The first reported outbreak of equine herpesvirus myeloencephalopathy in New Zealand

CASE HISTORY AND CLINICAL FINDINGS: On 9 January 2014 (Day 0) a mare from a stud farm in the Waikato region presented with urinary incontinence without pyrexia. Over the following 33 days 15 mares were clinically affected with neurological signs. All but one mare had a foal at foot. The most commonly observed clinical signs were hind limb paresis and ataxia. In some cases recumbency occurred very early in the course of disease and seven mares were subject to euthanasia for humane reasons.

LABORATORY FINDINGS: Equid herpesvirus (EHV) type 1 was detected using PCR in various tissues collected post mortem from two mares with neurological signs. DNA sequencing data from the DNA polymerase gene of the virus showed a nucleotide transition at position 2254, a mutation encoding amino acid D₇₅₂ that is highly associated with the neuropathogenic genotype of EHV-1. In total 12/15 mares were confirmed positive for EHV-1 on PCR. Results from a virus neutralisation test and ELISA on paired serum samples, and PCR on whole blood and nasal swabs, indicated that of four paddocks in a high-risk area where a cluster of cases had occurred, 20/21 (95%) horses were likely to have been exposed or were confirmed infected with EHV-1. Subsequent to the outbreak two mares aborted, one at 9 months and one at 10 months of gestation. The cause of abortion was confirmed as EHV-1 with the same genotype as that involved in the outbreak.

DIAGNOSIS: Equine herpesvirus myeloencephalopathy.

CLINICAL RELEVANCE: The outbreak described shows the considerable impact that can occur in outbreaks of equine herpesvirus myeloencephalopathy in New Zealand. Early biosecurity controls not only reduced the effect on the farm but mitigated the potential for the virus to spread to other horse enterprises.     

Fluctuating resources, disturbance and plant strategies:diverse mechanisms underlying plant invasions

This paper examines the hypothesis that non-native plant invasions are related to fluctuating resource availability as proposed by Davis et al.(2000).I measured relative functional responses of both invasive and native plants to changed resource availability due to nutrient enrichment and rainfall,and to increased disturbance.Data are presented from studies in two contrasting ecosystems.First is a series of glasshouse and field experiments on the invader Hieracium lepidulum and associated invasive and native species in subalpine temperate New Zealand.Second is a field study of invasive and native plant responses to altered disturbance regimes and rainfall from tropical savannas of north eastern Australia.Invaders responded differently from native species to changes in resource availability in both subalpine and tropical studies.However,invaders differed among themselves showing that different species exploit different functional niches to invade their respective habitats.These findings contribute to the contention that the fluctuating resource hypothesis does not provide a universal explanation for plant invasions.The diverse functional responses to increased resource availability among invaders in this and previous studies suggest that the cause of invasion depends on unique combinations of habitat and functional attributes of invaders and native assemblages.Such findings imply that universal predictions of what will happen under climate change scenarios across the globe will be difficult to make.     

Effects of Exogenous Tumour Necrosis Factor-α on the Secretory Function of the Bovine Reproductive Tract Depend on Tumour Necrosis Factor-α Concentrations

The aim of study was to correlate tumour necrosis factor-α (TNF) infused doses used with the TNF concentrations achieved and with the secretory function of both the ovary and the uterus in cows. We evaluated the concentrations of progesterone (P4), prostaglandin (PG)F_2α, PGE₂ nitric oxide (NO) and TNF in the jugular vein and vena cava caudalis as parameters of exogenous TNF action on the female reproductive tract. Aortae abdominalis of cows (n = 18) were infused with saline or two doses of TNF (luteolytic – 1 μg or luteotrophic – 10 μg). In the peripheral blood, 1 μg TNF concentrations achieved within the range of 30–45 pg/ml, and 10 μg TNF provoked a sharp increase in achieved concentrations at a range of 250–450 pg/mL). The TNF concentrations achieved in vena cava caudalis were five to six times higher than that in peripheral blood (p < 0.001). One microgram TNF increased PGF_2α and NO (p < 0.001) and decreased P4 (p < 0.05). The higher TNF dose stimulated P4 and PGE₂ (p < 0.01). TNF infusion at luteolytic dose achieved its concentrations at the physiological range previously observed in cows. Luteotrophic TNF dose achieved the concentrations in vena cava caudalis that are much higher than physiological level and were previously noted in pathological circumstances (i.e. mastitis , metritis ).     

Effect of eCG or eCG Plus hCG on Oestrus Expression and Ovulation in Prepubertal Gilts

To meet weekly breeding targets, it is occasionally necessary to inject exogenous gonadotrophins to induce oestrus in prepubertal gilts. However, the gilt oestrus response to equine chorionic gonadotrophin (eCG) either alone or in combination with human chorionic gonadotrophin (hCG) can be unpredictable. The objective of the present study was to examine possible reasons for this unpredictability. Prepubertal gilts (90 kg and 153 days of age, n = 109) received an injection of either 600 IU eCG or a combination of 400 IU eCG and 200 IU hCG (PG600), or were non-injected controls, and were then exposed to a mature boar for 15 min daily for 7 days for oestrus detection. At the time of injection, real-time ultrasound revealed that the gilt ovaries had primarily 1–2 mm follicles. Blood samples were obtained at time of hormone injection (day 0) and at days 3, 7 and 10 for assay of serum progesterone concentrations. The oestrus responses by 7 days were15.5%, 73.3% and 0%, for eCG, PG600, and control gilts, respectively (p < 0.001). The oestrus response improved (p < 0.05) with increasing body weight. Based on circulating progesterone levels, all oestrous gilts ovulated except for four of the PG600 gilts. Failure to express oestrus in PG600 gilts was not associated with a premature rise in progesterone.     

