Effects of dietary molybdenum on nematode and host during Haemonchus contortus infection in lambs.

The addition of molybdenum (0.05 mmol kg-1 dry-matter) to the diet of lambs given a trickle infection of Haemonchus contortus larvae (500 third stage larvae d-1 over six weeks) reduced mean faecal egg counts (epg) from 3952 to 2312 +/- 402 by 32 days (P less than 0.02) and greatly reduced the mean number of worms recovered from the abomasum 14 days after infection ceased (907 compared with 4167: P less than 0.01). Infection reduced haemoglobin concentrations less in lambs given molybdenum although the difference was small relative to the reduction in worm burden. Lambs not given molybdenum had low intraepithelial mast cell counts in the abomasal mucosa and less abomasal hypertrophy than expected from abomasal parasitism. Molybdenum did not consistently reduce the copper status of the host or the parasite. Previous exposure to molybdenum greatly reduced protein but not proteinase activity in, or secreted by, adult worms cultured for eight hours. It is suggested that molybdenum either increased the inflammatory response which preceded worm rejection or that it indirectly enhanced that reaction by reducing the effectiveness of copper-dependent, anti-inflammatory enzymes in the gastrointestinal mucosa.     

Isolation of oxfendazole resistant Cooperia oncophora in cattle

A field strain of Cooperia oncophora resistant to oxfendazole was isolated from a commercial cattle rearing property in Waikato, New Zealand. Resistance to oxfendazole was assessed by means of a faecal egg count depression test and an in vitro egg hatch test. This is the first documented case of anthelmintic resistance in Cooperia spp. and the first report of anthelmintic resistance in cattle in New Zealand.     

A perspective on ovine footrot control

A method for the control of ovine footrot is described which utilises the most appropriate measures to suit the circumstances for individual properties. This approach was used to eradicate the disease from three Central Otago fine-wool properties wintering in excess of 35,000 sheep on widely differing classes of land. This programme incorporates the use of proven.techniques and suitable planning together with input from the rural veterinarian, who plays an important role in demonstration and advising on control measures.     

Prevalence and spatial distribution of bovine tuberculosis in brushtail possums on a forest-scrub margin

Tuberculosis caused by Mycobacterium bovis was diagnosed in 36 of 68 (53%) brushtail possums (Trichosurus vulpecula) trapped in August 1992 from a population of exceptionally low density (trap catch <3%) on a forest-scrub margin in Westland, New Zealand. The prevalence of tuberculosis in possums, based solely on gross lesions, was at least twice that previously recorded in New Zealand, and was about seven times that recorded from the same population in 1980. More male (66%) than female (33%) possums had grossly visible tuberculous lesions. The distribution of infection appeared continuous along the forest-scrub margin. Both stoats (Mustela erminea) and one of six hares (Lepus europaeus occidentalis) trapped were also infected with M. bovis.     

In vitro effects of DDT analogs on trout brain Mg2+-ATPases: Inhibition kinetics

A continuous in vitro steady-state assay procedure was used to investigate the dependence of trout brain mitochondrial Mg²⁺-stimulated adenosinetriphosphatase specific activity on temperature and substrate concentration. The inhibition of enzyme activity by DDT was independent of substrate concentration. DDT and several analogs caused increases in the experimental activation energy and frequency factor of the enzyme-catalyzed reaction, which gave rise to a negative temperature coefficient of inhibition. It is suggested that DDT and other highly lipophilic compounds have the potential to allosterically affect membrane-bound enzymes by simply becoming a major lipoid component of the membranes.     

Policies for the vaccination of cats and dogs in New Zealand veterinary practices

AIMS: To determine current practices and attitudes towards vaccination of dogs and cats of veterinarians in New Zealand; the methods used for informing clients on which vaccines to use, and the preferred site for vaccination of cats.

METHODS: A postal questionnaire was sent to all 483 listed veterinary practices in New Zealand during February 2012. Some questions were specific to pet dogs, cats, or working farm dogs. Responses were categorised according to practice type and geographical region of the respondent. Factors associated with respondent recommendation of annual vaccination with modified live viral (MLV) vaccines were examined using logistic regression analysis. Vaccines that were considered to be essential for every animal were defined as core; those that may be recommended for animals whose location or lifestyle placed them at risk, were defined as non-core.

