Diseases of the Orbit of the Eye in Dogs

The orbit is the cavity where the eyeball sits, including the all the bones, muscles, and nerves that make up this area. Orbital disease is relatively common in dogs. Incomplete bone structure allows dogs to open their jaw very wide, but leaves little protection from foreign bodies or infection spreading up through the roof of the mouth. Many different types of orbital diseases can cause the eye to appear displaced, either protruding outward (exophthalmos) or retracting inward (enophthalmos). In many cases pain, swelling, and inflammation are also present. Dogs (unlike humans) have a protective third eyelid, which often becomes visible with infection and eyeball displacement. Retrobulbar masses are the most common source of orbital disease. This could be a foreign body, an abscess, a cyst, or a tumor. Infection, called orbital cellulitis, is often caused by bacteria carried on a foreign body, and in some cases, a pus-filled pocket may enclose a small object like a grass awn and create an abscess. Injury or trauma to the eye may also be a source of orbital infection. Because of the close proximity between the jaw and the orbit, inflammation of the jaw muscles and even tooth decay can cause symptoms similar to a retrobulbar mass. Different causes of orbital disease will require different treatment.

Many different conditions can affect the orbit, or eye-socket in dogs, including infection, abscess, a foreign body, or a tumor. The most common symptom of orbital disease is displacement of the eyeball and protrusion of the third eyelid across the eye.

Any of the following symptoms should be evaluated by a veterinarian.

• Exophthalmos – protrusion of the eyeball outward (more common)
• Enophthalmos – retraction of the eyeball inward (with retrobulbar masses located in the anterior part of the eye-socket)
• Third eyelid covering the eye (cherry eye)
• Strabismus – reduced range of motion in the eye
• Difficulty closing the eye
• Pain or inability to open the jaw
• Redness
• Swelling
• Discharge
• Fever

Types

These are some of the many types orbital disease.

• Orbital abscess – enclosed areas of infectious pus
• Orbital cellulitis – inflammation of the orbital area
• Cyst – either inherited or acquired
• Neoplasm – malignant or benign tumor
• Vascular anomaly (rare) – fistulas or orbital varices may cause exophthalmos without signs of inflammation
• Myositis – swelling of the jaw muscles

These are some of the most typical causes of orbital disease.

• Foreign body
• Injury or trauma to the eye
• Congenital
• Bacterial infection (actinomyces or another bacteria)
• Mycotic (fungal infection)
• Parasite
• Inherited condition
• Tooth abscess

The veterinarian will make a thorough examination of the eye. Discharge, redness, and pain tend to suggest infection or abscess. Fever is often also present with an abscess. If there are limited signs of infection, this is more likely to indicate cancer or a vascular anomaly. Cancer is more common in older dogs, so your dog’s age is also relevant. The veterinarian will also examine the mouth cavity since oral abscesses can cause similar symptoms.

An ultrasound of the orbital area can help to show where the problem is located, and whether it is a fluid-filled abscess, a tumor, or vascular anomaly. An aspirate of retrobulbar fluid may be taken to test for infection. In some cases, a CT or MRI could be ordered, or the veterinarian might perform exploratory surgery to identify a mass seen on an ultrasound. X-rays of teeth may be necessary to check for root abscesses.

The veterinarian will also test for signs of systemic disease as infection can spread to the eye from other parts of the body. Bloodwork and urine test can help to determine the overall state of your dog’s health.

Treatment for orbital diseases can be quite varied depending on the diagnosis. Medication may be given to help reduce pain and inflammation. Typically a non-steroid medication like meloxicam will be used. Eye drops may be prescribed to reduce dryness, especially for dogs with trouble closing the eye. If ocular pressure is high, anti-glaucoma medication may also be necessary.

Abscesses and infections will be treated with a systemic antibiotic or antifungal medication. In many cases, incisions will be made under anesthetic to help the area drain and eliminate all the infected material. A culture may be taken to identify the bacteria or fungi that are causing the problem. Small foreign objects, like a grass blade, will usually be removed during the draining process. Abscesses originating in the mouth will be treated in a similar fashion. Abscessed teeth may need to be removed.

Tumors or large foreign bodies could require surgery. Depending on the placement of the tumor or object, this could be difficult surgery and the veterinarian might refer your dog to a specialist ophthalmologist. In some cases, removing the eye is the only option. 

Tumors in the eye may be cancerous or benign. For malignant tumors, chemotherapy treatment may be ordered after surgery. If surgery is not an option, the veterinarian may suggest you manage your dog’s condition symptomatically. Some forms of orbital cancer are slow growing and your dog may live for months or years before it causes a serious problem. The recommended treatment may depend on the age of your dog.

Most local abscesses and infections can be treated successfully and your dog will make a complete recovery. However if an infection progresses too long without treatment, it could end up causing vison loss or even blindness. Cancerous tumors of the eye have a guarded prognosis since they can be difficult to remove. Your dog’s likelihood of recovery will depend on the diagnosis. The best way to manage orbital disease is to see a veterinarian as soon as you notice anything unusual about your dog’s eye. Early treatment will give your dog the greatest chance of recovery.