Effect of Clindamycin Hydrochloride on Oral Malodor, Plaque, Calculus, and Gingivitis in Dogs with Periodontitis*

J. M. Warrick, G. A. Inskeep, T. D. Yonkers, G. K. Stookey, and T. H. Ewing Effect of Clindamycin Hydrochloride on Oral Malodor, Plaque, Calculus, and Gingivitis in Dogs with Periodontitis* Janice M. Warrick, RLATg a Gregory A. Inskeep, DVM b Thomas D. Yonkers, DVM c George K. Stookey, PhD a Thomas H. Ewing, LAT a a Indiana University, School of Dentistry 1121 West Michigan Street Indianapolis, IN 46202-5186 b Noah s Ark Pet Hospital, P.C. 706 West Kannal Avenue Rensselaer, IN 47978 c Pharmacia and Upjohn Inc. Animal Health Division 700 Portage Road Kalamazoo, MI 49001-0199 ABSTRACT Periodontal disease is considered the most common disease of dogs and cats. The clinical sign most frequently reported by clients is oral malodor. Clindamycin hydrochloride has been used for several years for the treatment of periodontal disease in both cats and dogs. This study was designed to assess the effect of clindamycin HCl when used in two different postprophylaxis treatment regimens on oral malodor and periodontal disease in a controlled clinical trial. This study demonstrated that a 5- day postprophylaxis regimen was significantly effective in reducing oral malodor compared *This investigation was supported in part by Pharmacia and Upjohn Inc., Animal Health Division, Kalamazoo, Michigan. with a dental prophylaxis alone. Clindamycin HCl significantly reduced oral malodor from the animals baseline levels through 42 days. In addition, although no effect was observed on periodontal pocket depth, this treatment regimen also resulted in significant reductions in dental plaque, dental calculus, and gingival bleeding. INTRODUCTION Veterinarians see periodontal disease more often than any other infection in veterinary practice. 1 As many as 80% of dogs aged 2 years and older are affected, and nearly all dogs older than 5 years have periodontitis. 2 In addition, periodontal disease is the leading cause of tooth loss in dogs. 2 The presence and severity 5

Veterinary Therapeutics Vol. 1, No. 1, Winter 2000 of periodontal disease increases significantly with age if no preventive measures are taken and decreases significantly with increasing body weight. 2 Dental plaque is known to harbor the microorganisms and microbial byproducts responsible for the initiation of periodontal disease. Although dental calculus is not a primary factor in the etiology of periodontal disease, it provides a rough surface that harbors microorganisms, and its physical presence serves as an irritant to the oral soft tissues. 2 It is important to identify measures that are effective for the prevention and control of all etiologic factors that contribute to the development of periodontal disease. Oral malodor is often the first sign that an animal has periodontal disease. 2,3 Gingivitis, gingival bleeding, plaque, and calculus are typical clinical signs of periodontal disease. 2 The production of volatile sulfur compounds (VSCs) correlates with the accumulation of plaque and calculus and with the severity of gingivitis. 2,4 VSC production is also associated with the microbial load in the mouth. The presence of blood from periodontitis is known to stimulate bacterial growth, proteolysis, and odor production by putrescent saliva. Anaerobic conditions allow proliferation of odor-producing bacteria; gram-negative bacteria are primarily responsible for malodor production. Periodontal abscesses and bacteremia also may lead to heart and liver problems and kidney lesions. 5 Weight loss and poor physical condition are evident in affected animals. Although the assessment of oral malodor in dogs has been performed using a numerical scale to rate odor estimates by dog owners, 6 Tonzetich 7 described a method for performing these measurements using an instrument known as a halimeter. Because the primary sources of oral malodor are VSCs (primarily methyl mercaptans and hydrogen sulfide) a portable instrument capable of measuring sulfides in breath (i.e., the halimeter) was selected. The reproducibility and sensitivity of this instrument for measuring the sulfide content of the breath has been demonstrated for humans. 