About the Cavalier King Charles Spaniel

An inherited disorder in which affected dogs produce no tears, leaving the eyes chronically sore, alongside dry, flaky skin that can make standing and walking painful. It is recessive and present from birth. When the mutation was found in 2012 about one in seven unaffected UK Cavaliers was estimated to carry it (from 122 unrelated dogs), and UK Kennel Club records show it falling from roughly one carrier in twenty among 1,015 dogs born just before the DNA test to under one in a hundred among 4,839 born after it.

An inherited inability to break down xanthine, so it builds up in the urine and forms stones in the bladder or kidneys. The variant was found in affected Cavaliers and an English Cocker Spaniel. It is recessive, and roughly one Cavalier in twenty-five carried it in a screen of more than 2,200.

An inherited muscle-wasting disease described in this breed, caused by a variant in the dystrophin gene, the same gene as Duchenne muscular dystrophy in boys: affected males develop progressive muscle weakness. It is X-linked, so it shows in males while their mothers carry it silently. It looks very rare — none of more than 2,200 Cavaliers in a large screen carried it.