Diffuse Alopecia and Thyroid Atrophy in Sheep.

Rubia Avlade Guedes Sampaio,Vitória Maria Da Silva,Daniela Dantas De Gois,Alexandra Melo Oliveira,Raquel Costa Lima,Ricardo Barbosa Lucena,Franklin Riet-Correa,Iara Geovana Da Silva,Sara Vilar Dantas Simões,Francisca Maria Sousa Barbosa

doi:10.3390/ani11123530

Abstract

Simple SummaryThyroid dysfunction substantially affects quality of life, causing disturbances in different organs. A low intake of selenium and zinc can predispose to thyroid changes, resulting in hypothyroidism. A deficiency of selenium and zinc causes thyroid dysfunction and skin lesions. This paper describes natural cases of diffuse alopecia and thyroid abnormalities in sheep with selenium and zinc deficiency. The sheep had severe alopecia, and the thyroid hormones serum concentrations were below the reference values for the species. Zinc and Se concentrations were low in the serum and liver, and the thyroid gland was smaller than normal size. The present study is important as it is the first study examining zinc and Se deficiencies causing hypothyroidism in sheep. Furthermore, thyroid disorders affect the quality of life of humans and animals, and are associated with many organ-specific and non-organ-specific disorders.Thyroid dysfunction substantially affects the quality of life due to its association with various disorders in different organs. A low intake of selenium and zinc can predispose to thyroid alterations, resulting in hypothyroidism. A deficiency of selenium and zinc causes direct and indirect skin lesions, both by the action of free radicals on the skin and by thyroid dysfunction. The aim of this study was to describe natural cases of diffuse alopecia and thyroid abnormalities in sheep with selenium and zinc deficiency. Five adult sheep presented marked and diffuse alopecia, and the residual hairs were dry and brittle. The skin was thick and crusty, with marked peeling. The triiodothyronine (T3) and thyroxine (T4) serum concentrations were below reference values for the species. Zinc and Se concentrations were low in both the serum and liver. During necropsy, cachexia associated with serous fat atrophy was observed, and the thyroid glands showed marked atrophy. Microscopically, the thyroid presented multifocal to coalescent atrophy, with atrophied and dilated follicles, macrophage infiltration, and the presence of fibrous connective tissue. The skin revealed hyperkeratosis and edema. It is concluded that thyroid atrophy, alopecia, and hyperkeratosis are associated with low serum and liver concentrations of zinc and selenium in sheep.

Highlights

Thyroid hormones activate the nuclear transcription of many genes in practically all cells, influencing the functional activity of the entire organism [1]
This study aimed to describe natural cases of diffuse alopecia and thyroid alterations in sheep with low concentrations of selenium and zinc in the serum and liver
The animals were between three and five years old. They were raised with extensive grazing in the Caatinga, a semi-arid region

Summary

Introduction

Thyroid hormones activate the nuclear transcription of many genes in practically all cells, influencing the functional activity of the entire organism [1]. Thyroid hormone production may be affected by different factors, including mineral deficiencies such selenium [3], as these microelements are important for thyroid gland homeostasis [4,5]. Selenium is stored in the thyroid and is incorporated into selenoproteins (glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases), which protect the gland from oxidative injuries during hormone production [4]. The deficiency of this mineral decreases the function of important selenoproteins, in particular iodothyronine deiodinases, which are responsible for the conversion of T4 to T3 [6].

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