The effect of systemic antimicrobial therapy on plaque and gingivitis in dogs

Abstract
Six dogs with varying degrees of gingivitis wer divided into 3 groups of 2 dogs each. One pair of dogs received tetracycline HCI 250 mg, 2 times/day, for 4 weeks. The controls reveived no medication during the experimental period of 4 weeks. The results showed a decrease in the proportions of coccoid cells and straight rods in the periodontal flora with increasing gingival inflammation, while the proportions of spirochetes and motile bacteria were markedly reduced. Metronidazole appeared to be somewhat more effective in eliminating spirochetes than tetracycline. Treatment with the antimicropbial drugs tended to derease the size of th infiltrated connective tissue as well as the proportion of junctional epithelium occupied by inflammatory cells, but did not succeed in eliminating the inflammatory reaction entirely. At the initial examination around 60% of the leukocyte volume in junctional epthelium consisted of neutrophilic granulocytes. At the final examination less than 30 % of the leukocyte volume consisted of neutrophis. It was not clear from the results if the improvement in the clinical and histological parameters was due to the specific suppression of ertain organisms or to an overall. non‐specific reduction in volume of the periodontal flora.