# Evaluation of the lacrimal and nasolacrimal system in dogs treated at a veterinary ophthalmology service

## TL;DR

This study evaluates tear and nasolacrimal system health in dogs to better understand and diagnose eye disorders.

## Contribution

The study correlates tear test results with ocular and systemic conditions in dogs.

## Key findings

- Dogs with normal tear crystallization had significantly higher Schirmer tear test scores.
- Tear test interpretation depends on multiple factors, including ocular and systemic disorders.
- Comprehensive ophthalmic exams are essential for diagnosing lacrimal and nasolacrimal disorders.

## Abstract

In routine veterinary medicine, the lacrimal and nasolacrimal systems are associated with several ophthalmopathies. Understanding its physiology and improving specific diagnostic tests will help establish an assertive approach and avoid lacrimal and nasolacrimal disorders that cause damage to the ocular surface. This prospective study was conducted on 43 dogs treated at the Veterinary Ophthalmology Service and approved by the Ethics Committee for the Use of Animals under protocol number 5154141022. The study's objective of this study was to evaluate lacrimal and nasolacrimal system findings in dogs treated byat an ophthalmology service, determine the frequency of lacrimal and nasolacrimal system disorders, and correlate the diagnosed changes with the patient's main complaint. All dogs underwent a complete ophthalmic examination, emphasizing the lacrimal and nasolacrimal tests: the Schirmer tear test, tear film break-up test, tear crystallization test, and Jones test. The findings of these tests correlated with those of the ocular surface and the general condition of the dogs. Statistical analyses were performed using the Shapiro–Wilk test, Pearson's chi-square test, and Student's t test. The Student's t test revealed that dogs with normal tear crystallization test scores had a significantly higher score (25.5 ± 4.94) than dogs with altered tear crystallization test scores (15.35 ± 6.64) (t (40) = 2.121, p = 0.004). Our findings suggest that quantitative and qualitative tear tests should be performed together and their interpretation depends on several factors, including ocular and systemic disorders.