How corneal sensitivity changes in beagle puppies as they grow

Abstract

OBJECTIVE: To evaluate the evolution of corneal sensitivity in healthy beagle puppies during the first weeks of life, compare these results with adult corneal sensitivity, and determine the age at which adult corneal sensitivity levels are reached. ANIMALS STUDIED: Twelve puppies and five adult females. PROCEDURES: Corneal sensitivity was assessed in puppies weekly from 2 to 7 weeks of age and in their mothers by measuring the corneal touch threshold (CTT) in the central cornea using a Cochet-Bonnet esthesiometer. Hygrometric and temperature measurements were recorded throughout the study period. RESULTS: In puppies, esthesiometry indicated a progressive decrease in corneal sensitivity with age. Sensitivity was higher between 2 and 4 weeks, which stabilized between 5 and 7 weeks, with a median CTT values of 0.5, 0.5, 0.8, 1.4, 1.2, and 1.4 g/mmat 2, 3, 4, 5, 6, and 7 weeks, respectively. The median CTT in puppies reached the adult median value (1.4 g/mm) at 5 weeks. The median CTT at 2 weeks was significantly different from the median CTT at 7 weeks (0.5 vs. 1.4 g/mm). Humidity and temperature were not significantly associated with corneal sensitivity in adults. CONCLUSIONS: In this study, corneal sensitivity in beagle puppies was higher during the first 3 weeks of life compared to 7 weeks. During this early period, puppies exhibited corneal sensitivity levels exceeding those of adults, which subsequently decreased to adult-equivalent values between 5 and 7 weeks of age.