Signs and Symptom of Heart Failure in Dogs

The heart is responsible for pumping blood throughout a dog's body. It is an organ composed of two lower chambers called ventricles and two upper, somewhat smaller chambers called atria. The left and right sides of the heart are separated by a muscular wall. Four valves keep blood flow always in the same direction.

Heart failure occurs when these tissues are unable to carry out their important functions. For example, problems with the dog's heart valves can cause blood reflux and produce various alterations in the animal's organism. The valves are called mitral, aortic, tricuspid and pulmonary valves. It is important to know this distinction. Depending on whether one side or the other is affected, the symptoms will be different.

We can define heart failure in dogs as the inability of the heart to carry out blood circulation that meets the body's requirements. This alteration of cardiac function compromises the work of other organs such as the kidneys, liver or lungs. When a dog's heart begins to fail, compensation mechanisms are established that aim to replace the work that the heart is not doing. This is important because it will keep the dog asymptomatic for months and even years. For this reason, it will be crucial to go to the veterinarian as soon as we detect the first symptom.

With this context in mind, we can look at the various causes of heart failure in dogs:

• Degenerative heart disease: frequently occurs due to a chronic disease of the valves in which degenerative changes occur. The mitral valve is most commonly affected. These alterations cause the valve to lose its functionality, affecting cardiac performance. A reflux of blood and an enlargement of the atrium occurs. This is why we might see an enlarged heart in dogs when they are x-rayed.
  
  
• Dilated cardiomyopathy: consists of an enlargement of the chambers of the heart and a thinning of the walls of the ventricles.
  
  
• Filariasis: caused by parasitic worms transmitted by mosquitoes which live on the right side of the heart. They destroy the cardiac tissue and cause very serious complications such as pulmonary thromboembolism or liver failure, in addition to heart failure. They can be treated with antiparasitic drugs, but surgery may be required. The best treatment is prevention, making it necessary for a deworming schedule in dogs.
  
  
• Congenital heart disease: a condition which can be so serious, affected dogs do not survive more than 1 year. Moderate problems allow survival, although they will likely develop difficulties such as exercise intolerance or rickets. Dogs with mild congenital defects may be asymptomatic.

Among the congenital heart diseases that can lead to heart failure in dogs, we can find:

• Dysplasia (malformation) or stenosis (narrowing) of the valves.
• Septal defects, i.e. abnormal communication between the chambers of the heart.
• Opening of the ductus arteriosus which should otherwise close at birth.
• Tetralogy of Fallot which is a combination of four abnormalities causing blood to be insufficiently oxygenated.

Due to both congenital and acquired heart disease, any dog can experience heart failure, regardless of age. However, puppies and older dogs may be more likely to experience different types of heart failure in dogs. They are also more likely to develop specific, age-realted symptoms.

Heart failure in dogs can present the following characteristic symptoms. These are related to poor cardiac performance, resulting in both physical and behavioral signs:

• Heart murmurs: turbulence suffered by blood circulation as it passes through the heart. They can range from harmless to very serious. Mitral insufficiency is one of its main causes. Mitral heart murmurs in dogs can be heard via auscultation on the left side of the thorax. If the tricuspid valve is affected, the murmur will be heard on the right.
  
  
• Cough: caused by the presence of fluid in the lungs, as a reflux of blood occurs. Pulmonary edema may also occur. This cough may be more evident at night when the dog is resting or after exercise. It is typical of insufficiencies in the left ventricle. The cough will start out mild, but will worsen if the disease is allowed to progress without treatment.
  
  
• Tiredness and lethargy: we will often be able to identify this as exercise intolerance. A dog with heart failure will reduce their usual capacity for physical activity, such as walking, games or jumping. They will get tired from minimal exercise.
  
  
• Ascites: this is the abnormal buildup of fluid in the abdomen. It is characteristic of failure in the right ventricle. We will see that our dog has a swollen belly, but it won't be hard to the touch. Edema can also occur in the legs and fluid can accumulate in the chest (known as pleural effusion).
  
