Comment on "Insulative capacity of the integument of the dugong (Dugong dugon): thermal conductivity, conductance and resistance measured by in vitro heat flux" by Horgan, Booth, Nichols and Lanyon (2014)

Cold stress syndrome is an incompletely understood but clearly very complicated, multisystemic entity that has been described as affecting Florida manatees chronically exposed to cold water (Bossart et al. 2002). Florida and south-east Queensland (QLD) are very similar in climate, species composition and marine environment. In 2013, our group published an article comparing the lesions described in manatees with those we were seeing in many of the dugongs presenting to our post-mortem room during the colder months of the year in Queensland. This description was combined with presentation of supporting environmental data (Owen et al. 2013). Horgan, Booth, Nichols and Lanyon have made statements contradicting our argument in their article, namely: “with no credible pathological evidence of CSS (cf. Owen et al. 2013)” and “Skin lesions suggested as characteristic of cold stress and reported for dugongs by Owen et al. (2013) are grossly and histologically different to those reported for the Florida manatee, are found in dugongs throughout the tropics (Woolford and Lanyon unpublished data) and are also found in dugongs in cooler waters outside the winter period (the latter point also reported by Owen et al. 2013). Each of these factors casts serious doubt as to these skin characteristics being thermally related”. These statements are not based on sound scientific principles. In the former instance, this statement has been made without offering any supporting or qualifying evidence and is therefore an unsubstantiated opinion. The dugong samples used for Owen et al. (2013) were assessed and compared by experienced pathologists and experts in marine population health, one of whom (MF) is in the unique position of having first-hand experience with disease in both manatees in Florida and dugongs in southeast QLD. Data and the resulting interpretations in this article were also deemed as credible by multiple reviewers. The qualifying This article presents original research to investigate the relationship between integumentary composition and predictive thermal capacity. The authors suggest that cold stress syndrome (CSS) is unlikely to occur in dugongs, a claim that is at odds with a recent study from our group where we described the local appearance of mortality cases consistent with this syndrome. Horgan et al. (2014) made two statements, in particular, which disregarded a diagnosis following observations by specialist veterinary pathologists, yet without, to our knowledge, accessing the material themselves and instead quoting ‘unpublished data’ to support their conclusions. Further, and importantly, Horgan et al. (2014) ignore the pathological changes we described in other organ systems, which were consistent with changes noted during CSS in manatees and led to our diagnosis.