Genetic Welfare Problems of Companion Animals

An information resource for prospective pet owners

Cavalier King Charles Spaniel

Cavalier King Charles Spaniel (CKCS)

Mitral Valve Disease (MVD)

Related terms: myxomatous mitral valve degeneration (MMVD), mitral valve disease (MVD), degenerative valve disease (DVD), degenerative mitral valve disease (DMVD), endocardiosis, mitral regurgitation (MR), chronic valve (valvular) disease, chronic mitral valve disease, valvular insufficiency, acquired mitral regurgitation, chronic valvular degeneration, chronic valvular fibrosis

Outline: Mitral valve disease is a serious, progressive disease of the heart, caused by the deterioration of one of its valves. It is the most common heart disease of adult dogs and is about twenty times more prevalent in the Cavalier King Charles spaniel than other breeds. Most show some signs of the disease by 10 years of age. It has a serious impact on welfare, causing respiratory and other difficulties, with severe discomfort due to breathlessness and coughing. Unless animals are euthanased, the disease causes death by chronic heart failure.


Summary of Information

(for more information click on the links below)

1. Brief description

Mitral valve disease is a disease of the heart, caused by the deterioration of one of its valves. It is a very common disease in Cavalier King Charles spaniels. Because of the damage to the valve, with each heart beat some blood is forced backwards from one chamber into another rather than out of the heart. (This is called mitral regurgitation [MR]).

One effect of this backflow of blood is that the heart enlarges and that this can then interfere with breathing and cause the dog to cough. At the same time, as less oxygenated blood is being pumped around the body, any exertion can result in the dog panting heavily and struggling for breath. As the disease progresses the lungs become increasingly fluid filled resulting in further breathlessness and coughing. Affected dogs may be reluctant to sit or lie down, because of the extra pressure this puts on the chest, and may also show appetite and related weight loss (Prošek 2007). They may faint at exercise. Most dogs die or are euthanased when the disease has progressed to this stage.

Dogs with mitral valve disease, but without heart failure, appear normal to their owners and do not have any welfare problems at that time, although they generally have a detectable heart murmur on auscultation (listening with a stethoscope). Most develop heart failure within several years of the onset of mitral valve disease (Häggström et al 2009).

Surgical repair of the valves is rarely a feasible option. Combination drug therapy can usually help to control the early stages of heart failure but the prognosis is guarded (French 2005). Most dogs die less than two years after the onset of heart failure (Kittleson and Kienle 1998).

2. Intensity of welfare impact

Mitral valve disease has a serious impact on the welfare of affected dogs as a result of respiratory and other difficulties. The progressive heart failure causes discomfort associated with breathlessness and coughing. Unless animals are euthanased, they are likely to die of chronic heart failure.

3. Duration of welfare impact

Mitral valve disease is progressive. Treatment is usually aimed at relief of the symptoms rather than cure. Häggström (2004a) suggested that mitral regurgitation can be detected in male Cavalier King Charles spaniels from three to four years of age and in females from four to five years of age using ultrasound and/or a stethoscope. The period from when heart failure begins to develop and animals first show adverse welfare signs (eg coughing breathlessness) to death or euthanasia can be years.

4.  Number of animals affected

Mitral valve disease is about twenty times more prevalent in the Cavalier King Charles spaniel (CKCS) than other breeds of dog. The number of CKCS with heart murmurs characteristic of mitral valve disease increases at a rate of about 10% each year so that by five years of age 50% have a murmur (Swift 2009) and by ten years nearly all do.

From data on estimates of the total dog population in the UK and on the percentage of all micro-chip registered dogs that are Cavalier King Charles spaniels (Lucy Asher, 2011, personal communication), we estimate that the UK population size of this breed may be around 200,000.

5. Diagnosis

Initial diagnosis is by detection of a characteristic heart murmur with a stethoscope, and can be confirmed by ultrasound investigation. Other diagnostic tools may also be used to determine the severity of the disease and the presence of heart failure including ECG (electrocardiogram) recordings, chest radiography, blood tests and full physical examination.

6. Genetics

The genetic basis of the disease is under investigation (http://www.eurolupa.org/). There may be more than one gene involved. It has been estimated that about 70% of dogs bred from affected parents are likely to inherit the condition.

7. How do you know if an animal is a carrier or likely to become affected?

There is no genetic test yet. It has been suggested that the prevalence is such that it should be assumed that every Cavalier King Charles Spaniel that lives long enough will develop the condition (Smith 2006).

