[An experimental production of suppurative otitis media in dog, and a trial to evaluate the therapeutic effect of cefmetazole on this otitis media].

An experimental suppurative otitis media in dog was produced to evaluate the therapeutic effects of cefmetazole (CMZ) in this study. In order to induce a definite case of otitis media, 1.0 mg of dexamethasone was administered intramuscularly to dog, 12 hours before a bacterial inoculation into the middle ear of it. For inoculation, 5 x 10(8) live bacteria of S. aureus, strain 571 (UOP) was prepared from its 18 hour-bouillon culture and added 0.9 ml of 5% mucin solution for a total inoculation fluid of 1.0 ml. This fluid was injected into the middle ear on one side by inserting a 'mouse syringe' with a swollen tip down the external auditory meatus to pierce the tympanic membrane. On the opposite side, only 1.0 ml of micin solution was injected. In this way, suppurative otitis media which definitely lasted until the 15th day following the bacterial inoculation was realized. Since in each positive controls, the onset of suppurative otitis media had been confirmed on the 4th day after inoculation, the intravenous administration of CMZ (three times a day; 9 : 30, 15 : 30, 21 : 30) was started at the end of the 4th day and continued through the 7th day. The dogs thus treated were sacrificed on the 10th day after inoculation and the live bacteria count within the middle ear, signs of inflammation on the tympanic cavity, and accumulation of pus were examined. The therapeutic effect of CMZ was rated as 'effective' in cases where S. aureus-571 was found to be negative. All the animals administered a daily dose of 30 mg/kg or above it, were found to be S. aureus-571 free, thus the satisfactory therapeutic effect of CMZ was demonstrated. Especially, at the daily dose of 120 mg/kg the membrane of the tympanic cavity in all cases exhibited a picture of a radical cure to almost the same degree as the control side membranes, and any signs of inflammation were hardly observed. The last mentioned phenomena had been observed too by the authors on the treatment of the experimentally induced pyometra in bitches, with CMZ. Thus it is assumed that in treating some suppurative diseases with CMZ, it may be advisable to initiate the administration at relatively large doses in order to achieve generally better and quick effect.