Eyeworm Disease in Dogs

Eye worm is a vectorborne disease carried by fruit flies. It can infect a wide range of mammals including cats and humans but, at present, vets are most concerned about it spreading among canine population

This eyeworm causes conjunctivitis and keratitis (inflammation of the cornea). Corneal ulcers, perforation and blindness may also occur in distinct, severe forms.

They are whitish, 0.5 to 0.75 inches (7 to 19 millimeters) long, and move in a rapid snake-like motion across the eye. Up to 100 eyeworms may be seen in the conjunctival sac, tear ducts, and on the conjunctiva under the nictitating membrane (third eyelid) and eyelids. Filth flies (including the common house fly) and, possibly, fruit flies serve as intermediate hosts and deposit the infective eyeworm larvae on the eye while feeding on secretions from the eyes.

The most frequent ocular signs observed in infested dogs include conjunctivitis, epiphora (excessive lacrymation), pruritus, purulent exudation, and blepharospasm (involuntary eye closure).

Transmission

The eyeworm lifecycle is fairly straightforward. Adults that are living on the eyes an infected animal breed and lay their eggs. When a fly comes by to feed on the tears of the animal, it picks up the larvae that have hatched from the eggs. These larvae mature within the fly and then migrate to the fly’s mouthparts. At this point they are deposited on the eyes of another animal when the fly feeds again. Eyeworms can infect dogs, cats, wildlife, livestock, and even people.

Symptoms of Eyeworm in Dogs

One or more of the following symptoms are usually noticed during an infection of dog eyeworms:

• Excessive tearing of the eyes
• Inflamed conjunctiva (conjunctivitis)
• Opaque corneas of the dog’s eyes
• Slow healing sores or ulcers on the corneas of the eye
• Blindness (rare)
• Itching of the dog’s eyes
• Excess of blood vessels on the whites of the eyes

• Small, white to cream colored, active worms on the dog’s eyes, looking similar to nylon fishing line
• Light sensitivity to the eyes
• Swollen eyes
• Pus in the eyes

Diagnosis and Treatment of Eyeworm in Dogs

Veterinarians can usually diagnose eyeworms based on a physical examination alone. It may be necessary to numb the dog’s eyes with a topical anesthetic or to sedate the dog to get a good look under the eyelids.

If caught early and is treated in time, pets should make a full recovery with no lasting implications. But if left untreated, there is a risk of permanent blindness.

The treatment has to be performed by your veterinarian. It consists on the mechanical removal of the worms with a swab and/or by the flushing of the conjunctival sac of the eyes. A pharmaceutical treatment may be added.