A diagnosis of heart failure for your dog means that his or her heart is not working as efficiently as it should. To understand how you can help your dog, it is useful to know how a healthy heart works.
A healthy dog’s heart works to pump blood around the circulation. This system provides oxygenated blood to all the vital body organs or muscles. Your dog’s heart is just like a human heart and consists of a muscular pump containing four chambers.
The chambers are separated by four one-way valves. The closure of these valves is what makes the typical ‘lub-dup’ sound we all associate with a normal heartbeat.
Mitral valve disease (MVD) is the most common heart disease in the dog, and tends to occur most commonly in the small to medium sized breeds, such as the Cavalier King Charles Spaniel.
In MVD, one of the valves of the heart becomes thickened and misshapen so it does not close with a tight seal. The valve therefore no longer acts as a non-return valve, but results in a squirt of blood through gaps in the valve backwards. This may lead to accumulation of fluid (blood volume) into your dog’s lungs.
This squirt of blood flowing the wrong way through a heart valve creates a sound, which is called a murmur. In the early stages of MVD, a murmur may be the only symptom your dog displays.
This type of heart disease tends to affect larger breeds of dog such as the Dobermann. The muscle of the heart becomes weak over time and the chambers of the heart become dilated.
The heart has to work faster to pump blood around the body. Gradually, not enough blood is pumped out of the heart and some blood builds up backwards, leading to fluid accumulating in your dog’s lungs.
When does heart disease become heart failure?
For most dogs, heart disease is progressive. In the early stages, the hearts’ of dogs with MVD and DCM generally compensate for the disease.
However, eventually the extra work becomes too much and the heart is unable to pump enough blood out into the circulation. At the same time, fluid accumulates in the lungs and it is at this point that a dog is considered to be in heart failure.