8 Similarly, this methodology has been shown to be capable of assessing malodor in dogs. 9 11 Further, a recent study has demonstrated that the amount of VSCs in the breath of dogs is directly related to the presence of periodontal disease. 3 The provision of diets or snack foods that reduce the accumulation of dental plaque and calculus have shown contradictory results regarding oral malodor. Although the use of a snack biscuit coated with hexametaphosphate 11 and meticulous oral hygiene through daily toothbrushing 12 were found to reduce oral malodor, the provision of a dental hygiene chew was without effect. A diet that reduces plaque and gingivitis was also found to reduce oral malodor. 13 Thus, the primary purpose of this investigation was to determine the effect of two different clindamycin treatment regimens following a complete dental prophylaxis (thorough dental cleaning including scaling and polishing) upon oral malodor in dogs with secondary assessments of the effect on periodontal disease. MATERIALS AND METHODS Animal Resources Forty-nine adult, mixed-sex, mixed-breed dogs were screened under general anesthesia. Thirty dogs that met the study criteria were enrolled in the study. Their owners agreed to comply for 3 months with the study protocol, including baseline screening, feeding of a complete dry ration with fresh water ad libitum, complete veterinary dental prophylaxis, home administration of treatment, and regular follow-up visits. The animals health was assured by complete blood count (CBC) and serum chemistry profiles at study initiation and at the 6

J. M. Warrick, G. A. Inskeep, T. D. Yonkers, G. K. Stookey, and T. H. Ewing TABLE 1. Study Design Postprophylaxis Treatments Group Days 0 4 Days 28 32 Days 56 60 A Placebo Placebo Placebo B Clindamycin HCl Placebo Placebo C Clindamycin HCl Clindamycin HCl Clindamycin HCl 14-, 42- and 70-day examinations. Weight and daily food intake were also monitored. Dogs were examined daily by owners and during each recall visit by the on-site attending veterinarian. Baseline Screening and Stratification Under general anesthesia, the animals were evaluated for oral malodor, gingivitis, pocket depth, bleeding on periodontal probing, plaque, and calculus approximately 2 weeks before treatment began. Only animals with a mean VSC reading of >130 parts per billion (ppb) and at least two periodontal pockets measuring >3 mm were admitted. Animals were then stratified into blocks of three in descending order using oral malodor, gingivitis, and severity of periodontal pockets as criteria in a random block design. Animals within each block were randomly assigned to receive one of the three regimens by the on-site study coordinator, independent of the examiners (Table 1). Treatment Phase The treatment phase of the study was initiated with all animals receiving a thorough dental prophylaxis under general anesthesia (day 0). The dogs received clindamycin HCl or a placebo for 5 days after prophylaxis. The dose was 2.5 to 5.0 mg/lb body weight daily. The test agent or placebo was administered for two additional 5-day regimens on days 28 to 32 and 56 to 60. All packages were prepared and dispensed by the on-site study coordinator. The pill vials were labeled with the owner s name, dog s name, and dates to be administered (days 0 4, 28 32, and 56 60). On designated examination days, 10 days after the 5 th consecutively administered dose, dogs were examined. The animals were anesthetized, oral malodor was measured, and dogs were examined for gingivitis, pocket depth, bleeding on periodontal probing, plaque, and calculus. Observations were recorded on prepared forms by persons not directly involved in the examinations. Anesthesia The animals were given atropine sulfate (0.05 mg/kg), acepromazine maleate (0.1 mg/ kg), and butorphanol tartrate (0.22 mg/kg) intramuscularly 20 minutes before the anesthesia. The animals were anesthetized using ketamine HCl (3.7 mg/kg) and diazepam (0.37 mg/kg) intravenously, intubated, and maintained on a mixture of isoflurane and oxygen. Oral Assessment Methods The methods used for scoring gingivitis, plaque, and calculus are modifications of human techniques that have been validated for veterinary use. 9,14 16 These techniques are summarized in Tables 2 to 4. Oral malodor was assessed by electrochemical sensor using a portable VSC monitor 7

