Like most dog breeds, Cocker spaniels can have health issues but these are no more commonplace than in most other breeds.
Responsbile dog owners will make sure that their dog is vaccinated annually and regularly wormed. Cocker spaniels are no exception to this and their demands are normal and no greater than other dogs.
One of the main areas of concern with Cocker spaniels can be their ears, which can collect foreign bodies and become infected if not cared for. This is true of all of the spaniel breeds though, and Cockers are no more prone to this problem.
In older dogs arthritis can be a problem, but, again, many active dogs experience this as they grow older.
A well cared for, exercised Cocker spaniel, will be a healty dog and will be no more high maintenance health wise than any other dog breed.