Salivary gland tumors in cats and dogs.

Salivary Gland Cancer in Cats and Dogs

What are salivary gland tumors?
Salivary glands are exocrine glands that produce saliva. Dogs and cats have four major pairs of salivary glands, all of
which can develop tumors (abnormal growths that can spread to other parts of the body). The most common tumors of
the salivary gland in both dogs and cats are adenocarcinomas the mandibular gland is the most commonly affected.

How common are these tumors?
Primary salivary gland tumors are rare in both dogs and cats and most cases will affect older pets. Some salivary gland
tumors can acquire metastatic potential and spread to lymph nodes (39% for cats and 17% for dogs). Metastasis to
distant organs have been reported in some cases (16% for cats and 8% for dogs at time of diagnosis)

What are the symptoms?
Symptoms are typically nonspecific and can include foul breath, difficulty swallowing, lack of appetite, weight loss, or
swelling of the upper neck, base of the ear, upper lip, or tongue.

How is the diagnosis made?
Fine-needle aspiration cytology of suspected tumors is typically done to help differentiate between benign and malignant
masses. Standard imaging such as X-rays and/or advanced imaging such as CT scan or MRI are used to evaluate the
extent of the disease and if the tumor has spread to other organs.

Do these tumors cause pain?
It is imperative that pets with cancer are provided with pain medication to relieve discomfort caused by the disease as well
as by the treatments. To learn more, please visit the Cancer Pain Management section.

What food should be fed to pets with cancer?
Pets with cancer need to be fed diets specifically designed to support a cancer patient. To learn more, please visit the
Cancer Nutrition section.

What are the treatment options?
Surgical removal of the tumor is the recommended course of action whenever possible, but may be difficult because of
the complexity of salivary gland anatomy and the invasiveness of the tumor in this location. Both dogs and cats will have
increased survival times with surgery alone (if the entire tumor can be removed) or with surgery and radiation therapy (if
the entire tumor can not be removed). The use of chemotherapy for the treatment of salivary gland tumors has not been
widely reported in medical journals.

What are the potential treatment complications?
Removal of the parotid gland (located over the ear canal) may result in damage to the facial nerve, which can result in the
inability of the pet to blink an eye, drooling, or drooping of the face on the affected side. Removal of the mandibular gland
(located behind the jaw bone) may result in damage to the nerves of the tongue which can result in decreased function of
the tongue.

What is the prognosis?
The prognosis for a pet diagnosed with salivary gland cancer is unknown. As is the case with other types of cancer, it can
be expected that pets whose tumors spread to distant organs face poorer prognosis than those whose tumors remain
localized. One study of 24 dogs and 30 cats showed that the median survival with surgery alone was 516 days and
increased to 550 days when combined with radiation therapy. Another study of 6 dogs showed the median survival of 74
days and all six dogs having developed lung metastases. The prognosis for long-term survival of cats is poorer compared
to dogs.

Are there any clinical trials?
There are no clinical trials specifically designed to treat salivary gland cancer but please click here to check if your pet
may qualify for clinical trials for general malignancy.

Sources:

www.michvet.com/library/oncology_salivary_tumors.asp
Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins,
1998.