RESULTS: There were 204 useable returns, equivalent to a response rate of 42.2%, distributed across the country. Annual vaccination with MLV vaccines of dogs was recommended by 54/198 (27.3%) respondents, and of cats by 107/181 (59.1%) respondents. Factors associated with the recommendation of annual administration of MLV vaccines to dogs included being a companion animal practice, a desire for policies on vaccination to be left to individual clinics, and having one veterinarian in the practice. Administration of the final vaccination for puppies was recommended at ≥14 weeks old by 55/185 (29.7%) respondents, and for kittens at ≥13 weeks old by 42/183 (23%) respondents. Of respondents that administered MLV vaccines annually, 62/103 (60.2%) believed reducing the frequency of vaccination would reduce income, and 52/103 (50.5%) considered it would have a negative effect on animal health. Advice to enable clients to decide which non-core vaccines were administered was given by 181/199 (91%) respondents. Factors considered when recommending a vaccine included consideration of risk to individual patients (190/203; 93.6%), requirements of boarding kennels/catteries (165/203; 81.3%) and clinic vaccination policy (142/203; 70%). The preferred site for administering MLV vaccines to cats was the dorsal neck or inter-scapular region (137/198; 69.2%). Amongst respondents, 18 wanted disease surveillance information to allow for truly informed decisions to be made about vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE: Veterinarians can now compare their own vaccination practices and attitudes with those of veterinarians nationally, and internationally. There is a need for national surveillance information and for continued education of the public and commercial kennel and cattery owners for optimal vaccination strategies to be developed.     

Pharmacological characterisation of the electrically evoked release of monoamines from chicken brain in vitro

1. A study was conducted to develop an in vitro model for examining the basal and electrical-stimulation-induced release of [3H]monoamines from chicken hyperstriatal neurones in order to demonstrate the presence of presynaptic autoreceptors for the three main monoamine transmitters: noradrenaline, dopamine and 5-HT. 2. Two sets of experiments were carried out: the first was to evaluate the effect of calcium and tetrodotoxin (TTX, sodium channel conductance inhibitor) in order to demonstrate that evoked release of monoamines was a consequence of exocytotic processes; the second to investigate the effect of selective agonists and antagonists on neurotransmitter release. 3. Ross and Cobb broiler chickens of either sex (approximately 7 to 8 weeks old) were used. Slices of hyperstriatal tissue were preincubated with [3H]noradrenaline, [3H]dopamine or [3H]5-hydroxytryptamine (5-HT), washed, perfused and electrically stimulated at three time points (S1, S2 and S3) which released [3H]noradrenaline, [3H]dopamine and [3H]5-HT, as determined by scintillation spectrometry. 4. When calcium was removed from, or TTX added to, the superfusion medium prior to and including the second period of electrical stimulation (S2) the evoked releases of [3H]noradrenaline, [3H]dopamine and [3H]5-HT at S2 were abolished. 5. In the presence of the selective alpha2-adrenoceptor agonist UK 14304 during the S2 period, the S2/S1 ratio was lower than the control ratio due to a reduction in the stimulated release of [3H]noradrenaline. The selective alpha2-adrenoceptor antagonist RX 821002 blocked the UK 14304-induced reduction of evoked release and the S2/S1 ratio was similar to the control ratio. 6. The D2-like receptor agonist quinpirole reduced the S2/S1 ratio for [3H]dopamine release, an effect blocked by the antagonist AJ 76. The 5-HT1B receptor agonist CP 94253 during S2 reduced the S2/S1 ratio due to a reduction in evoked [3H]5-HT. This effect was blocked by the 5-HT1B receptor antagonist GR 55562. 7. The results demonstrate, for the first time, the functional presence of presynaptic alpha2-adrenoceptors, presynaptic 5-HT1B autoreceptors and presynaptic D2-like autoreceptors in broiler chicken hyperstriatal neurones in vitro.