Sonographic measurements of ocular biometry of indigenous Nigerian dogs in Zaria, Nigeria

Abstract

This study was aimed at conducting ophthalmic sonographic examination of Nigerian indigenous dogs to provide baseline information on some major ocular parameters. Healthy eyes of eighty (80) indigenous dogs were used for the study. The dogs were adequately restrained physically and the structure of the ocular globe was evaluated at a depth of 4-6 cm. For each dog, baseline data were obtained for D1= corneal thickness, D2= anterior chamber depth, D3= lens thickness, D4= vitreous chamber depth, and D5= the sagital axial length of the eye. Similarly, the baseline data were obtained for A1= anterior chamber area, A2= lens area, A3= vitreous chamber area and A4= globe area. Result revealed that the baseline ocular parameters of the Indigenous Nigerian dogs’ (in puppy, adult and older dogs respectively) were D1: 1.2 ± 0.2 mm, 1.4 ± 0.2 mm, 1.8 ± 0.2 mm; D3: 12.6 ± 0.6 mm, 13.6 ± 0.8 mm, 15.1 ± 0.9 mm and D5: 39.1 ± 1.4 mm, 42.5 ± 1.5 mm, 43.2 ± 2.1 mm. similarly, area biometry were obtained for A1: 30.8 ±3.0 mm², 34.5 ± 3.6 mm² and 32.0 ± 4.6 mm² and A2: 213.7 ± 21.1 mm², 250.3 ± 23.6 mm², 264.8 ± 21.0 mm². Analysis of variance (ANOVA) with turkey’s multiple comparison post-hoc test was used to compare the level of significance among the test groups. Values of P < 0.05 were considered significant at 95 % confidence. As such, it was deduced that these baseline ocular parameter values varied in two patterns: corneal thickness (D1), lens thickness and area (D3 and A2) and axial length and area (D5 and A4) increased with age from puppy to the adult and the older dogs in both sexes. However, the anterior chamber depth and area (D2 and A1) and vitreous depth and area (D4 and A3) increased initially with age from puppy to the adult dogs and then decreased slightly in the older dogs. The three (3) major ocular segments- anterior chamber, lens capsule and vitreous chamber was demonstrated in this study to represent approximately 2%, 17% and 76% respectively of the entire ocular globe area. The ciliary body and muscles, suspensory ligament and posterior chamber makes up the remainder 5%. This study has presented the baseline sonographic values of some major parameters of Indiginous Nigerian dogs in Zaria, and the values will be useful in the disgnosis ocular conditions that these may present.

Keywords: Ultrasonography, Baseline Value, Nigerian indigenous Dog, Ocular Biometry