Ocular Tumors In Dogs

Ocular tumors, also known as eye tumors, are tumors associated with the eye. Ocular tumors or ocular neoplasia can appear in the eye (retina, conjunctiva, or choroid), on the eyelids, and in the orbit (the bony cavity that houses the eyeball).

Ocular tumors are of two types; primary tumors that arise within the eye itself (Melanoma and retinoblastoma) and secondary tumors are caused by cancers that have spread from other parts of the body, especially the bowel, lung, prostates, or mammary glands.

There are more than two dozen different types of tumors that can develop in intraocular and periocular structures, including subtypes of lymphoma, melanoma, carcinoma, and sarcoma. The main intraocular tumors include Uveal melanoma, Eyelid neoplasia, Iris melanoma, Orbital neoplasia, and Corneal Squamous Cell Carcinoma.

Given their fragile location, prompt diagnosis and appropriate treatment are indispensable. Timing is a significant factor to save the eye, vision and in the most serious cases, the life of the dog.

Symptoms will vary from one type to another as there are a number of ocular tumors in existence. Some of the important tumors and their symptoms are listed here.

• Eyelid Neoplasia:
• Mass on within the eyelid margin or in the margin.
• A change in the skin appearance of the eyelid.
• Swelling of the eyelid.
• Ulceration/thickening / spreading color mass (from pink to very dark brown).
• Uveal Melanoma:
• Mass/dark spot on the iris or ciliary body.
• Change in size/shape of a pupil.
• Changed position of the eyeball in the eye socket.
• Ruptured Blood vessels.
• Tearing Eyes

• Iris Melanoma:

• Distinct, circular black or brown spots on the iris.
• Freckles on their irides.
• Iris nevus enlarged or ovalization (pulling on the pupil).
• Corneal Squamous Cell Carcinoma:
• Redness in eye / Irritation.
• White or pink mass growth on the epithelial surface of the cornea.
• The cornea, conjunctiva, and eyelid are affected.
• Orbital Neoplasia:
• Flattened Eyeball
• Bulging / Protruding eyelid
• Swollen eyelid, conjunctiva, or cornea
• Dilated Pupils
• Often the two eyes do not move together.

Treatment for ocular tumors is to reduce the risk of spreading and to maintain the health and vision of the dog’s eye.

Ocular tumors Treatment options depend on several factors, including the type and stage of cancer, the dog’s overall health, and possible side effects.

Benign Tumors:

Vets consider surgical removal of benign tumors on the outside of the eye with chemotherapy or cauterization. When the growths inside the eye or freckles are truly diagnosed to be benign, they are usually left alone to be examined every 2 to 3 months for any possible changes.

Malignant Tumors:

When your dog is diagnosed with eye cancer your vet may recommend surgery, chemotherapy, radiation, or a combination of these treatments. However, it's important for pet owners to understand that most cancer will relapse after some time.

Ocular Cryosurgery:

Therapeutic usage of cold temperatures to treat tumors of the eyes or lids. Tumoricidal cryogens used are liquid nitrogen (–195.6°C), freon (–29.8°C to –40.8°C), solid carbon dioxide (–79°C) or nitrous oxide (–88.5°C).

Keratectomy Or Sclerectomy:

Laser surgical procedure for lesions with the extra step of graft replacement.

Enucleation:

Surgical removal of the eye with preservation of the extraocular muscles, conjunctiva, optic nerve, and orbital fat.

As with any disease, the prognosis is dependent on the extent of the tumor, its location, and the treatment chosen. Discuss home treatments with your vet to ensure there won’t mess with other medications.

This may include dietary changes, exercise, supplements to administer, and other holistic treatments.

The best way to prevent eye tumors is to maintain proper eye hygiene with products engineered specifically for dogs and to maintain overall health.