Veterinary Therapeutics Vol. 1, No. 1, Winter 2000 TABLE 2. Gingivitis Scoring TABLE 3. Plaque Scoring Teeth Scored Maxilla: Mandible: I3, C, P2, P3, P4, and M1 C, P2, P3, P4, and M1 Teeth Scored Maxilla: Mandible: I3, C, P2, P3, P4, M1 C, P2, P3, P4, M1 Criteria 0 = no gingivitis 1 = incipient or very mild gingivitis (i.e., red and swollen, but no bleeding on probing) 2 = mild gingivitis (i.e., red and swollen and delayed bleeding on probing) 3 = moderate gingivitis (i.e., red and swollen and immediate bleeding on probing) 4 = severe gingivitis (i.e., ulceration, spontaneous hemorrhage, and profuse bleeding on probing) The buccal gingiva for each scored tooth was divided into thirds (mesial, buccal, distal). Each site was evaluated by the criteria above. Calculation The score of each tooth is the mean score of the three sites. The score for each dog is the mean score for all teeth scored. (halimeter). The methodology is detailed in Table 5 and has been validated in clinical studies in the dog. 8,10,17 19 Periodontal pocket assessments are described in Table 6. This methodology was adapted from human techniques. 20,21 All examinations were performed by trained and experienced examiners. The examiners were blinded to the treatment assignment until study completion. The data were recorded on prepared examination forms by a recorder who was not directly involved in the examinations. The study conduct and data analysis were monitored by the Indiana University School of Dentistry Quality Assurance officer for compliance to the approved protocol and established examination procedures. Criteria 0 = no detectable plaque 1 = scattered plaque covering less than 24% of the buccal tooth surface 2 = plaque covering between 25% and 49% of the buccal tooth surface 3 = plaque covering between 50% and 74% of the buccal tooth surface 4 = plaque covering more than 75% of the buccal tooth surface Thickness 1 = Light 2 = Moderate 3 = Heavy Scoring Method Plaque was disclosed by applying the undiluted disclosing solution, Red Cote (John O. Butler Company) 1.5% D&C Red No. 28, to the buccal surface of each tooth and immediately rinsing with water. The gingival and occlusal half of each tooth was scored for coverage and thickness. Calculations The coverage score was multiplied by the thickness score to give a gingival and occlusal score for each tooth. The gingival and occlusal values for each tooth were added together to obtain a tooth total score. The score for each dog is the mean score for all teeth scored. ANALYSIS The treatments were compared for differences in the measurements (oral malodor, gingivitis, calculus, plaque, pocket depth, bleeding, weight, and average daily food intake per 8

J. M. Warrick, G. A. Inskeep, T. D. Yonkers, G. K. Stookey, and T. H. Ewing TABLE 4. Calculus Scoring (Warrick-Gorrel Method) Teeth Scored Maxilla: Mandible: I3, C, P2, P3, P4, M1 C, P2, P3, P4, M1 Criteria 0 = no detectable calculus 1 = scattered calculus covering less than 24% of the buccal tooth surface 2 = calculus covering between 25% and 49% of the buccal tooth surface 3 = calculus covering between 50% and 74% of the buccal tooth surface 4 = calculus covering more than 75% of the buccal tooth surface Thickness <0.5 mm = 1 0.5 1.0 mm = 2 >1.0 mm = 3 Scoring Method The disclosed plaque was removed by gentle tooth brushing and rinsing with a dental airwater syringe. The tooth was then air-dried. The buccal surface of the tooth was divided vertically into mesial, buccal, and distal thirds, and each third assigned a numerical score for both coverage and thickness. A probe was used to verify the visual impression of cover and measure thickness. Calculations The coverage score was multiplied by the thickness score for each of the three surfaces evaluated per tooth. The tooth score is the sum of the scores for each of the three tooth surfaces. The sum of the teeth scores is averaged to obtain a whole mouth mean calculus score for