Congestive Heart Failure in Dogs


Dogs can get heart problems just like humans do but the type and causes of any heart disease are very different from our own. The breed of your dog will determine which type of heart disease they are likely to get and at what age, lifestyle is much less relevant. There are two main types of canine heart disease; one which affects smaller and older dogs called Mitral Valve Disease (MVD) and another which affects bigger dogs at any age called Dilated Cardiomyopathy (DCM). A few dogs might also be born with a heart that has not formed properly, this is known as a ‘congenital’ heart problem, which might cause them problems early in life or sometimes cause no problems at all.

In MVD one of the valves in the heart deteriorates and stops working as efficiently. Valves in the heart keep blood flowing in one direction so that when the heart squeezes, blood can only go forwards, not forwards and backward. The thickening and altering in shape of this valve in middle-aged to older small dogs is almost considered a normal aging change. In the early stages when small amounts of blood are starting to leak backward from the valve the heart can cope by working a little harder. If, however, the valve continues to become less and less efficient then this compensation by the heart is no longer entirely successful. It is then not able to do its job of keeping the right amount of blood circulating around the body, especially when exercising. Breeds more commonly affected by MVD are Cavalier King Charles Spaniels, Miniature Poodles, Miniature Schnauzers and Chihuahuas although any small breed (or crossbreed) dog can develop the problem.

DCM, on the other hand, affects large breed dogs and often at a younger age. Breeds such as Great Danes, Mastiffs, Dobermans, Boxers, St Bernards and Cocker and Springer Spaniels are prone. In this disease, the heart muscle itself becomes weak and flabby so that instead of a firm, strong, muscly organ powerfully squeezing blood round the body it becomes distended and rather baggy and struggles to do its job. Because it is a muscle that is affected there is rather less than the heart can do to compensate for the loss in performance.

While the heart is able to do a good enough job, albeit with some increased effort, to get blood to where it’s needed there is little to indicate from the outside that there is a problem. If the heart valves or muscle keep on deteriorating though there will come a time when symptoms of poor circulation and an inability to cope with exercise will become apparent. Initially, these signs might be subtle; faster breathing, being less active, the appearance of a cough, getting short of breath, some weight loss, a reduced appetite. Once the heart is no longer compensating adequately for the shortcomings of the valves or muscle and is showing outward signs of a problem it is considered to be ‘failing’ and your dog is now suffering from Congestive Heart Failure (CHF). Symptoms will tend to appear more quickly with DCM than in MVD and the disease often progresses more rapidly.


We now know that if dogs start on medication at the very early stages of heart failure it is likely to slow down the progression of the disease. The key is identifying those dogs who are on the cusp of developing a problem. Your vet will be able to discuss with you whether this applies to your dog. Sadly there is no way to reverse the changes that occur in MVD or DCM and once heart failure, or CHF, has begun it will keep progressing although it is difficult to predict how rapidly. Some dogs will live with CHF for quite some time but others will decline much more quickly.

Medication is aimed at helping the heart to beat more efficiently and in a more economical way as well as counteract some of the problems resulting from poor circulation. When the circulation is inefficient fluid can build up excessively in some parts of the body like the lungs and abdomen. ‘Diuretic’ drugs help to reduce this fluid buildup by encouraging the body to eliminate excess water, basically by urinating more. You may well, therefore, find your dog on two or more types of medication, especially as the condition or symptoms progress. There might be side effects of the medication, your dog might need to pee much more and have the odd accident, for example, so your vet may need to discuss this with you and make adjustments. All treatments for heart disease will require your dog to take tablets regularly. This might be a problem for some dogs who won’t take them in food or a treat.


There will be questions your vet wants to ask in the first instance about the symptoms your dog is showing. Some parts of this ‘history’ that you tell the vet will be relevant to making a diagnosis. The first way a vet is likely to check out your dog’s heart is by listening with a stethoscope to check if the heart sounds normal. Most of us have heard the familiar ‘lub dub’ heartbeat which we share with dogs. The sounds are made by valves in the heart closing rhythmically. When blood flow through the heart is changed because of faulty muscle or valves the sound becomes more like ‘whoosh dub’ or even ‘whoosh whoosh’. The ‘whoosh’ is called a heart murmur. Not all heart murmurs indicate heart disease but it is a common finding when heart disease is present.

The vet may also check your dog’s pulse and the color of the gums to see how well blood, and oxygen, is circulating. To find out more your vet will need to do more tests which might include a chest X-ray, an ultrasound scan, an electrical trace (ECG) and blood tests. There may be situations when only some tests will be carried out because of financial concerns, the equipment available in the practice or the symptoms shown by your dog. To obtain a detailed picture of exactly how well a dog’s heart is functioning you may be referred to a specialist who has particular expertise and equipment.


A heart problem is obviously a serious health issue to have. If your heart isn’t doing well then its hard for anything else to work well either. In the early stages, your dog may well feel fine and they can compensate pretty well for a mild loss in function. Medication can make a great difference to the symptoms as they begin to develop, again especially early on. The most significant signs are likely to be breathing problems with a cough and a general lack of energy.

Because the body is working much harder than it used to, just circulating blood and breathing, many dogs will lose weight. In addition to burning more calories their appetite can suffer and they may not want a large, full stomach as this can make it harder to breathe. They are likely to spend much more time resting. Sleep can be disturbed because lying down can trigger coughing, especially noticeable at night time. Some dogs will develop a distended abdomen because of the fluid they are retaining and this can be uncomfortable.

Dogs don’t have heart attacks in the way that humans do but some dogs with heart disease will have a crisis where the heart dramatically becomes overwhelmed and they will die suddenly and quite quickly. Other dogs may arrive at a point where they are finding it so difficult to do the bare minimum and are no longer taking any pleasure in life. At this point its necessary for us to intervene and consider dog euthanasia.