 Another problem that plagues the breed is heart disease.Cardiologist Simon Swift explained that about half of all Cavaliers aged 5 would have heart murmurs and the rate increases, such that by age 10 to 11 almost all Cavaliers would have the condition.About three-quarters of the 7 million dogs in the UK are pedigree breeds, and the programme revealed that they chalk up 10 million pounds' worth of vet fees every week.