each animal. TABLE 5. Oral Malodor Scoring Method A halimeter was used to measure VSC. The sampling tube was placed parallel to the mucogingival line at the mid-buccal maxillary P4. The cheek mucosa was kept away from the end of the sampling tube as the animals mouths closed. The highest reading after the meter stabilized was recorded. Both right and left sides were sampled. Calculations The score for the animal was the mean of these two readings. kg) using analysis of variance (ANOVA). The models included a random effect to correlate the measurements made on the same dog during the study; the variances and covariances of the repeated measurements were allowed to differ for each examination. The models included fixed effects for block, day, treatment, and the day-by-day treatment interaction. If the day-by-day treatment interaction was not significant, comparisons between pairs of treatments and between day 0 and subsequent days were made if the main effects were significant. If the day-by-day treatment interaction was significant, comparisons between pairs of treatments were made for each day and between day 0 and subsequent days for each treatment. No adjustments were made for multiple comparisons. Comparisons were considered statistically significant when the P value was <0.05. Analyses were performed using statistical analysis system (SAS) software. 22 Following the initial data analysis, it was determined that additional analysis of the oral malodor data were appropriate. The data were compared using mixed model analysis of variance. The models included fixed-effect terms for treatment, day, and treatment-by-day inter- 9

Veterinary Therapeutics Vol. 1, No. 1, Winter 2000 TABLE 6. Periodontal Pocket Assessment Teeth Scored Maxilla: Mandible: I3, C, P2, P3, P4, M1 C, P2, P3, P4, M1 Periodontal Pocket Depth Scoring Method Using a periodontal probe marked in 1-mm increments, four sites of each tooth were measured. The sites correspond with the mesial, mid-buccal, distal, and mid-lingual/palatal sides of each tooth. The probing depth was recorded as the distance in mm from the height of gingival margin to the bottom of the pocket. Calculations Tooth scores (sum of the four measurements) were added and divided by the number of teeth to determine the mouth pocket depth score. Bleeding on Periodontal Probing After withdrawing the probe from the pocket, the area was observed for presence of bleeding within thirty seconds. Criteria 0 = no bleeding observed 1 = focal bleeding point or fine line of blood 2 = interdental triangle or direct margin became filled with blood 3 = profuse bleeding observed immediately after probing Calculations Tooth scores (sum of the four measurements) were added and divided by the number of teeth to determine the mouth bleeding score. action, and random effects terms for block, dog, and error. The literature on oral malodor assessment and the data obtained indicate that a logarithm transformation is necessary to normalize the data and stabilize the variances. 8,9,18 The log-transformed values were analyzed using the mixed procedures of the SAS. 22 Comparisons were considered statistically significant when the P value was <0.05. The data were analyzed as both changes from baseline within each treatment regimen and differences between the treatment regimens. Over the course of the study, three dogs discontinued participation for various reasons. Results There were no statistically significant differences observed among the groups in body weight or weight change. There were also no significant differences in consumption (g food per lb body weight) among or within groups. Serum chemistry data were unremarkable, except for one dog that was dropped from the study due to increased liver enzyme blood levels at baseline and the 14-day examinations. Oral malodor data are presented in Table 7. There were no statistically significant differences among the groups at the baseline examination. At the 14-day examinations, both groups receiving clindamycin had significantly lower measurable VSC readings, indicating lower oral malodor, than the group receiving the placebo (P < 0.004). There were no other statistically