Preliminary observations on the inhibitory effect of tetracycline on alveolar bone loss in beagle dogs

Alveolar bone loss of selected periodontally diseased teeth in four beagles receiving daily tetracycline per os. was compared to three untreated beagle dogs. The percentage and rate of bone loss was measured radiographically over a 47 month period. This included a preliminary period of 20 months when no animals received antibiotics, and 27 months in which 4 animals were each given 250 mg tetracycline hydrochloride daily. During the preliminary period, all dogs progressively lost alveolar bone. However, with the institution of tetracycline treatment further loss of alveolar bone in the treated animals was arrested or markedly diminished for various intervals of time before resuming the original more accel;erated rate of bone loss. Bone loss in one animal was arrested for 27 moknths, whereas in another dog, the period of arrested bone loss was only 5 monghs. In two animals, bone loss was arrested for 17 months. Bacterial samples from one periodontal pocket in each dog revealed that a Gram negative flora predominated in all animals. Tetracycline administration altered the pocket flora slightly with a shift to more gram positive organisms in the treated animals. The data suggest that daily tetracycline administered orally may be effective in slowing the progressive loss of alveolar bone in beagle dogs.