EGF and spondylocostal dysostosis: This mutation, located at the splice acceptor site preceding exon 5, is predicted to disrupt critical EGF-like domains and O-fucosylation sites essential for <i>DLL3</i> protein function.<h4>Conclusions</h4>This study identifies a DLL3 splice variant causing SCDO in dogs, demonstrating phenotypic conservation with humans.