Heart disease is increasingly common in dogs - probably because their average life expectancy is being extended due to improved veterinary care. Some heart defects, eg hole in the heart, are present from birth (congenital heart defects) but may only cause signs as the dog gets older. Other diseases develop later in life as a result of the effects of ageing or damage to the heart. The most common heart diseases in the dog develop in older dogs as the heart starts to wear out.
The signs of heart disease are often very similar whatever the cause. Many of the signs of heart disease can be confused with natural ageing changes. Reduced energy and less desire to exercise are common. Dogs with severe heart disease often have poor appetites and may lose weight. If water retention occurs as a result of the heart failure you might not notice that your dog is losing weight. Other common signs of heart failure are panting and coughing due to fluid build up in the lungs - but remember these signs may be seen with many other diseases too. Less commonly, dogs with heart disease may faint or collapse.
In almost all cases the sooner heart disease is recognised and treated the better the outcome will be. If you are worried about your dog in any way always seek further advice from your vet.