Abstract: The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with different reported prevalences of R. equi pneumonia. Colony blotting and DNA hybridization were used to detect and measure concentrations of virulent R. equi. The prevalence of R. equi pneumonia was associated with the airborne burden of virulent R. equi (both the concentration and the proportion of R. equi bacteria that were virulent) but was not associated with the burden of virulent R. equi in the soil. Univariable screening and multivariable model building were used to evaluate the effect of environmental and management factors on virulent R. equi burdens. Lower soil moisture concentrations and lower pasture heights were significantly associated with elevated airborne concentrations of virulent R. equi, as were the holding pens and lanes, which typically were sandy, dry, and devoid of pasture cover. Few variables appeared to influence concentrations of virulent R. equi in soil. Acidic soil conditions may have contributed to an elevated proportion of virulent strains within the R. equi population. Environmental management strategies that aim to reduce the level of exposure of susceptible foals to airborne virulent R. equi are most likely to reduce the impact of R. equi pneumonia on endemically affected farms.

Abstract: A selective broth enrichment technique was used to study the distribution of Rhodococcus equi in soil and grazing animals. Rhodococcus equi was isolated from 54% of soils examined and from the gut contents, rectal faeces and dung of all grazing herbivorous species examined. Rhodococcus equi was not isolated from the faeces or dung of penned animals which did not have access to grazing. The isolation rate from dung was much higher than from other samples and this was found to be due to the ability of R. equi to multiply more readily in dung. Delayed hypersensitivity tests were carried out on horses, sheep and cattle, but only horses reacted significantly. The physiological characteristics of R. equi and the nature of its distribution in the environment suggested that R. equi is a soil organism.

Abstract: In 2004, Natalie Lloyd and Jane Mulcock initiated the Australian Animals & Society Study Group, a network of social science, humanities and arts scholars that quickly grew to include more than 100 participants. In July 2005, about 50 participants attended the group“s 4-day inaugural conference at the University of Western Australia, Perth. Papers in this issue emerged from the conference. They exemplify the Australian academy”s work in the fields of History, Population Health, Sociology, Geography, and English and address strong themes: human-equine relationships; management of native and introduced animals; and relationships with other domestic, nonhuman animals-from cats and dogs to cattle. Human-Animal Studies is an expanding field in Australia. However, many scholars, due to funding and teaching concerns, focus their primary research in different domains. All authors in this issue-excepting one-are new scholars in their respective fields. The papers represent the diversity and innovation of recent Australian research on human-animal interactions. The authors look at both past and present, then anticipate future challenges in building an effective network to expand this field of study in Australia.