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  • Author or Editor: Laura L. May x
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SUMMARY

Effects of furosemide, exercise, and atropine on tracheal mucus transport rate (tmtr) in horses were investigated. Atropine (0.02 mg/kg of body weight) administered iv or by aerosolization significantly (P < 0.05) decreased tmtr at 60, but not at 30 minutes after its administration in standing horses. Furosemide (1.0 mg/kg, iv) did not have any significant effect on tmtr when measured at 2 or 4 hours after its administration in standing horses. Exercise alone or furosemide (1.0 mg/kg, iv) administration followed 4 hours later by exercise did not alter tmtr, compared with values for standing control or exercised horses administered saline solution. Atropine (0.02 mg/kg, iv) administered after exercise significantly (P < 0.05) decreased tmtr, compared with values for no exercise standing controls, for exercise after administration of saline solution, and for furosemide and exercise.

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To determine whether an enrofloxacin–silver sulfadiazine emulsion (ESS) labeled for treatment of otitis externa in dogs has ototoxic effects in rabbits following myringotomy.

ANIMALS

6 healthy adult New Zealand White rabbits.

PROCEDURES

Rabbits were anesthetized for brainstem auditory-evoked response (BAER) tests on day 0. Myringotomy was performed, and BAER testing was repeated. Saline (0.9% NaCl) solution and ESS were then instilled in the left and right middle ears, respectively, and BAER testing was repeated prior to recovery of rabbits from anesthesia. Application of assigned treatments was continued every 12 hours for 7 days, and rabbits were anesthetized for BAER testing on day 8. Rabbits were euthanized, and samples were collected for histologic (6 ears/treatment) and scanning electron microscopic (1 ear/treatment) examination.

RESULTS

Most hearing thresholds (11/12 ears) were subjectively increased after myringotomy, with BAER measurements ranging from 30 to 85 dB in both ears. All day 8 hearing thresholds exceeded baseline (premyringotomy) values; results ranged from 30 to 85 dB and 80 to > 95 dB (the upper test limit) in saline solution–treated and ESS-treated ears, respectively. All ESS-treated ears had heterophilic otitis externa, epithelial hyperplasia of the external ear canal, various degrees of mucoperiosteal edema, and periosteal new bone formation on histologic examination. Scanning electron microscopy revealed that most outer hair cells in the ESS-treated ear lacked stereocilia or were absent.

CONCLUSIONS AND CLINICAL RELEVANCE

Results supported that ESS has ototoxic effects in the middle ear of rabbits. Further research is needed to confirm these findings. Myringotomized laboratory rabbits may be useful to study ototoxicity of drugs used in human medicine.

Full access
in American Journal of Veterinary Research