8. Methods and prospects for elimination of the problem

The genes involved with mitral valve disease have not been determined. The apparently very high prevalence of the disease presents a major challenge for breeding schemes aimed at eliminating the problem. Efforts are underway to determine how best to reduce the incidence of the disease (Häggström 2004a).

This has resulted in the publication of guidelines for breeders and the setting up of health registers where the cardiac health of (potential) stud dogs can be checked.

As with other polygenetic diseases, it has been suggested that animals used for breeding should be those from lines with a better than average “breeding value”, ie from lines with low incidence of the disease. A scheme to try to develop a breeding strategy is being developed in the UK by the British Veterinary Association and the Kennel Club

Some may consider that perpetuating a breed in which the welfare of a high proportion is likely to be at risk is not justifiable. Outcrossing with other breeds may be a way forward.


For further details about this condition, please click on the following:
(these link to items down this page)


1. Clinical and pathological effects

Mitral valve disease is the most common heart disease of adult dogs (Häggström 2004a). When functioning normally, the mitral valve prevents blood flowing from the high-pressure left ventricle – which is the chamber of the heart which pumps blood around the body – back into the smaller left atrium, which receives blood from the lungs. As the valve degenerates, it becomes thicker and less flexible and cannot close fully. As a result, some blood is forced backwards from the ventricle into the atrium during contractions. As the disease progresses and the valve becomes increasingly distorted more and more blood gets forced backwards into the atrium during each contraction and consequently less and less blood is pumped out, around the body (this process is known as mitral regurgitation (MR) (Rishniw 2005)).

The backward flow of blood causes a heart murmur, - a change to the normal ‘lubb-dupp’ heart sound. This is often the first sign of the condition (detectable using a stethoscope). In the final stages of the disease, the tendons supporting the valve snap and the valve fails completely (www.cavalierhealth.org, Corcoran 2009, Häggström 2004a), causing heart failure and death.

It is the effect that this valve failure has on the normal functioning of the heart that causes the problems. One effect of the backflow of blood under high pressure into the left atrium is compensatory enlargement of the atrium. In time, the enlarged heart can begin to interfere with breathing, through increasing pressure on the windpipe, causing coughing. Because the pumping of oxygenated blood around the body is compromised, the heart has to pump harder and faster and any exertion can result in the dog panting heavily and struggling for breath (Merck 2009). Circulation to other parts of the body is weakened as blood flow to the vital organs, such as the brain and lungs, is conserved. Also, because of the higher pressure in the atrium because of the back flow, blood flow from the lungs into the heart is compromised and fluid leaks from the blood vessels of the lungs into the chest and lungs themselves, resulting in further breathlessness and coughing – which in severe chronic heart failure may include coughing up blood-tinged sputum. These signs often imminently precede death (Rishniw 2005).

Affected dogs may be reluctant to sit or lie down, because of the extra pressure this puts on the chest cavity, and may hold their elbows away from their body in an attempt to reduce this (www.cavalierhealth.org). Affected dogs may also show appetite and related weight loss and have a distended abdomen (Häggström 2004a, Prošek 2007).They may even faint on exercise.

Dogs with mitral valve disease, but without heart failure, appear normal to their owners and do not have any welfare problems Most dogs go on to develop heart failure within several years of the onset of mitral valve disease (Häggström et al 2009).

Other signs of heart disease (before it becomes apparent due to heart failure) can be detected using more sophisticated equipment. Radiographs (x-rays) of the chest may show evidence of heart enlargement and other signs of heart failure.

Some individuals may have irregular heartbeats – arrhythmias which can be detected by electrocardiography (ECG) or using a stethoscope.

The most powerful tool for examining the heart is ultrasonography. This enables measurement of the thickness of the heart muscle, the size of each chamber, and the position, shape and movement of each valve. With colour-flow ultrasonography it is also possible to measure the speed and direction of blood flow in the heart and the great vessels. This will show mitral regurgitation.

Many dog breeds are susceptible to mitral valve disease, especially small dog breeds such as Cocker spaniels, Toy and Miniature poodles, Papillons, Chihuahuas, Dachshunds, Miniature schnauzers, Shih tzus and Lhasa apsos (French 2005; Rishniw 2005; Lundin and Kvart 2010). Cavalier King Charles spaniels differ from other breeds in that they develop the disease at a younger age. Typically, in other breeds, mitral regurgitation is diagnosed from six to seven years of age onwards whereas in Cavalier King Charles spaniels it is diagnosed at from three to four years of age in males and at from four to five years of age in females (Häggström 2004b).