significant differences among the groups. When change from baseline was analyzed within each group, all treatment regimens produced a statistically significant drop in oral malodor at 14 days, and this drop remained statistically significant through 42 days for the three 5-day courses of clindamycin HCl (P = 0.014). The difference between the control group and the group receiving one 5-day treatment approached significance (P = 0.069). At 70 days the threecourse clindamycin HCl regimen reduced oral malodor from baseline by 20% compared with a 4% reduction for the one-course regimen and an 18% increase for placebo. Gingivitis data are presented in Table 8. 10

J. M. Warrick, G. A. Inskeep, T. D. Yonkers, G. K. Stookey, and T. H. Ewing TABLE 7. Oral Malodor (VSC ppb; Value ± SEM) One 5-day Course of Three 5-day Courses of Placebo Clindamycin HCl Clindamycin HCl % Malodor Change (baseline to 70 days) 4 20* Malodor baseline group score 186.60 ± 15.28 195.95 ± 19.93 188.05 ± 14.56 Malodor 14-day group score 147.10 ± 21.18** 76.00 ± 10.30*, ** 79.45 ± 6.99*, ** Malodor 42-day group score 179.50 ± 25.48 141.00 ± 27.84*, ** 118.95 ± 20.50*, ** Malodor 70-day group score 219.38 ± 66.53 188.33 ± 21.39 150.60 ± 20.30* *Statistically significant compared with placebo (P<0.05). **Statistically significant compared with baseline in that group (P<0.05). TABLE 8. Gingivitis Scoring (Value ± SEM) One 5-day Course of Three 5-day Courses of Placebo Clindamycin HCl Clindamycin HCl Gingivitis baseline group score 1.07 + 0.03 1.19 + 0.07 1.09 + 0.06 Gingivitis 14-day group score 1.00 + 0.03* 1.09 + 0.04* 1.05 + 0.04* Gingivitis 42-day group score 0.96 + 0.04* 1.07 + 0.07* 1.01 + 0.05* Gingivitis 70-day group score 1.08 + 0.04 1.16 + 0.07 0.99 + 0.12 *Statistically significant compared with baseline in that group (P<0.05). There were no significant differences observed between the groups at baseline. However, there was a significant reduction in gingivitis for all groups at 14 and 42 days compared with the baseline gingivitis score. Periodontal pocket data are presented in Table 9. There were no statistically significant differences among groups in mean pocket scores at baseline. However, all treatment groups had significantly lower pocket scores at days 42 and 70 than at baseline. Periodontal pocket bleeding scores are presented in Table 10. At baseline, dogs receiving the single 5-day regimen of clindamycin HCl had significantly greater bleeding scores than dogs receiving three 5-day courses of clindamycin or placebo. There were no other significant differences among the groups. All groups experienced a significant drop from the baseline pocket bleeding scores at 14, 42, and 70 days. The magnitude of this decrease in bleeding score was appreciably greater in the 5- day treatment group (57%) compared with the placebo group (26%). Plaque data are presented in Table 11. Dogs receiving the placebo had significantly less plaque at baseline than dogs in the other groups. Dogs receiving the placebo had significant reductions only at the 14- and 42-day examinations. However, both clindamycin HCl regimens had significantly reduced plaque accumulation at 14, 42, and 70 days compared 11

Veterinary Therapeutics Vol. 1, No. 1, Winter 2000 TABLE 9. Pocket Scoring (Value ± SEM) One 5-day Course of Three 5-day Courses of Placebo Clindamycin HCl Clindamycin HCl Pocket depth baseline group score 8.32 + 0.6 9.17 + 0.8 8.4 + 0.6 Pocket depth 14-day group score 8.3 + 0.7 9.0 + 0.7 8.0 + 0.5 Pocket depth 42-day group score 7.5 + 0.6* 8.6 + 1.0* 6.7 + 0.5* Pocket depth 70-day group score 7.5 + 0.5* 9.1 + 0.9* 7.0 + 0.5* *Statistically significant compared with baseline in that group (P<0.05). TABLE 10. Bleeding Assessment (Value + SEM) One 5-day Course of Three 5-day Courses of Placebo Clindamycin HCl* Clindamycin HCl Bleeding baseline group score 1.36 + 0.13 2.16 + 0.38 1.80 + 0.24 Bleeding 14-day group score 1.05 + 0.17** 1.51 + 0.29** 1.10 + 0.13** Bleeding 42-day group score 0.91 + 0.17** 1.39 + 0.45** 0.76 + 0.26** Bleeding 70-day group score 1.01 + 0.33** 1.45 + 0.33** 0.78 + 0.25** *Dogs in this group had significantly greater bleeding scores (P<0.05) than dogs