Recommendations for the testing and control of bovine viral diarrhoea in New Zealand pastoral cattle production systems.

Eradicating bovine viral diarrhoea (BVD) from cattle populations requires a clear approach for determining the epidemiological status of individual herds and implementing the appropriate control measures to ensure the transmission cycle is cost-effectively broken. This is particularly important in countries such as New Zealand where there is currently no coordinated national programme and the herd-level decisions to control BVD are left to the discretion of individual farmers and veterinarians. To ensure greater consistency in the information being delivered by different stakeholders, we review the epidemiology of BVD in the context of New Zealand pastoral production systems and provides a series of simplified recommendations for the future control of BVD in beef and dairy herds. Based on analysis of BVD test accession data from commercial diagnostic laboratories, it has been estimated that 40.6% of dairy herds and 45.6% of beef herds tested had positive results for antibodies to BVD virus. While BVD continues to remain widespread and under voluntary control in New Zealand, it is recommended that herds test all individual mixed-age cows and replacement heifers for BVD virus or antigen and remove persistently infected animals from the breeding population. All new breeding animals that have entered the herd either through purchase or birth should also be tested for BVD virus. Biosecurity risks should be managed by reducing contacts with other herds and implementing targeted vaccination programmes. All individual purchased cattle should be tested and confirmed negative for BVD virus before being moved onto the buyer's property, even if the herd of origin had a negative antibody-based screening test. Herds should continue annual antigen or virus testing of all calves as soon as possible after birth to identify any persistently infected animals.

Elimination of bovine viral diarrhoea virus in New Zealand: a review of research progress and future directions.

The major impacts of bovine viral diarrhoea (BVD) on cattle health and production have prompted many countries to embark on national elimination programmes. These programmes typically involve identifying and removing persistently infected (PI) cattle in infected herds and implementing biosecurity measures, such as pre- or post-movement testing. In order to design a systematic national control programme to eliminate BVD in New Zealand, which achieves the greatest benefits to the industries at the lowest cost to individual farmers, an accurate understanding is necessary of the epidemiology, economics and social motivation for BVD control in New Zealand. In this article we briefly review the pathogenesis of BVD, transmission and diagnosis of BVD virus infection, and effectiveness of vaccination. We summarise the current state of knowledge of the prevalence, risk factors for transmission, and financial impacts of BVD in New Zealand. We describe control programmes in Europe and then discuss the challenges that must be addressed to design a cost-effective national control programme to eliminate BVD in New Zealand.

Excision of benign laryngeal lesions: comparison of carbon dioxide laser with conventional surgery.

Twenty-six cases of patients presenting with benign laryngeal lesions treated by laser excision were compared with age and sex matched controls treated by conventional surgery. There was no statistically significant difference post-operatively between the groups in analgesic requirement, length of hospital stay, voice quality or laryngoscopic appearance.

The first case of a bull persistently infected with Border disease virus in New Zealand.

CASE HISTORY: Poor reproductive performance was observed in 62 dairy heifers, with a pregnancy rate of 23% following 57 days mating with one 3-year-old and two 2-year old Belted Galloway bulls that were sourced from separate sheep and beef farms. CLINICAL FINDINGS: The 3-year-old bull was small for its age with small testes. This bull was seropositive for bovine viral diarrhoea virus type I (BVDV 1) using an Ag-ELISA, and positive on PCR for border disease virus (BDV). DIAGNOSTIC INVESTIGATION: Phylogenetic analysis of the BDV isolate from the affected bull indicated that it was part of the BDV 1 group. For 40 of the heifers exposed to the bull that were tested, all of them had a positive VNT (virus neutralisation test) titre to both BDV (titre≥1:4) and BVDV 1 (titre>1:4). On the farm of origin of the affected bull there was no evidence of BDV circulating between cattle. DIAGNOSIS: Persistent infection of a bull with BDV. CLINICAL RELEVANCE: Cattle persistently infected with BDV can act as a source of virus for infection of other cattle. The benefit of testing cattle for bovine viral diarrhoea could be enhanced by using tests that also detect BDV.

Reproductive management of dairy herds in New Zealand: attitudes, priorities and constraints perceived by farmers managing seasonal-calving, pasture-based herds in four regions.

