Diagnostic utility of clinical and laboratory test parameters for differentiating between sudden acquired retinal degeneration syndrome and pituitary‐dependent hyperadrenocorticism in dogs

Abstract

Objective: To identify discriminating factors, using clinical ophthalmic examination findings and routine laboratory testing, that differentiate dogs with early sudden acquired retinal degeneration (SARDS; vision loss <6 weeks' duration), age-and breed-matched control dogs, and dogs with pituitary-dependent hyperadrenocorticism (PDH). Animals: Client-owned dogs: 15 with SARDS with <6 weeks duration of vision loss, 14 age-and breed-matched control dogs, and 13 dogs with confirmed PDH. Procedures: Dogs underwent ophthalmic examination, electroretinography (ERG) fundus photography, and spectral-domain optical coherence tomography (SD-OCT) in addition to physical examination, urinalysis, serum biochemistry, complete blood count, and adrenocorticotrophic hormone (ACTH) stimulation testing. Statistical analysis was performed using receiver operating curve area under the curve analysis, principal component analysis with sparse partial least squares analysis, and one-way ANOVA. Results: Dogs with SARDS all had absent vision and ERG a-and b-waves. SD-OCT demonstrated that dogs with SARDS had significantly thicker inner retina, thinner outer nuclear layer, and thicker photoreceptor inner/outer segment measurements than either controls or dogs with PDH. Discriminating laboratory parameters between dogs with SARDS and PDH with high specificity included post-ACTH serum cortisol (<19.3 μg/dL), AST:ALT ratio (>0.343), and urine specific gravity (>1.030). Conclusions and Clinical Relevance:We have identified significant discriminators between SARDS and PDH. This work provides the basis for future studies that could identify and examine dogs with SARDS prior to vision loss, which may extend the potential therapeutic window for SARDS. K E Y W O R D S biomarker, dog, hyperadrenocorticism, retina, sudden acquired retinal degeneration syndrome | 843 OH et al.

Circulating neurohormone imbalances in canine sudden acquired retinal degeneration syndrome and canine pituitary‐dependent hypercortisolism

“…Clinical demographics, examination, and laboratory findings for the 3 groups were previously described in detail . All enrolled dogs were included in the analysis.…”

“…Our observation that plasma melatonin correlates with post‐ACTH cortisol in dogs with PDH raises some interesting questions. The initial motivation was to study SARDS and utilize PDH as a comparison group because these 2 diseases have shared clinical features . It is likely that our results were affected by the season of recruitment, as daylight duration was significantly longer in dogs with PDH compared to dogs with SARDS.…”

“…This study was conducted with full institutional approval (Institutional Animal Care and Use Committee approval) and client written informed consent. Full details of recruitment and inclusion/exclusion criteria for the dogs used in this study are described in a previously published study …”

“…All dogs underwent full physical and ophthalmic examination, electroretinography (ERG), spectral‐domain optical coherence tomography (OCT), fasted CBC, serum biochemistry, urinalysis, and ACTH (cosyntropin) stimulation testing as previously described …”

Canine sudden acquired retinal degeneration syndrome: Owner perceptions on the time to vision loss, treatment outcomes, and prognosis for life

“…The systemic clinical signs and clinicopathologic abnormalities associated with SARDS have been well characterized in numerous studies. Typical associated signs and clinical findings include polyuria, polyphagia and weight gain, and laboratory findings consistent with liver damage and endocrinopathy, 3,5‐8 Differences between SARDS and canine pituitary‐dependent hyperadrenocorticism have recently been described 9 . The timeframe between onset of systemic clinical signs and vision loss has not been described in detail, yet has been suggested to either precede vision loss or coincide with vision loss 2…”