Arrythmogenic Right Ventricular Cardiomyopathy
What is Arrythmogenic Right Ventricular Cardiomyopathy of dogs?
Arrythmogenic Right Ventricular Cardiomyopathy (ARVC) is a disease of the heart muscle that typically starts to show symptoms when the dog is an adult (around 6 years of age). The progression of the disease can occur very quickly in an affected dog and in some cases an affected dog can go from apparently healthy to having what looks like a heart attack in a matter of hours. Symptoms vary from fainting, heart failure or sudden death between individuals. This is an inherited disease that we now have DNA testing for to reduce the incidence of this condition in the dog population. Arrythmogenic Right Ventricular Cardiomyopathy (ARVC) is also known as “Boxer Cardiomyopathy” due to it’s very high incidence in the Boxer dog breed.
Genetics of Arrythmogenic Right Ventricular Cardiomyopathy in dogs
Arrythmogenic Right Ventricular Cardiomyopathy (ARVC) is thought to be inherited via an autosomal recessive pattern meaning that 2 faulty copies of the gene responsible (1 from each parent) need to be present in an individual dog for the dog to affected by the disease. Even when there are 2 copies of the faulty gene present, the disease has incomplete penetrance so there is variation in the population of dogs in terms of how many dogs show the symptoms of the disease even though they are genetically affected.
What is the severity of Arrythmogenic Right Ventricular Cardiomyopathy?
The severity of Arrythmogenic Right Ventricular Cardiomyopathy is high as many dogs will have a shortened life, while some may have morbidity and a loss of vigour for the remainder of their lives after the onset of symptoms.
What are the symptoms of Arrythmogenic Right Ventricular Cardiomyopathy in dogs?
Due to the incomplete penetrance of the condition, Arrythmogenic Right Ventricular Cardiomyopathy has a very variable set of symptoms. Being a disease that weakens the heart and its ability to pump blood, symptoms such as fainting, weakness, lethargy to sudden death are often seen. Over a longer period of less blood pumping volume, the dog may develop congestive heart failure.
Diagnosis of Arrythmogenic Right Ventricular Cardiomyopathy
Depending on the stage that symptoms are expressed by the individual dog, diagnosis of Arrythmogenic Right Ventricular Cardiomyopathy may be too late to help the affected dog. Aside from DNA disease testing, a Holter monitor (mobile ECG monitor) is a small device that is the size of a deck of cards placed on the dog to monitor the dog’s heart is used. Holter monitors are effective in detecting the irregular ECG of an affected dog even before the dog shows any outward symptoms.
Treatment of dogs with Arrythmogenic Right Ventricular Cardiomyopathy
A number of treatments for Arrythmogenic Right Ventricular Cardiomyopathy have been tried with varying degrees of success but the most common and effective treatment at this stage is the use of oral anti-arrhythmic drugs to treat the arrhythmia. Another method that would in theory would be able to help and has been effective in human cases of Arrythmogenic Right Ventricular Cardiomyopathy, is the implantation of a cardioverter-defibrillator. Unfortunately, these devices have not been successful in dogs at this stage, but future research may develop better devices more suitable for dogs. Supplementing an affected dog’s diet with omega-3 fatty acids has been tried in addition to conventional drug therapy with anecdotal success, and the lack of side effects makes it a recommended addition to the treatment options by many canine cardiologists.
Prognosis for dogs with Arrythmogenic Right Ventricular Cardiomyopathy
Prognosis is variable for dogs with Arrythmogenic Right Ventricular Cardiomyopathy as it depends on the stage of the disease as well as the individual dog affected.It is generally agreed that affected dogs showing symptoms of the disease will have a reduced lifespan and quality of life. DNA disease testing of breeding dogs will help to reduce the incidence of dogs inheriting this condition.
Basso C, Fox PR, Meurs KM, Towbin JA, Spier AW, Calabrese F, Maron BJ, Thiene G. Arrhythmogenic right ventricular cardiomyopathy causing sudden cardiac death in boxer dogs: a new animal model of human disease. Circulation, 2004; 109:1180-5.
Baumwart RD, Meurs KM, Atkins CE, Bonagura JD, DeFrancesco TC, Keene BW, Koplitz S, Luis Fuentes V, Miller MW, Rausch W and Spier AW (2005) Abnormalities in Boxers with cardiomyopathy and left ventricular systolic dysfunction: 48 cases (1985–2003) Clinical, echocardiographic, and electrocardiographic. Journal of the American Veterinary Medical Association 226: 1102-1104
Baumwart RD, Meurs KM, Raman SV. Magnetic resonance imaging of right ventricular morphology and function in boxer dogs with arrhythmogenic right ventricular cardiomyopathy. Journal of Veterinary Internal Medicine, 2009; 23:271-4.
Bell JS (2010) Genetic Testing and Genetic Counselling in Pet and Breeding Dogs. World Small Animal Veterinary Association World Congress Proceedings
Buse C, Altmann F, Amann B, Hauck SM, Poulsen Nautrup C, Ueffing M, Stangassinger M andDeeg CA (2008) Discovering novel targets for autoantibodies in dilated cardiomyopathy.Electrophoresis 29: 1325–1332
Calvert CA and Meurs KM (2000) CVT update: Doberman pinscher occult cardiomyopathy. In: Bonagura JD ed. Kirk’s Current Veterinary Therapy XIII pp756 W.B. Saunders: Philadelphia.
Harpster N (1991) Boxer cardiomyopathy. Veterinary Clinics of North America Small Animal Practice 21: 989
Kittleson MD, Kienle RD. Arrhythmogenic Right Ventricular Cardiomyopathy. In: Small Animal Cardiovascular Medicine. St Louis, MO:Mosby; 1998.
Lynne Nelson, Sunshine Lahmers, Terri Schneider, and Pam Thompson. The Use of an Implantable Cardioverter Defibrillator in a Boxer to Control Clinical Signs of Arrhythmogenic Right Ventricular Cardiomyopathy J Vet Intern Med 2006;20:1232–1237
Martin MWS, Stafford Johnson MJ, Strehlau G and King JN (2010) Canine dilated cardiomyopathy: a retrospective study of prognostic findings in 367 clinical cases. Journal of Small Animal Practice 51: 428–436
Meurs KM and Spier AW (2009) Cardiomyopathy in Boxer dogs. In: Bonagura JD and TwedtDC (eds) Kirk’s Current Veterinary Therapy XIV pp797 W.B. Saunders: Philadelphia
Meurs KM, Spier AW, Wright NA and Hamlin RL (2001a) Use of ambulatory electrocardiography for detection of ventricular premature complexes in healthy dogs. Journal of the American Veterinary Medical Association 218: 1291–1292
Meurs, K.M et al;Genome-wide association identifies a deletion in the 30 untranslated region of Striatin in a canine model of arrhythmogenic right ventricular cardiomyopathy. Hum Genet (2010) 128:315–324
Roden, DM., Mechanism and management of proarrhythmia. Am J Cardiol 20 August 1998;82(4A):49I-57I.
Scansen BA, Meurs KM, Spier AW, Koplitz S, Baumwart RD. Temporal variability of ventricular arrhythmias in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy. Journal of Veterinary Internal Medicine, 2009; 23:1020-4.
Spier AW, Meurs KM. Assessment of heart rate variability in Boxers with arrhythmogenic right ventricular cardiomyopathy. Journal of the American Veterinary Medical Association, 2004; 224:534-7.