Advances in Canine Cardiac Research

Intriguing developments in canine genetic and health research presented by experts made last fall’s AKC Canine Health Foundation National Parent Club Canine Health Conference one of the best ever. The seventh biennial conference, sponsored by Purina, provided insights and led to thought-provoking discussions among parent club health liaisons and researchers, among them a presentation on advances in canine cardiology research.

Heart diseases, such as mitral valve disease, generally have fewer treatment options for dogs than for people. Dogs are neither candidates for open heart surgery nor for extensive heart repair procedures performed during a cardiac catheterization. Advancements in the development of genetic tests and new treatments are making great strides to help dogs that suffer from heart disease.

Mark Oyama, D.V.M., DACVIM-Cardiology, associate professor at the University of Pennsylvania School of Veterinary Medicine, hopes to discover a way to decrease risk of mitral valve disease in small breeds, particularly Cavalier King Charles Spaniels, through therapeutic treatment.

“When people develop mitral valve disease, it is treated surgically by replacing the mitral valve,” Oyama explains. “The tremendous expense of this surgery and its limited availability make it a prohibitive option in dogs.”

Mitral valve disease (MVD) is considered a hereditary condition in both dogs and humans, but in humans it can also be caused by certain drugs. Several years ago many people developed MVD after taking the infamous Fen-Phen combination diet pill. The pill caused an increase in activation of a neurotransmitter known as serotonin.

Recent studies in dogs have shown that dogs with MVD have more serotonin in their mitral valve cells than dogs without disease. Higher levels of serotonin are associated with higher levels of glyco­sa­min­o­glycans, one of the pathological features of MVD.

Comparing the blood of small and large dogs with and without MVD, Oyama found high levels of serotonin in small dogs and dogs with MVD. Breeds noted for having a high frequency of MVD, such as Cavaliers, had even higher serotonin levels. The importance of this finding requires more study, and Oyama and co-investigators are evaluating a pharmaceutical that appears to successfully block activation of serotonin receptors in Cavalier King Charles Spaniels.

Meanwhile in other canine cardiology research, Oyama is investigating whether a blood test used in humans to diagnose heart failure and the grade of severity can also be used in dogs. “When dogs come into veterinary hospitals in respiratory distress, it’s sometimes difficult to know if they are having a respiratory or heart problem,” Oyama says. “Such a test could speed effective treatment and also help decide if a dog should be referred to a veterinary cardiologist before undergoing more expensive testing.”

The blood test measures levels of N-terminal pro B-type natriuretic peptide (NT-proBNP), which is produced by the heart when stressed or injured. The test is given to people suspected of heart failure when entering emergency rooms and is currently available to veterinarians with next-day results. Oyama hopes to determine whether NT-proBNP is an accurate diagnostic or prognostic tool in dogs, and if so, how it can be used with quicker results.

New ground was broken last year with discovery of the genetic mutation for a potentially fatal heart disease common in Boxers, arrhythmogenic right ventricular cardiomyopathy (ARVC). The discovery by researchers at Washington State University School of Veterinary Medicine means that breeders can now have their dogs’ DNA tested for the autosomal dominant disease.

Boxers with ARVC often die suddenly due to ventricular arrhythmia, or abnormal heartbeats, without any sign of heart disease. In rare cases, affected dogs experience a gradual decline in heart function that results from congestive heart failure. The research was supported by the AKC Canine Health Founda­tion and the American Boxer Charitable Foundation. For information about DNA testing, visit http://www.ncstatevets.org/genetics/submitdna/ (the researcher who made this discovery has since relocated her lab to NCSU).

This article originally appeared in Today's Breeder, a Nestlé Purina Publication Dedicated to the Needs of Canine Enthusiasts.