals 2 h before induction of anesthesia and throughout surgery and early recovery. Seven months after hypothalamic deafferentation, all experimental and sham operated heifers were ovariectomized and treated with vegetable oil (i.m.) plus saline (i.v.), vegetable oil plus gonadotropin releasing hormone (GnRH), estradiol benzoate (EB, 1 mg) in vegetable oil. After ovariectomy basal plasma concentrations of LH increased (P < 0.01) compared with the low circulating hormone levels before ovariectomy. The amplitude of LH response to GnRH was greater (P < 0.01) in CHD and PHD when compared with SOC and AHD heifers. Injection of EB failed to induce a LH surge in CHD and PHD 900–1100 min later when compared with the robust response seen in SOC and AHD heifers. Injection of EB plus GnRH elicited LH release in all deafferentated and sham operated heifers. These results indicate a transient change in LH secretion after AHD or CHD in prepuberal heifers with intact ovaries. After OVX, the integrity of the neural connection of the posterior hypothalamus is required for EB-induced LH release in beef heifers.     

Preference among 7 bait flavors delivered to domestic dogs in Arizona: Implications for oral rabies vaccination on the Navajo Nation

Less than 20% of the domestic dogs on tribal lands in the United States are vaccinated against rabies. One method to increase vaccination rates may be the distribution of oral rabies vaccines (ORVs). ONRAB^® (Artemis Technologies, Inc., Ontario, Canada) is the primary ORV used in Canada to vaccinate striped skunks and raccoons. To investigate the potential use of ONRAB^® ORV baits to vaccinate feral domestic dogs against rabies on tribal lands and beyond, we performed a flavor preference study. A total of 7 bait flavors (bacon, cheese, dog food, hazelnut, sugar-vanilla, peanut butter, and sardine) were offered in pairs to 13 domestic dogs. Each dog was offered all possible combinations of bait pairs over a period of 10 days, with each bait offered 6 times. The proportion of times each bait was consumed first by individual dogs was calculated and comparisons among dogs were conducted using the MIXED procedure in SAS (SAS Institute, Cary, NC). Pairwise comparisons between baits were performed using “contrast” statements with sugar-vanilla flavor as the default for comparison. Type 3 tests of fixed effects showed a significant treatment effect (F_6,72 = 9.74, P < 0.0001). Sugar-vanilla was selected first during 14% of the offerings and exhibited the least preference among all bait types (F_1,72 = 22.46, P < 0.0001). Dog food was selected first 56% of the time, and more frequently than all other bait types (F_1,72 = 13.09, P = 0.0005).     

Gastrointestinal parasitism reduces the plasma availability of doramectin in lambs

A study was undertaken to investigate the effect of parasitism on plasma availability and pharmacokinetic behaviour of doramectin (DRM) in lambs. Fourteen parasitised grey face Suffolk lambs (26.9 ± 1.5 kg bodyweight) were selected for the study. Seven pairs of lambs were allocated to two groups to obtain an approximately even weight distribution. Group I (non-parasitised) was pre-treated with three repeated administrations of 5 mg/kg fenbendazole to maintain a parasite free condition. In group II (parasitised), the lambs did not receive any anthelmintic treatment. After the 85-day pre-treatment period, both groups of animals were treated with DRM by subcutaneous (SC) injection in the shoulder area at 200 μg/kg. Throughout the experimental period, both groups were maintained together under similar feeding and management conditions. Blood samples were collected by jugular venepuncture at different set times between 0.5 h and 60 days post-treatment. After plasma extraction and derivatisation, samples were analysed by high performance liquid chromatography (HPLC) with fluorescence detection. A computerised kinetic analysis was performed and the data were compared using the Student’s paired t test.The parent molecule was detected in plasma between 30 min and either day 20 (parasitised) or day 35 (non-parasitised) post-DRM treatment. The AUC values of the parasitised group (143.0 ± 18 ng d/mL) were significantly lower (P < 0.05) than those observed in the parasitically naïve animals (229.6 ± 21.7 ng d/mL). The mean residence time (MRT) in the parasitised group (3.4 ± 0.3 days) was significantly shorter (P < 0.05) than in the healthy group (6.6 ± 0.6 days). Study results have shown that parasitic disease, through alteration in the body condition, can produce significant changes in the plasma disposition of DRM when administered SC to parasitised lambs.     

