| Abstract | Hormoni štitaste žlijezde imaju značajnu funkciju u mnogobrojnim fiziološkim
procesima u ljudi i životinja uključujući u regulaciji metabolizam, rasta i razvoj jedinke pa tako
u reproduktivnoj funkciji. Hormoni štitaste žlijezde, trijodtironin (T3) i tiroksin (T4), imaju
izravan učinak na reproduktivne organe i neizravan u interakciji s drugim hormonima. Hormoni
štitaste žlijezde utječu na reproduktivni sustav regulirajući metabolizam i razvoj tkiva jajnika,
maternice i posteljice. Promjene u serumskim koncentracijama T3 i T4 dovode do poremećaja
u radu cijelog organizma. Disfunkcija štitaste žlijezde, uključujući hipotireozu i hipertireozu,
može dovesti do značajnih reproduktivnih problema. Stoga je cilj ovog preglednog rada opisati
funkcije hormona štitaste žlijezde te prikazati učinke hipotireoze i hipertireoze na reproduktivni
sustav životinja s posebnim osvrtom na pse i mačke. Hipotireoza, često uzrokovana autoimunim
bolestima, poput limfocitnog tireoiditisa, povezana je s kasnijim spolnim sazrijevanjem,
smanjenom plodnošću i poremećajima u razvoju reproduktivnih organa. Hipotireoza može
uzorkovati produljeni interestrusni interval, izostanak ciklusa, tihe estrusne cikluse, produljeno
estrusno krvarenje i nedostatak libida uz pojavu neplodnosti, pobačaja, mrtvorođenosti i
mumificiranih fetusa. U mužjaka hipotireoza dovodi do smanjenja libida, kvalitete sjemena,
volumena ejakulata, atrofije testisa, hipospermije i azoospermije. Nasuprot tome, hipertireoza
je najčešće posljedica karcinoma štitaste žlijezde koji proizvodi prekomjerne količine hormona
štitaste žlijezde. Povećane koncentracije hormona štitaste žlijezde dovode do poremećaja
fiziološke ravnoteže reproduktivnih hormona, nepravilnih estrusnih ciklusa, anovulacije i
smanjene plodnosti, te smanjenja mase jajnika i broja normalnih folikula s povećanjem broja
atrezirajućih folikula. Učinci hipertireoze na plodnost mužjaka uključuju poremećaje u
spermatogenezi, promjene u razinama spolnih hormona i promjene u kvaliteti sjemena, poput
hipospermije, oligozoospermije, astenozoospermije i teratozoospermije. Važno je naglasiti
važnost pravovremene dijagnoze i liječenja poremećaja štitaste žlijezde kako bi se spriječili
negativni učinci na plodnost i reprodukciju životinja. |
| Abstract (english) | Thyroid hormones have an important function in numerous physiological processes in
humans and animals, including the regulation of metabolism, growth and development of the
individual and thus also the reproductive function. The thyroid hormones, triiodothyronine (T3)
and thyroxine (T4), have a direct effect on the reproductive organs and an indirect effect in
interaction with other hormones. Thyroid hormones influence the reproductive system by
regulating the metabolism and tissue development of the ovaries, uterus and placenta. Changes
in the serum concentrations of T3 and T4 lead to disturbances in the function of the entire
organism. Thyroid dysfunction, including hypothyroidism and hyperthyroidism, can lead to
significant reproductive problems. The aim of this review is therefore to describe the functions
of thyroid hormones and the effects of hypothyroidism and hyperthyroidism on the reproductive
system of animals with special reference to dogs and cats. Hypothyroidism, which is often
caused by autoimmune diseases such as lymphocytic thyroiditis, is associated with later
puberty, reduced fertility and abnormalities in the development of the reproductive organs.
Hypothyroidism can lead to a prolonged interval, absent cycles, silent estrus cycles, prolonged
estrus bleeding and a lack of libido with the occurrence of infertility, miscarriages, stillbirths
and mummified fetuses. In males, hypothyroidism leads to a decrease in libido, semen quality,
ejaculate volume, testicular atrophy, hypospermia and azoospermia. Hyperthyroidism, on the
other hand, is usually the result of thyroid cancer, which produces excessive amounts of thyroid
hormones. Increased concentrations of thyroid hormones lead to disturbances in the
physiological balance of reproductive hormones, irregular oestrus cycles, anovulation and
reduced fertility as well as a decrease in the weight of the ovaries and the number of healthy
follicles with a simultaneous increase in the number of atretting follicles. The effects of
hyperthyroidism on male fertility include disorders of spermatogenesis, changes in sex
hormone levels and changes in sperm quality, such as hypospermia, oligozoospermia,
asthenozoospermia and teratozoospermia. It is important to emphasize the importance of timely
diagnosis and treatment of thyroid disorders to prevent negative effects on fertility and
reproduction in animals. |
