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Ask the Vet: How Long Can a Dog Live With a Heart Tumor?

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If you are wondering how long can a dog live with a heart tumor, most likely your dog is suffering from this. It's an unfortunate fact that cancer has been affecting more and more dogs, and the whole process can be heartbreaking for dog owners. How much can a dog with heart tumor live? What type of quality of life with the dog have? Veterinarian Dr. Ivana discusses heart tumors in dogs, what they are, how they impact the dog's heart and what causes them. She also goes into detail on how they are diagnosed and treated, along with the prognosis for heart tumors in dogs.

Clogged arteries leading to heart disease is mostly seen in humans.

Heart tumors in dogs can be benign or malignant.

Heart Tumors in Dogs 

A tumor is an abnormal mass of tissue that forms when cells in a specific area of the body reproduce at an increased rate. Tumors are divided into two broad categories: malignant (cancerous) and benign (non-cancerous). Malignant tumors invade surrounding tissues and may also spread via the bloodstream or lymphatic fluid to other organs in the body. Benign tumors lack the tendency to spread and usually grow slowly.

Heart tumors may develop inside the heart or around the heart. Additionally, they can arise directly from the heart tissue or can spread to the heart from another part of the body.

What causes heart tumors? While benign tumors have a variety of possible causes, from infection to injury, all cancers arise from the same basic mechanism – damage to genes. A cell may become cancerous when certain genes that control vital processes, such as cell division, become damaged. These faulty genes may be inherited. Whatever the genetic predisposition, cancer formation is usually triggered by environmental factors (stress, diet).

The immune system is normally very efficient at destroying abnormal cells, but cancer cells trick the natural killer cells of the immune system into regarding them as "self" and therefore not destroying them. Having eluded the body’s natural defenses, cancer cells multiply rapidly to form a tumor, and may then spread around the body.

There are several risk factors leading to heart tumors in dogs. Although heart tumors can develop in any dog, they are more commonly reported in middle-aged to older dogs (over 6 years of age). Additionally, heart tumors are more frequently seen in certain large dog breeds such as Golden Retrievers, Labrador Retrievers and German Shepherds.

Types of Heart Tumors in Dogs 

Depending on where they form and the tissue from which they originate, there are several types of heart tumors in dogs. Here is a list.

Fibromas (benign) and fibrosarcomas (malignant) are tumors that arise from the heart’s fibrous tissue (the heart valves). These types are common among Boxers, Dobermans and Golden Retrievers.

Myxomas (benign) and myxosarcomas (malignant) are tumors that arise from the softer connective tissue in the heart’s upper chambers. This type is common in large breed dogs.

Rhabdomyosarcomas (malignant) are tumors that arise from the heart’s skeletal muscles

Hemangiosarcomas (malignant) are tumors that form in the blood vessels lining the heart and are the most commonly diagnosedtype of heart tumor in dogs. Cardiac hemangiosarcomas in dogs usually affect the right side of the heart. More often than not, hemangiosarcomas remain undiagnosed until complications arise. Once complications develop, the chances of successful treatment decline significantly. Namely, since hemangiosarcomas arise from blood vessels, as they grow, they tend to fill up with blood. If the growth continues, they are very likely to rupture causing major and life-threatening internal bleeding.

Chemodectomas are tumors that form either in the carotid or in the aortic body. They are particularly common among brachycephalic dogs (such as Boxers) with more than 7 years of age.

As mentioned, some tumors may develop elsewhere in the body and then spread (metastasize) to the heart. Based on their origins we can differentiate several types:

Lymphomas (primarily affecting the lymph nodes)

Neurofibromas (primarily affecting the nerves)

Osteosarcomas (primarily affecting the bones)

Granular cell tumors (their exact origin is unknown and they can be either benign or malignant).

The Dangers of Heart Tumors in Dogs 

The presence of a newly formed mass inside or around the heart is risky business as it impairs its normal ability to function. When the blood's pumping into and out of the heart is blocked or even slowed, the heart rhythm changes.

Additionally, depending on its exact location in the heart, the tumor may cause a buildup of fluid in the chest cavity, and thus interfere with breathing or it may interrupt the supply of blood from the liver to the heart, causing the liver to enlarge which eventually leads to fluid buildup in the abdominal cavity.

Both of these complications are life-threatening and often present a greater immediate danger to health than the potential malignancy of the tumor.

The signs and symptoms of heart tumors in dogs are various. The exact clinical presentation depends on the tumor’s location. However, generally speaking, a dog with a heart tumor is likely to exhibit the following signs and symptoms:

  • Arrhythmia (irregular heartbeats)
  • Heart murmurs
  • Enlargement of the heart
  • Impaired breathing (even while resting)
  • Coughing
  • Distended abdomen
  • Exercise intolerance
  • General fatigue
  • Fainting
  • Lack of appetite
  • Weight loss.

Diagnosing heart tumors in dogs entails several exams. When setting a diagnosis the vet will start by taking the dog’s history and performing a thorough physical examination. Based on the findings, the vet will suggest performing an x-ray of the chest. If the radiography does not offer conclusive diagnosis, an exploratory surgery is likely to be performed. If possible and indicated, the tumor may be removed at the same time.

The treatment of heart tumors in dogs will vary and ultimately depends on the tumor’s type and location. Simply put, there are two treatment options – surgery and chemotherapy.

Surgery is recommended only if the tumor has not metastasized by the time of diagnosis. Chemotherapy is an invasive approach that controls the tumor’s growth and prevents it from metastasizing. The most popular chemotherapy drug is doxorubicin. The doxorubicin is quite effective, but unfortunately it has an unfortunate side effect (it damages the heart muscle). In some cases, combining surgery and chemotherapy is the best option. The average cost of treating heart tumors in dogs is $10.000.

How Long Can a Dog Live With a Heart Tumor?

Because of their delicate location, heart tumors, regardless of their type and location, are particularly life-threatening. That specificity affects the prognosis which in most cases is guarded to poor.

The prognosis is guarded to poor because, more often than not, at the time of diagnosis the condition is already widespread. What is more, it is not unusual for heart tumors to reoccur even after full surgical removal. Sadly, in most cases, even with successful treatment, the life expectancy for dogs with heart tumors is less than 6 months.

About the Author

Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.

ivana crnec

She currently practices as a veterinarian in Bitola and is completing her postgraduate studies in the Pathology of Domestic Carnivores at the Faculty of Veterinary Medicine in Zagreb, Croatia.

Ivana’s research has been published in international journals, and she regularly attends international veterinary conferences.

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