Assessment of the Thyroid Profile in the Iberian Lynx (Lynx pardinus)

• Autor(a) principal: Fernandes, Adriana Maia
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/11869
• topic: Conservation; Lynx pardinus

The Iberian Lynx (Lynx pardinus) conservation status has been suffering alterations through the years. Having been considered extinct in Portugal and critically endangered in Spain, is the species of felids most endangered in the world. Nowadays its conservation status is classified as endangered (by IUCN). This was due to the increase in the numbers of animals after in situ and ex situ conservation programmes took place, in united efforts between Portugal and Spain. Despite the extensive scientific knowledge about behavioural and reproductive endocrinology areas, others need to be developed. In the last years the populations are growing and evolving toward a geriatric phase which justifies the importance of studies on the thyroid hormones to discard thyroid disfunction in this species. As so, the objective of this study was to establish the reference intervals for total T4 (TT4) and TSH for the Lynx pardinus, either in captive or wild populations. In this study, they were included samples of 71 animals of both environmental statuses (ncaptive=32; nwild=39), of both genders (nfemales=32; nmales=39) and of different ages, organized in groups (n[juveniles]=32; n[adults]=14; n[geriatrics]=25). The samples were analyses by IDEXX Laboratories Spain, using enzyme immunoanalysis for the measurement of TT4 (Beckman Coulter – AU5800 series®) and chemiluminescence for the measurement of TSH (IMMULITE® 2000 XPi Immunoassay System). The reference interval established (RI) for TT4 was 0.80-2.00 µg/dl for captive animals, and 0.70-2.20 µg/dl for wild animals, being that difference not statistically significant (p=0.065). The RI established for TSH were 0.00-1.10 ng/ml and 0.00-0.10 ng/ml, for captive and wild animals, respectively, being the difference statistically significant (p<0.001). Regarding the gender and age in captive animals, the TT4 is proven to be significantly affected by the gender (meanfemales=1.256±0.242 µg/dl; médiamales=1.487±0.297 µg/dl; p=0.024), but not by the age (meanjuveniles=1.256±0.188 µg/dl; meanadults=1.263±0.358 µg/dl ; meangeriatrics=1.500±0.263 µg/dl; p=0.066), and TSH is not influenced by any of the factors in the population under study [(meanfemales=0.228±0.240 ng/dl; meanmales=0.209±0.181 µg/dl; p=0.808); (meanjuveniles=0.136±0.078 ng/dl; meanadultss=0.148±0.137 ng/dl ; meangeriatrics=0.328±0.270 ng/dl; p=0.054)]. In the wild set of samples, the gender also seems to have influence in TT4 (meanfemales=1.069±0.212 µg/dl; meanmales=1.326±0.393 µg/dl; p=0.023), but not in TSH (meanfemales=0.034±0.007 ng/dl; meanmales=0.040±0.024 ng/dl; p=0.395). The age factor does not have statistic influence in neither of the hormones under study in the wild population, similarly to the captive set [(meanjuvenilesTT4=1187±0.321 µg/dl; meanadultsTT4=1.500±0.533 µg/dl; meangeriatricsTT4=1.130±0.221 µg/dl; pTT4=0.095); (meanjuvenilesTSH=0.040±0.025 ng/dl; meanadultsTSH=0.033±0.008 ng/dl; meangeriatricsTSH=0.034±0.005 ng/dl; pTSH=0.630)]. The presented study allowed, for the first time, the definition of the RI for TT4 and TSH for Iberian Lynxes’ captive and wild populations. Additionally, it was possible to conclude that the gender and age may influence some of the parameters analysed and, as so, these factors must be taken under consideration when determining these hormones.