The researchers said that each dog is affected by a similar number of health conditions, but larger breeds may suffer from more serious conditions.
In a study of 238 breeds of dogs and more than 25,000 puppies, US scientists found that small dogs tend to live longer than large dogs.
Large dogs are prone to cancer, bone-related diseases, gastrointestinal problems, neurological and endocrine disorders, ear, nose and throat problems and infectious diseases, while small dogs are more likely to develop liver or pancreatic diseases, as well as eye, heart and respiratory problems, the study said.