  
• Syncope and fainting: may occur and are related to arrhythmias. Will likely result in general weakness. Learn more with our article on syncope in dogs.
  
  
• Pallor: the dog may also have cold and grayish mucous membranes due to poor oxygenation, heart rhythm disturbances or accelerated breathing.
  
  
• Rapid weight loss: poor blood flow and other issues causes the body to work harder to mee the deficit. This burns more calories and can result in weight loss.
  
  
• Enlarged heart: myocarditis (inflammation of the heart) or hypothyroidism may be behind dilated cardiomyopathy. This is a symptom of heart failure in dogs which can only be seen using imaging tests, although other symptoms will appear due to the inflammation.

If we notice any of the above signs of heart failure in dogs, we should go to a veterinarian immediately. Heart disease is a killer in dogs and the longer it is left untreated, the worse the prognosis. Since older dogs are more prone to certain types of heart failure, it is important we provide regular veterinary checkups. It is best to increase this to twice a year in some cases.

Regular veterinary checkups mean we are best able to detect health disorders that would otherwise go unnoticed. This is especially important with issues such as heart failure in dogs which can be asymptomatic for a long time. Symptoms of certain types of heart failure are detectable with a simple auscultation. Early treatment of heart failure in dogs will be very important to achieve a better quality of life and overall life expectancy.

The veterinarian will begin diagnosis with a physical examination. Other tests to confirm a diagnosis of heart failure will likely include:

• Chest x-ray: allows us to see the size of the heart and the integrity of the lungs. It is normal for the cardiac picture to show an increase in size and for fluid to be seen in the lung.
  
  
• Cardiac ultrasound (echocardiogram): using Doppler, which will give us information about the flow of blood inside the heart, both its speed and its direction.
  
  
• ECG (electrocardiogram): to determine the functioning of the heart and its systole and diastole movements.
  
  
• Blood tests: sometimes the presence of filariae can be determined with a PCR blood test for dogs.
  
  
• Other diagnostic tests: you can also measure blood pressure, do a urine test and, as we mentioned, a blood test. All of this will provide important information, since the failure in cardiac activity will affect the entire organism and we may find damage to other organs. T more data we collect, the more specific the treatment can be.

We must go to a veterinarian with experience in canine heart disorders, since they will have the necessary material to perform all the relevant tests. This may mean we will be given a referral by our regular veterinarian.

Once the diagnosis is confirmed all the appropriate data has been taken into account, the veterinarian will classify the type of heart failure in the dog. They will also determine the degree of failure based on their symptoms and severity. This categorization facilitates the establishment of treatment which must be instituted immediately.

In general, the following treatment for heart failure in dogs is carried out:

• Heart medication: these will be in the form of tablets that help maintain our dog's cardiac functionality. These include ACE inhibitors for congestive heart disease in dogs, amlodipine for hypertension or diltiazem for arrhythmia. Only the veterinarian can prescribe the appropriate medication.
  
  
• Other drugs: such as diuretics can be used for cases that present fluid accumulations.
  
  
• Diet: such as kibble or wet food which is specifically formulated for dogs with heart disease. In general, they help maintain kidney function, which is the second system that is usually affected when the heart fails. They are foods low in salt.
  
  
• Veterinary check-ups: are very important to keep the disease under control and be able to adjust the medication if necessary. It is also essential to go for a consultation if we observe any change or worsening in the signs and symptoms of heart failure in dogs.
  
  
• Maintain a good quality of life: this includes providing the dog with all the necessary care. This includes restriction physical activity. In doing so, we must into account that exercise is beneficial for asymptomatic dogs, but should be suspended if symptoms appear when performing it.
  
  
• Surgery: in cases of persistent ductus arteriosus, surgery is recommended. Septal defects may also be candidates for surgical intervention.

The prognosis for heart failure in dogs is guarded. It will depend on the time at which the disease is diagnosed, the cardiac involvement, as well as the dog's general health and age.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Signs and Symptom of Heart Failure in Dogs, we recommend you visit our Cardiovascular diseases category.