in the other groups at baseline. **Statistically significant compared with baseline in that group (P<0.05). TABLE 11. Plaque Scoring (Value ± SEM) One 5-day Course of Three 5-day Courses of Placebo* Clindamycin HCl Clindamycin HCl Plaque baseline group score 8.69 + 0.33 12.83 + 1.09 11.13 + 0.84 Plaque 14-day group score 6.13 + 0.50** 5.73 + 0.40** 5.46 + 0.49** Plaque 42-day group score 6.82 + 0.58** 7.85 + 0.85** 6.76 + 0.66** Plaque 70-day group score 8.64 + 1.00 8.60 + 0.84** 8.40 + 0.57** *Dogs in this group had significantly less plaque (P<0.05) than dogs in the other groups at baseline. **Statistically significant compared with baseline in that group (P<0.05). with baseline scores. At the end of the 70-day test period, reductions in plaque in the placebo, one-treatment, and three-treatment groups were 0.6, 33.0, and 24.5%, respectively. Calculus data are presented in Table 12. The group receiving the placebo treatment had significantly less calculus at baseline than the other groups; presumably this reflects a difference in calculus formation between the parallel groups of animals since the dogs were not strat- 12

J. M. Warrick, G. A. Inskeep, T. D. Yonkers, G. K. Stookey, and T. H. Ewing Table 12. Calculus Scoring (Value ± SEM) One 5-day Course of Three 5-day Courses of Placebo* Clindamycin HCl Clindamycin HCl Calculus baseline group score 4.55 + 0.65 10.89 + 2.12 9.45 + 1.68 Calculus 14-day group score 1.11 + 0.17** 0.99 + 0.30** 1.10 + 0.02** Calculus 42-day group score 2.14 + 0.19 2.53 + 0.48** 2.20 + 0.35** Calculus 70-day group score 4.08 + 0.61 3.59 + 0.74** 4.34 + 0.74** *Dogs in this group had significantly less calculus (P<0.05) than dogs in the other groups at baseline. **Statistically significant compared with baseline in that group (P<0.05). TABLE 13. Analysis of Variance Table for Log e Transformed Oral Malodor (peak volatile sulfur compounds [VSCs] ppb) Source DF* Variance Estimate Error DF* F Statistic P Value Block 9 0.0145 Treatment 2 16.5 3.48 0.055 Between-dog error 18 0.1029 Day 2 50.9 25.76 0.000 Treatment day 4 50.9 2.34 0.068 Within-dog error 50 0.0955 *Satterthwaite degrees of freedom. ified on pretest calculus scores. Dogs receiving the placebo had a significant reduction in calculus at the 14-day examination due to the dental prophylaxis, but the scores had returned nearly to baseline by the end of the 70-day test period. Both clindamycin HCl regimens had significantly reduced calculus accumulation at 14, 42, and 70 days compared with the baseline scores. At the conclusion of the 70-day test period the reductions in calculus formation in the placebo and clindamycin groups were 10.3, 67.0, and 54.1%, respectively. Using the logarithmic transformation of the data, Table 13 displays the ANOVA table for malodor. The split plot model provided an adequate accounting of the variance and covariance among the repeated measurements when compared with the general multivariate unstructured model. The ANOVA indicates that both the treatment and treatment-by-day effects approached significance (P = 0.055, P = 0.068, respectively; Table 13). The least squares means are provided in Table 14; comparisons of least squares means are provided in Table 15. At day 14, both clindamycin HCl groups were significantly different from the control group (P 0.004; Table 15). The back-transformed clindamycin HCl treatment group means at day 14 were 76.59 ppb for the three 5-day regimen, 70.92 ppb for the one 5-day regimen, and 134.41 ppb for the control group (Table 14). At day 42, the clindamycin HCl three 5-day regimen was significantly different from control (P = 0.014; Table 15) and the 13

