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 salivary gland tumors in cats and dogs?
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 of salivary gland tumors in cats and dogs?
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.

Does cancer cause pain in pets?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role
in educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets
is to prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.

To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what
cancer pain management options are available for your pet, please visit the Cancer Pain Management section.

How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for
example, some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need
to be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more,
please visit the Cancer Nutrition section.

What are the treatment options for salivary gland tumors in cats and dogs?
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.

How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your
pet's cancer condition, please visit the "Locate a veterinary oncologist" section.

What is the prognosis for cats and dogs with salivary gland tumors?
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 cats and dogs with salivary gland tumors?
There are no clinical trials specifically designed to treat salivary gland cancer but there are several clinical trials available
for cats and dogs with any tumor type for which your pet may qualify. To learn more these trials (which are partially or fully
funded by the institutions), please visit the Dog Clinical Trials (any tumor type) or C at C linical Trials (any tumor type )
section.

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.