Small breed dogs and heart disease

Small breed dogs with heart disease is not uncommon. In fact, heart disease is fairly common among dogs in general but small dogs and big dogs generally suffer different types.  There are two main types: valvular heart disease which affects small breeds and dilated cardiomyopathy which affects large breed dogs. These diseases are quite different in their symptoms and how the disease develops, and it is important to know what to look out for so that we can diagnose and treat the heart disease as early as possible.

Small breed dogs: who is at risk?

The heart is a muscle with four chambers. The chambers are separated from each other by valves which ensures that blood flows only in one direction through the heart to pump the blood to the lungs and the rest of the body. Small breed dogs, particularly Cavalier King Charles Spaniels, Malteses and Poodles, develop wear and tear on their valves as they age and this can lead to the valve weakening and leaking.

If the valve leaks it results in blood flowing backwards through the heart and decreases the heart’s ability to effectively pump blood to the lungs and other organs. The heart then has to work harder and harder to compensate for this inefficiency and this weakens the heart muscle. This progresses to heart failure. The rest of the dog’s organs also start struggling because they don’t receive enough oxygen and heart disease can lead to kidney and liver failure.

How is it diagnosed?

Firstly, your vet will need to check all small breed dogs’ hearts regularly. It is essential to take your dog to your veterinary clinic for a check up every year for the vet to listen to the heart. “We listen for changes in the heart rate (how fast it beats), rhythm (does it have the normal ‘lub-dub’ sound) and we listen for heart murmurs,” says Dr Ingrid de Wet of Country Animal Clinic. “Heart murmurs occur when the heart valve is leaking and there is backward flow of blood through the heart. We will often pick up a heart murmur many years before the dog develops other symptoms of heart disease and this presents us with a golden opportunity! Once we pick up the heart murmur we can then take steps to monitor the dog’s heart more closely and start treatment when needed, to prolong their lives and delay full heart failure with other organ failure for as long as possible.”

Once a heart murmur is detected, your vet will recommend an x-ray of the chest to measure the heart’s size. This will be a baseline x-ray which enables your vet to monitor for changes as the dog ages. It is important to repeat the x-ray every year and as soon as the heart begins to enlarge, medication is prescribed.

Small breed dogs: other symptoms of heart disease

In some cases, your vet won’t detect the heart murmur until other symptoms appear. Other symptoms of heart disease in small breed dogs include:

  1. Exercise intolerance: you might notice that your dog doesn’t walk/run as far as he or she could before, or they are very tired or out of breath when exercising
  2. Coughing
  3. Fainting spells
  4. Heavy or fast breathing
  5. Swollen abdomen

If you notice any of the above symptoms it is essential to take your dog for a consultation so that your vet can check their heart and start treatment as soon as possible. Once a dog shows symptoms of heart disease, it means that their heart muscle has already weakened. “Although we cannot reverse that, we can manage their symptoms and give them a great quality of life,” says Dr de Wet.

Treatment of heart disease

The vet will assess your pet’s heart as well as their lungs and other organs and then choose the most appropriate treatment for your pet. Treatment normally entails giving medication in tablet form. In most cases a vet will give three types of medication:

  1. Medication to slow the heart rate and encourage the heart muscle to pump properly
  2. Medication to decrease the dog’s blood pressure to decrease the load on the heart.
  3. A diuretic (water pill) to draw fluid off the lungs and make it easier for the dog to breathe and to make it easier for the heart to pump.

What to expect?

In cases where we diagnose the heart murmur early, monitor for subtle changes and start treatment when necessary, you can expect that your dog will live a happy life for many years. Their heart will be able to cope for much longer and we can delay the onset of symptoms and weakening of the heart muscle to the point of heart failure, Dr Ingrid says.

Unfortunately heart disease can develop into full heart failure and impact other organs such as the liver and kidneys. Some patients may also struggle to breathe at some point if the fluid in the lungs builds up. “If we see that the patient does struggle to breathe or has other organ failure or poor quality of life then we will recommend euthanasia for that patient.

“Our aim, though, is always to give the patient the best possible quality of life for the longest time and this is why early screening and diagnosis is so important.”

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