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Heart Tumor (Rhabdomyoma) in Dogs

Rhabdomyoma in Dogs

Rhabdomyoma, a rare benign tumor of the cardiac muscle, occurs less frequently than its malignant counterpart, rhabdomyosarcomas, which are invasive and metastatic. Typically found in the heart, rhabdomyomas are believed to be congenital, present at birth, and do not exhibit malignant behavior or spread throughout the body. While predominantly located in the heart, they can occasionally occur in other areas such as the tongue or larynx in dogs. Rhabdomyomas can affect both dogs and cats.

Symptoms and Types

Rhabdomyoma in the heart:

  • Typically asymptomatic
  • Occasionally, signs of right-sided congestive heart failure (CHF) may occur due to obstruction

Rhabdomyoma outside the heart:

  • Manifests as localized swelling


Idiopathic (cause unknown)


To diagnose rhabdomyoma in your dog, your veterinarian will first gather a comprehensive history of your pet’s health leading up to the appearance of symptoms. Following this, a thorough physical examination will be conducted along with blood tests including a chemical profile, complete blood count, urinalysis, and electrolyte panel. These tests will help to eliminate other potential diseases, although bloodwork typically appears normal in cases of rhabdomyoma due to its benign nature.

Diagnostic imaging such as X-rays and an echocardiogram of the heart may be utilized to aid in diagnosis. Additionally, an electrocardiogram can identify any heart arrhythmias. For a conclusive diagnosis, a biopsy of tissue from the tumor may be necessary.


Rhabdomyomas located in the heart typically do not require treatment as surgery on the heart poses greater risks than benefits. However, for rhabdomyomas found in areas other than the heart, surgical removal is generally straightforward as these tumors are not highly invasive.

Living and Management

After your dog is discharged, your veterinarian will schedule monthly follow-up appointments for the first three months to monitor progress. Subsequently, follow-up visits may be scheduled at three to six-month intervals for up to a year. The primary concern is the potential development of right-sided congestive heart failure due to obstruction caused by rhabdomyomas in the heart.

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