Heart Tumor (Rhabdomyoma) in Dogs

Rhabdomyoma in Dogs

A rhabdomyoma is an extremely rare, benign, non-spreading, cardiac muscle tumor that occurs only half as often as its malignant version: rhabdomyosarcomas, an invasive, metastasizing (spreading) tumor.

Rhabdomyomas are usually found in the heart, and are suspected of being congenital in origin (present at birth). This type of tumor does not become malignant, nor does it metastasize through the body. They are very rarely found outside of the heart, but do occur in other places of the body on occasion. They have been reported in the tongue, and in the larynx (voice box) in dogs.

Rhabdomyoma can affect both dogs and cats. If you would like to learn more about how this disease affects cats, please visit this page in the PetMD health library.

Symptoms and Types

• Rhabdomyoma in the heart:
  • Usually no symptoms
  • Rarely, there will be signs of right-sided congestive heart failure (CHF) due to obstruction
• Rhabdomyoma outside the heart:
  • Localized swelling

Causes

Idiopathic (unknown)

Diagnosis

You will need to provide a thorough history of your dog's health leading up to the onset of symptoms. From there, your veterinarian will perform a complete physical exam on your dog, with a blood chemical profile, a complete blood count, a urinalysis, and an electrolyte panel. Your veterinarian will use the results of the bloodwork to confirm, or rule out, other diseases. Bloodwork will typically appear normal in patients with a rhabdomyoma, since the tumor is relatively harmless.

X-ray imaging, and an echocardiogram of the heart may help your veterinarian to diagnose a rhabdomyoma. Additional examination using an electrocardiogram will note heart arrhythmias (rhythm abnormalities). For a definitive diagnosis, an examination of tissue from the tumor (biopsy) can be performed.

Treatment

Treatment is not usually necessary for a rhabdomyoma in the heart, since surgery of the heart would carry more risk than any benefit it might provide. But for rhabdomyomas located in an area other than the heart, surgery to remove them should be fairly uncomplicated since they are not very invasive.

Living and Management

Your veterinarian will schedule monthly follow-ups for the first three months after your dog has been discharged in order to do progress checks. Follow-up visits may then be scheduled at three to six month intervals for another year. The concern is that rhabdomyomas in the heart may lead to right-sided congestive heart failure due to obstruction of blood flow.