Adverse effects of gentamicin in scarlet macaws and galahs.

The adverse effects of administration of gentamicin (5 mg/kg of body weight, IM, q 12 h) for 7 days were studied in healthy scarlet macaws (Ara macao) and galahs (Eolophus roseicapillus; cockatoos). Polydipsia and polyuria developed in each species, but were greater and persisted longer in the cockatoos. Peak water intake in the cockatoos more than quadrupled, and remained increased for 23 days after cessation of gentamicin administration. Plasma aspartate transaminase activity increased significantly (P less than 0.05) after treatment in the macaws, and plasma aspartate transaminase and lactate dehydrogenase activities increased in the cockatoos. Single IM administration of gentamicin (5 mg/kg) resulted in mean (+/- SEM) plasma concentration of 20.6 (+/- 1.85) micrograms/ml at 0.5 hour for either species of birds. There were no significant differences between mean plasma gentamicin concentrations for cockatoos and macaws at any time after drug administration, except at 12 hours, when values for cockatoos were significantly (P less than 0.05) greater than those for macaws. The elimination half-life for gentamicin after IM administration of 5 and 10 mg/kg was 1.17 and 1.07 hours, respectively, for macaws and 1.23 and 1.44 hours, respectively, for cockatoos. Correlation between drug disposition and adverse side effects could not be detected.

Species-related differences in the incidence of gram-negative bacteria isolated from the cloaca of clinically normal psittacine birds.

Cloacal swabs from 506 clinically normal psittacine birds of 22 species were aerobically cultured for bacteria and yeasts. In 45 (9%) samples, no microbial organisms were recovered. Gram-positive bacteria were recovered from 474 (91%) samples. The incidences of gram-negative bacteria and yeasts were: Escherichia coli 157 (31%), Enterobacter sp. 21 (4%), Klebsiella sp. 3 (0.6%), Pseudomonas sp. 4 (0.8%), and yeasts 26 (5%). Differences were noted in the recovery rate of E. coli among the various species of birds cultured. Escherichia coli was recovered from 101 of 168 cockatoos (60%) of the genus Cacatua but from only 18% of 338 non-Cacatua species. As all birds were housed in the same facility under similar conditions, this difference in the incidence rate of E. coli cannot be explained on the basis of differences in husbandry or diet alone.