Pupillometric studies in the beagle dog

Area of Science:

• Veterinary Ophthalmology
• Pharmacology
• Toxicology

Background:

• Accurate measurement of pupillary diameter is essential for assessing drug effects in preclinical studies.
• Existing methods may lack precision or detailed characterization in canine models.

Purpose of the Study:

• To describe and validate a method for measuring pupillary diameter in dogs using a fundus camera.
• To investigate the influence of age, sex, and light intensity on pupillary diameter.
• To evaluate the dose- and time-dependent effects of mydriatic and miotic agents.

Main Methods:

• Utilized a Kowa RC-2 fundus camera with an eyepiece graticule for direct or photographic measurement of pupillary diameter.
• Measured pupillary diameters in 105 untreated English beagles across different ages and light intensities.
• Administered atropine and propantheline intravenously to assess mydriatic effects and plotted time- and dose-effect curves.

Main Results:

• Established a precise method for pupillary diameter measurement in dogs.
• Identified significant differences in pupillary diameter based on sex and age.
• Demonstrated a linear dose-effect relationship for propantheline, with a specific dose increasing diameter by 3 mm within 20 minutes.

Conclusions:

• The described fundus camera method is accurate and suitable for pharmacological and toxicological studies in dogs.
• Age and sex are significant factors influencing pupillary diameter and drug responses.
• The study provides valuable data for the design and interpretation of veterinary drug efficacy and safety studies.