Surgical treatment of mitral valve disease is unlikely to be practically or economically feasible (Griffiths et al 2004; Orton 2004; Orton et al 2005; Williams et al 2008; Borgarelli and Häggström 2010). A combination drug therapy protocol, including diuretics, ACE inhibitors, inodilators such as pimobendan, and others depending on the specific individual’s needs and stage of disease, is commonly used to control heart failure (Häggström et al 2009; Borgarelli and Häggström 2010). However, drugs therapy, at best only works for a time (Gordon 2004; Häggström et al 2009).

Once the degenerative process associated with mitral valve disease begins, it is unstoppable and worsens with time. The process from asymptomatic heart murmurs to valve failure may take several years ((Häggström et al 2009; Corcoran 2009). A life-threatening stage may be reached within 1-3 years of diagnosis (Kittleson and Kienle 1998). Once severe congestive heart failure has developed, survival has been found to average about seven months, with 75% mortality within a year (French 2005).

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2. Intensity of welfare impact

Mitral valve disease has a serious impact on the welfare of affected dogs as a result of respiratory and other difficulties.

As the disease progresses (murmur graded 3-4), the condition starts to affect the dog’s ability to exercise, with the extra work required of the heart during exercise resulting in respiratory distress, seen as rapid breathing and breathlessness, even after exercise has ceased. Humans who experience such breathlessness report that it is very unpleasant and talk about feelings of suffocation and nausea and it is likely that the dog experiences it similarly. Further progression of the disease, as fluid begins to accumulate in the lungs, results in increasing dry, hacking coughing and persistent laboured breathing, even during rest. This is most common when the dog is lying down. Dogs may feel generally tired or fatigued.

Towards the latter stages of the disease, with the heart failing, the dog may faint, collapse and/or show signs of general weakness. Exercise tolerance becomes extremely limited and exercise may cause great distress. Breathing difficulty is becomes constant and animals and may be reluctant to lie down because extra pressure on the chest causes increased difficulty with breathing. Affected dogs may remain standing until the point of collapse (www.cavalierhealth.org). Kidney and/or liver function becomes seriously impaired and there fluid congestion occurs in the heart, lungs, and abdominal cavity. All of effects seriously add to the impact on the animal’s welfare. At or before this stage, euthanasia is generally recommended.

The progressive heart failure causes discomfort associated with breathlessness and coughing. Unless animals are euthanased, they are likely to die of chronic heart failure.

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3. Duration of welfare impact

Mitral valve disease is a progressive disease.  During the early stages, when murmurs are at their weakest (graded 1 or 2), the condition has relatively little impact on welfare (Merck 2009). A life-threatening stage may be reached within 1-3 years of diagnosis (Kittleson and Kienle 1998). Once severe congestive heart failure has developed, survival has been found to average about seven months, with 75% mortality within a year (French 2005). In these late stages the adverse welfare effects become constant rather than episodic.

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4. Number of animals affected

Mitral valve disease is the single most common heart disease of dogs and is the main cause of death in Cavalier King Charles spaniels, accounting for 42.8% of deaths (KC and BSAVA 2008, Corcoran 2009). It accounts for 25% of all illness in this breed (Evans 2008). Mitral valve disease is about twenty times more prevalent in the Cavalier than other breeds of dog, and the onset of the disease is typically earlier and its progression swifter (www.cavalierhealth.org). Studies in the UK and the USA have shown that the percentage of CKCSs which develop heart murmurs characteristic of mitral valve disease increases at a rate of about 10% with each year of age. Thus, about half of all Cavaliers have a murmur by the time they are 5 years old. (Swift 2009) and by 10 years nearly all surviving Cavaliers have, at least, a low grade murmur (www.cavalierhealth.org).

If this figure is representative of the prevalence around the world then this would suggest that, worldwide, hundreds of thousands of these dogs are affected by this condition.

From data on estimates of total dog population in the UK and on the percentage of all micro-chip registered dogs that are Cavalier King Charles spaniels (Lucy Asher, 2011, personal communication), we estimate that the UK population size of this breed may be around 200,000.

