 A natural bobtail can be found in some members of the breed , which is not a mutation of the T @-@ box gene , and so is allowed under conformation show rules . Health @-@ related research on the breed has been limited , with no major studies conducted in Britain . However , it has been included in studies outside the UK , including by the Orthopedic Foundation for Animals ( OFA ) in the United States . The King Charles Spaniel has a number of eye and respiratory system disorders common to brachycephalic dogs , and endocrine and metabolic diseases common to small breeds , as well as specific breed @-@ associated health conditions . The average lifespan is 10 to 12 years , and the breed should be able to reproduce naturally . 
