Issue Description The primary tumors of the heart are tumors
that arise from the normal tissues that make up the heart. This is in
contrast to secondary tumors of the heart, which are typically either
metastatic from another part of the body, or infiltrate the heart via
direct extension from the surrounding tissues. Other Names Canine Heart Tumors
Myocardial Tumors Myocardial tumors refer to tumors that
specifically affect the heart. These types of tumors are rare, and
when they do occur, they tend to occur in older dogs. Benign tumors
are masses of tissue that do not metastasize, whereas malignant tumors
metastasize throughout the body. Abnormal tissue growth arising from
the blood vessels in the heart can be malignant, as with
hemangiosarcomas - rare, rapidly reproducing tissue growths; or they
may be benign, as is the case with hemangiomas - harmless growths
consisting mainly of newly formed blood or lymph vessels.
When a tumor arises from the fibrous tissue, like heart valve tissue,
the tumor is called a fibroma if it is benign, and a fibrosarcoma if
it is malignant. There are also tumors that develop in the softer,
connective tissue in the upper chambers of the heart (atria). Benign
tumors of this sort are called myxomas, and malignant tumors are
called myxosarcomas. Tumors that arise from the skeletal muscle in the
heart are referred to as rhabdomyosarcomas, and they are always
There are also tumors that can spread to the
heart secondarily. Some tumors which do not arise in the heart, but
which spread to it are: lymphomas - malignant tumors of the lymph
nodes; neurofibromas - benign tumors of nerve fiber origin; granular
cell tumors - origin is unknown, and they can be malignant or benign;
and osteosarcomas - malignant tumors that originate in the bone.
Difficulty breathing, even while at rest
Lack of appetite
Bloated, fluid filled abdomen
Diagnosis Your veterinarian will perform a thorough
physical exam on your dog, including a baseline blood work profile.
This will include a chemical blood profile, a complete blood count, a
urinalysis, and an electrolyte panel. A chest x-ray and ultrasound
imaging will allow your veterinarian to visually examine the heart, so
that a complete assessment can be made of the heart and any masses
that are present within it. An electrocardiogram (ECG, or EKG)
recording can be used to examine the electrical currents in the heart
muscles, and may reveal any abnormalities in cardiac electrical
conduction (which underlies the heart's ability to contract/beat).
Your veterinarian may also need to take a surgical tissue sample of
the mass for biopsy.
Treatment If the mass in the heart is extensive, or has
begun to spread through the body, surgical resection is still the
recommended treatment of choice for most heart tumors. This holds even
if the surgery will not cure the condition, but if the tumor is
benign, surgical resection may be curative. Chemotherapy can be
administered in the case of malignant heart tumors, but unfortunately,
in many cases patients will die in spite of treatment.
Prognosis The final prognosis for most malignant
myocardial tumors is guarded to poor.