distichia (where extra eyelashes or hairs cause irritation to the eye). Inheritance is suspected in the other conditions, with ages of onset ranging from six months for cataracts to two to five years for corneal dystrophy. Heart conditions related to the King Charles Spaniel include mitral valve disease, in which the mitral valve degrades, causing blood to flow backwards through the chambers of the heart and eventually leading to congestive heart failure. Patent ductus arteriosus, where blood is channelled back from the heart into the lungs, is also seen and can lead to heart failure. Both of these conditions present with similar symptoms and are inheritable. The OFA conducted a survey on cardiac disease, where of 105 breeds, the King Charles Spaniel was found to be 7th worst, with 2.1% of 189 dogs affected. Other common issues Being a brachycephalic breed, King Charles Spaniels can be sensitive to anesthesia. This is because in brachycephalic dogs, there is additional tissue in the throat directly behind the mouth and nasal cavity, known as the pharynx, and anesthesia acts as a muscle relaxant causing this tissue to obstruct the dogs' narrow airways. These narrow airways can decrease the dogs' ability to exercise properly and increase their susceptibility to heat stroke. Other congenital and hereditary disorders found in the King Charles Spaniel are hanging tongue, where a neurological defect prevents the tongue from retracting into the mouth; diabetes mellitus, which may be associated with cataracts; cleft palate and umbilical hernia. The English Toy Spaniel Club of America recommends that umbilical hernias be corrected only if other surgery is required, due to the risk of surgery in brachycephalic breeds. In another study conducted by the OFA, the King Charles Spaniel was the 38th worst of 99 breeds for patella luxation; of 75 animals tested, 4% were found to have the ailment. However, surveys conducted by the Finnish breed club between 1988 and 2007 found that the occurrences were higher in some years, ranging from 5.3% to 50%. There are several breed traits which may cause concern as health issues. They include skull issues such as an open fontanelle, where in young dogs there is a soft spot in the skull; it is common in dogs under a year old. A complication from that condition is hydrocephalus, also known as water on the brain. This condition may cause neurological symptoms that require the dog to be