Though not common, Leonbergers do inherit and/or develop a number of diseases that range in their impact from mild to devastating. In addition to hip dysplasia, Leonbergers can inherit and/or develop heart problems, inherited Leonberger paralysis/polyneuropathy, osteosarcoma, hemangiosarcoma, osteochondrosis dissecans, allergies, digestive disorders, cataracts, entropion/ectropion eyelids, progressive retinal atrophy, perianal fistulas, and thyroid disorders. Though rumors persist of Leonbergers being more sensitive to anesthesia than other breeds of dog, they are largely untrue. Leonbergers, like other large breed dogs, require less dosage per pound of sedative than smaller breeds to yield the same effect. The Leonberger Health Foundation, a private nonprofit foundation whose sole mission is to support major researchers who are seeking to identify genetic markers for serious diseases which affect the breed, is currently focusing on osteosarcoma, hemangiosarcoma, and Leonberger polyneuropathy. Leonbergers in UK and USA/Canada surveys had a median lifespan around 7 years, which is about 4 years less than the average purebred dog, but typical of similarly sized breeds. About 20% of Leonbergers in the surveys lived to 10 years or more. The oldest dogs in both surveys died at about 13. In France, the breed has a median lifespan of 8.75 years. Serious diseases can affect the Leonberger—certain types of cancers are very common in the breed. Gastric dilatation volvulus, commonly called bloat, is another serious condition that affects many of the large- and giant-breed dogs, particularly those with deep chests. It causes the stomach to twist and can be fatal quite quickly. Adult Leonbergers should always be fed twice a day rather than one large meal to reduce the likelihood of bloat. Leonbergers are not alone in inheriting serious diseases, and according to the University of Sydney's LIDA taskforce, Leonbergers have relatively few health issues compared to other dog breeds. In a 2004 UK Kennel Club survey, the most common causes of death were cancer (45%), cardiac disease (11%), and "unknown" (8.5%). In a 2000 USA/Canada Leonberger Club of America survey, the most common causes of death were cancer (37%), old age (12%), cardiac disease (9%), and "sudden death" (8%).