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Several studies have shown that a considerable proportion of horses are eliminated from endurance rides due to lameness and metabolic problems. Limited information is available on specific veterinary issues in endurance horses and there are no descriptive data on veterinary problems in a large population of endurance horses. The aim of this study was to describe veterinary problems occurring in endurance horses in England and Wales, the regions of the United Kingdom where endurance rides are organised and regulated by Endurance Great Britain (Endurance GB). A comprehensive online self-completed questionnaire was used for data collection (30th December 2015-29th February 2016) All members of Endurance GB who were the main rider of one or more endurance horses were eligible to participate. From the target population of 1209 horses, 190 questionnaires were completed by riders, resulting in a 15.7% response rate. The most common rider-reported veterinary problem was lameness, affecting 152/190 (80.0%) of endurance horses at some point during their careers and 101/190 (53.2%) of horses in the previous 12 months. Detailed information on the most recent episode of lameness was available for 147 horses. Seventy-six percent of these lameness episodes (112/147) had been initially identified by a veterinarian, but only 52% of these lameness episodes were investigated further by a veterinarian, despite the high proportion of horses affected by lameness and the proportion of horses with recurrent lameness episodes. The second most common veterinary problem was thoracolumbar region pain, followed by non-specific cough, skin disease and colic. Education of endurance riders may improve the number, quality and timing of veterinary investigations, especially for lameness and thoracolumbar region pain.

The movement of animals between farms contributes to infectious disease spread in production animal populations, and is increasingly investigated with social network analysis methods. Tangible outcomes of this work include the identification of high-risk premises for targeting surveillance or control programs. However, knowledge of the effect of sampling or incomplete network enumeration on these studies is limited. In this study, a simulation algorithm is presented that provides an estimate of required sampling proportions based on predicted network size, density and degree value distribution. The algorithm may be applied a priori to ensure network analyses based on sampled or incomplete data provide population estimates of known precision. Results demonstrate that, for network degree measures, sample size requirements vary with sampling method. The repeatability of the algorithm output under constant network and sampling criteria was found to be consistent for networks with at least 1000 nodes (in this case, farms). Where simulated networks can be constructed to closely mimic the true network in a target population, this algorithm provides a straightforward approach to determining sample size under a given sampling procedure for a network measure of interest. It can be used to tailor study designs of known precision, for investigating specific livestock movement networks and their impact on disease dissemination within populations.

This paper reviews the past contributions of epidemiology and economics to the control of tickborne infections of cattle in Africa. The factors affecting successful and unsuccessful control are evaluated on a geographical and on a production systems basis, with particular reference to Theileria parva infection. The paper then discusses four areas of the emerging disciplines of epidemiology and economics which are likely to play an important role in better control of tick-borne diseases in the future, and illustrates their potential contributions. The four areas are: predicting target populations for vaccines through the use of serological tests, determining the appropriate sampling strategy to quantify tick-borne infection prevalence, modelling distributions and dynamics of tick-borne infections and predicting the economic impact of tick-borne diseases and their control.

This retrospective study examined associations between herd management techniques and litter size in a target population of Ontario swine farms that marketed at least 1000 hogs or 35 sows in 1987. A survey was sent to these producers to determine their use of computerized records and to solicit their cooperation for the study. Thirty-two percent of the respondents ( 162 501 ) kept computerized records in 1989. The final study population included 76 producers who agreed to participate in the study and used either the Pigtales ™ or PigCHAMP™ software programs. Yearly average litter size in primiparous sows was higher in herds that were small, where the breeding manager was either a hired person or the husband rather than another family member, and where the boars or sows were moved to one another's pens for estrus detection. In multiparous sows factors associated with higher average litter size included small herds, breeding the sow twice rather than three or more times during estrus, and spending more time on estrus detection and breeding sows. The attitude of the producer was measured by asking if they thought breeding sows was a preferred chore, a least preferred chore, or an activity about which they were ambivalent. Although this factor was associated with litter size, it did not have a monotonic relationship as expected. The factors not significantly associated with litter size in the multivariate analyses included: vaccination for Leptospira spp., hand mating sows, and the timing of breeding with respect to the onset of estrus.

