Comprehensive diagnosis and management of Musladin–Lueke syndrome in a Beagle in Japan

Musladin–Lueke syndrome (MLS) is an inherited connective tissue disorder in Beagle caused by a homozygous missense mutation in the ADAMTSL2 gene. It is rare, but recognized globally. This report presents the first case in Japan definitively diagnosed via genetic testing. The 6-month-old male Beagle exhibited characteristic "tiptoe" gait, joint stiffness, lateral deviation of the eye socket, and undescended testes. At 10 months of age, bilateral Cryptorchidectomy was performed, and echocardiography revealed no abnormalities. At 12 months of age, the patient demonstrated progressive forelimb stiffness, chronic digital abrasions, and mild left atrial enlargement on echocardiography. As no curative treatment exists, we implemented symptomatic management using custom-made orthotic boots, which significantly improved the patient’s quality of life. The high probability that this condition remains underdiagnosed in Japan underscores the necessity to raise awareness among veterinary clinicians.