Development of retinal bullae in dogs with progressive retinal atrophy

Abstract

Objective To report the development of focal bullous retinal detachments (bullae) in dogs with different forms of progressive retinal atrophy (PRA). Procedures Dogs with three distinct forms of PRA (PRA‐affected Whippets, German Spitzes and CNGB1‐mutant Papillon crosses) were examined by indirect ophthalmoscopy and spectral domain optical coherence tomography (SD‐OCT). Retinal bullae were monitored over time. One CNGB1‐mutant dog was treated with gene augmentation therapy. The canine BEST1 gene coding region and flanking intronic sequence was sequenced in at least one affected dog of each breed. Results Multiple focal bullous retinal detachments (bullae) were identified in PRA‐affected dogs of all three types. They developed in 4 of 5 PRA‐affected Whippets, 3 of 8 PRA‐affected Germans Spitzes and 15 of 20 CNGB1‐mutant dogs. The bullae appeared prior to marked retinal degeneration and became less apparent as retinal degeneration progressed. Bullae were not seen in any heterozygous animals of any of the types of PRA. Screening of the coding region and flanking intronic regions of the canine BEST1 gene failed to reveal any associated pathogenic variants. Retinal gene augmentation therapy in one of the CNGB1‐mutant dogs appeared to prevent formation of bullae. Conclusions Retinal bullae were identified in dogs with three distinct forms of progressive retinal atrophy. The lesions develop prior to retinal thinning. This clinical change should be monitored for in dogs with PRA.

Preliminary characterization of a novel form of progressive retinal atrophy in the German Spitz dog associated with a frameshift mutation in GUCY2D

“…Although these were no longer apparent on funduscopy as the dogs got older, they were still detectable by OCT at 15 months of age. With age they tended to flatten, perhaps making them less obvious ophthalmoscopically while they are still detectable by OCT. A similar feature has been observed in PRA‐affected Whippets and CNGB1 ‐mutant Papillon crosses 23,24,37 . A comprehensive description of these lesions in these dog breeds can be found elsewhere 37 .…”

“…With age they tended to flatten, perhaps making them less obvious ophthalmoscopically while they are still detectable by OCT. A similar feature has been observed in PRA-affected Whippets and CNGB1-mutant Papillon crosses. 23,24,37 A comprehensive description of these lesions in these dog breeds can be found elsewhere. 37 Retinal bullae formation has not been reported in humans affected with GUCY2D-Associated LCA.…”

“…23,24,37 A comprehensive description of these lesions in these dog breeds can be found elsewhere. 37 Retinal bullae formation has not been reported in humans affected with GUCY2D-Associated LCA. This lesion seems to be an exclusive feature of dogs affected with some early-onset retinal dystrophies.…”

Progressive retinal atrophy in a poodle dog: Case report

“…The retina, also called the nerve tunic of the eye bulb, is responsible for converting light energy into chemical energy and electrical impulses, which are transmitted to the brain. Among the cells that compose it are the photoreceptors, represented by cones, specialized cells that allow the visualization of colors, in addition to the rods, which are more used for night vision (PETERSEN-JONES;MOWAT, 2021;MARINHO et al, 2022).…”