Veterinary Therapeutics Vol. 1, No. 1, Winter 2000 TABLE 14. Least Squares Means and Standard Errors for Log e Transformed Oral Malodor (peak volatile sulfur compounds [VSCs] ppb; also provided are the back transformed means exp[ls Mean]) Day 14 Day 42 Day 70 Overall LS Mean Back LS Mean Back LS Mean Back LS Mean Back Treatment (SE) Trans* (SE) Trans (SE) Trans (SE) Trans Clindamycin 4.34 76.59 4.64 103.52 4.94 139.65 4.64 103.45 3 5 day (0.15) (0.15) (0.15) (0.12) treatments Clindamycin 4.26 70.92 4.79 119.79 5.16 174.77 4.74 114.08 1 5 day (0.15) (0.15) (0.15) (0.12) treatments Control 4.90 134.41 5.09 163.20 5.17 176.73 5.06 157.09 (0.15) (0.15) (0.16) (0.12) *Back transformed least squares means = exp (LS Mean) = geometric mean VSC (ppb). TABLE 15. Comparisons of Treatment Least Squares Means for Log e Transformed Oral Malodor (peak volatile sulfur compounds [VSCs] ppb) Treatment Comparison Day Mean Difference (SE) DF* P Value Clindamycin 3 5 vs. Clindamycin 1 5 14 0.08 (0.20) 32.8 0.702 Clindamycin 3 5 vs. Control 14 0.56 (0.20) 32.8 0.004 Clindamycin 1 5 vs. Control 14 0.64 (0.20) 32.8 0.002 Clindamycin 3 5 vs. Clindamycin 1 5 42 0.15 (0.20) 34.4 0.478 Clindamycin 3 5 vs. Control 42 0.46 (0.20) 32.8 0.014 Clindamycin 1 5 vs. Control 42 0.31 (0.20) 34.4 0.069 Clindamycin 3 5 vs. Clindamycin 1 5 70 0.22 (0.20) 34.4 0.277 Clindamycin 3 5 vs. Control 70 0.24 (0.21) 36.5 0.132 Clindamycin 1 5 vs. Control 70 0.01 (0.21) 38.0 0.479 Clindamycin 3 5 vs. Clindamycin 1 5 Overall 0.10 (0.17) Clindamycin 3 5 vs. Control Overall 0.42 (0.17) Clindamycin 1 5 vs. Control Overall 0.32 (0.17) *Satterthwaite degrees of freedom. One-sided tests. clindamycin HCl one 5-day regimen approached significance in comparison to the control group (P = 0.069; Table 15). The backtransformed means for the clindamycin HCl 14

J. M. Warrick, G. A. Inskeep, T. D. Yonkers, G. K. Stookey, and T. H. Ewing three 5-day regimen was 103.52 ppb, the clindamycin HCl one 5-day regimen was 119.79 ppb, and the control mean was 163.20 ppb. At day 70, neither of the clindamycin HCl treatments were different from the control group (P 0.132; Table 15). The clindamycin HCl three 5-day regimen had a backtransformed mean of 139.65 ppb at day 70, the clindamycin one 5-day regimen had a mean of 174.77 ppb, and the control group had a mean of 176.73 ppb (Table 15). The two clindamycin HCl treatments were not significantly different at any of the test days (Table 15). Because of the large changes over time and the nearly significant interaction of treatment by day, it is not appropriate to compare regimens across time, hence group means and differences between means are provided, but P values were not calculated. DISCUSSION Measurement of VSCs allows an objective assessment of the malodor associated with periodontal disease. This study evaluated the results of complete dental prophylaxis accompanied by antimicrobial therapy or placebo. Prophylaxis alone had a significant impact on oral malodor, as evidenced by the significantly reduced VSC reading in the placebo group at 14 days. Yet, the reduction in the placebo group was not as durable as in the groups receiving clindamycin HCl, which continued to have significant reductions at 42 days as well. At 70 days, the group treated with three courses of clindamycin still had significantly reduced VSC readings compared with the placebo group. Furthermore, although dogs in the placebo group had significantly less plaque and calculus than dogs in the active treatment groups at baseline, untreated dogs failed to maintain significant reductions for as long as treated dogs. It is likely that antimicrobial therapy decreased microbial loads in the mouth, leading to less malodor. In all groups, VSC readings plunged after prophylaxis, started to rise between 14 and 42 days, and continued rising to the end of the study. Yet, readings in the active treatment groups had not returned to baseline by the end of the study, while the final VSC reading in the placebo group exceeded the baseline reading by 18%. Without regular oral hygiene, VSC levels in all groups could be expected to return to pretreatment values eventually. 