This study was conducted to examine the outbreak rate and the causative agents of otitis externa in 26 dogs(49 ears; 23 dogs = bilateral, 3 dogs = unilateral), and the normal microfloras of external ear canal in 68 dogs(133 ears; 65 dogs = bilateral, 3 dogs = unilateral) in Taegu, 1997. The breed, living environment, sex, age and season distribution of otitic dogs were as follows: Dogs with erect and hairy ears(42.3%), pendulous and hairy ears(38.5%), indoor(92.3%), female(65.4%) and below one year old(38.5%) were more prevalent. According to season, otitis externa was mainly occurred between July and October. The major causative agents of canine otitis externa were Malassezia pachydermatis(32.7%), Staphylococcus aureus(26.5%) and S intermedius(16.3%). The major causative agents of canine otitis externa were Malasszia pachydermatis(32.7%), Staphylococcus aureus(26.5%) and S intermedius(16.3%). In the microorganism isolated 39 otitic ear canals, single infection was 53.8% and mixed infection was 46.2%. The normal microfloras of canine external ear canal were fungi including M pachydermaits, Aspergillus spp, Microsporum canis, Alternaria spp, Verticillium spp and Yeast, and bacteria including Staphylococcus spp(10 species including S xylosus), Bacillus spp, Corynebacterium spp, Listeria spp, Actinomyces pyogenes and Escherichia coli. No growth was 34.6%.

An Escherichia coli bacterial prostatitis was experimentally induced to determine the effect of bacterial infection on prostatic tissue zinc concentrations in castrated and gonadally intact male dogs. Five of the 22 mixed-breed dogs (group 1) had no culture evidence of infection 2 weeks after the instillation of bacteria into the prostate gland. The remaining 17 infected dogs were allotted to 2 groups; 1 group of dogs was subjected to castration (group CA, 7 dogs), and the other group of dogs was subjected to sham operation (group SO, 10 dogs). The groups were divided into groups of dogs with prostatic infection at necropsy (groups CA-I and SO-I), and those dogs without prostatic infection at necropsy (groups CA-N and SO-N). Urine, prostatic fluid, and prostatic tissue (week 0, 7, +/- 12) specimens were obtained for bacteriologic culturing to determine whether prostatic infection was present. Prostatic tissue was obtained at necropsy (week < 6, 7, or 12) for analysis of zinc concentration by atomic absorption spectrophotometry. The logarithmic mean prostatic tissue zinc concentrations were compared between groups. Group CA had a significantly lower prostatic zinc concentration than all other groups. Zinc concentrations were not statistically different between any of the other groups. Castration did decrease the prostatic tissue concentration of zinc, a known natural antibacterial factor. However, resistance to infection and resolution of infection were not correlated with prostatic tissue zinc concentrations in this experimental model.