Abstract
This study is devoted to morphological and histological changes in the intestines of saigas (Saiga tatarica) infected with the cestode Moniezia expansa. The results show that parasitic invasion is accompanied by pronounced pathological changes, mainly in the duodenum and colon. Macroscopically, wrinkled, bumpy intestinal walls resembling beads, edema and hyperemia of the mucous membrane, as well as hemorrhages and exudation were observed. Histological examination revealed numerous nodular folds and hyperplasia of the mucosa, increased depth of crypts, degenerative-necrotic changes in the epithelium, wave-like deformation and lysis of smooth muscle fibers. Microcirculation disorders in the form of blood stasis and accumulations of formed elements were also recorded. A large number of intraepithelial lymphocytes were observed in the epithelial layer, indicating an inflammatory process and partial necrosis. The subserous membrane was characterized by lymphocyte infiltration and the presence of small vessels in the connective tissue. The frequency of individual signs ranged from 60% to 90% in the samples examined (n=13), with the most pronounced changes observed in the mucous membrane and muscle layers of the duodenum. The data obtained indicate that M. expansa has a complex destructive effect on the intestinal structures of saigas, causing inflammatory and degenerative processes that can significantly weaken the health of the population. The presented materials allow for a deeper understanding of the pathogenesis of parasitic diseases in wild ungulates and enable the use of these data in veterinary diagnostics and the development of biosecurity measures.