Corneal Endothelial Dystrophy in Boston Terriers: A Spontaneous, Canine Model for Fuchs Endothelial Corneal Dystrophy

Abstract

Purpose: Boston Terriers have a greater prevalence of corneal endothelial dystrophy (CED) in comparison to many other canine breeds. Similar to Fuchs endothelial corneal dystrophy (FECD), this condition is characterized by endothelial cell degeneration with secondary corneal edema; vision compromise and bullous keratopathy can occur in advanced stages. While in vivo advanced imaging techniques are commonplace in physician-based ophthalmic practice for the management of endothelial disorders, in vivo confocal biomicroscopy (IVCM) and Fourier-domain optical coherence tomography (FD-OCT) are not routinely used for the diagnosis of CED in canine patients. The purpose of this study was to assess corneal morphology using IVCM and FD-OCT in Boston Terriers with CED as well as unaffected, age-matched Boston Terriers.

Methods: The cornea of 16 Boston Terriers with CED and 15 unaffected, age-matched Boston Terriers were imaged using FD-OCT and IVCM. A two-sample t test or Mann-Whitney rank sum test was used to statistically compare parameters between the two groups. Data are presented as mean ± SD.

Results: Mean age did not significantly differ in affected and unaffected dogs at 10.0 ± 2.0 and 10.6 ± 2.4 years, respectively (P = 0.437). Similar to FECD, females (69%) were overrepresented among the CED-affected dogs. IVCM demonstrated obvious differences in corneal endothelial cell morphology with marked polymegathism and pleomorphism in CED patients and a regular arrangement of hexagonal cells in unaffected controls. Corneal endothelial density was significantly less (P < 0.001) in dogs with CED (1280 ± 241 cells/mm²) in comparison to age-matched controls (2383 ± 358 cells/mm²). FD-OCT demonstrated a significant increase in central corneal thickness in dogs with CED versus age-matched controls at 1004 ± 314 and 563 ± 59 mm, respectively (P < 0.001). Corneal endothelium-Descemet’s membrane complex was also significantly thicker (P = 0.003) in CED patients (33 ± 9.3 mm) in comparison to unaffected dogs (25 ± 4.1 mm).

Conclusions: CED in Boston Terriers is a bilateral, adult-onset condition that shares many similarities with FECD. Identifying the gene(s) responsible for CED in dogs may uncover new target genes for FECD in humans. Furthermore, CED could serve as a spontaneous disease model for studying the pathogenesis of and novel treatments for FECD.