Periodontal disease is one of the most common conditions affecting companion dogs. The objectives of this cross-sectional study were: to determine 1) the agreement between visual assessments (VA) of periodontal disease (PD) performed on awake dogs and the reference standard (RS) of a dental examination and radiographs performed with the dog under general anesthesia, and 2) inter-rater reliability (IRR) for two individuals performing VAs of PD on the same dogs. One hundred and eight dogs were recruited from three veterinary practices. An oral examination and visual PD staging based on the American Veterinary Dental College's (AVDC) 5-point scale was performed by the investigators prior to general anesthesia and the dental procedure. After the anesthetic evaluation and radiographs, the attending veterinarian staged each dog based on the AVDC's 5-point scale. Agreement between the VA and RS as well as IRR were determined using percent agreement and a weighted kappa statistic. Eighty-nine dogs received a complete oral examination under general anesthesia with periodontal probing and full-mouth radiographs. Fifty-nine dogs received a VA by both raters. VA agreed with the RS 41.57% of the time with a weighted kappa of 0.42 (95% confidence interval 0.29-0.55), indicating moderate agreement. Between raters, VA agreed 61.02% of the time with a weighted kappa of 0.63 (95% confidence interval 0.49-0.76), indicating substantial IRR. The results of this study reinforce the idea that an oral examination in an awake dog can be a helpful screening tool, but should not be considered a comprehensive evaluation of periodontal health. In facilities housing large numbers of dogs such as shelters, breeding kennels, and research facilities, use of a VA can aid in identifying and prioritizing dogs most in need of procedures such as professional cleaning, periodontal treatment, including closed root planing, or surgical care.