Eyeworm Disease in Cats: Diagnosis, Treatment, and Prevention Causes of Eyeworm Disease in Cats and How to Prevent It

Eyeworm Disease in Cats: Diagnosis, Treatment, and Prevention https://www.pexels.com/photo/orange-tabby-cat-lying-on-blue-comforter-1418239/

Ocular dirofilariasis, often known as eyeworm sickness, is a parasite condition that affects cats' eyes. We discuss its treatment and management here.

Eyeworm disease, also known as ocular dirofilariasis, is a parasitic infection that affects the eyes of cats. This condition is caused by tiny, thread-like worms (Thelazia californiensis and Thelazia callipaeda) that invade the eye and cause discomfort, pain, and vision problems. Owners of cats should be aware of the signs and risk factors for eyeworm illness, even though it is a very rare disorder.

In this article, we will discuss the causes, symptoms, and treatment options for thelaziasis in cats, as well as steps that can be taken to prevent infection.


The cause of cat eye worm disease is a parasitic worm known as Dirofilaria immitis. Cats are most frequently exposed to this worm through the bite of an infected mosquito. The worm's larvae enter the cat's bloodstream through the mosquito, which serves as a vector. The worm larvae enter the circulation and go to other tissues, including the eye, where they develop into adult worms and spread illness. Other species, such as dogs, ferrets, and foxes, can also be affected by this parasite. However, cats are less commonly infected compared to other species. The risk of infection is higher in areas with a high mosquito population and during the warmer months when mosquitoes are most active.


The symptoms of thelaziasis in cats can vary, depending on the severity of the infection and the number of worms in cat’s eyes present. Some common symptoms include:

  • Eye discharge: The infected eye may produce a thick, yellowish discharge.

  • Pain and discomfort: The presence of the worms can cause pain and discomfort in the affected eye, leading to squinting, rubbing, and pawing at the eye.

  • Swelling: The eye may become swollen due to inflammation caused by the worms in the cat's eyes.

  • Vision problems: In severe cases, the worms can cause vision problems, such as cloudiness, double vision, and even blindness.

  • Irritability: The discomfort and pain associated with the eyeworm disease can make infected cats irritable and less active.

It is important to note that some cats may not show any noticeable symptoms, even though they are infected.


A comprehensive physical examination, a study of the cat's symptoms, and information about their past health are often required for the diagnosis of eyeworm illness in cats. The presence of the worms may occasionally be detectable with the naked eye, but more often than not, further diagnostic testing is required to confirm the diagnosis. Eyeworm illness in cats is frequently diagnosed using the following procedures:

  • Ophthalmic examination: A thorough examination of the affected eye can help determine the presence of worms and assess the extent of the infection.

  • Microscopic examination: To confirm the existence of worms, a sample of the ocular discharge or tissue can be obtained and inspected under a microscope.

  • Blood test: A blood test can be used to check for the presence of antibodies against the eye parasites in cats, indicating an active infection.

  • Imaging tests: In some cases, imaging tests, such as ultrasound or MRI, may be needed to see the worms and determine the severity of the infection.

Once the diagnosis of an eyeworm disease is confirmed, your veterinarian will recommend a treatment plan to eliminate the worms and prevent further damage to the eye.

Treatment and Management

Recovery options for eyeworm disease in cats include:

  • Follow-up visits with the veterinarian: Regular check-ups with the veterinarian are important to monitor the cat's recovery and prevent a recurrence.

  • Mosquito control: Preventive measures, such as mosquito control, can help reduce the risk of future infections.

  • Medications: Ongoing treatment with antiparasitic medications may be needed to prevent a recurrence of the infection.

  • Monitoring: Regular monitoring of the affected eye, including eye exams and imaging tests, may be necessary to ensure that the infection has been fully eliminated and to monitor for any signs of recurrence.

Together with your veterinarian, create a treatment and recovery plan that is suitable for your cat. Most cats that receive quick and effective treatment are able to totally recover from eyeworm disease without any long-term impact on their vision or general health.

Preventive Tips

You can prevent cat eye parasites through the following steps:

  • Mosquito control: Mosquitoes are the primary carriers of the eyeworm parasite, so controlling their populations can help reduce the risk of infection. This can be done by using mosquito repellent sprays, installing screens on windows and doors, and removing standing water sources around the home.

  • Regular veterinary check-ups: Regular check-ups with a veterinarian can help identify and treat an eyeworm disease early before it becomes severe.

  • Parasite prevention: Using preventive medications, such as monthly topical treatments or oral medications, can help prevent the development of an eyeworm disease and other parasitic infections.

  • Cleaning and disinfecting: Cleaning and disinfecting areas where the infected cat has been can help prevent the spread of the eyeworm parasite to other cats.

  • Avoiding infected cats: If you have multiple cats, it is important to keep infected cats isolated from healthy cats to prevent the spread of the parasite in the cat's eyes.

You can lessen the chance that your cat may contract an eyeworm illness and safeguard its general health and well-being by using these preventative steps. However, you should consult a veterinarian as soon as you think your cat has an eyeworm disease to ensure a quick diagnosis and effective treatment.

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