AIMS: To examine attitudes, priorities, and constraints pertaining to herd reproductive management perceived by farmers managing seasonal-calving, pasture-based dairy herds in four regions of New Zealand, and to explore how these varied with demographic and biophysical factors. METHODS: Key decision makers (KDM) on 133 dairy herds in four dairy regions (Waikato, Taranaki, and north and south Canterbury) were interviewed between May and July 2009. They were asked to provide demographic and biophysical data about the farm, and to rate their attitude in relation to their own personality traits, management issues and priorities, and likely constraints affecting reproductive performance in their herds. Associations between demographic factors and attitudes, priorities and constraints were analysed using univariable and multivariable proportional-odds regression models. RESULTS: Farms in the regions studied in the South Island were larger, had larger herds and more staff than farms in the regions studied in the North Island. The farms in the South Island were more likely to be owned by a corporation, managed by younger people or people who had more education, and the herds were more likely to be fed a higher percentage of supplementary feed. The majority of KDM rated the current genetics, milksolids performance and reproductive performance of their herds as high or very high, and >70% believed that the reproductive performance had remained the same or improved over the preceding 3 years. Despite this, improving reproductive performance was the most highly rated priority for the next 3 years. The constraints considered most likely to have affected reproductive performance in the last 2 years were anoestrous cows, protracted calving periods, and low body condition scores; those considered least likely were artificial breeding and heat detection. Of the variables examined related to attitudes, priorities and likely constraints, there were significant differences between region for 10/40, and with age and occupation of the KDM for 24/40 and 5/40, respectively (p<0.05). CONCLUSIONS: The majority of KDM reported the current reproductive performance of their herds to be high or very high, yet rated improving reproductive performance as a very high priority for the next 3 years. Mismatch between perceived and actual performance may result in reduced uptake of extension programmes designed to improve performance, and accurate benchmarking may help increase uptake and engagement. Further work is needed to determine whether the attitudes and perceptions about performance of farmers affect the likelihood of changes in their management behaviour which translate to measurable change in the actual reproductive performance of their herds. The variation in attitude, priorities and perceived constraints among age groups and region indicates that design of extension programmes may need to vary with these demographics.

The patellar tendon bar! Is it a necessary feature?

The purpose of this investigation was to vary the load on the patellar tendon bar and to study the subsequent effect this has on the pattern of the pressure distribution at the stump-socket interface. Ten male subjects from the Southern General Hospital in Glasgow, UK participated in this study. Measuring systems utilising strain gauge and electrohydraulic technologies were designed, developed and constructed to enable pressure measurements to be conducted. One transducer, the patellar tendon (PT) transducer, was attached to the patellar tendon bar of the socket such that the patellar tendon bar was capable of being translated by +/-10 mm towards or away from the tendon. The results of this study showed that the position of the patellar tendon bar had no significant effect on the pressure distribution around the socket indicating that it is an unnecessary feature, which, we propose, may be eliminated during manufacture of a trans-tibial socket.

Effect of application of an external teat sealant and/or oral treatment with a monensin capsule pre-calving on the prevalence and incidence of subclinical and clinical mastitis in dairy heifers.

AIM: To assess the effect of applying an external teat sealant or a slow-release intraruminal monensin capsule pre-calving on the prevalence and incidence of subclinical or clinical mastitis in dairy heifers post-calving. METHODS: The studies were undertaken in 13 herds. In two herds application of an external teat sealant was compared with a negative control; in nine herds treatment with monensin was compared with controls, and in two herds treatments were applied in a 2 x 2 factorial design. Heifers were randomly assigned within herd to be treated with a slow-release intraruminal device containing 32 g monensin (n=383), or left as untreated controls (n=389), approximately 30 days before the start of the spring calving period; or to be treated with a latex external teat sealant (n=206) when calving was impending, or be left as untreated controls (n=205). Milk samples were collected from each gland between 0 and 5 days after calving and from any gland diagnosed with clinical mastitis. The effect of the treatments on the prevalence of intramammary infection (IMI), i.e. subclinical mastitis, and clinical mastitis were initially analysed at the univariate level, with associated variables (p<0.2) being used in construction of multivariable models. RESULTS: The prevalence of IMI was 18.4% at the gland level, and coagulase-negative staphylococci followed by Streptococcus uberis were the most common isolates. Treatment with an external teat sealant reduced the prevalence, compared with controls, of any IMI (12.1 (SE 1.7)% vs 16.5 (SE 2.1)%, respectively; p=0.05) or IMI caused by a major pathogen (3.8 (SE 0.8)% vs 6.0 (SE 1.1)%, respectively; p=0.05). Monensin treatment did not affect the prevalence of any IMI (p=0.68) or IMI due to a major pathogen (p=0.11). The cumulative incidence of clinical mastitis was 14.2%. Neither monensin treatment (p=0.47) nor application of an external teat sealant (p=0.71) altered the risk of clinical mastitis. There was no interaction between the monensin and external teat sealant in the two herds where the treatments were applied in a 2 x 2 factorial design. CONCLUSIONS: Application of an external teat sealant resulted in a lower prevalence of any IMI and of an IMI caused by a major pathogen. Despite monensin reducing the mobilisation of body tissue and the risk of subclinical ketosis, it had no effect on the prevalence or incidence of IMI or clinical mastitis. CLINICAL RELEVANCE: Application of an external teat sealant is an option for reducing the prevalence of IMI in pasture fed dairy heifers.

Clinical and bacteriological response to treatment of clinical mastitis with one of three intramammary antibiotics.

