cfa-mir-599: Cfa-mir-599 is a type of microRNA that has been found to exhibit changes in expression levels in relation to disease progression, development of heart failure, and age in dogs [PMC8400600]. It has been associated with naturally occurring myxomatous mitral valve disease (MMVD) in dogs, which closely resembles mitral valve prolapse (MVP) in humans [PMC7696149]. Studies have shown that cfa-mir-599 expression is increased in older normal dogs compared to young normal dogs and dogs with MMVD [PMC5533140]. However, there is a downregulation of cfa-mir-599 in dogs with MMVD compared to normal older dogs [PMC5533140]. Other microRNAs, such as cfa-miR-9, cfa-miR-181c, and cfa-miR-495, have also been found to exhibit changes in expression levels that correlate with disease progression and age [PMC8400600] [PMC7696149] [PMC5533140]. These findings suggest that cfa-mir-599 and other microRNAs may play a role in the development and progression of heart disease in dogs. Further research is needed to fully understand the mechanisms underlying these changes and their potential as diagnostic or therapeutic targets.