What are eye tumors?
Eyes are organs of vision which can develop abnormal growth in many of their anatomical components. The outer layer of
the eyeball consists of the cornea and sclera (giving the eye most of its white color). The middle layer includes the iris,
ciliary body, and choroid. The choroid gives the inner eye a dark color. The inner sensory  layer includes the retina.
Abnormal growths, whether benign or malignant, can have a devastating consequence on the animal's vision and can
become life-threatening if they begin to invade into the central nervous system. The earlier the eye tumors are detected,
the better chance the pet has for saving its vision.

The following table summarizes common eye tumors in pets, their treatment and prognosis.

Source: Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998.

The following section summarizes available information on eyelid tumors in cats.

What are eyelid tumors?
An eyelid is a thin fold of skin and muscle protecting the eye which can develop both noncancerous (benign) and
cancerous (malignant) growths. The most common cat eyelid tumor is called squamous cell carcinoma (SCC), which
usually first appears as a small plaque on a poorly pigmented eyelid, which subsequently becomes thicker, larger, irregular
and can eventually ulcerate. White cats with nonpigmented eyelid  are at higher risk of developing this type of tumor.

What are the symptoms and diagnosis of eyelid tumors in cats?
A typical symptom of cat eyelid SCC tumors is the appearance of a mass which can be accompanied by inflammation and
discharge. To confirm the suspected SCC diagnosis, the mass should be
biopsied and sent to a pathologist (a board
certified veterinarian who specializes in diagnosing diseases) for analysis prior to treatment. SCCs are malignant tumors
but generally slow growing. However, they do have the potential for invading surrounding tissues and can cause death if
the tumor cells travel along the optic nerve into the brain. Occasionally, eye ultrasound, skull X-rays, CT (computed
tomography), MRI (magnetic resonance imaging, chest X-rays, and lymph node
cytology are required to evaluate the
localization and extent of the disease, especially in the case of malignant tumors such as SCCs or adenocarcinomas.

What are the treatment options for eyelid tumors in cats?
All eyelid tumors, whether benign or malignant, have the potential to affect the cat's vision. Cryosurgery and/or surgical
removal are the recommended treatment options. Cryosurgery provides several advantages: it is a quick procedure, less
technically demanding, and can be performed in older or sick animals since only a topical anesthesia or sedation is
required. Swelling and temporary loss of pigmentation is usually expected after the procedure. The specific treatment of
choice will depend on the tumor type, size, location, how advanced it has become, the animal's life expectancy, whether the
procedure will re-establish the eyelid's functionality and the financial limitations of the owners. Tumors that involve  more
than one third of the eyelid typically require more advanced reconstructive surgery and the use of skin graft. Invasion of
the eyelid tumor into surrounding tissues will be typically treated by a procedure called exenteration, which refers to
removal of the eye along with additional tissues surrounding the eye. This procedure is done even if the eye has retained
its visual functionality in order to prevent the tumor's spread to the central nervous system where it can become life
threatening. Multiple tests are done prior to this procedure to evaluate the extent of the disease and include skull X-rays,
eye ultrasound, CT scan or MRI.

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.  

Are there any clinical trials for eye tumors in dogs?
There are no clinical trials specifically designed to treat eye tumors but there are several clinical trials available for cats
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
Cat Clinical Trials (any tumor type) section.  

To learn more about veterinary clinical trials in general, please visit the
Pet Clinical Trials section.

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.

Is nutritional support important 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 is the prognosis for cats with eyelid tumors?
Most eyelid tumors in cats are malignant, therefore, the prognosis for cats is not as good as for dogs. Fortunately, the
metastatic potential of these tumors (tendency to spread to other organs) is generally very low although the tumors are
locally invasive. The prognosis is excellent for cats who undergo surgical removal for tumors that are relatively small in
size. Cats should be monitored every 3 months to check for any tumors coming back. SCCs often come back and are
typically treated with multiple cryosurgeries. White cats are at increased risk of developing SCCs are additional sites,
including the nose tip and the ears.

  • 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.
Eye Cancer in Cats
Cancer type
Eyelid squamous cell
Cryosurgery or surgical
Conjunctival squamous cell
Cryosurgery or surgical
Diffuse iris melanoma
Monitoring for small lesion;
eye removal for large lesion
Intraocular lymphosarcoma
Iris/ciliary body melanoma
Eye removal
Intraocular sarcoma
Eye removal
Comprehensive guide to cancer diagnosis and treatment in cats and dogs
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 2/19/2017