The resistance of meat chickens vaccinated by aerosol with a live V4 Newcastle disease virus vaccine in the field to challenge with a velogenic Newcastle disease virus

Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days-of-age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination-inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non-HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia.     

Nutritional muscular dystrophy in a four-day-old Connemara foal

This report describes a four-day-old, full-term Connemara colt, presented for the evaluation of a progressive inability to rise unassisted. A diagnosis of nutritional muscular dystrophy was made based on muscular weakness, elevated muscle enzymes and low vitamin E, selenium and glutathione peroxidase activity. The foal was treated with intramuscular vitamin E-selenium and made a full recovery.     

Comparison of inoculation regimes for the experimental production of swine erysipelas arthritis: II Serological findings in a gel diffusion precipitin test and enzyme-linked immunosorbent assay

The serological response of pigs to Erysipelothrix rhusiopathiae inoculation was monitored by a gel diffusion precipitin test (GDPT) using a crude, serotype-specific, autoclaved antigen and an enzyme-linked immunosorbent assay (ELISA) using a heat-extracted, alcohol precipitated and molecular seived antigen previously shown to react with serum from pigs infected with serotypes 1 or 2. All pigs receiving 3 or 5 weekly intravenous inoculations of either a highly virulent (VRS 229) or a lowly virulent isolate (VRS 252) produced GDPT-reactive antibody within 3 weeks, but only 44% were still reactive at 8 to 9.5 weeks. The ELISA response was significantly higher in pigs inoculated with the highly virulent strain, and was similar in pigs receiving 3 or 5 doses of either strain. In a dose-response trial, after 3 doses of VRS 229, GDPT reactivity occurred earlier and was stronger in pigs given higher doses of E. rhusiopathiae, but the response peaked 3 to 5 weeks after the start of challenge and was short lived. GDPT reactivity correlated with dose, but not with the severity of arthritis. The ELISA demonstrated specific IgG antibody was present by 2 weeks, and persisted to at least 11 weeks. The ELISA reactivity was significantly higher in pigs with arthritis than in pigs that received low doses and were not arthritic. Within groups of pigs with arthritis a significant, dose dependent, linear ELISA response developed but did not correlate with the presence or degree of arthritis at slaughter. Non-arthritic pigs had similar low ELISA responses to uninoculated controls.     

Serological characterisation of Haemophilus parasuis isolates from Australian pigs

A total of 31 isolates of Haemophilus parasuis obtained from Australian pigs were serotyped by the Kielstein-Rapp-Gabrielson scheme. The isolates were assigned to serovar 1 (1 isolate), serovar 2 (1 isolate), serovar 4 (4 isolates), serovar 5 (7 isolates), serovar 9 (2 isolates), serovar 10/7 (4 isolates), serovar 12 (1 isolate) and serovar 13 (6 isolates). The remaining 5 isolates could not be assigned to a serovar. Two different serovars (5 and 13) were detected in one herd. The only 2 isolates obtained from clinically normal pigs (from the same herd) were serovar 9. The common serovars were isolated from pigs with pneumonia as well as from pigs with conditions of the Glässer's disease type. The serological heterogeneity amongst Australian isolates of H parasuis has important implications for the use of vaccines to control Glässer's disease.     

The prevalence of itchmite, Psorergates ovis, among sheep flocks with a history of fleece derangement

An investigation of sheep flocks in the main sheep raising areas of New South Wales showed that the itchmite Psorergates ovis was frequently associated with fleece derangement. In 26 of the 41 flocks examined, P. ovis was the only ectoparasite detected. P. ovis and the sheep body louse Damalinia ovis, were found in 5 flocks. No external parasites were found on sheep examined from the 10 remaining flocks. The type of fleece derangement most frequently recorded was rubbing which in some cases was combined with areas of chewed fleece. Among flocks, there were positive relations between the prevalence of fleece derangement and prevalence of itchmite or scurf and between itchmite count and mean scurf score. Within flocks, itchmite infested sheep or sheep with scurf had higher prevalences of fleece derangement than sheep on which no mites or no scurf were found. Itchmite infested sheep had a higher prevalence of scurf than those with no detectable mite infestation. There were no significant differences in itchmite populations or fleece derangement between untreated flocks and flocks treated with synthetic pyrethroids, organophosphates or arsenic and rotenone.     

Safety of a topically applied spot-on formulation of metaflumizone plus amitraz for flea and tick control in dogs

