Occurrence of Gram-Negative Black-Pigmented Anaerobes in Subgingival Plaque During the Development of Canine Periodontal Disease

It has been estimated that more than 80% of adult dogs have periodontal disease. However, published information on canine oral microbiology-especially anaerobic microbiology-is scant. Few published studies have used stringent anaerobic techniques and culture media, and most of these investigations predate the many recent taxonomic changes and additions relevant to anaerobic bacteriology. No published studies to date have reported concurrent, thorough microbiological and clinical evaluations of canine periodontitis, and none has monitored temporal changes in the subgingival flora during the development of disease. We recently completed two studies that correlated microbiological changes in canine subgingival plaque with concomitant changes in periodontal health. We used an established disease model in which periodontal ligatures greatly accelerated the development of periodontitis; disease was allowed to progress naturally in control dogs without ligatures. The animals used were healthy adult male and female mixed-breed dogs (mean weight, similar to 45 pounds) with preexisting severe gingivitis to mild periodontitis, as determined by clinical indices and measurements. The objective of the first study (Study A) was to qualitatively characterize the total culturable subgingival-plaque flora of one dog with ligatures and one dog without. Thus. at numerous time points, plaque samples were collected, diluted, and plated onto nonselective enriched media; representative aerobic and anaerobic isolates were subcultured to purity and presumptively identified. During the 21-day study, similar to 700 representative anaerobes from seven time points were isolated in pure culture from the two dogs.