Presumed cancer‐associated retinopathy (CAR) mimicking Sudden Acquired Retinal Degeneration Syndrome (SARDS) in canines

Abstract

Objective To describe functional and structural features of presumed cancer‐associated retinopathy (CAR) mimicking sudden acquired retinal degeneration syndrome (SARDS) in dogs and describe treatment outcomes. Animals Subjects were 17 dogs from 8 eight US states and Canada diagnosed with SARDS or immune‐mediated retinitis (IMR) by 12 ophthalmologists. Nine eyes from seven deceased patients were used for microarray (MA), histology, or immunohistochemical (IHC) analysis. Procedures Dogs underwent complete ophthalmic examination, including retinal photography, optical coherence tomography (OCT), chromatic pupil light reflex testing (cPLR), and electroretinography (ERG), in addition to complete systemic examination. Histology, microarray, and IHC analysis were performed in CAR retinas to evaluate histological and molecular changes in retinal tissue. Results None of the patients evaluated satisfied previously established criteria for diagnosis of SARDS (flat ERG+ no red – good blue PLR), and all were diagnosed with IMR. All patients were diagnosed with a cancer: meningioma (24%), sarcoma (18%), pituitary tumor (12%), and squamous cell carcinoma (12%), other (34%). Median survival time was 6 months from diagnosis (range 1‐36 months). Most frequent systemic abnormalities were as follows: proteinuria (78%); elevated liver enzymes (47%); and metabolic changes (PU/PD, polyphagia – 24%). Immunosuppressive therapy resulted in the reversal of blindness in 44% of treated patients, with 61% of all treated patients recovering and/or maintaining vision. Median time for preservation of vision was 5 months (range 1‐35 months). Conclusions Observed changes are highly suggestive of immune‐mediated damage in IMR‐CAR eyes. A relatively high percentage of patients with CAR responded positively to immunosuppressive therapy.

Unilateral blindness presumed as sudden acquired retinal degeneration syndrome (SARDS) in one Dachshund and four Maltese dogs

“…In addition, a previous study demonstrated several focal retinal detachments on the OCTs of dogs with SARDS that were otherwise not identified during fundus examination. 3,8 No such findings were found in the OCT from Case 1 in our study. In the sighted OS, the band corresponding to the external limiting membrane (asterisk) was consistently present, while the ellipsoid zone and RPE photoreceptor interdigitations appeared to be merged as one band, except for in several areas where these bands were still discernable (arrows).…”

“…Therefore, it is interesting that despite having a barely discernible ellipsoid zone, the eye in this study still maintained vision and had a recordable ERG. In addition, a previous study demonstrated several focal retinal detachments on the OCTs of dogs with SARDS that were otherwise not identified during fundus examination 3,8 . No such findings were found in the OCT from Case 1 in our study.…”

Manifestations of systemic disease in the retina and fundus of cats and dogs

“…The condition resembles sudden acquired retinal degeneration syndrome (SARDS), though differences have been reported in the profile of retinal responses to different wavelengths of light (e.g., chromatic pupillometry). The condition is reported in people and suspected in dogs ( 85 ). As with SARDS a comprehensive workup including electroretinography and advanced imaging is recommended for a diagnosis that is largely reliant on exclusion.…”