Objective: This study was designed to determine if hearing status monitoring during intravenous infusion of EA reduces individual variability and to evaluate the correlation between EA dose and Bwt.
Materials and methods: Twenty-five cats with the mean age of 24 ± 3.7 weeks (range = 20.6-28.3) and a mean weight of 3.21 ± 0.84 kg (range = 1.9-5.1) were administered a subcutaneous injection of KM (300 mg/kg) followed by an intravenous infusion of EA (1 mg/min). Click-evoked auditory brainstem responses (ABRs) were recorded to monitor hearing during the infusion. When ABR thresholds exceeded a 90 dB sound pressure level, the infusion of EA was terminated. Histopathology forapex, middle, and base sections of the cochlea were examined after 6 months.
Results: The dose of EA was optimized for deafening through simultaneous ABR measurements. Bwt was positively correlated with EA dose (mg) (p < 0.001, R(2) = 0.548), which was different from a study previously reported. Cochlear histopathology assessments revealed an absence of organ of Corti in the majority of cochleae.
Conclusion: Co-administration of kanamycin (KM) and ethacrynic acid (EA) was an easy and effective method for deafening procedures in adult animals. Body weight (Bwt) was positively correlated with EA dose (mg) and an optimal EA dose can be calculated.
Keywords: Ethacrynic acid; body weight; deafness; kanamycin.