If your dog's eye appears swollen, take him to the vet immediately. If you're lucky it's something minor and easily treated, but there's always the possibility that the swelling results from a serious condition and time is of the essence to avoid vision loss. Treatment for a swollen eye depends on veterinary diagnosis. Depending on the cause, your vet might refer you to a veterinary ophthalmologist.
If the conjunctiva lining your dog's eyelid appears pink and swollen, it's possibly he's developed conjunctivitis, commonly called "pinkeye." If both eyes are affected, it's likely your dog suffers from a bacterial or viral infection. Your vet diagnoses conjunctivitis via scraping the conjunctiva or conducting a tear test. Depending on the results, she might prescribe topical antibiotics to treat the condition. If only one eye is involved, swelling and redness might result from a foreign body, allergens or congenital eye deformities. Besides removing any foreign particle, your vet might conduct allergy tests on your pet to determine the source of the irritation.
Some symptoms of blepharitis (eyelid inflammation) resemble those of conjunctivitis. The dog's eyelid swells and itches, and any scratching aggravates the problem. Affected dogs often experience eye discharge and crusting on the eyelid. Blepharitis can result from trauma, tumors, eye abnormalities, infection or allergic reaction, with treatment depending on the cause. Short-term treatment includes applying warm compresses to the eye several times daily and cleaning off any eye discharge.
The initial signs of canine eye tumors, or ocular neoplasias, usually involve swelling and squinting, but no obvious pain. Unfortunately, the majority of eye tumors are malignant, with a poor prognosis for the dog's long-term survival. Your vet determines the type of tumor by using ultrasound, computed tomography and magnetic resonance imaging. She'll perform surgery to remove the tumor, which generally means taking out the entire eye and some adjacent bone -- which sounds frightening, but dogs generally adjust well after such an operation. Treatment with radiation and chemotherapy might follow.
Tear Duct Issues
Tear duct inflammation can result in swollen eyes. Prolapse of the nictitans gland, in which the gland falls out of place, causes a condition colloquially known as "cherry eye." The out-of-place gland resembles a swollen red cherry jutting out of the dog's eye. The nictitans gland aids in tear production, so your vet will want to preserve rather than remove it. Otherwise, your dog is susceptible to keratoconjunctivitis sicca, or dry eye, which causes pain and vision loss. Surgery consists of resetting the gland and stitching it back in place.