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5. Diagnosis

It is recommended that all Cavaliers should be screened for heart murmurs once a year from when they are aged one. Initial diagnosis is by stethoscope. Murmurs are categorised on a six point scale from Grade 1, the mildest and least audible, which can be heard with a stethoscope only in a quiet room, to Grade 6, the loudest and most turbulent, which can be heard with the stethoscope not touching the chest, or even without using the stethoscope. The loudness of the murmur is thought to increase with the severity of the valve leak. If a murmur is detected, then confirmation through further stethoscopic examination or, more definitively, using ultrasound examination is recommended; this should occur within 3-6 months from first detection of a murmur. Using ultrasound, heart size, function including the direction and speed of blood flow, and valve appearance can be evaluated. Other diagnostic tools used to determine the severity of the disease and the presence of heart failure, include: ECG recordings, blood tests, chest radiography and full physical examination.

Current research is aimed at earlier diagnosis of mitral valve disease before the development of a heart murmur. Such research seeks to measure concentrations of circulating hormones -natriuretic peptides- secreted by areas of the heart that regulate the excretion of sodium in the urine. Elevated blood levels of these natriuretic peptides are found in dogs with heart problems and when the heart is having to work harder, eg because of mitral valve leakage. (MacDonald et al 2003). However, whilst testing for these peptides is non-invasive, it remains to be shown that their measurement offers a means of diagnosing mitral valve disease significantly sooner than by listening for a heart murmur.

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6. Genetics

Studies of the patterns of incidence of mitral valve disease in Cavaliers have concluded that it has an hereditary basis and the indications are that it is caused by more than one gene (ie it is polygenetic) (Swenson et al 1996; Häggström 2004a, b). The heritability of cardiac murmur in Cavaliers has been estimated to be 0.64 (0.07) meaning that most of the variation in severity of mitral valve prolapse in UK Cavaliers is genetic in origin (Lewis, Woolliams and Blott 2010b). The implication is that affected animals are highly likely to pass the condition on to their offspring and animals without the condition are more likely to produce young free from the condition.

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7. How do you know if an animal is a carrier or likely to become affected?

There is no genetic test for detection of animals which carry genes causing mitral valve disease. It has been suggested that the prevalence is such that it should be assumed that every Cavalier King Charles Spaniel that lives long enough will develop the condition (Smith 2006).

Choosing a dog born to older parents (5 years plus) which have not themselves developed mitral valve disease has been advocated (Swenson et al 1996; Häggström 2004a)

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8.  Methods and prospects for elimination of the problem

The genes involved with mitral valve disease have not been determined. The apparently very high prevalence of the disease presents a major challenge for breeding schemes aimed at eliminating the problem. Efforts are underway to determine how best to reduce the incidence of the disease (Häggström 2004a).

 The American College of Veterinary Internal Medicine’s (ACVIM) Registry of Cardiac Health (ARCH) specifies that:

  • Every breeding CKCS should be examined annually by a specialist veterinary cardiologist
  • Any CKCS diagnosed with a murmur under the age of five years should not be used for breeding.
  • No CKCS should be used for breeding before the age of two and half years of age.
  • No CKCS should be used for breeding under the age of 5 years, unless its parents were free of a murmur at five years of age. (http://cavalierhealth.org/mvdprotocol.htm)

Although this scheme has been recommended by veterinary cardiologists and the breed club for a number of years, it has been reported that the majority of Cavalier King Charles spaniel breeders have not adopted it (http://cavalierhealth.org/mvdprotocol.htm).

The guidelines of the Cavalier King Charles Spaniel Club of the UK are similar. These specify, as a minimum, that any animal to be used for breeding should preferably be at least 2½ years old (for stud dogs) and a minimum of 2½ years old (for brood bitches) with a clear heart, and with parents with clear heart certificates issued at 5 years of age or older – a list of which dogs appears on their website (www.cavalierclub.co.uk). However, it is also strongly advised that clear heart certificates should be a requirement for any dog or bitch used for breeding.  It is also recommended that it is highly desirable to use older stud dogs with clear certificates issued as late in life as possible (in pursuit of raising the age of onset of mitral valve disease). Finally it is recommended that any dog to be used for breeding should be checked annually for good health.

Buyers should ask breeders whether the parents have any signs of mitral valve disease and how old they are.

The Kennel Club of Great Britain has decided to co-opt the breeding scheme into the British Veterinary Association/Kennel Club Health scheme and accredited breeders’ scheme which will hopefully strengthen its uptake and effectiveness (Swift 2009)

In Sweden, the current breeding protocol, introduced in 2001, is slightly less restrictive. It recommends that dogs should be over 4 years of age before use for breeding and have had a clear auscultation within eight months of commencement of breeding. Dogs can be used for breeding from 24 months if they themselves and their parents are free of heart disease. Dogs which have a heart murmur or whose parents do before four years of age are not allowed to be used for breeding. Under this scheme, male stud dogs free of a heart murmur at seven years of age do not need heart re-evaluation (Lundin and Kvart 2010). The results of Lundin and Kvart’s (2010) research suggested that this protocol has not brought about significant change in the prevalence of heart murmurs in six year old Cavaliers in Sweden.

