Case 170421-2

Twelve-year-old, female spayed, English springer spaniel

The patient was previously diagnosed with glaucoma in the right eye. Her intraocular pressures at the time of diagnosis were 53 in the right eye and 9 in the left eye. She was treated with timolol, neopolydex, tramadol, and carprofen. She was presented approximately two months later for enucleation of the right eye, due to continued discomfort. At the time of surgery, her glaucoma was adequately controlled and she had an intraocular pressure of 10 to 11 in the right eye and 10 to 13 in the left eye.

No significant gross lesions were evident in the formalin-fixed tissues received.

One parasagittal section of ocular globe is examined, in which there is multifocal, severe atrophy of the outer nuclear layer of the inferior retina. Few lymphocytes are scattered along the detached posterior aspect of the outer nuclear layer of the retina, along the anterior aspect of the retinal pigmented epithelial layer, and in the space between those layers. Few retinal, pigmented epithelial cells are mildly hypertrophied. Multiple subretinal cysts of varying sizes are present in the anterior portion of the retina. The optic nerve has a small amount of hemorrhage and has small amounts of scattered vacuolation, disorganization, and rare dilated myelin sheaths. The iridocorneal angle is decreased and is deeply recessed. A thin, pre-iridal fibrovascular membrane sweeps from the anterior aspect of the iris down to the sclera. The iridal connective tissue has small numbers of lymphocytes and plasma cells. Large clumps of cells containing dark brown, granular pigment (melanin), are in the iridocorneal angle. Small numbers of lymphocytes, plasma cells, and neutrophils are scattered throughout the superficial corneal stroma, along with multiple small caliber vessels. Few neutrophils, lymphocytes, and plasma cells are scattered in the posterior chamber. Peripheral fibers within the lens are variably swollen and there are rare swollen lens epithelial cells (bladder cells).

None

Eye: Severe, segmental, inferior, outer-nuclear-layer, retinal atrophy

Eye: Mild, lymphoplasmacytic anterior uveitis with diffuse, mild pre-iridal fibrovascular membrane formation, pigment dispersion, and iridocorneal angle collapse

Eye: Mild, multifocal optic nerve vacuolation and myelin sheath dilation with minimal hemorrhage

Eye: Mild, chronic, lymphoplasmacytic, neutrophilic keratitis with corneal neovascularization

Eye: Cataract

The pre-iridal fibrovascular membrane likely caused the glaucoma. Only mild evidence of glaucoma was present, which may be due to successful treatment of the disease shortly after diagnosis. The asymmetric atrophy of the outer nuclear layer of the retina is most consistent with progressive retinal atrophy (PRA), which is an inherited disease seen in many different breeds of dogs.

Progressive retinal atrophy is a diverse group of disorders that can be broadly subdivided into early onset (photoreceptor dysplasias and dystrophies) and late onset (photoreceptor degenerations). Due to the age of the animal, this is most likely a form of retinal degeneration and not a dysplastic process. It is seldom possible to definitively diagnoses PRA on the basis of morphologic findings alone, but knowledge of commonly affected breed can be useful. The English springer spaniel is reported to be a breed predisposed to PRA in “Ocular Disorders Presumed to be Inherited in Dogs”, published by the American College of Veterinary Ophthalmologists.

References