EDITORIAL

Chronic degenerative valvular disease – where are we now? Chronic degenerative valvular disease (CDVD) is the most common acquired heart disease in dogs - accounting for approximately 75% of all cases of congestive heart failure in dogs (Sisson and others 1999).In the last few decades, there have been great therapeutic advances in veterinary cardiology, with the development of multiple new therapies: ACE inhibitors, Spirono lactone and Pimobendan to name but a few.These advances have coincided with an increasing recognition of the importance of evidence based medicine. Cardiology is one of the few disciplines where evidence based medicine has flourished. Well funded and expertly designed prospective clinical trials have resulted in good clinical data, which has changed our approach to many diseases. In addition this data has led to better understanding of common cardiac diseases, the best example of which is canine CDVD. In this disease, our understanding of the pathophysiology, disease course and treatment has increased greatly over the last decade. We are now able to advise owners when to treat, how to treat and can also give a fairly accurate prognosis in most cases. Knowledge is a process of piling up facts; wisdom lies in their simplification. Martin H. Fischer This supplement on CDVD is designed for the general practitioner - although we hope it will have something of interest for everyone involved in small animal veterinary medicine. The current barrage of conflicting advice presented to general practitioners can make it hard to choose the most appropriate care for your patients.We have tried to collate all the new information from the last decade in a clear and concise way and to provide useful conclusions from the latest published research. We have been honoured by the involvement of world class leaders in this field who together have produced a comprehensive review of this common clinical condition. It is the advancement of our understanding of the complex neuroendocrine nature of the heart and our (albeit as yet) crude understanding of how this is altered in CDVD that has led to many of the advances in treatment (Oyama, 2009).Despite our increasing knowledge some areas of controversy remain. Not least of these is the naming of the disease which is also known as chronic canine mitral valve disease, myxomatous mitral valve disease and valvular endocardiosis. One area of particular controversy in the management of canine chronic degenerative valvular disease is the treatment of asymptomatic dogs. Two large double blinded placebo controlled trials have failed to show a statistically significant clinical benefit (Kvart and others 2002, Atkins and others 2007). Owners naturally feel frustrated when their pet is diagnosed with a degenerative disease that is very likely to progress in severity, and for which there is no medical treatment with proven significant benefit in the early stages.However they can be reassured that this disease has a long asymptomatic phase, often many years

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(Kvart and others 2002, Borgarelli and others 2008, Häggström and others 2009 ). Many owners need to be reassured that close monitoring is the best clinical option during this time period. Once dogs have progressed into congestive heart failure (CHF), many types of medication have been shown to influence outcome (Häggström and others 2009).Diagnosis of CHF in these cases should be made on the basis of history, typical loud left apical heart murmur, appropriate clinical signs and changes on thoracic radiographs. The classical triad of left sided congestive heart failure; cardiomegaly, pulmonary venous distension and a pulmonary infiltrate are not always as obvious as one would expect.An accurate diagnosis becomes dependant on many variables including operator experience (Hansson and others 2009). Echocardiography is a useful tool to confirm a diagnosis of canine CDVD and has revolutionised our ability to assess the severity of the lesions, cardiac remodelling and cardiac function. However, the presence of severe mitral regurgitation leads to challenges when assessing systolic and diastolic function (Bonagura and Schober 2009).It is only with the increasing availability of this modality in practice that our knowledge base has increased. Pulmonary hypertension is a relatively common complication of canine CDVD that was rarely considered twenty years ago. Pulmonary hypertension is a difficult diagnosis to reach without Doppler echocardiography since many of the clinical signs are similar to those of left sided congestive heart failure ie cough, exercise intolerance, breathlessness (Stepien 2009).It is only the increasing availability of Doppler echocardiography that has resulted in this complication being more commonly diagnosed and recognised. One study showed 31% of dogs with CDVD had pulmonary arterial pulmonary hypertension (Borgarelli and others 2004). Dr Stepien’s review of pulmonary hypertension as a complication of chronic left sided dysfunction in this supplement provides good practical advice on diagnosis and treatment Currently CDVD is medically managed in veterinary medicine. In human medicine this ‘mechanical problem’ is treated with a mechanical solution.At present open heart surgery is not financially feasible in veterinary medicine but this may change. In the meantime the veterinary profession should be proud of its innovative approaches and constant striving towards best clinical practice for its patients given the limitation of resources we have. I hope that this supplement becomes a useful reference aid to all those with an interest in cardiology and brings clinical based medicine to the forefront in general practice.As we celebrate 40 years since the first man on the moon, this supplement is a celebration of the steps that have been made in our understanding of canine CDVD during the last 40 years.I look forward to the next 40 years when I am sure we will make further giant leaps in the world of Veterinary Cardiology.

