ARVC In Boxers

arrhythmogenic right ventricular cardiomyopathy

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What is ARVC?

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), also known as "Boxer Cardiomyopathy," is a heart disease found primarily in Boxer dogs. It is a disease of the main pumping chamber of the heart called the ventricle. In the case of ARVC, the normal muscle tissue is replaced by fibrous, fatty tissue which disrupts the electrical current of the heart and causes irregular heart beats.

The Evidence

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Above is a an ECG from a healthy dog. The beats are regularly spaced and have narrow complexes
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Above is an ECG from a dog with ARVC. When the electrical current of the heart gets disrupted from the fatty tissue. The beats start to look wide, complex, and irregular.
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The Genetics Behind it all

  • Strong evidence that ARVC in Boxers is of genetic influence
  • Genetic deletion in gene that produces striatin - though in a study from the UK 29% of dogs with ARVC did not have the gene mutation.
  • This gene is associated with proteins that hold cardiac muscle cells together and is autosomal dominant
  • Suspected to be an autosomal dominant genetic conditions with incomplete penetration
  • Suggested that this gene is more severe in homozygous individuals

Diagnosis

  • Best diagnostic tool is the Holter monitor. This devise records the dog's heartbeat for 24 to 96 hours
  • Testing for one of the genetic mutations thought to lead to ARVC has recently become available
  • No current tests are completely accurate, instead a veterinary cardiologist can asses how likely it is that a dog has ARVC.

Eradication Barriers

  • Often times the first sign of ARVC is sudden death
  • In humans with ARVC, there are 141 different mutations at 8 different genes, and this could be the case with boxers, though it is unknown at this time.
  • Though breeders can avoid breeding boxers that have the known gene mutation, in many cases of ARVC, the dog does not have the known gene mutation.

Experts advice on breeding

  • Boxers that are heterozygous positive, should be carefully evaluated for the disease
  • Boxers that do not show signs of the disease may be bred with boxers that are negative for the mutation
  • Puppies should be screened over a couple generations
  • Puppies who are mutation-negative should replace parents who are mutation-positive
  • Boxers who are homozygous positive should not be bred
  • Under special cases where a homozygous positive Boxer has special qualities that must be maintained, Boxer must be bred to homozygous negative Boxer
  • After two generations of breeding to negative homoygous Boxer, negative puppy should be chosen to breed as replacement

Treatments

The treatment for ARVC is primarily antiarrhythmic drugs, the most common being Sotalol. This treatment is intended to reduce clinical signs and sudden death.

Opinion

All Boxer breeders should have their dog tested for the ARVC mutation. I do not believe that any Boxer who is homozygous positive for the mutation should be bred so that most cases of ARVC will be eliminated. With the possibility of so many genes effecting the chance of a dog receiving ARVC, should we expect to come to a solution to eradicate the disease or does it seem impossible?

References

"Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) "Boxer Cardiomyopathy"" The Big Hearts Fund. The Big Hearts Fund, 2010. Web. 01 May 2016.


Boxer
. Freehold, NJ: Kennel Club, 2009. American Boxer Club. Purina Pro Club, May 2010. Web. Apr. 20.


"Boxer ARVC." NC State Veterinary Hospital. NC State University, 2015. Web. 01 May 2016.



"Genetic Welfare Problems of Campanion Animals." Universities Federation of Animal Welfare. UFAW, 2011. Web. 01 May 2016.



Meurs, Kate. "Boxer ARVC (Cardiomyopathy) by Dr Kate Meurs." YouTube. Washington State University College of Vetrinary Medicine, 30 Aug. 2011. Web. 01 Apr. 2016.


"Orivet DNA Testing." Breedid. Orivet Genetics Laboratory, 2010. Web. 20 Apr. 2016.