Necrotizing ulcerative gingivitis in beagle dogs. I. Attempts at unilateral induction and intraoral transmission of NUG, a microbiological and clinical study

The induction and transmission of Necrotizing Ulcerative Gingivitis (NUG) lesions in beagle dogs have been reported previously. In the present experiments the contagious nature of these NUG lesions was further investigated by studying the unilateral induction and the intraoral transmission of NUG lesions. Six beagle dogs were treated with Kenacort A40®. The control quadrants of their dentition were cleaned while the experimental quadrants were not. The experimental quadrants were inoculated with pooled dental debris from the same dogs. NUG lesions were induced in the experimental quadrants, but NUG lesions were observed also at some sites of the control quadrants. In the second part of the experiment, reinoculation of non‐affected experimental sites with debris from lesions of the same dog or cage companion increased the number of NUG lesions in both experimental and control quadrants. The study of experimental intraoral transmission of NUG lesions was restricted to the non‐diseased sites in experimental and control quadrants. Topical application of debris of NUG lesions on the test sites did not spread the disease to these sites. Microscopic and cultural evaluation of subgingival microflora revealed no differences in the presence of Bacteroides, Fusobacteria, Spirocheata , and Spirillum in relation to the presence or absence of NUG. Three different types of black pigmental Bacteroides species were observed. It is concluded, that the morphology of the interdental sites is of great importance for the clinical occurence of NUG lesions and that the increase in number and severity of lesions after local reinoculation indicates that in the phase of primary infection, iatrogenic NUG lesions might be possible in a susceptible host.