Luxation of the tendon of the Musculus flexor digitalis superficialis, or heel cap rupture, limits the function of the ankle and toe. Affected animals go suddenly and recurrently severely lame after light exercise. The disease occurs more frequently in Shetland Sheepdog and two thirds of the affected dogs show the first symptoms before the age of two years. The aim of our research on heel cap rupture is the exact clarification of the heredity and thus the possibility of targeted breeding planning away from sick dogs. For the research we need blood samples from sick dogs, as well as their next of kin (parents and if possible unaffected full siblings). If you would like to participate in our project and can provide a blood sample of your dog, please follow the instructions in our leaflet and send the blood sample to us together with a copy of the pedigree.