A mail survey was conducted to determined the frequency of epidemics of swine reproductive failure syndrome (SRFS) (based on reports by accredited veterinary diagnostic laboratories in the US between 1987 and 1990), their geographic distribution, and tests used to study the syndrome. Twenty-seven accredited diagnostic laboratories in 17 states, nine diagnostic specialties, and 73 veterinary diagnosticians were included in the target population. The responce rates for the states, the diagnostic laboratories, the diagnostic specialtiesm, and the diagnoticians were 100%, 96%, 100%, and 88%, respectively. Epidemics of SRFS had been diagnosed in 12 (70%) of the 17 states and by 16 (61%) of the 26 responding diagnostic laboratories. The estimate of the minimum number of herds in which SRFS had been diagnosed nationwide was 160. The rank order (highest to lowest) of the diagnostic tests that had been used to search for an etiologic agent of SRFS was bacteriology, serology, virology, toxicology, histology, nutritional, and electron microscopy. The results of the study suggest that standardization of the diagnostic protocols may reduce the potential for misclassification of herds due to diagnostic test bias, reduce investigator prejudices and the selective incrimination of putative etiologic agents, increase the comparability of results among laboratories, and increase the efficiency of identifying the true etiologic agent(s) of new animal diseases.

Prevalence estimates are used by decision makers such as policy makers and risk assessors to make choices related to certain diseases and infections. Paratuberculosis, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic infection particularly resulting in economic losses among farmed ruminants. Therefore, this infection is of concern for many farming industry decision makers. As a result, multiple studies have been carried out to determine the within-herd and between-herd prevalence of MAP infections. The objective of the present study was to conduct a review and, if possible, compare animal and herd level prevalences of MAP among farmed animals in Europe. European data on prevalences of MAP in all farmed animal species were included from a review of literature. Information on target population and study design, tests used and apparent prevalences were recorded, and subsequently true prevalences were calculated when possible. A critical review of the included studies indicated that although a wide range of studies have been conducted, likely and comparable true prevalence estimates could rarely be calculated. Based on a few studies where the prevalences appeared to be plausible, it was concluded that prevalences of MAP would have to be guesstimates based on available data. The true prevalence among cattle appeared to be approximately 20% and was at least 3–5% in several countries. Between-herd prevalence guesstimates appeared to be >50%. No countries had published sufficient information to claim freedom from MAP or just a near-zero prevalence of MAP infections. No within-flock prevalence estimates were available for goats and sheep. The between-flock prevalence guesstimates were >20%, based only on estimates from Switzerland and Spain. Major critical issues were identified in the majority of the studies, primarily due to lack of knowledge of the test accuracy of the diagnostic test used, or due to studies where the study population did not reflect the target population. Because most of the reported studies did not yield prevalence estimates which were comparable to other studies, there is a continuing need for well-designed studies of the prevalence of MAP infections.

Two experiments were carried out to identify the target population of cattle for immunisation against East Coast fever (ECF) using the infection-and-treatment method. Firstly, a sentinel-calf study was used to determine the age window for ECF immunisation by determining ages at clinical detection of infection with Theileria parva. Six groups of five naive cross-bred (Bos taurus/Bos indicus) male calves, introduced at intervals of 2 months at a mean age of 26 days, were exposed to natural tick challenge on a high ECF-risk, small-holder farm in the coastal lowland, coconut–cassava agro-ecological zone of coastal Kenya. Secondly, a challenge study evaluated the relationship between the presence of T. parva antibodies and immunity. Ten indigenous adult Zebu cattle and nine Zebu young stock purchased from farmers in the same zone, and eight cross-bred calves (survivors of the sentinel-calf study) were challenged with 10 times the immunising dose of T. parva Marikebuni stock. Twenty-four of these 27 cattle had high antibody titres before challenge. Two cross-bred calves, obtained from an ECF-free area and seronegative to T. parva schizont antigen, also were challenged and used as susceptible controls. Twenty-five (83%) of the 30 sentinel calves contracted ECF over an age range of 36–116 days (mean 72 days). The remaining five calves died of other causes within 2 months of arrival on the farm. Fourteen of the 25 calves survived the infection and developed antibodies to T. parva. Despite tick control, seven of these 14 calves had a second episode of ECF and two died. In total, 13 of the 25 calves that contracted ECF died. Only one of 19 indigenous Zebu animals developed clinical ECF when challenged with T. parva Marikebuni (mild clinical signs with spontaneous recovery). Of the eight cross-bred survivors from the first experiment, only one succumbed to ECF when challenged and it died. Both susceptible cross-bred calves developed severe clinical signs of ECF and one died. The experimental studies show that in the high ECF-risk areas of the coconut–cassava zone of coastal Kenya, immunisation against ECF in cross-bred (B. taurus/B. indicus) cattle should be targeted at an early age (preferably within 1–2 months of birth).