[The study of ototoxicity in Gallus domesticus by recording distortion products]

Distortion products (DP) were recorded and a morphological cochlear study was made of a sample of 60 ears from chickens (Gallus domesticus. Leghorn breed) and the ages of 15, 23, 29 and 60 days, after intoxication by intramuscular gentamicin injection (40 mg per kg weight and day for 8 days). Spontaneous or transitory otoacoustic emissions were not obtained in any case. DP recordings showed a 2F1-F2 response in every frequency band ranging from 0.7 to 6 KHz. The DP incidence shifted with the age of the chickens and differed significantly (p < 0.001) in the groups of 29 and 60 day-old chickens (m = 100%) and in the 29-day-old (m = 64%) and 60-day-old (m = 62%) intoxicated chickens. We found no significant differences in DP amplitude in subpopulations. In the intoxicated groups, the proximal segment of the ototic membrane disappeared in the macula lagenae and a loss of contact with the hair cells appeared. Degenerative vacuolar phenomena were observed in the support cells and cellular loss in the spiral ganglion.