Heart disease is present in around 15% of dogs in the UK. This can progress to heart failure, often called “Congestive heart failure” or CHF. It is a progressive disease which, without veterinary intervention, will slowly worsen; dogs do not have a sudden heart attack as people can.
The heart is a muscular pump with four chambers which pumps blood to the lungs to pick up oxygen and then around the rest of the body to deliver that oxygen and pick up waste products. The heart can compensate for disease for a while but heart failure will follow when the heart cannot compensate any longer and the pump is not sending enough blood around the body. There are a variety of medicines that can be used to support the heart and keep dogs with heart disease comfortable for sometimes quite long periods of time.
Symptoms are mainly related to fluid that has not been effectively pumped by the heart, building up in various areas of the body. These include:
If you notice any of these signs then you should have your pet examined by the vet as soon as possible. A history of the above signs will arouse the vet’s suspicion of heart disease and they may also detect things such as weak pulses, an enlarged liver or crackles in the lungs which would all point towards heart failure. A heart murmur is also often heard. This is an abnormal “swoosh” sound that is heard between or during normal heart sounds and is caused by turbulent blood flow.
What causes heart failure in Dogs?
The underlying causes of heart failure can be broadly divided into acquired disease and congenital disease.
Ø Acquired disease is disease that has developed over the course of the animal’s life, often due to general wear and tear but sometimes as a result of other problems such as infection. Acquired heart disease includes:
Ø Congenital disease is a disease that an animal is born with. With heart disease, these are usually anatomical defects and can be detected by a heart murmur. Congenital heart defects include:
The clinical signs and history described above would be very suggestive of heart disease but further tests may be needed. These may include imaging of the heart and lungs, often by chest x-rays or ultrasound of the heart. An electrocardiogram or ECG can also be performed which shows the electrical conduction of the heart. Occasionally other tests such as blood screens will be advised to check things like kidney function.
How can heart failure in dogs be treated?
Angiotensin Converting Enzyme Inhibitors (ACEI): These are drugs that suppress the compensation of the heart which relieves stress on the heart therefore reducing damage. These are drugs such as Fortekor and Benazecare which contain the ACEI benazapril, Vasotop which contains ramipril and Enacard which has the active ingredient enalapril. These are a mainstay of treatment of heart disease and can be given alone or in combination with other drugs.
Diuretics: These are drugs which cause the body to reabsorb fluids from places that it shouldn’t be such as the lungs and abdomen as described above. The fluid is absorbed into the bloodstream then these drugs act on the kidney which produces more urine to get rid of the fluid. There are different diuretics which act on different parts of the kidney. These include Frusemide or Frusecare, frusemide is the active ingredient and also Prilactone which contains spironolactone. These drugs can be used separately or together and your vet may want to monitor kidney function when using these drugs.
Inotropes: An inotrope is a drug which causes the heart muscle to pump more strongly and they are often combined with agents which slow the heart rate, giving it more time to fill fully with blood. Vetmedin is an example of this used in veterinary medicine and this contains the drug pimobendan and can be very helpful when used in combination with the other classes of drugs.
There are other drugs that may be used depending on the specific heart disease that your pet is suffering from such as drugs to control blood pressure or abnormal heart rhythms.
Diet and exercise are also very important. Animals with heart disease are often exercise intolerant but it is important not to let these animals become overweight as this can worsen the heart disease. There are prescription diets specially formulated for animals with heart disease such as Hills h/d and RCWC Cardiac. These diets are low in salt so as not to raise blood pressure which can further damage the heart.
Surgery: In a small number of cases there may be a surgical solution to the heart disease but this is only rarely done and is incredibly specialist surgery. Cases where this may be indicated are in some of the congenital defects that can be fixed surgically, implanting a pacemaker in dogs with dangerously slow heartbeats or in cases of pericardial disease and the protective sac around the heart can be removed if needed.