Hemorrhagic gastroenteritis is a potentially fatal disease especially in untreated animals. Total samples of 202 rectal swabs collected from dogs and cats were subjected to bacteriological examination. One hundred four bacterial isolates were identified from the total 202 examined samples. The identified bacterial isolates were E. coli (46; 44.23%), Proteus species (22; 21.15%), Klebsiella species (9; 8.65%), C. perfringens (5; 4.80%), Enterobacter species (4; 3.84%), Pseudomonas aeruginosa (4; 3.84%), Salmonella species (3; 2.88%), Shigella species (3; 2.88%); Citrobacter species (2; 1.92%), Providencia rettgeri (2; 1.92%), Serratia liquefaciens (1; 0.96%), Hafnia species (1; 0.96%), C. bifermentans (1; 0.96%), C. putrefaciens (1; 0.96%). Serological identification for some E. coli isolates revealed that EHEC strains represent (12/26, 46.15%), EPEC (9/26, 34.61%), ETEC (4/26, 15.38%) and EIEC (1/26, 3.85%). Serotyping of Salmonella isolates detected S. Typhymurium, S. Heidelberg and S. Infantis. In case of canine E. coli isolates, resistance was recorded against amoxicillin/clavulanic acid, cephalexin, ceftriaxone, tetracycline, erythromycin and trimethoprim/sulphamethoxazole. Moderate resistance was recorded among feline E. coli isolates to amoxicillin/clavulanic acid, tetracycline and trimethoprim/ sulphamethoxazole. Salmonella isolates were highly resistant to amoxicillin/clavulanic acid, cephalexin, erythromycin, tetracycline and trimethoprim/sulphamethoxazole. In experimentally infected puppies with S. Typhymurium, histopathological examination showed necrosis in the tips of the villi and leukocytic infiltration in the submucosa of the jejunum, degeneration and fibrosis of the liver. In experimental salmonellosis in cats, histopathological examination showed coagulative necrosis in the tips of the villi of the jejunum and multifocal necrosis in the liver. In experimental E. coli infection in cats, histopathological examination showed ulceration and necrosis of the small intestine. The liver showed congestion of the blood vessels and fibrosis around the hepatic areas.