Rhabdomyomas are very rare, benign tumors of striated (striped) muscles that most commonly occur in the cardiac region of the dog. This type of tumor occurs only half as frequently as its malignant counterpart, rhabdomyosarcomas, which is a malignant and metastasizing tumor.
The most common site for occurence of this tumor is heart and extracardiac rhabdomyomas are very very rare. However, rhabdomyomas have been reported in tongue and larynx (voice box) in the dogs. These tumors are believed to be congenital (present at birth) in nature.
Many a dogs with cardiac rhabdomyoma remain asymptomatic. Those that do display signs they are related to heart disease such as lethargy, ascites, exercise intolerance, auscultatable murmurs, cardiomyopathy, congestive heart failure and sudden death.
Dogs suffering from laryngeal rhabdomyomas usually present with signs such as localized swelling, difficulty breathing (dyspnoea), exercise intolerance and stridor ( a harsh vibrating noise during breathing).