Small Dogs but Big HeartedIt is a sad fact that some breeds are at greater risk of developing heart disease than others. For example small breeds with big characters such as the Chihuahua, Cavalier King Charles spaniel, Dachshund, Shih Tzu, and toy Poodle, boss the statistics of dogs with leaky heart valves. Whilst a heart murmur is different to heart failure, one thing can lead to another. So a murmur flags up the need for monitoring.
Heart MurmursWhen a vet listens with a stethoscope, blood leaking in the wrong direction through the heart is heard as a murmur. Often the murmur is of no consequence, so the traditional advice to the owner was the wait-and-see approach. Pet parents were told to be alert for the dog being breathless or coughing as a sign the heart is now struggling to cope. But the advice vet’s give has changed, and as a result dogs are living longer…months and years longer.
The EPIC StudyUntil recently a dog with a murmur but no clinical signs, was not given treatment. This was because there was no proof that starting heart meds early was of benefit in the long term. Instead, vets waited until the dog developed a cough or shortness of breath. But the new ‘EPIC’ (Evaluation of Pimobendan in Dogs with Cardiomegaly) study has turned this on its head. In this scientific study, the heart med (pimobendan) was started as soon as the heart appeared enlarged on an ultrasound scan, but before the dog had a cough. In other words, meds were started in an earlier stage of heart disease.A control group of identical dogs received a placebo sugar tablet. But, the trial had to be stopped because the dogs receiving the real drug outlived the control group by so long it became unethical to withhold the drug from them. In real terms this means dogs on pimobendan lived three-and-a-quarter years, whilst the controls survived barely two years. That’s a lot of extra dog years just for taking a pill!
Identifying when a Dog Needs MedsThe sweet spot for starting the med pimobendan is when the heart starts to enlarge (a sign it’s struggling to cope) but the dog doesn’t have obvious symptoms. However many dogs with heart murmurs have normal sized hearts, are doing just fine, and don’t need meds. This leaves the owner with a dilemma: How do you know when the dog’s heart is enlarged if he doesn’t have any outward symptoms? This is down a careful physical exam by the vet. They are alert for subtle signs such as:
- The heart murmur is louder than it was
- The resting heart rate is faster
- The resting respiratory rate is faster
- The heart rhythm is not regular
- The quality of the dog’s pulse
A Heart ScanThis is a painless procedure where the heart size is measured with an ultrasound device. These measurements give a yes/no answer about whether heart enlargement is present or not. If the heart is enlarged, we now know starting pimobendan can extend your dog’s active life by months to years. What pet parent doesn’t want that for their dog?
Home VigilanceMaybe your dog only sees the vet once a year, at booster time. Perhaps at the clinic your dog is super-anxious, so his heart rate shoots through the roof and he pants with fear. How then, does the vet assess your dog’s heart? Great question! And in truth there is no easy answer. In fact, it's super helpful if the pet’s parent comes equipped with measurements of their dog’s heart and breathing rate when relaxed at home. Indeed, many vets train owners to do just that.
- Wait until your dog is calm or asleep
- Watch for a full rise and fall of the chest. This is one breath
- Count how many breaths the dog takes in one minute and write this down
- Repeat this on a couple of occasions to get an average
What are ‘Normal’ Heart and Respiratory RatesAll dogs are different. For example, small dogs have much faster heart rates than giant dogs, and puppies have faster hearts than seniors. Thus it’s important to recognize what’s normal for your dog when they’re healthy, so you can spot any change and alert your vet.
Signs of Heart FailureIf your dog is already on treatment or if you are suspicious his heart is struggling to cope, the following signs can indicate a problem:
- Shortness of breath
- A fast resting heart rate and respiratory rate
- Heavy breathing at rest
- A cough, especially when the dog is resting
- Tires easily
- Poor appetite
- Weight loss
- A swollen belly