Is there really such a thing as Boxer cardiomyopathy?

In a word, yes! This disease of the heart is quite a common condition seen by veterinary practices at least several times a year. In this Pets4Homes article, we will look further into the condition, what causes it, and any treatment that is available.

Can’t heart disease affect all breeds, not just Boxers?

Yes, it can, heart disease, in general, is not breed specific, although certain breeds are more susceptible to certain types of heart disease. In Boxer cardiomyopathy, the disease almost always affects Boxers, with the only exception of a very close relation in the Bulldog. The disease can also strike animals at any age, not just in the senior years.

So, what exactly is Boxer cardiomyopathy?

The proper name for it is Arrhythmogenic Right Ventricular Cardiomyopathy which understandably is shortened to ARVC. It is a disease of the muscle wall of the heart, much like dilated cardiomyopathy which is more often seen in dogs such as Dobermans. With ARVC, everything on a heart x-ray will look normal, with no swelling or unusual shape to the heart image. Even heart scans are not helpful, as they will also not find anything wrong.

What this condition does is cause the dog to have an irregular heartbeat called an arrhythmia. In ARVC it’s the bottom two chambers of the heart that occasionally contract out of synchronisation from the other chambers. In a normal heart, all the chambers should contract at the same time.

Because the heart rate has been put out of synchronisation, the blood going around the system may not carry enough oxygen. When the bottom chambers contract, this is termed ‘ventricular premature complex’ or VPC short. In a dog with Boxer cardiomyopathy, VPC’s can be common, sadly some dogs have so many of these episodes, that the heart stops working and the dog will suffer sudden death.

That sounds scary, why does it happen?

In Boxer dogs, it is a genetic disease, from a mutant gene carried in the body. Dogs that carry one of the mutant genes in their body are at increased risk from being affected by cardiomyopathy. Sometimes a dog will have two genes of the mutant variety carried in their body, one each from their mother and father. These dogs are at much greater risk of having cardiomyopathy. Of the Boxer population, it is thought as many as 50% of dogs in the UK carry at least one of these mutant genes.

So, what are the symptoms to look out for?

Unfortunately, this disease manifests itself in such a way there are only four ways it is usually discovered.

The dog seems completely normal – their general health is very good, although they will have the occasional issue when their heart skips a beat. This is only sometimes picked up by a vet when they are having a clinical examination prior to boosters, surgery, or any situation where a stethoscope is used to listen to the heart.

The dog shows complete disease signs – the arrhythmia is so bad that the dog can faint from lack of oxygen being carried around the body in the blood. The dog being weak and not responding to exercise are other signs.

CHF or Congestive Heart Failure, this is extremely rare for dogs to suffer from if they have Boxer cardiomyopathy. If they do present with signs, they are usually blue gums from lack of oxygen, the swelling of the abdomen (also known as ascites), coughing and breathing issues.

The last symptom, unfortunately, is sudden death. Sometimes a dog dying is the first the owner will know about it.

So how can the vet diagnose this condition?

As discussed above a heart scan, known as an echocardiogram, is pointless with this condition, as it will not show anything. What has to be discovered is how the electrical impulses in the heart are affecting its function.

The one test for this is an ECG, where electrical pulses are measured. Because the vet needs to get a complete overview of what is happening with the heart, and the fact that VPCs affect the dog over a 24-hour period, the dog may wear a specialist piece of equipment for an ECG, called a Holter Monitor. This monitor is worn by the dog for 24-hours and is adapted into a specialist harness pack where the dog does not even realise they are being monitored.

The results from the monitoring are then analysed by a vet and appropriate treatments are started.

What treatments are available for this condition?

There is no cure for this condition at present, however, the number of times that a VPC is triggered can be reduced. This is usually provided by the use of antiarrhythmic drugs. Most of these types of drug are actually a human form, so your vet should use them from the medicine cascade.

Medication is usually started after a lengthy consultation with the owner as the drugs can sometimes make the condition worse. If the amount of VPCs has reached the point where it is dangerous for the dog, the medication is reduced then.

Another way to help reduce the frequency/amount of VPCs is to keep the dog happy, not stressed, and calm. This is much, much easier if the dog is not a bouncy Boxer!

What is the usual outcome?

Dogs that are treated early for the disease and stabilised can live several years longer. Sadly, it is also a condition where the animal can have a sudden death, with no outward signs of any issues that were wrong beforehand. Dogs affected with this disease all carry the risk of sudden death. The bottom line is, the worse the dog is affected, the more guarded the long-term prognosis is.

Conclusion

Although this article has been for predominantly Boxer owners, heart disease as discussed before can affect any dog. If you are worried about your pet at all, especially if they are reluctant to exercise, seem very breathless, or even have a reluctance to eat, please speak to your vet. Like almost all diseases, the earlier it is caught and diagnosed, the earlier the treatment can start, and the outcome could be more positive.