Evaluation of normal ophthalmic parameters and fundoscopic images along with the comparison of two methods of A-mode ocular ultrasonographic biometry and intraocular pressure in healthy working canines.

Abstract

Background: Working canines play a very important role in assisting forces by uncovering evidences that might be missed by the human eye. To date, there is no published data on normal ophthalmological parameters for working dogs.

Aims: This study aims to document normal reference ranges of ophthalmological parameters and blood pressure (BP). Additionally, the study compared the two methods of intraocular pressure (IOP) measurement and A-scan biometry, and assess correlations between IOP to both systolic blood pressure and axial globe length.

Methods: The study was conducted on 18 dogs of Sashastra Seema Bal (SSB), Alwar (Rajasthan), aged 3.5-6 years, which were divided into three breed-specific groups, i.e., group 1 (Belgian Shepherd), group 2 (German Shepherd) and group 3 (Labrador Retriever) with six animals each. Schirmer's tear test strips were used to perform the Schirmer's tear test (STT). To measure intraocular pressure (IOP), rebound tonometry (Tonovet) and indentation tonometry (Schiotz) were used. A-scan ultrasonography was performed by contact and immersion method. Fundoscopic images were recorded using Fundus-On-Phone equipment.

Results: STT values revealed non-significant differences among groups, sexes, and eyes. The cumulative mean reflected a higher reading by the rebound tonometer than the indentation tonometer. In all the three groups, a significantly longer anterior chamber depth and axial globe length were observed in the immersion method. Axial globe length was longest in the Labrador breed, followed by German Shepherd and Belgian Shepherd. Systolic and diastolic pressure were significantly different among groups.

Conclusion: These breed-specific various ophthalmic parameters of working canines will be useful in the clinical diagnosis of various ophthalmic affections.