AIM: To compare the proportions of clinical and bacteriological cure of glands of dairy cows diagnosed with clinical mastitis, following treatment with one of three different intramammary antibiotic preparations. METHODS: Cows from dairy cow herds (n=28) across New Zealand which were diagnosed with clinical mastitis in one or more glands at any stage of lactation were randomly assigned at the cow level within sequentially presented groups of three animals to be treated with one of three intramammary antibiotics. The treatments were 1 g procaine penicillin, 0.25 g cefuroxime, and a combination of 1 g procaine penicillin and 0.5 g dihydrostreptomycin (DHS). All treatments were infused on three occasions at 12-hourly intervals. Duplicate milk samples were collected for bacteriology before initial treatment, and 21-42 days later. Logistic regression or generalised linear mixed models were used to analyse the proportion of cows or quarters retreated for mastitis within 30 days of initial treatment ('clinical treatment failure'), and the proportion of glands from which bacteria were isolated initially but from which the same bacterial species was not re-isolated ('bacteriological cure'). RESULTS: The annual herd average cumulative incidence rate of clinical mastitis was 12.7 cases/100 cows. The incidence rate was higher in young (2-year-old) and old (> or = 9-year-old) cows relative to 3- and 4-year-old cows, and was higher in Friesian than Jersey or crossbred cows. Streptococcus uberis was the pathogen most commonly isolated, and its relative prevalence declined with time postpartum. Cows treated with cefuroxime were more likely (p<0.01) to be re-treated for clinical mastitis in the 30 days after initial treatment than cows treated with procaine penicillin or procaine penicillin and DHS. Bacteriological cure occurred in 74% of treated glands and there was no difference in the proportion of cures among the treatments (p=0.4). The proportion of cures was lower when treatment occurred 28-72 days after calving (p<0.01) and if a major pathogen was isolated (p<0.001). CONCLUSIONS AND CLINICAL RELEVANCE: There was no benefit in terms of clinical or bacteriological cure rate in treating clinical mastitis cases with the combination of procaine penicillin and DHS compared to treatment with procaine penicillin alone. The proportion of clinical mastitis cases re-treated differed among herds, and more cows treated with cefuroxime were retreated within 30 days of initial treatment. However, the bacteriological cure proportion was the same among the treatments. Cure proportions were lower in cows from which major mastitis pathogens were isolated and when treatment commenced 28-72 days after calving.

Management of dairy heifers and its relationships with the incidence of clinical mastitis.

AIM: To describe aspects of management of dairy heifers before calving and determine risk factors for clinical mastitis postpartum in heifers, at the herd level, under pasture-based management systems in the Waikato and Taranaki regions of New Zealand. METHODS: Dairy herdowners (n=578) provided information via a prospective survey about their practices for rearing heifers and management of mastitis. A proportion of herdowners (n=250) subsequently provided data on the cases of clinical mastitis in their herds, including the date, cow identification, age and quarter affected from cases occurring in the 4 months after the planned start of calving (PSC) in the subsequent lactation. The relationship between management factors and the proportion of heifers diagnosed with clinical mastitis within a herd was examined using bivariate and multivariate analyses. RESULTS: The herd average percentage of heifers with clinical mastitis was 13.6 (95% confidence interval (CI)=12.3-14.9)%, and multiparous cows with clinical mastitis was 9.0 (95% CI=8.2-9.8)% in the first 4 months of lactation. There were positive relationships between the proportion of heifers with clinical mastitis and average milk production per cow (kg milksolids/ lactation; p<0.001), number of cows milked per labour unit (p=0.003), stocking rate (<> 3.30 cows/ha; p=0.002), and incidence of clinical mastitis in multiparous cows (%/120 days; p<0.04), in the final multivariate model. The proportion of heifers with clinical mastitis per herd was lower in herds that milked their lactating cows in multiple groups (p=0.02). CONCLUSIONS: The risk of clinical mastitis in heifers was significantly associated with management practices. It may be possible to reduce the incidence of clinical mastitis in heifers by modification of management practices at the herd level, and further studies are required to investigate this.

Interobserver variability in assessment of the larynx.

Recent papers have shown a high degree of disagreement between observers in the assessment of physical signs. In order to determine the interobserver variation in assessment of the larynx, 63 patients were each examined by 2 ENT registrars. The examiners agreed on the assessment of the voice in 80% of cases, and on the indirect laryngoscopy appearance in 76%. These results compare favourably with those reported previously for other forms of clinical examination.

Acute disseminated encephalomyelitis: a case history.

Acute disseminated encephalomyelitis (ADEM) is a rarely reported demyelinating condition of the central nervous system, usually affecting children and young adults. The case of a 23-year-old woman diagnosed as suffering from ADEM is presented. Details are given of her assessment and attempted rehabilitation with particular reference to speech and language. Differentiation of ADEM from multiple sclerosis (MS) is problematic and may be clarified by examination of the pathological effects of the disease processes on speech and language. A general review of the scant literature is included and findings in this patient are compared and contrasted to them.

Is a pre-discharge checklist useful?

A pre-discharge checklist of requirements for equipment, services, benefits and follow-up has been developed in a general rehabilitation unit. An analysis of 66 inpatients discharged after rehabilitation following a stroke or amputation within the past 2 years suggests that such a checklist is a useful tool in ensuring that patients are sent home with optimum services and support. It is also a simple way of recording discharge data for audit and quality control purposes. It may be of benefit to a wider range of hospital services.