Curva tensional ocular fisiológica diária e proposição da mini curva correlacionadas com os níveis circadianos de cortisol sanguíneo em cães adultos da raça Shih Tzu

Abstract

Measuring intraocular pressure (IOP) is essential for the diagnosis and control of ophthalmic diseases, such as uveitis and glaucoma, making it essential to know its normal values for a specific tonometer, species and breed. The IOP of dogs, a species frequently affected by blood pressure changes, varies over time, breed, age, sex and physiological state, so clinical tonometry performed 24 hours a day and night would reveal the normal distribution of IOP in this species. The objective of this study was to analyze the IOP values in healthy Shih Tzu dogs, during a period of 24 hours, to establish the daily physiological ocular tension curve (CTD) and propose the mini curve using the rebound tonometer (TonoVet), in addition to checking whether there is a correlation between IOP and circadian cortisol levels in this category of animals. IOP was measured every hour during the day and night in 12 Shih Tzu dogs, aged between 2 and 6 years, male and female, and, during 8 moments, serum cortisol was evaluated. Prior to the study, the animals were selected and, on the day of data collection, the activities of each one were maintained and the restraint used was minimal, in order to reduce interference with the data. No statistically significant difference was observed between the IOP of the right and left eyes. The overall average IOP obtained with TonoVet was 15.61 ± 2.15 mmHg, with the averages varying from 14.51 to 16.86 mmHg. No statistically significant differences were observed between the mean IOP of both eyes (MAOh) from 08:00h to 18:00h (p = 0.379), however a reduction was detected at 04:00h and 06:00h, correlating them with daily luminosity. The mini curve was proposed to include the maximum and minimum blood pressure peaks, with measurements at 04:00h, 06:00h, 08:00h and 18:00h. There was no correlation between IOP and circadian cortisol levels evaluated in the category of animals studied.