Development and validation of a clinical risk score for early identification of sudden acquired retinal degeneration syndrome in dogs: A retrospective case-control study.

Background and Aim: Sudden acquired retinal degeneration syndrome (SARDS) is an important cause of acute, irreversible blindness in dogs and is frequently accompanied by systemic clinical and biochemical abnormalities. Despite numerous studies describing the disease, no clinically applicable prediction tool has been developed to facilitate early recognition before electroretinographic confirmation. This study aimed to identify demographic, hematological, and biochemical factors associated with SARDS and to develop and internally validate a practical clinical risk score for early identification of affected dogs. Materials and Methods: A retrospective case-control study was conducted using medical records of dogs that underwent electroretinography between January 2018 and December 2023 at the Kasetsart University Veterinary Teaching Hospital in Thailand. Fifty-three dogs with electroretinography-confirmed SARDS were compared with 219 breed-frequency-matched cataract patients exhibiting normal electroretinographic responses. Demographic characteristics, complete blood count results, and serum biochemical parameters were analyzed. Variables associated with SARDS in univariable logistic regression (p < 0.20) were entered into multivariable logistic regression using a manual purposeful selection approach. Independent predictors were incorporated into a weighted clinical risk score. Diagnostic performance was evaluated using receiver operating characteristic analysis, sensitivity, specificity, and area under the receiver operating characteristic curve (AuROC). Results: Dogs with SARDS exhibited significantly higher neutrophil counts, alkaline phosphatase (ALP) activity, plasma protein concentration, alanine aminotransferase activity, creatinine concentration, and white blood cell counts than control dogs. Multivariable logistic regression identified elevated neutrophil count (odds ratio [OR] = 8.80; p < 0.001), elevated ALP activity (OR = 6.80; p < 0.001), and increased plasma protein concentration (OR = 3.94; p = 0.004) as independent predictors of SARDS. Based on optimal cutoff values (neutrophils ≥10,525 cells/µL, ALP ≥74 U/L, and plasma protein ≥7.3 g/dL), a weighted clinical risk score ranging from 0 to 5 points was developed. A threshold score of ≥3 demonstrated good discriminative ability, with an AuROC of 0.83 (95% confidence interval: 0.76-0.90), sensitivity of 74.47%, and specificity of 79.79%, outperforming each individual laboratory parameter. Conclusion: This study identified readily available hematological and biochemical variables that are independently associated with SARDS and developed the first weighted clinical risk score for early identification of the disease in dogs. The proposed model demonstrated good diagnostic performance and may assist veterinarians in prioritizing dogs for ophthalmic evaluation and electroretinography. Although external validation in independent populations is warranted, this practical scoring system represents a valuable adjunct for improving early clinical suspicion and diagnostic decision-making in canine SARDS.