There are some medical problems, which are pretty common in all large breeds, which breeders, owners, and potential owners should know about.
Hip dysplasia. Unfortunately, many large breeds have this problem. All the clubs that work with Leonbergers do their best to minimize this problem in their loved breed. OFA informs that less than 11% of all the dogs have this illness.
Eosinophilic osteomyelitis. This problem starts without a reason and ends the same way. Healthy puppy starts to limp without any obvious reason or a trauma. It is good that this illness will not last for a long time and will not deal any significant damage to the dog's body.
Addison's disease. This is a very rare hormonal sickness of the adrenal gland. It has been diagnosed in both American and European Leonbergers. It is a very serious disease that should be treated immediately, or it can cause death of your pet. It can be cured with medication if it has been diagnosed in its early stage.
The entropy and ectropion of the eye. This disease exists in Leonbergers at the genetic level. This problem can be solved by a small surgical procedure. But it is still considered to be a serious disadvantage, so the dogs with this gene are banned from being used in breeding.
Answer for dog breed "Leonberger"