The objective of the study was to investigate the long-term effects of feeding a dental hygiene chew that has been shown to be effective in promoting periodontal health in dogs in short-term studies. Oral malodor, calculus, and plaque scores were still significantly lower after 21 months in the group that was receiving the dental hygiene chew, although gingivitis scores no longer differed significantly. There were no reports of any adverse reactions during the study. The results of the study support that feeding of the dental hygiene chew six days per week reduces accumulation of dental deposits, helps maintain periodontal health, and increases the time interval between professional periodontal intervention.