The advantages of using a combination of LDL and glutamine in comparison with TRIS egg yolk and Equex® STAMP extenders in the cryopreservation of canine semen

Twenty semen samples taken from 5 dogs were frozen in liquid nitrogen at ?196 °C in four different extenders: one control extender based on 20% egg yolk, 6% LDL alone (low density lipoproteins: the active cryoprotective principle in chicken egg yolk), 6% LDL combined with 20 mmol glutamine, and Equex® (a reference extender that we wish to compare with the LDL-glutamine combination). After thawing, spermatozoal motility was evaluated using a HAMILTON THORNE CERROS 12 image analyzer; the percentage of motile spermatozoa was 27.7% in the egg yolk extender (p < 0.05), 49.9% with 6% LDL alone (p > 0.05), 54.7% in the 6% LDL + 20 mmol glutamine extender, and 47.9% with Equex® (p > 0.05). The motility parameters (VAP, VCL, VSL and ALH) were also superior in the 6% LDL + 20 mmol glutamine extender in comparison with the other extenders.Finally, the spermatozoa were generally better protected during freezing with the 6% LDL + 20 mmol glutamine association than with the egg yolk, 6% LDL, or Equex extenders in terms of the flagellar plasma membrane (HOS test), DNA (Acridine orange test), and acrosome integrity (Spermac® test: no significant difference). The Equex® extender obtained the best results for the acrosome, followed by 6% LDL + 20 mmol glutamine (FITC-PSA test: p < 0.05 between each extender).     

Microsphere immunoassay for the detection of cytokines in domestic cat (Felis catus) plasma: elevated IL-12/23 in acute feline immunodeficiency virus infections

We recently described the development and validation of a highly sensitive and specific microsphere immunoassay capable of simultaneously quantifying three domestic cat cytokines in tissue culture supernatant. Here we describe the modification of this assay to measure interferon gamma (IFNγ), interleukin (IL)-10 and IL-12/IL-23 p40 (IL-12/23) in domestic cat plasma, report values obtained from plasma collected after feline immunodeficiency virus (FIV) exposure, and compare plasma concentrations to blood cell mRNA expression. The validated quantitation limits of this assay are 31–1000 pg/ml for IFNγ, 63–2000 pg/ml for IL-10, and 20–625 pg/ml for IL-12/23. Plasma cytokine levels from domestic cats infected with pathogenic and/or apathogenic FIV were determined at 3–4 and 7–8 weeks post-infection. IL-12/23 was elevated (p < 0.05) during acute infection with both FIV strains in two similar studies, conducted five years apart in different feline cohorts (n = 44 total animals). IL-12/23 concentrations ranged from 377 to 1904 pg/ml in naïve cats and 552 to 3460 pg/ml in infected cats. In contrast, the majority of plasma samples had IFNγ and IL-10 concentrations below the lowest standard tested. The inability to consistently detect levels of IFNγ and IL-10 in plasma, despite the fact that mRNA changes were detected, suggests that these cytokines may be secreted and/or cleared in a more highly regulated manner than IL-12/23, or perhaps exert local effects under tighter peripheral constraints and/or at a lower effective concentration.     

The effect of supplementation of flax-seed oil on interaction of Lactobacillus plantarum--Biocenol™ LP96 and Escherichia coli O8:K88ab:H9 in the gut of germ-free piglets

We investigated the influence of administration of flax-seed oil on interaction of Lactobacillus plantarum – Biocenol? LP96 and Escherichia coli O8:K88ab:H9 in the gut of germ-free piglets. When compared to animals supplemented with L. plantarum, the counts of lactobacilli in the jejunal and ileal mucosa and in the intestinal content were significantly higher in LMK group (p < 0.0001). Inter-groups comparison of the counts of E. coli K88 adhering to the jejunal and ileal mucosa revealed a significantly decrease in LMK animals (p < 0.001; p < 0.05).     

The development of the pupillary light reflex and menace response in neonatal lambs and kids

The aim of this study was to investigate the development of the pupillary light reflex and menace response in neonatal lambs and goat kids. Thirty lambs and 33 kids were assessed daily from birth until the pupillary light reflex and menace response had become established. All animals had a controlled pupillary light reflex within 20 h of birth. Lambs and kids had developed menace responses by 8 ± 3 and 14 ± 2 days, respectively. The Mann–Whitney test revealed a significant difference (P < 0.001) in the ages at which lambs and kids developed a menace response. Male kids developed this response significantly (P = 0.006) later than females. There was no sex difference in the menace response in the lambs. Overall, the findings indicated that lambs develop a menace response earlier than kids, and female kids develop this response more rapidly than their male counterparts.     

Pharmacokinetics and effects of cetirizine in horses with insect bite hypersensitivity

Horses with insect bite hypersensitivity (IBH) have difficulty in completely avoiding allergens, so effective treatment options are required. A randomised, placebo controlled and double blinded field study was conducted to determine the pharmacokinetics and efficacy in reducing dermatitis of the antihistamine cetirizine given orally at 0.4 mg/kg twice daily for 3 weeks. The influence of protection blankets and stabling were also investigated.The estimated maximum plasma concentration (C_max) and trough plasma concentration of cetirizine were 135 ng/mL and 18 ng/mL, respectively. There was no difference in dermatitis reduction between the treatment and placebo groups (P = 0.77). The findings indicated that cetirizine was of no apparent benefit in treating IBH at the dose rate tested. The use of blankets and stabling were shown to have favourable influence on the dermatitis (P < 0.05) and may be the preferred options to prevent this condition.     

