The article presents the results of assessing the morphometric and densitometric parameters of biofilms of reference strains and clinical isolates of Enterobacterales. In a private rabbit farm, there was an outbreak of indigestion among young animals. Thirteen young rabbits with severe diarrhea were observed for over a week. Other animals did not have such symptoms. Sick rabbits were placed in a separate room. They took a stool test and blood from the ear (experience, n=13). For comparison purposes, the same samples were taken from healthy animals of the same age from the same farm (control, n=13). Among the 20 Gram-negative bacteria of Enterobacterales isolated from the fecal mass of ill rabbits, 14(70.0%) isolates Escherichia coli O78, O20, and O101; 4(20.0%) isolates Klebsiella pneumoniae; 2(10.0%) isolates Salmonella genus: one S. enteritidis and one S. dublin were identified. Morphometric and densitometric indices of biofilms of reference strains and fecal isolates from ill animals had common patterns of biofilm formation. However, the clinical isolates formed more robust biofilms than the museum strains. Many types of microorganisms can increase their pathogenicity when exposed to susceptible animals. Our study proved this fact in Enterobacterales by comparing it with museum strains at all stages described in detail, which formed one of the main pathogenic factors-robust biofilms. © 2024, Unique Scientific Publishers. All rights reserved.