There is a lack of scientifically proved data about change of specious composition and quantitative ratio of microbiota in digestive tract when panleukopenia progresses. So, analysis of these indicators can help to find out mechanics of development and processing of dysbiotic statements, make a prognosis of it’s course and develop methods of efficiency evaluation of preventive and treatment measures dealing with cats’ panleukopenia. In course of virus illnesses including panleukopenia good conditions for activation of opportunistic microorganisms appear in cats macroorganism. The multiplication of accompanying can considerably complicate the main illness course. Also, opportunistic microorganisms that frequently figure as representatives of resident and transit organism microflora can affect it detrimentally in while the ecological balance of major and minor microbiote is broken. Analysis of these indicators will allow to find out the mechanics of dysbiotic statements development and progressing, prognose the difficulty of their courses and understand methods of efficiency evaluation of preventive and treatment measures dealing with cats’ panleukopenia. Accompanying microflora during cats panleukopenia isolated from different seek animals’ biotopes. It was found that during cats panleukopenia in different biotopes of the organism dysbacteriosis appear and it’s accompanied by sharp decrease of normoflora representatives and their replacing with opportunistic microorganisms. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.