Monitoring chronic infection with a field strain of Aleutian mink disease virus

Aleutian mink disease virus (AMDV) readily spread within farmed mink and causes chronic infections with significant impacts for welfare and economy. In the present study a currently circulating Danish AMDV strain was used to induce chronic experimental infection of farmed mink.PCR was used to detect viral DNA in full blood, organs, faeces and oro-nasal swabs weekly for the first 8 weeks and then biweekly for another 16 weeks after AMDV challenge inoculation of wild type mink. The mink (n = 29) was infected and seroconverted 2–3 weeks after AMDV inoculation and AMDV antibodies persisted during the maximum experimental period of 24 weeks. Viraemia and faecal excretion of viral DNA was detected in the mink (n = 29) at various and intermittent time intervals. Excretion of viral DNA in oro-nasal swabs was detected for 1–8 weeks in 21 mink. This highlights the risk of transmitting AMDV between infected farms.PCR was successfully used to detect viral DNA in organs 8, 16 and 24 weeks after AMDV inoculation with only minor differences between these weeks which is of diagnostic interest.This AMDV challenge model was also used to mimic natural infection of susceptible sapphire mink. Four of 6 sapphire mink were infected indirectly via the AMDV inoculated wild type mink whereas the other 2 sapphire mink remained uninfected.     

Methods and normal values for echocardiography in adult dairy cattle

ObjectiveThe objective of the study was to report normal ultrasonographic appearance and intra-cardiac dimensions in two dairy breeds and to calculate cardiac output (CO) using echocardiography.BackgroundIntra-cardiac dimensions, time indices and CO estimation have not previously been reported in adult cattle.Animals, materials and methodsEchocardiograms were obtained from healthy adult dairy cows (10 Jersey (J) and 12 Holstein Friesians (HF)) in the body weight range of 400 to 700 kg. Standard echocardiographic images were obtained from the left and right hemithoraces. Velocity time integrals were obtained in order to calculate CO using pulsed wave Doppler of aortic flow in the J cows. Measurements obtained included pulmonary artery and aortic diameters, left and right ventricular diameters (and calculated fractional shortening and left ventricular ejection fraction), left atrial size and time indices assessing valve function.ResultsHF cows had significantly (p < 0.05) larger pulmonary artery and aortic diameters, larger left atrial diameters and left ventricular internal diameters during diastole, but these were not different when corrected for body weight. Left and right ventricular dimensions, adjusted for body weight, were significantly larger (p = 0.02 and p = 0.035 respectively) in J cows when compared to HF cows. No differences were noted in the time indices between the two groups. No significant differences were noted in intra-operator variability and the only significant difference in inter-operator variability was in measurement of the pulmonary artery (p = 0.03; ICC = 0.63).ConclusionsIt is possible to obtain repeatable, reliable echocardiograms in order that meaningful intra-cardiac dimensions can be obtained in adult dairy cattle.     

Cross-sectional study of the prevalence and clinical features of osteoarthritis in 100 cats

To assess clinical signs and relevance of osteoarthritis (OA) in cats, the radiographic prevalence of OA in the appendicular skeleton of 100 client-owned cats (?6 years old) was assessed. Possible associations between radiographic OA, clinical locomotor system examination, and owner-perceived behavioural changes were evaluated. OA was most prevalent in the shoulders, elbows, hips and tarsal joints with 61% of cats having OA in at least one joint and 48% in more than one joint. Overall, clinical examination of the larger peripheral joints had the highest sensitivity and specificity for radiographic OA. Regression analysis showed age to be related to OA (P = 0.002), as were decreased mobility and grooming (P = 0.008), although there was a correlation with age. Finally, increased inappropriate elimination was associated with OA (P = 0.046). It was concluded that the prevalence of OA in cats is strikingly high and increases with age. OA in cats seems to be associated with behavioural changes.     

Canine heartworm (Dirofilaria immitis) in Fresno and Madera Counties, California: prevalence differences between foothill and valley habitats

The aim of this study was to assess the prevalence of heartworm in domestic dogs in Madera and Fresno Counties, California, dependent on habitat and other host and environmental factors. Dogs were screened for presence of heartworm antigen using the PetChek^® ELISA on blood samples (N = 519) collected at seven sites during April-July 2009. Eighteen dogs were heartworm antigen positive. Pearson Chi-square analyses were conducted testing the presence of heartworm antigen against the following independent variables: elevation range, percentage of time spent outdoors during the day, percentage of time spent outdoors during the night, pet coat length, weight class, prevention status, and sex. Dogs that spent at least 50% of their time outdoors during the day were significantly more likely to have heartworm that those who spent less time outside (N = 519, df = 1, p = 0.031). Overall prevalence (3.47%) was lower than expected, with Madera County having 3.8% positive samples and Fresno County 3.5%; this prevalence is lower than in many previous studies. The effect of time spent outdoors on heartworm prevalence was similar to previous studies. The impact of elevation on infection, though not significant, requires further investigation, as does the prevalence and viability of larval stages in mosquitoes.