© 2009 British Small Animal Veterinary Association

Rachel James Supplement guest editor

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Editorial

Rachel graduated from Cambridge in 1999. She spent 4 years in general practice during which time she gained her RCVS Certificate in Small Animal Internal Medicine. She then undertook a residency in Veterinary Cardiology at the University of Liverpool, where she gained the RCVS Diploma in Veterinary Cardiology. Following a period in private referral practice at Nantwich Veterinary Hospital she is now an Associate Professor in Small Animal Medicine at Nottingham University. Her current interests include syncope, canine chronic degenerative valvular disease and cardiomyopathies. Conflicts of interest: Rachel James declares no conflicts of interest.

References ATKINS, C., KEENE, B., BROWN, W., COATS, J., CRAWFORD, M., DEFRANCESCO, T., EDWARDS, N., FOX, P., LEHMKUHL, L., LUETHY, M., MEURS, K., PETRIE, J., PIPERS, F., ROSENTHAL, S., SIDLEY, J., STRAUS, J. & AGOZZINO, L. (2007)Results of the veterinary enalapril trial to prove reduction in onset of heart failure in dogs chronically treated with enalapril alone for compensated, naturally occurring mitral valve insufficiency.Journal of the American Veterinary Medical Association 231 , 1061-1069

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BONAGURA, J. D. & SCHOBER K. E. (2009) Can ventricular function be assessed by echocardiography in chronic canine mitral valve disease? JSAP 50 (Suppl. 1), 12-22 BORGARELLI, M., ZEE, E., D’AGNOLD, G., TARDUCCI, A., SANTILLI, R. A., CHAVEGATO, D., TURSI, M., PRUNOTTO, M. & HÄGGSTRÖM, J. (2004) Comparison of primary mitral valve disease in German Shepherd dogs and in small breeds.Journal of Veterinary Cardiology 6, 27-34 HÄGGSTRÖM, J., HOGLUND, K. & BORGARELLI, M. (2009) An update on treatment and prognostic indicators in myxomatous mitral valve disease. JSAP 50 (Suppl. 1), 23-31 HÄGGSTRÖM, J., BOSWOOD, A., O’GRADY, M., JONS, O., SMITH, S., SWIFT, S., BORGARELLI, M., GAVAGHAN, B., KRESKEN, J., PATTESON, M., ABLAD, B., BUSSADORI, C., GLAUS, M., KOVACEVIC, A., RAPP, M., SANTILLI, R.A., TIDHOLM, A., ERIKSSON, A., BELANGER, M. C., DENERT, M., LITTLE, C., KVART, C., FRENCH, A., RONN-LANDRO, M., WESS, G., EGGERTSDOTTIR, A.V., O’SULLIVAN, M. L., SCHNEIDER, M., LOMBARD, C. W., DUKES-MCEWAN, J., WILLIS, R., LOUVET, A. & DIFRUSCIA, R. (2008) Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease: the Quest study.Journal of Veterinary Internal Medicine 22, 1124-1135 HANNSON, K., HÄGGSTRÖM, J., KVART, C. & LORD P. (2008)? Or 2009 Reader performance in radiographic diagnosis of signs of mitral regurgitation in cavalier King Charles spaniels. JSAP 50 (Suppl. 1), 42-51 OYAMA, M. A. (2009) Neurohormonal activation in canine degenerative mitral valve disease: implications on pathophysiology and treatment. JSAP 50 (Suppl. 1), 3-11 SISSON, C., KVART, C. & DARKE, P. G. G. (1999) Acquired Valvular Heart Disease in Dogs and Cats In: Fox, P. R., Sisson, D. D & Moise, N. S.eds.Textbook of Canine and Feline Cardiology:Principles and Clinical Practice, 2nd Edition.Philadelphia. PA: WB Saunders: 1999:536-580 STEPIEN, R. (2009) Pulmonary arterial hypertension secondary to chronic left-sided cardiac dysfunction in dogs. JSAP 50 (Suppl. 1) ,32-41

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