This thesis is an investigation of the use of various infection control practices, including hand hygiene, in companion animal veterinary clinics and a public petting zoo. Video observation of petting zoo visitors found overall hand hygiene compliance was 58% (340/583). Improved signage with offering hand sanitizer (odds ratio (OR) 3.38, p<0.001) and verbal hand hygiene reminders (OR 1.73, p=0.037) had a significant positive association with compliance. Video observation of preoperative preparation practices in ten veterinary clinics found contact times with preparatory solutions were often shorter than recommended: 10-462s for patients and 7-529s for surgeons using soap and water. Practices that did not conform to guidelines available in major companion animal surgical textbooks were commonly observed. A survey of veterinary staff found that over 80% of respondents ranked hand hygiene as of high importance in all clinical situations queried. The most frequently reported reason for not performing hand hygiene was forgetting to do so (40%, 141/353). Video observation of various infection control practices in 47 veterinary clinics found that poor sharps handling practices were common, yet only one needlestick injury was observed. Exam tables were cleaned following 76% (2015/2646) of appointments, and contact time with spray used to do so ranged from 0-4611s (mean 39s, median 9s). Appropriate personal protective clothing was worn for 72% (3518/4903) of staff-animal contacts. Video observation of hand hygiene practices in 38 veterinary clinics found overall hand hygiene compliance was 14% (1473/10894). Soap and water was used for 87% (1182/1353) of observed hand hygiene attempts with a mean contact time of 4s (median 2s, range 1-49s). A hand hygiene poster campaign had no significant effect on compliance. There is clearly room for improvement with regard to many frequently used infection control measures in veterinary clinics in Ontario. Use of active interventions to improve practices such as hand hygiene should be investigated in clinics, as such measures have been effective in other settings. The video monitoring system used in this research may be a useful tool for conducting these and similar studies in the future. A better infection control culture needs to be established in veterinary medicine. Accompanying data files are located at: http://hdl.handle.net/10864/10445 / Canadian Institutes of Health Research (CIHR), Ontario Veterinary College Pet Trust, Canada Foundation for Innovation