Clinical case of tularemia in a thoroughbred roadster stallion on the territory of Omsk region

Differential diagnosis of tularemia from brucellosis in a sick stallion kept in one of private stables in Omsk Region was given in the study. There were cases of mass death of wild rodents (small mouse-like rodents, wild hamsters, ground squirrels) and, subsequently, cats in the territory of the private stable during two months (July, August). The main clinical symptoms of the sick stallion were: cachexia in the combination with normal appetite, arthritis of the put joints of the pelvic limbs and subfebrile body temperature. Laboratory serological diagnosis included a complex of reactions such as Wright Agglutination Test, Complement Fixation Test (CFT), Rose Bengal Antigen Test, Indirect Hemagglutination Test (IHT). Antibody titers for the tularemia causative agent in IHT were 1: 320, which was a diagnostically important indicator. A highly sensitive Polymerase Chain Reaction (PCR) method was also used, which made it possible to carry out differential diagnostics, exclude brucellosis. Additional serological studies (IHT) gave negative reactions to yersiniosis (serovars 03 and 09) and to brucellosis (CFT). At compelled slaughter pathological changes in separate bodies were revealed. The liver was enlarged, there were multiple small grayish-yellow foci on the surface, scraping in the section was copious. The spleen was greatly enlarged, there were small spotted hemorrhages on its surface, the consistency of the organ was pasty and the edges were rounded. In the section, the pulp was dark cherry in color, while scraping it was copious. Mesenteric lymph nodes were also enlarged, swollen, with areas of hemorrhage and necrosis. On the serous membrane of the small intestine and mesentery, point hemorrhages were observed. The described clinical case confirms the need for a thorough differential diagnosis of horse tularemia in order to exclude other infections (brucellosis, yersiniosis) using highly sensitive laboratory diagnostic methods.