Understanding heart failure in dogs
Your dog’s heart is very similar in structure and function to your own. The most common causes of heart disease in dogs affect either the valves or muscle of the heart. If your dog has been diagnosed with congestive heart failure, there is no need to feel despondent - with help from you and your vet a better, longer life is possible. Understanding your dog’s condition will help you to help your dog.
There are two main causes of heart failure in dogs:
- Myxomatous Mitral Valve Disease (MMVD)
- Dilated Cardiomyopathy
Myxomatous Mitral Valve Disease
Myxomatous Mitral Valve Disease (MMVD) - sometimes also know as “endocardiosis” or “chronic valvular insufficiency” - is the most common form of heart disease in dogs. It usually occurs in small to medium size dogs and some breeds are more susceptible than others. Breeds that are more commonly affected include: Cavalier King Charles Spaniel, Poodle, Schnauzer, Chihuahua, Fox Terrier and Boston Terrier. It is mostly older dogs who suffer from this disease and male dogs are more commonly affected than females.
MMVD is a disease affecting the surface of the heart valves. The valves normally form a perfect seal between the chambers of the heart, ensuring that when the heart contracts, blood flows in the correct direction. MMVD causes the edges of the valves to become thickened, lumpy and distorted. This means that the seal is “leaky” when the ventricle (the large muscular heart chamber) pumps blood, some of the blood flows the wrong way back into the atrium (the collecting chamber). This backward flow creates turbulence which results in a noise, or murmur, that your vet can usually detect with a stethoscope.
Once the valves are leaky, circulation becomes impaired. Initially your dog’s body may make adjustments to allow it to cope, and often dogs which have a heart murmur are unaffected for many years. However, many dogs with MMVD will eventually become unwell and show clinical signs of heart failure.
These signs may initially be mild and difficult to pick up, however as the disease progresses the symptoms can become more severe. The symptoms most commonly seen in dogs with congestive heart failure include
- Coughing
- lack of energy and intolerance of exercise
- loss of appetite and / or weight loss
- laboured breathing
- fainting and swelling of the abdomen (tend to be seen in more severely affected cases)
Regular veterinary visits are important for early detection of heart disease and to monitor the treatment of a dog with heart disease.
Dilated Cardiomyopathy (DCM)
Dilated Cardiomyopathy (DCM) is a disease of the heart muscle, rather than the valves. DCM is most common in medium to large breeds of dogs, with young to middle aged male dogs most frequently affected. Although the exact underlying cause of DCM is not clear, certain breeds tend to be predisposed to the disease, suggesting a genetic component.
In DCM the heart muscle becomes weak and flabby, so the heart fails to pump effectively. Circulation is greatly reduced as a result, with blood supply to the organs reduced. In addition the heart stretches and enlarges. Usually dogs with DCM tend to develop clinical signs more quickly than those with MMVD.
Treating heart failure in dogs
Although your dog may have been diagnosed with a heart disease such as MMVD or DCM there are many things you can do to help your dog live a longer, better life.
As well as using medication recommended by your veterinarian, lifestyle changes may also have a role. It may be necessary to change your dog’s exercise regime, in some cases this may mean complete rest, in others a controlled exercise regime may be recommended. Your vet may also recommend dietary changes. It is important to remember that, as yet, there is no cure for either of these causes of congestive heart failure in dogs. However, there are treatments that not only greatly improve your dog’s quality of life but can also significantly expand your dog’s lifespan.
Medical treatments may consist of some or all of the following:
- Diuretics that remove excess fluid from the lungs or abdomen
- Medicines that ‘open up’ constricted blood vessels, so reducing the work your dog’s weakened heart has to do
- Medicines that improve the strength, or rate of, your dog’s heart beat. This will improve the amount of blood pumped
- Medicines that allow the heart to work more efficiently which should help your dog to live longer