Introduction
Dogs can develop eye conditions like styes and tumors that require veterinary attention. Styes are bumps that form on the eyelid when oil glands get blocked. They are relatively common in dogs. Eye tumors may develop from eyelid tissue, connective tissue, or cancer spreading from other parts of the body. Eye tumors are less common than styes in dogs.
Styes usually clear up on their own or with simple treatment. Most are benign and do not impact vision. Some eye tumors like melanoma can be malignant. Catching eye tumors early and removing them surgically gives dogs the best prognosis.
Causes of Eye Styes
Eye styes are most commonly caused by a bacterial infection of an eyelash follicle or oil gland on the eyelid. The most frequent bacteria involved is Staphylococcus aureus. When the bacteria multiply, they cause the oil gland or follicle to become inflamed and swollen. This results in a small, red, and painful bump on the eyelid.
Blocked oil glands on the eyelid can also lead to styes. The medical term for this is internal hordeolum. Sebum and dead skin cells can clog up the oil glands, causing a buildup of pus and swelling. The stye will appear as a tender, red bump at the base of the eyelashes.
Symptoms of Eye Styes
Eye styes often cause noticeable symptoms affecting the eyelid. The most common symptoms of a stye include:
- Swelling – A stye will appear as a red, swollen bump on the eyelid, often along the edge or underside of the lid. The swelling may feel firm or tender to the touch.
- Redness – The bump itself will be red and inflamed. The skin surrounding the stye may also become red and irritated.
- Itchy eyes – A stye can cause itching or irritation in the affected eye. There may be a scratchy, dry sensation. Rubbing the eye tends to make symptoms worse.
- Discharge – A stye may leak a thick, yellowish discharge. Crusting and sticky drainage may accumulate along the eyelashes. This can cause the eyelids to stick together, especially after sleeping.
In most cases, a stye will only affect one eye at a time. Symptoms tend to worsen over a few days as the bump grows larger, then gradually improve over a week or two as the stye resolves.
Diagnosing Eye Styes
If you notice signs of an eye stye in your dog, it’s important to have a veterinarian examine them. The vet will do a physical exam of the eye, looking for a red bump on the eyelid and signs of inflammation or discharge. They may collect a sample of the discharge from the stye to examine under a microscope. This can help identify the type of bacteria causing the infection.
Some other tests the vet may conduct include:
- Fluorescein stain – This fluorescent dye can reveal ulcers or scratches on the cornea.
- Schirmer tear test – Measures tear production.
- Tonometry – Checks pressure inside the eye.
These tests help rule out other possible eye conditions. The presence of a firm nodule on the eyelid along with inflammation and swollen lymph nodes will confirm the diagnosis of an eye stye.
If the stye does not respond to treatment or keeps recurring, further testing may be needed. This includes cytology of the lump or a biopsy to examine the cells. Your vet may recommend referral to a veterinary ophthalmologist (eye specialist) for advanced diagnostics.
Treating Eye Styes
There are several effective treatment options for eye styes:
Antibiotics
Antibiotic eye drops or ointments are commonly prescribed to treat eye styes. Antibiotics help clear up infection and inflammation caused by bacteria. Some common antibiotics used for eye styes include erythromycin, bacitracin, and polymyxin B. Ointments are usually applied 3-4 times per day. Eye drops may be prescribed for more severe cases, to be used every 1-2 hours throughout the day.
Warm Compresses
Applying warm, moist compresses to the affected eye can help speed healing and relieve discomfort from an eye stye. Compresses should be used 3-4 times a day for 10-15 minutes. The warmth helps open up the oil glands and drain the stye. Using clean compresses and water each time is important to avoid spreading infection.
Surgery
If an eye stye is very large, painful and does not respond to antibiotics, a minor surgical procedure may be required. This involves making a small incision to drain the stye. The procedure is done under local anesthesia and takes just a few minutes. Draining a stye helps relieve pressure and promotes faster healing. Most styes will resolve without needing surgery.
Causes of Eye Tumors
There are several potential causes of eye tumors in dogs:
UV Radiation Exposure
Prolonged exposure to ultraviolet radiation from sunlight can potentially lead to the development of certain types of eye tumors in dogs, such as squamous cell carcinoma of the cornea and conjunctiva.
