Faculty of Veterinary Medicine University of Zagreb
Abstract
The objective of this experiment was to determine pathological and biochemical changes in hypothyroid sheep. Experiments were carried out using 12 Iranian crossbred sheep aged between 3-3.5 years old and weighing 45-65 kg. The animals were divided into two groups, 4 sheep as control and 8 as the experimental group. Hypothyroidism was induced in experimental animals by giving thiourea 50 mg/kg body mass daily for 4 weeks. Blood samples were taken weekly for T3 and T4 measurements. There was a highly significant decrease (P<0.01) in values of T3 and T4 in experimental animals as compared to the control group. At the end of the experiment all the animals of control and experimental groups were sacrificed and necropsied. Tissue samples
were collected from the thyroid, kidney, liver, skin and spleen and stained by hematoxylin and eosin and sudan 3 and 4. In the experimental group the following changes were observed: the thyroid gland was moderately enlarged and firm in texture and darker in color. Histopathologically, the epithelial lining of the thyroid follicles showed hypertrophy and hyperplasia which projected into the lumen. The lumens of the follicles were empty of
colloid. Kidneys were apparently normal but microscopically showed glomerular lipidosis and tubular changes including mild congestion and lipidosis. The liver was pale, anemic, friable and enlarged. The hepatocytes exhibited fatty change and some inclusion bodies in their nuclei. Moreover, hyperplasia of bile ducts and mononuclear cell infiltration of liver were seen. The skin was mainly normal in the majority of the cases but histologically one case showed hyperkeratosis of the epidermis, associated with excessive keratin formation within the hair follicles. In the spleen, the number and size of macrophages were increased and one case showed some petechial hemorrhages on its surface. The treated ewes showed significant hyperlipidemia (P<0.01) and
hypercholesterolemia (P<0.01). A significant decline (P<0.01) was detected in HDL as well as a significant increase (P<0.01) in LDL serum levels of the treated ewes.Svrha pokusa bila je istražiti patološke i biokemijske promjene u ovaca s hipotireoidizmom. U pokus je uzeto 12 iranskih križanih ovaca u dobi od 3 do 3,5 godine tjelesne mase 45 do 65 kg. Ovce su bile podijeljene u dvije skupine: četiri su uzete u kontrolnu, a osam u pokusnu skupinu. Hipotireoidizam je u pokusnih životinja bio potaknut davanjem 50 mg/kg tjelesne mase tioureje dnevno u tijeku četiri tjedna. Uzorci krvi uzimani su tjedno za mjerenje T3 i T4. Ustanovljeno je značajno smanjenje (P<0,01) vrijednosti T3 i T4 u pokusnih životinja u odnosu na kontrolnu skupinu. Na kraju pokusa sve su životinje pokusne i kontrolne skupine bile žrtvovane
i razuđene. Uzeti su uzorci tkiva štitnjače, bubrega, jetre, kože i slezene te su pripremljeni histološki preparati obojeni hematoksilin-eozinom i sudan 3 i 4 postupkom. U pokusnoj skupini štitasta žlijezda bila je blago povećana, čvrste strukture i jače obojena. Epitel tireoidnoga folikula je hipertrofirao, a uočena je i hiperplazija projicirana u lumen. U lumenu folikula nije ustanovljen koloid. Bubrezi su makroskopski bili nepromijenjeni, ali je mikroskopski ustanovljena glomerularna lipidoza i tubularne promjene uključujući blagu kongestiju i lipidozu. Jetra su bila blijeda, anemična, prhka i povećana. U hepatocitima je ustanovljena masna degeneracija
i inkluzijska tjelešca u jezgrama. Povrh toga ustanovljena je hiperplazija žučovoda i mononuklearna infiltracija jetrenoga tkiva. Koža je makroskopski bila normalna u većine životinja, ali je patohistološki u jednom slučaju ustanovljena hiperkeratoza epidermisa povezana s obilnom tvorbom keratina unutar dlačnih folikula. U slezeni je bio povećan broj makrofaga i njihova veličina, a u jednom slučaju ustanovljena su petehijalna krvarenja na površini. Pokusne ovce pokazivale su značajnu hiperlipidemiju (P<0,01) i hiperkolesterolemiju (P<0,01). Ustanovljen je značajan pad razine (P<0,01) lipoproteina velike gustoće kao i značajno povećanje (P<0,01) razine lipotroteina male gustoće u pokusnih ovaca