17 Following a complete dental prophylaxis (cleaning) in this study both clindamycin HCl regimens effectively reduced malodor, plaque, and calculus compared with the placebo treatment. However, neither of the clindamycin treatment regimens was more effective than the prophylaxis and placebo treatment in reducing gingivitis, pocket depth, or gingival bleeding. CONCLUSIONS The use of a 5-day regimen of clindamycin HCl following a complete dental prophylaxis significantly reduced oral malodor in dogs with periodontitis compared with the placebo treatment group. In addition, the reduction in oral malodor from the baseline readings remained statistically significant through 42 days for both of the clindamycin regimens. Seventy days after a complete dental prophylaxis the three 5-day clindamycin regimen resulted in a numerical reduction of 20% from baseline values in oral malodor compared with a small (4%) reduction for the one 5-day clindamycin HCl regimen and an 18% increase for the placebo treatment group. Both clindamycin HCl regimens resulted in significant reductions from baseline scores for plaque and calculus throughout the study. Neither of the clindamycin HCl regimens had a greater benefit than prophylaxis alone on gingivitis, pocket depth, or bleeding. Thus, the results of this 15

Veterinary Therapeutics Vol. 1, No. 1, Winter 2000 study indicate that the use of clindamycin HCl reduced oral malodor associated with periodontal disease. Based on this study, owners can be reassured that dental prophylaxis alone improves oral health, but antimicrobial treatment following prophylaxis maintains the improvements for a longer time. REFERENCES 1. Harvey CE, O Brien JA, Rossman LE, et al: Oral, dental, pharyngeal, and salivary gland disorders, in Ettinger SJ (ed): Textbook of Veterinary Internal Medicine. Philadelphia, WB Saunders Co., 1983, pp 1147 1160. 2. Harvey CE: Periodontal disease in dogs. Etiopathogenesis, prevalence, and significance. Vet Clin North Am Sm Anim Prac 28(5):1111 1128, 1998. 3. Culham N, Rawlings JM: Oral malodor and its relevance to periodontal disease in the dog. J Vet Dent 15(4):165 168, 1998. 4. Simone AJ, Logan EL, Livgren R, Suelzer M: Oral malodor in dogs: Association with indicators of periodontal disease. J Clin Dent 8(6):163 168, 1997. 5. DeBowes LJ, Mosier D, Logan E, et al: Association of periodontal disease and histological lesions in multiple organs from 45 dogs. J Vet Dent 13(2):57 60, 1996. 6. Renn T, Setser C, Richardson D, et al: Predicting consumer response to canine oral malodor using sensory testing. Proceedings, Vet Dent Forum 107 110, 1998. 7. Tonzetich J: Direct gas chromatographic analysis of sulfur compounds in mouth air in man. Arch Oral Biol 16:587 597, 1971. 8. Rosenberg M, Kulkarni GV, Bosy A, McCulloch CAG: Reproducibility and sensitivity of oral malodor measurements with a portable sulfide monitor. J Dent Res 70(11):1436 1440, 1991. 9. Hennet P, Delille B, Davot JL: Oral malodor in dogs: Measurement using a sulfide monitor. J Vet Dent 12(3):101 103, 1995. 10. Hennet P, Delille B, Davot JL: Oral malodor measurements on a tooth surface of dogs with gingivitis. Am J Vet Res 59(3):225 257, 1998. 11. Warrick JM, Miller LL, Ross SR, Stookey GK: Reducing oral malodor and calculus formation in dogs. J Dent Res 75 (Abst #3303): 430, 1996. 12. Gorrel C, Bierer TL: Benefit of a new dental hygiene chew on the periodontal health of dogs. Proceedings, Vet Dent Forum 114 116, 1998. 13. Clarke DE: Plaque and calculus accumulation in respect to feeding canned diets and Hill s T/D diet as a treat compared to 100% of the diet. Proceedings, Vet Dent Forum 122 123, 1998. 14. Logan EI, Boyce EN: Oral health assessment in dogs: parameters and methods. J Vet Dent 11(2):58 63, 1994. 15. Hefferren JJ, Schiff TG, Smith MR: Assessment methods and clinical outcomes: Chemical and microbial composition, formation, and maturation dynamics of pellicle, plaque, and calculus. J Vet Dent 11(2): 75 79, 1994. 16. Warrick J, Gorrel C: A more sensitive method of scoring calculus. Proc 11 th Annual Vet Dent Forum 134 136, 1997. 17. Rawlings JM, Culham N: Studies of malodor in the dog. J Vet Dent 15(4):169 173, 1998. 18. Hennet P, Delille B, Davot JL: Oral malodor measurements on a tooth surface of dogs with gingivitis. Am J Vet Res 59(3):255 257, March 1998. 19. Gorrel C, Warrick J, Bierer TL: Effect of a new dental hygiene chew on periodontal health in dogs. J Vet Dent 16(2):77 81, 1999. 20. Ramfjord SP: The periodontal index. J Periodontal 38(6):602 610, 1967. 21. Lindhe J: Textbook of Clinical Periodontology. Munksgaard, 1983, pp 67 82. 22. SAS Institute Inc.: SAS/STAT software: Changes and enhancements through release 6.11. Cary, NC, SAS Institute Inc., 1996. 16