Despite this finding, Rishniw (2005) suggests selective breeding has reduced the incidence and severity of disease. Lewis et al (2010a, 2010b) suggested that because of the high heritability of mitral valve disease, selective breeding programmes should be successful.

Mitral valve disease is not the only genetic disease that has a significant welfare impact in this breed, Syringomyelia also causes severe problems. Because of this, an approach is being developed in the UK to take both diseases into account when pairing animals from breeding This scheme, that will run alongside disease monitoring programmes, involves the estimation of breeding values (EBV) for each disease for each breeding animal (Lewis et al 2010b). The EBV is a “numerical prediction of the relative genetic value of a particular dog” or a genetic risk of disease eg for MMVD and syringomyelia (http://www.cavalierhealth.org/estimated_breeding_values.htm). The EBV of individual can be compared to the population mean in selecting animals for breeding. For these schemes to work many breeders and owners need to submit their animals for monitoring and analysis. Lewis et al (2010a) have suggested that the population structure of CKCS in the UK provides sufficient scope for this method to be used and that it is feasible to develop these methods. This method has proven success in tackling genetic problems in other species and breeds e.g. the reduction of epilepsy in the Belgian Tervuren (Oberbauer 2005), but it may take many generations.

Research is currently underway (for example at the Universities of Minnesota, Missouri and Davis in the USA; the University of Toronto in Canada, and at The Animal Health Trust in England) to improve understanding of the genetic basis of mitral valve disease in various breeds. This is the LUPA project (http://www.eurolupa.org/).  The development of genetic tests to help identify the genes involved in the condition may help to eliminate this condition in the future.

Some may consider that perpetuating a breed in which the welfare of a high proportion is likely to be at riskis not justifiable. Outcrossing with other breeds may be a way forward.

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9. Acknowledgements

UFAW is grateful to Rosie Godfrey BVetMed MRCVS and David Godfrey BvetMed FRCVS for their work in compiling this section.

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10. References

ACVIM ARCH http://www.careanimalfoundation.org/vision/studies/certify_cardiac/website/arch.html

Borgarelli M and Häggström J (2010) Canine degenerative myxomatous mitral valve disease: natural history, clinical presentation and therapy. Veterinary Clinics of North American Small Animal Practice 40: 651-63

CAWC (2008) Fixing ancestral problems: Genetics and welfare in companion animals focusing on syringomyelia in Cavalier King Charles Spaniels as an example. Report of the Companion Animal Welfare Council Workshop Tuesday 29th April 2008, House of Lords

Cochron BM (2009) Understanding mitral valve disease. http://www.thecavalierclub.co.uk/health/hearts/reports/MVD_Report_Mar_09.pdf

Evans K (2008) Kennel Gazette April 2008 htttp://www.cavalierhealth.co.uk/kcgazettearticle.htm

French A (2005)Mitral Valve disease in the Cavalier King Charles Spaniel. http://www.thecavalierclub.co.uk/health/hearts/french.html.

Griffiths LG, Orton EC and Boon JA (2004) Evaluation of techniques and outcomes of mitral valve repair in dogs. Journal of the American Veterinary Medical Association 224: 1941-1945

Gordon S (2004) Chronic Valvular Disease: Pharmacotherapy, Current and Future Directions. 1st International Canine Valvular Disease Symposium, Paris, October 30-31, 2004. Available from VIN Associate

Häggström J (2004a) Aetiology and Pathophysiology of Myxomatous Mitral Valve Disease in Dogs. World Small Animal Association Conference Proceedings 4-6th Oct 2004, Rhodes, Greece. Available from VIN Associate

Häggström J (2004b) Is the Cavalier King Charles Spaniel a Useful Model for Myxomatous Mitral Valve Disease in Other Dogs? 1st International Canine Valvular Disease Symposium, Paris, October 30-31, 2004. Available from VIN associate

