Cone degeneration in two Shih Tzu dogs: clinical and genetic investigation

ABSTRACT: Two cases of cone degeneration in adult Shih Tzu canine patients are reported herein. Definitive diagnosis was made based on the ophthalmic examination finding, typical clinical signs, and characteristic electroretinography results that demonstrated normal rod function and absence of recordable cone function. Sanger sequencing of the entire coding sequence of the cyclic nucleotide gated channel β3 (CNGB3) gene did not reveal disease causing variants in these dogs. To the authors’ knowledge, this is the first report of clinical, electroretinographic and genetic investigation of cone degeneration in Shih Tzu.