The Prevalence of Protozoa During Canine Periodontal Disease

Canine periodontal disease is a widespread oral disorder of dogs and has a population prevalence estimated to range from 44-64% of all individuals. For several decades researchers have focused on examining the bacterial communities present in plaque, the aetiological agent of periodontal disease. Other microorganisms, such as protozoa, are also known to exist in plaque, however, the role they play in contributing to periodontal disease is less well understood. Molecular biology protocols were developed that enabled the rapid, multiplexed identification of protozoa in mixed-microorganism canine plaque samples collected from dogs with diverse oral health states. Protozoa from the genera Trichomonas and Entamoeba were detected with overall prevalence in the total sample population being 56.52 % (52/92) and 4.34 % (4/92) respectively. To address primer bias weaknesses inherent in PCR-based methods, a protozoa identification techniques not based on the use of pre-existing sequence information and PCR was also devised. These methods were based on the sequencing of ribosomal RNA extracted from plaque samples using state-of-the-art sequencing technologies. Quantitative molecular assays (qPCR) were also developed to enable the detection and quantification of the organisms localised to teeth. The method revealed the abundance of both protozoa to be correlated with more diseased samples and to specific tooth types (molars and premolars) within the mouth. Finally, investigations were conducted, to assess the potential of these organisms to contribute to canine periodontal disease. The research outcomes of this thesis provide the first conclusive evidence that oral protozoa are present in canine mouths, are associated with periodontal disease samples and are capable of contributing to the disease process. Researchers of periodontal disease and those attempting to reduce the diseases burden in dogs and humans should focus more attention to both Entamoebae and Trichomonad presence in the mouth and investigate their biology and function further