Genetics
Genetics may play a role in the development of some types of eye tumors in dogs. Certain breeds, such as Golden Retrievers, are at increased risk for developing pigmented tumors of the eye like iris melanoma.
Chemical Exposure
Exposure to certain chemicals has been linked to increased risk of eye tumors in dogs in some studies. For example, herbicide exposure has been associated with higher rates of ocular squamous cell carcinoma in dogs.
However, the causes of eye tumors are often complex and not entirely understood. More research is needed to better determine the potential risk factors involved in the development of various canine ocular tumors.
Symptoms of Eye Tumors
Some of the most common symptoms of eye tumors include:
Visible Mass
One of the most obvious signs of an eye tumor is a visible mass on the eye. The tumor may appear as a round, dome-shaped bump on the white part of the eye. In some cases, it may emerge from underneath the eyelid. The mass may change in size over time.
Vision Changes
Eye tumors can affect vision in various ways. You may experience blurred or distorted vision, shadows in your field of view, or complete loss of vision on one side. Side vision loss, known as peripheral vision loss, is common with certain eye tumors. The vision loss may be painless and progress slowly over time.
Discomfort
Some types of malignant eye tumors can cause pain and discomfort. You may feel like there is something in your eye even when nothing is there. Eye pain, tenderness, soreness, burning, or excessive tearing can also signal a tumor. In rare cases, eye tumors may cause bulging of the eye, double vision, or retinal detachment.
Diagnosing Eye Tumors
If a dog is suspected of having an eye tumor, the vet will perform a thorough ophthalmic examination. This involves evaluating the eyelids, third eyelid, conjunctiva, cornea, anterior chamber, iris, lens, vitreous chamber, retina and optic nerve. The vet will look for abnormalities in eye structure, cloudiness, swelling, masses or bleeding.
Some diagnostic tests the vet may use include:
- Fluorescein stain test to check for ulcers or other problems on the cornea
- Tonometry to measure pressure inside the eye
- Slit lamp exam to closely inspect the front structures of the eye
- Gonioscopy to evaluate the drainage angle where fluid leaves the eye
- Ultrasound to see structures behind the eye
- CT or MRI scans to visualize the tumor and see if it has spread
The most definitive way to diagnose an eye tumor is to take a biopsy of the mass. This involves surgical removal of a small sample that is then sent to a lab for analysis. The biopsy report will identify if the tumor is benign or malignant.
Based on the results of the examination, diagnostic testing and biopsy, the vet can determine the type of eye tumor present and if/how far it may have spread. This information guides the treatment approach.
Treating Eye Tumors
Treatment for eye tumors often involves surgery, radiation therapy, and/or chemotherapy depending on the type, size, and location of the tumor. The main treatment options include:
Surgery
Surgical removal of the tumor is a common treatment for certain eye tumors such as ocular melanomas. The type of surgery depends on the size and location of the tumor. Some surgical options include:
- Laser surgery – Using laser beams to destroy cancer cells.
- Cryotherapy – Freezing cancer cells using extreme cold.
- Enucleation – Removal of the entire eye.
- Orbital exenteration – Removal of the eye and muscles/tissues surrounding the eye.
Reconstructive surgery may be done after tumor removal to help restore appearance and function.
Radiation Therapy
High energy radiation is used to shrink and destroy cancer cells. External beam radiation aims radiation from a machine outside the body. Proton beam therapy is a specialized type of radiation that uses protons. Brachytherapy involves implanting radioactive material near the tumor site.
Chemotherapy
Anti-cancer drugs are used to kill cancer cells. Chemotherapy may be injected directly into the eye or given systemically through a vein. Chemotherapy helps treat cancers that have spread beyond the eye.
Prevention
There are steps you can take to help prevent eye problems in dogs:
-
Limit UV exposure. UV radiation from the sun has been linked to some forms of eye problems in dogs. Use doggie sunscreen, limit time in the sun during peak hours, and provide shade when possible.
-
Monitor for changes. Check your dog’s eyes regularly for any abnormalities or changes. Look for redness, swelling, discharge, or growths. Catching problems early is important.
-
Regular vet checkups. As part of your dog’s routine veterinary care, the vet should examine the eyes during annual checkups. This allows early detection of any issues.
Following these prevention tips can help minimize your dog’s risk of developing eye health problems like styes or tumors.