Spinal dermoid sinus in a Burmese cat with paraparesis

A 2-year-old, male, Burmese cat was evaluated for chronic progressive hindlimb weakness, ataxia and urinary incontinence. Radiographic examination, myelography and magnetic resonance imaging defined congenital vertebral anomalies and a space-occupying intradural, extramedullary mass. A dermoid sinus was subsequently identified dorsal to the affected spine. Surgical excision of the tract necessitated a dorsal laminectomy and removal of a 1-cm diameter intradural dermoid sinus 'cyst' that contained hair and sebaceous debris. The cat recovered hindlimb function after surgery and remains asymptomatic 50 months after surgery except for a persistent inability to urinate voluntarily.     

Antimicrobial use in the Australian pig industry: results of a national survey

Objective   To describe how various antimicrobials are used in commercial pig herds in Australia and for what disease conditions.
Procedure   Managers of large pig herds (> 200 sows) across Australia and their veterinarians participated in an internet-based survey in 2006. Questions were asked about herd management, the occurrence of bacterial diseases and the type and frequency of antimicrobial use. An antimicrobial usage index for each herd was derived as a summary of the risk of selection for antimicrobial resistance. Relationships between responses were explored with univariate and multivariate analysis.
Results   Responses were received for 197 herds estimated to represent at least 51% of all large pig herds in Australia. Most piggeries relied on drugs of low importance in human medicine (e.g. tetracyclines, penicillins and sulfonamides). For the two drugs of high importance in human medicine that can be legally prescribed to pigs in Australia, ceftiofur use was reported in 25% of herds and virginiamycin in none. Infections attributed to Lawsonia , Mycoplasma and Escherichia coli motivated the most use of antimicrobials. No useful association was found between management factors and the antimicrobial use index.
Conclusion   Most antimicrobial use in the Australian pig industry is based on drugs of low importance to public health. Enhanced control of E. coli infections without reliance on antimicrobials would further reduce the risk of selecting for antimicrobial resistance relevant to public health. The amount of variation in the usage index between herds suggests that antimicrobial use should be constantly reviewed on a herd by herd basis.     

Integrating practical, regulatory and ethical strategies for enhancing farm animal welfare

OBJECTIVE: To provide an integrated view of relationships between assessment of animal welfare. societal expectations regarding animal welfare standards, the need for regulation, and two ethical strategies for promoting animal welfare, emphasising farm animals. APPROACH: Ideas in relevant papers and key insights were outlined and illustrated, where appropriate, by New Zealand experience with different facets of the welfare management of farm animals. CONCLUSIONS: An animal's welfare is good when its nutritional, environmental, health, behavioural and mental needs are met. Compromise may occur in one or more of these areas and is assessed by scientifically-informed best judgement using parameters validated by directed research and objective analysis in clinical and practical settings. There is a wide range of perceptions of what constitutes good and bad welfare in society, so that animal welfare standards cannot be left to individual preferences to determine. Rather, the promotion of animal welfare is seen as requiring central regulation, but managed in a way that allows for adjustments based on new scientific knowledge of animals' needs and changing societal perceptions of what is acceptable and unacceptable treatment of animals. Concepts of 'minimal welfare', representing the threshold of cruelty, and 'acceptable welfare', representing higher, more acceptable standards than those that merely avoid cruelty, are outlined. They are relevant to economic analyses, which deal with determinants of animal welfare standards based on financial costs and the desire of the public to feel broadly comfortable about the treatment of the animals that are used to serve their needs. Ethical strategies for promoting animal welfare can be divided broadly into the 'gold standard' approach and the 'incremental improvement' approach. The first defines the ideal that is to be required in a particular situation and will accept nothing less than that ideal, whereas the second aims to improve welfare in a step-wise fashion by setting a series of achievable goals, seeing each small advance as worthwhile progress towards the same ideal. 'Incremental improvement' is preferred. This also has application in veterinary practice where the professional commitment to maintain good welfare standards may at times conflict with financial constraints experienced by clients.     

Failure of a single postpartum prostaglandin treatment to improve the reproductive performance of dairy cows

A study was conducted to evaluate the effects of postpartum prostaglandin treatment on reproduction in 3 seasonal calving dairy herds. Recently calved lactating dairy cows were paired on herd, age, calving date and previous production index. One cow in each of the 196 pairs received a single intramuscular injection of 25 mg of the prostaglandin analogue, dinoprost, between 14 and 28 days after calving. Subsequent reproduction was monitored. Within each herd and overall, there was no significant effect of treatment on the intervals from calving to first service, mating start date to first service, calving to conception, mating start date to conception and first service to conception. Treatment also had no significant effect on 21-day submission and pregnancy rates, on the proportion of each group not pregnant at the end of mating, and on first service pregnancy rates. Responses to treatment did not vary between cows calving within 50 days of mating start date and earlier calving cows or between cows aged less than 5 years and older cows.     

The distribution and prevalence of Theileria buffeli in cattle in Queensland

The distribution and prevalence of Thelleria buffeli in Queensland cattle were investigated using serum samples and blood films collected primarily for brucellosis surveillance and tick fever diagnosis. Serums from 8654 cattle from 357 farms throughout Queensland were examined by an indirect fluorescent antibody test for antibody to T buffeli. In addition, 347 peripheral blood films collected from 147 farms in south-eastern Queensland were examined for piroplasms of T buffeli. The overall herd and animal prevalences for T buffeli were 75% and 41%, respectively. There was significant variation among regions in both herd and animal prevalences (P less than 0.001). Herd and animal prevalences were highest in the north and east decreasing westward. The results indicate that T buffeli is more widespread in Queensland than previously thought.