RITA GRACE SACHARIA2024-01-182024-01-182022-09-20https://krishikosh.egranth.ac.in/handle/1/5810206393Otitis externa is the acute or chronic inflammation of externa ear and dogs are more prone to this disease. The disease occurs due to many factors, bacteria and fungi are only the opportunistic pathogens rather than the primary cause of the disease. A total of 20 dogs that were presented in Teaching Veterinary Clinical Complex, Pookode with otitis externa were selected randomly and their epidemiological details viz. age, sex , breed, body weight, skin condition and management practices were recorded. Ear swabs were collected and subjected to cultural and biochemical identification. Whole blood was collected for determining haematological parameters. Genomic DNA isolation was done for samples positive for Pseudomonas spp. after cultural and biochemical identification, and were subjected to PCR for genus specific confirmation of Pseudomonas. Detection of virulence genes viz. Las A, Las B, Lec A, Lec B and Apr was conducted on samples identified as Pseudomonas at genus level. Clinical trial was conducted on 12 randomlyselected dogs with otitis externa. The animals were separated into two groups, one treated with antibiotics alone and the second group with a combination of antibiotic and a biofilm cleaving agent that is Tris EDTA as topical application. Present study revealed that 45 per cent of the bacterial isolates from canine otitis externa cases belonged to Pseudomonas spp., 40 per cent Staphylococcus spp. and 15 per cent Streptococcus spp. on cultural and biochemical identification. All the Pseudomonas isolates were further confirmed by PCR. Among them identification of virulence genes revealed presence of Las B and Apr gene in all the isolates and 55.56 per cent of the isolates were positive for Lec B gene. Haematological parameters showed marked leucocytosis, neutrophilia and lymphopaenia in affected animals. Though there were no statistically significant improvement between both the groups in clinical trial, it was noticed that animals treated with combination of antibiotic and biofilm cleaving agent had more numbers of complete recovery. Acad. Form No.EnglishThesis