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Degree

Master of Science, Ohio State University, Veterinary Clinical Sciences, 2011.

Abstract

The tympanic membrane and external auditory canal serve auditory and non-auditory functions. Both the luminal surface of the external auditory canal and the lateral surface of the tympanic membrane are composed of a stratified squamous, keratinizing epithelium. Epithelial migration is a process that serves as a self-cleaning and repair mechanism for the external auditory canal and tympanic membrane. Epithelial migration has been evaluated in humans and several other species, but not in dogs. The majority of these studies employ an ink drop method in which discrete markers of ink are placed on the lateral surface of the tympanic membrane and the pattern and rate of these markers are monitored over time. Failure or abnormal epithelial migration has been implicated as a potential cause of some otic diseases in humans and has been assessed in otitis externa, keratosis obturans, external auditory canal cholesteatomas, retraction pockets, and middle ear cholesteatomas. The objectives of this study were to determine the rate and pattern of epithelial migration on the tympanic in clinically normal laboratory dogs and to describe a technique for ink drop placement on the canine tympanic membrane to be used for future studies. Eighteen dogs were anesthetized, and three drops of waterproof drawing ink were placed on two sites of the pars tensa and one on the pars flaccida. Images were recorded with a video otoscope and digital capture system. Each dog was evaluated and images recorded every six to eight days for four evaluations. Migration pattern analysis and epithelial migration rate calculation were performed with image processing software. Descriptive statistics for epithelial migration rate (mean, standard deviation, 95% confidence interval) were calculated for all ink drop locations on the tympanic membrane (pars tensa 1 [PT1], pars tensa 2 [PT2], and pars flaccida [PF]) at each time point. Eight fox hounds had digital images from both ears that met the criteria for image analysis, while all beagles and two fox hounds only had images from one ear that met the criteria for image analysis. No significant differences in the mean epithelial migration rates were identified between right and left ears of the eight fox hound dogs, between breeds (beagle, fox hound), or between locations PT1 and PT2. The mean overall epithelial migration rates (±standard deviation) were 96.4 (±43.1) and 225.4 (±128.1) micrometers per day for the pars tensa and pars flaccida, respectively. All ink drops moved outwards, the majority (48 of 53) in a radial direction, from the original location to the periphery of the tympanic membrane. Migration of the ink drops off the tympanic membrane was observed during the study period for all three locations. The ink drop placement method used in this study can be used in future studies to determine the epithelial migration rate of the canine tympanic membrane. Future investigations of epithelial migration should focus on dogs of different ages, dogs predisposed to otic diseases, as well as dogs with existing otic conditions.

Subject Headings

Anatomy and Physiology; Animal Diseases; Audiology

Keywords

tympanic membrane; canine; epithelial migration; otology; veterinary medicine; ear drum; dog

Committee / Advisors

Lynette Cole, DVM, MS (Advisor)
Andrew Hillier, DVM, MS (Committee Member)
Paivi Rajala-Schultz, DVM, PhD (Committee Member)

Pages

99p.

Document number: osu1306719375
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=osu1306719375

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