Modifiable risk factors for the prevention of eye cancer:

1. Eye cancer can be prevented by making the dogs avoid a few lifestyle behaviors.
2. One of the most significant changes you can make is reducing carcinogenic exposure such as pesticides, secondary smoking, and other chemicals.
3. Avoid the Engine exhaust, Scented candles/air fresheners, laundry detergents, and other household items that sneak carcinogens into our household.
4. Stay away from Industrial pollution and chemicals (arsenic, plastic, leather, textiles, dyes).
5. Check and dispose of overflowing waste bins and trash in the backyard carefully to protect your dogs from infections.
6. When going for walks, keep your dog away from rotting plant matter, dead leaves, and other decayed substances in the woods.
7. Maintain your lawn or garden. Keep it neat and clean to avoid unwanted pests.

Breeds more susceptible to ocular tumors are

• Boxer
• Bulldog
• Boston Terrier
• Great Dane
• German Shepherd
• Golden Retriever
• Labrador Retriever
• Schnauzer
• Cocker Spaniel

The exact causes of ocular tumors are unknown, however, there are several factors that may be involved There could be a viral cause -

• Congenital or primary causes: Hereditary.
• Metastatic or secondary causes: Tumor that spreads to the eye from other parts of the body.
• Metabolic: Hypothyroidism and diabetes mellitus.
• Infectious: Leishmania, Canine Distemper Virus, etc.
• Drug-induced ocular toxicity : Temporary: Local or systemic anesthetic, atropine, and the sedatives, potentiated sulfonamides.
• Radiation: Less common.
• Latrogenic: In the case of “Cherry Eye”, surgical removal of the gland of the third eye.
• Immune-mediated: Oculardegenerations that are immune-mediated.

Morbidity:

Vets also use a simpler staging system for eye tumors. They use the terms small, medium, and large which are based on the thickness and width of the tumor.

For instance, in uveal melanoma:

• Small – ≤ thickness: 2.4 mm and < width: 16mm
• Medium – thickness: between 2.5 - 10 mm, < width: 16mm
• Large – thickness: >10 mm and width: > 16 mm

Sometimes, vets use the terms Limited stage or advanced stage.

For instance, in ocular lymphomas:

The limited disease generally means dogs have stage 1 or stage 2 lymphoma.

Advanced disease means dogs have stage 3 or stage 4 lymphoma.

Diagnosis:

• Serum biochemistry profile and complete blood count.
• Tonometry, slit lamp, and fundoscopy.
• Inner eye
• X-rays of the skull, chest, and abdomen or ultrasound to check metastasis.
• CT scan (bone involvement) and MRI (to check soft tissue damage).
• Fine needle aspiration or biopsy.

Mortality:

Although the mortality rate due to ocular tumors is less compared to other tumors, ocular tumors hugely impact the quality of life of dogs.

Prognosis:

The prognosis is poor for dogs in advanced stages of ocular tumors. Prognosis is often positive with early diagnosis and appropriate treatment. The prognosis deteriorates in dogs that are not treated promptly or with severe signs.

Emergency - Immediate Veterinary Assistance Needed:

• Severe unsteadiness or loss of muscle control, confusion, or disorientation.
• Abnormal levels of aggression or agitation.

Diet for eye health with an anti-cancer diet:

The diet should be included foods containing vitamins A, C, zinc, carotenoids, beta-carotene, lycopene, phytonutrients—and the special partnership of zeaxanthin and lutein (natural sunblock).

35 to 50 percent protein + less than 25 percent carbs + 25 to 35 percent fat (including omega-3 fatty acids and arginine). (All these measurements apply to dry matter).

• 35% to 50% Protein - Animal meat (avoid raw meat), Lean Boiled Meats, Seafood, Eggs.
• 25% Carbohydrates - Brown Rice, Barley (pearled), Grains.
• Fatty Acids - Cooked Egg Yolks, Plant Oils, Sunflower, Corn.
• Avoid trans fat, a small amount of beef fat, and steak fat.
• Calcium - Powdered or crushed eggshells, supplements.
• Include dog - Safe spices like turmeric, ginger, cumin, and coriander.

For dogs with ocular tumors, the long-term prognosis is generally poor, regardless of treatment. Dogs can have an improved quality of life for a period of time with proper treatment.