Four laboratory studies were conducted in Beagle dogs to evaluate the safety of a novel ectoparasiticide combination of metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) when applied according to the recommended dosage of >/=20mgmetaflumizonekg(-1) plus >/=20mgamitrazkg(-1), at exaggerated and repeated dosages, and if accidentally orally ingested. Parameters evaluated included body weight, food consumption, clinical, physical and neurological examinations, clinical pathology and gross and microscopic pathology. Exaggerated and repeated topical treatment with metaflumizone plus amitraz administered at 1x, 3x and 5x the recommended dose had no effect on clinical findings, heart rates, body weight, food consumption, physical/neurological examinations, macroscopic and microscopic pathology. Very slight, transient, clinically insignificant increases in serum urea nitrogen were noted in some dogs treated at all dose rates tested. This effect was not persistent, was not dose-responsive, nor aggravated by repeated applications and was not associated with a corresponding increase in creatinine or renal pathology. Therefore, these increases in urea nitrogen were suspected to be of non-renal origin and were not considered toxicologically significant. Exaggerated doses (3x and 5x) caused very mild, transient hyperglycemia, most notably in some adult females. Transient and inconsistently noted mild increases in leukocytes, neutrophils and monocytes were observed in some 3x and 5x treated dogs at some intervals. None of the effects noted were aggravated by repeated administration. When 10% of the recommended topical dose was orally administered to mimic exposure due to licking the application, avoidance behaviors including spitting, head shaking, and salivation were noted immediately in all animals. Consequently, voluntary oral ingestion is considered unlikely. Transient decreased activity, slightly reduced body temperature and pale oral mucous membranes were noted in some animals beginning 1-2h posttreatment. Ataxia, resolving within 4h posttreatment, was noted in one female. Oral administration had no effect on clinical pathology. Results from these four studies indicate repeated use of metaflumizone plus amitraz causes no adverse health effects when used as recommended in dogs as young as 8 weeks of age.     

An evaluation of the cross-protection afforded by inactivated infectious coryza vaccines

The cross-protection afforded by three inactivated infectious coryza vaccines was evaluated. Each vaccine contained one of the following strains of Haemophilus paragallinarum, HP31, HP60 and HP14. Strain HP31 belongs to Kume serovar C-2, strain HP60 belongs to Kume serovar C-4 while strain HP14 belongs to Kume serovar A-4. Four groups of twenty six-week-old specific-pathogen-free chickens were either given a single dose of an aluminium-hydroxide based vaccine (three groups) or left as unvaccinated controls. Three weeks after vaccination, all four groups were challenged with virulent H paragallinarum. One half of each group was challenged with the strain HP31 and the other half with strain HP60. The efficacy of the vaccines was assessed in terms of the prevention of the typical clinical signs and macroscopic lesions of infectious coryza as well as the prevention of any colonisation by the challenge organism. The serovar C-2 and serovar C-4 vaccines protected more than 50% of birds against either a serovar C-2 or C-4 challenge while the serovar A-4 vaccine protected less than 50% of birds.     

Potential enhancement of degradation of the nematicides aldicarb,oxamyl and fosthiazate in UK agricultural soils through repeated applications

BACKGROUND: The potential for enhanced degradation of the carbamoyloxime nematicides aldicarb and oxamyl and the organophosphate fosthiazate was investigated in 35 UK agricultural soils. Under laboratory conditions, soil samples received three successive applications of nematicide at 25 day intervals. RESULTS: The second and third applications of aldicarb were degraded at a faster rate than the first application in six of the 15 aldicarb‐treated soils, and a further three soils demonstrated rapid degradation of all three applications. High organic matter content and low pH had an inhibitory effect on the rate of aldicarb degradation. Rapid degradation was observed in nine out of the ten soils treated with oxamyl. In contrast, none of the fosthiazate‐treated soils demonstrated enhanced degradation. CONCLUSION: The potential for enhanced degradation of aldicarb and oxamyl was demonstrated in nine out of 15 and nine out of ten soils respectively that had previously been treated with these active substances. Degradation of fosthiazate occurred at a much slower rate, with no evidence of enhanced degradation. Fosthiazate may provide a useful alternative in cases where the efficacy of aldicarb and oxamyl has been reduced as a result of enhanced degradation. Copyright © 2009 Society of Chemical Industry     

Efficacy of an injectable, sustained-release formulation of moxidectin in preventing experimental heartworm infection in mongrel dogs challenged 12 months after administration

The objective of this study was to ascertain the ability of a single subcutaneous injection of a sustained-release (SR) formulation of moxidectin to protect dogs against challenge inoculation with infective Dirofilaria immitis larvae 364 days after administration. Twenty four purpose-bred adult mixed-breed dogs were grouped into three blocks of eight based on weight and sex. Saline solution (0.9% NaCl) or a moxidectin SR formulation at volumes designed to deliver 0.17 or 0.27 mg moxidectin/kg b.w. was injected subcutaneously on day 0. Throughout the post-treatment period, injection sites of all dogs were periodically examined visually and by palpation. Palpable swellings were characterized as to size, consistency and the presence of associated pain or erythema. On day 364, each dog was inoculated subcutaneously with 50 D. immitis L3. On days 510 and 511, dogs were euthanatized, and their hearts, lungs and thoracic cavities were inspected for the presence of adult heartworms. number, sex and viability of recovered heartworms were determined. The mean number of heartworms recovered from dogs that had received the saline control injection was 35.7. No heartworms were recovered from any dog treated with either 0.17 or 0.27 mg moxidectin/kg b.w. For variable periods of time following treatment, small (1-4 mm diameter), firm, subcutaneous swellings could be palpated at the injection sites of dogs treated with 0.17 or 0.27 mg moxidectin/kg b.w. These swellings contracted progressively and eventually disappeared except for the case of one animal treated with 0.27 mg/kg, in which the swelling persisted for the entire study period. At no time during the study was pain or erythema noted at the injection site of any dog, and no dog exhibited any adverse systemic reaction related to treatment. We conclude that under conditions pertaining in this study, a single subcutaneous injection of a moxidectin SR formulation at dosing rates of either 0.17 or 0.27 mg/kg b.w. can safely protect adult dogs against experimental challenge inoculation with infective heartworm larvae for a period of 12 months.