Heartworm Infection Among Domestic Dogs in Canada with a Focus on Ontario: Temporal Trend, Spatial Distribution and Risk Factors

Abstract

The heartworm infection status of domestic dogs in Canada, specifically Ontario is described in this thesis. The analysis was based on annual survey data collected from veterinary clinics across Canada during 1977 to 2010, as well as serological laboratory test results collected from 2007 to 2016. A temporal trend in heartworm infection was assessed using survey and laboratory data. Furthermore, the survey data were used to assess the efficacy of preventive medication through the Attributable Fraction Exposed. The spatial extent of heartworm was visually assessed through choropleth maps. The impact of reported risk factors on heartworm infection prevalence was assessed. Descriptive analysis revealed temporal changes in prevalence and changes in spatial distribution. Further analysis of risk factors illustrated that climate and human population size have impacted canine heartworm infection prevalence in southern Ontario. This thesis contributes to the understanding of heartworm infection in domestic dogs in both Ontario and Canada.