TL;DR: Eye worms (Thelazia) are parasitic infections that cause intense pain and potential blindness if not treated promptly. Contact a veterinarian within 24 hours for professional removal and medication.
What are eye worms and how do they affect my dog?
If you notice thin, white, thread-like organisms moving across the surface of your dog's eye or tucked beneath the eyelids, your pet likely has a parasitic infection called Thelazia, commonly known as "eye worms." These parasites are typically transmitted by certain types of flies and live in the tear ducts and conjunctival sac of the eye.
Is it an emergency if I see worms in my dog's eye?
- Urgency Level: High. While not immediately life-threatening, this condition causes intense physical discomfort and pain.
- Potential Complications: If left untreated, the movement of the worms can cause corneal ulcers, chronic inflammation, and even permanent blindness.
- Recommended Action: Contact your veterinarian or an emergency clinic within 24 hours to arrange for professional removal and a prescription for appropriate antiparasitic medication.
How does taking a photo help the vet triage my dog's eye condition?
- Verification: Because worms often hide behind the third eyelid or move quickly, a clear photo or video provides definitive proof of the infestation.
- Prioritization: Visual evidence allows the clinic to prioritize your case effectively.
- Clinical Preparation: Photos help the veterinary team prepare necessary numbing agents and specialized instruments for safe removal before you arrive.
Clinical Context (Merck Veterinary Manual)
Thelazia species eyeworms, including T. californiensis and T. callipaeda, can infect dogs, causing clinical signs such as excessive lacrimation, epiphora, ocular pruritus, conjunctivitis, keratitis with corneal opacity and ulceration, and hyperemia; blindness is rare. The worms are whitish, 7-19 mm long, and move rapidly in a serpentine motion across the eye, and up to 100 may be observed in the conjunctival sac, tear ducts, and on the conjunctiva under the nictitating membrane and eyelids. Diagnosis and treatment involve observation and manual removal of the parasites with forceps after local anesthetic application. Systemic treatment options include ivermectin (0.2 mg/kg SC), milbemycin oxime (minimum dosage of 0.5 mg/kg PO, two treatments 1 week apart), or spot-on moxidectin 2.5%. Ocular solutions (1% moxidectin or 2% levamisole) or ointments (1% levamisole or 4% morantel) also may be effective.
Chapter: Ophthalmology, Parasitology
Source: The Merck Veterinary Manual, 11th Edition (Page 512)