Häggström J, Boswood A, O'Grady M, Jöns O, Smith S, Swift S, Borgarelli M, Gavaghan B, Kresken JG, Patteson M, Ablad B, Bussadori CM, Glaus T, Kovacevic A, Rapp M, Santilli RA, Tidholm A, Eriksson A, Belanger MC, Deinert M, Little CJ, Kvart C, French A, Rønn-Landbo M, Wess G, Eggertsdottir AV, O'Sullivan ML, Schneider M, Lombard CW, Dukes-McEwan J, Willis R, Louvet A and 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

Häggström J, Höglund K and Borgarelli M (2009) An update on treatment and prognostic indicators in canine myxomatous mitral valve disease. Journal of Small Animal Practice 50: (S) 1: 25-33

Häggström J, Pedersen HD and C Kvart (2004) New insights into degenerative mitral valve disease in dogs Veterinary Clinics of North America: Small Animal Practice 3: 1209-1226

KC and BSAVA, Anon Report from the Kennel Club/British Small Animal Veterinary Association Scientific Committee Summary results of the Purebred Dog Health Survey for Cavalier King Charles Spaniels http://www.thekennelclub.org.uk/download/1533/hscavalierkingcharlesspaniel.pdf

Kittleson M and Kienle R (1998) Myxomatous atrioventricular valve degeneration. In: Kittleson M and Kienle R. Small Animal Cardiovascular Medicine. 1st edition. pp 297-318. Mosby: St Louis, USA

Lewis T, Swift S, Woolliams J and Blott S (2010a) Heritability of premature mitral valve disease in Cavalier King Charles spaniels. The Veterinary Journal, currently in press

Lewis T, Woolliams J and Blott S (2010b) Optimisation of breeding strategies to reduce the prevalence of inherited disease in pedigree dogs. Animal Welfare 19 (S): 93-98

Lundin T and Kvart C (2010) Evaluation of the Swedish breeding program for cavalier King Charles spaniels. Acta Veterinaria Scandinavica 52: 54

MaccDonald KA, Kittleson MD, Munro C and Kass P (2003) Brain Natriuretic Peptide Concentration in Dogs with Heart Disease and Congestive Heart Failure. J Vet Intern Med 17(2):172–177

Merck (2009) Degenerative Valve Disease. http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/11213.htm

Moonarmart W, Boswood A, Luis Fuentes V, Brodbelt D, Souttar K and Elliott J (2010) N-terminal pro B-type natriuretic peptide and left ventricular diameter independently predict mortality in dogs with mitral valve disease.Journal of Small Animal Practice 51: 84–96

Oberbauer A (2005) Strategies for Identifying and Managing Complex Genetic Disorders. Tufts’ Canine and Feline Breeding and Genetics Conference 30th Sept – 1st Oct 2005, Sturbridge, MA, USA. Available from VIN Associate.

Orton EC (2004) Mitral Valve Surgery: Current Veterinary Practice. 1st International Canine Valvular Disease Symposium Paris, October 30-31, 2004. Available from VIN Associate

Orton EC, Hackett TB, Mama K and Boon JA (2005) Technique and outcome of mitral valve replacement in dogs. Journal of the American Veterinary Medical Association 226: 1508-1511

Prošek R (2007) Degenerative Valve Disease. Client leaflet. Available from VIN Associate. http://www.vin.com/Members/SearchDB/vp/vpa02515.htm. accessed 28.2.11.

Rishniw M (2005) Myxomatous Mitral Valve Degeneration (MMVD). Available from VIN Associate. Accessed 28.2.11

Rishniw M (2009) Syncope With Mitral Valve Disease. Medical FAQS. VIN Associate. Accessed 28.2.11

Smith P (2006) Management of chronic degenerative mitral valve disease in dogs In Practice 28: 376-383

Swenson L, Häggström J, Kvart C and Juneja K (1996) Relationship between parental cardiac status in Cavalier King Charles Spaniels and prevalence and severity of chronic valvular disease in offspring. Journal of  American Veterinary Medical Association 208: 2009-2012

Swift S (2009) Cavaliers King Charles Spaniels and Heart Disease: Where have we been and where are we going?. http://www.thecavalierclub.co.uk/health/hearts/reports/swift_09.html. accessed 2.3.11

Williams JL, Toyoda Y, Ota T, Gutkin D, Katz W, Zenati M and Schwartzman D (2008) Feasibility of Myxomatous Mitral Valve Repair Using Direct Leaflet and Chordal Radiofrequency Ablation. Journal of Internal Cardiology 21: 547–554

http://www.cavalierhealth.org

http://www.eurolupa.org

http://www.thecavalierclub.co.uk

© UFAW 2011


Credit for main photo above:

By Philippe Brizard (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons