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Eyeworms in Cats

Eyeworms in Cats

Thelaziasis

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Updated on September 26, 2024

SUMMARY OF CONTENT

The eyeworm, *Thelazia californiensis*, is a parasitic worm that can infest the eye of dogs, cats, sheep, deer, and other mammals and cause a disease known as thelaziasis.

SEVERITY:

Severity is mild to moderate
  • Time to Cure
    Resolves within weeks with proper treatment
  • Treatment Icon
    Treatable by a veterinarian, by the pet parent
  • Prevention Icon
    Keep pets indoors and control the fly population
  • Spread Icon
    Transmission is not possible between animals or between animals and people
  • Lab Icon
    Diagnosis requires an examination of the eye

VERY COMMON IN

Eyeworms are most common on the Pacific Coast in animals that spend time outdoors.

Symptoms & Signs

Generally, animals show few signs of the infestation. Due to irritation of the eye, animals may produce more tears, may be sensitive to light, and occasionally develop conjunctivitis (inflammation of the mucous membranes of the eyelids). This can become more serious if a secondary bacterial infection develops.

Diagnosis

Eyeworms are diagnosed by examination of the cat’s eyes. The eyeworms can usually be seen, however it might be necessary to place the cat under anesthesia to thoroughly examine the eyes.

Causation

The eyeworm can infect dogs, cats, sheep, deer, and other mammals and cause a disease known as thelaziasis. Eyeworms live in the tear ducts, between the eye and the lids. The adult female worm lays her eggs in the tears. There they develop into larvae that are ingested by certain flies, such as the face fly. The larvae develop in the fly for about 30 days and then move to the mouth of the fly. When the fly feeds near the eye, the larvae move out of the fly’s mouth and migrate to the eye of the new host. In three to six weeks, the larvae develop into adults and repeat the cycle.

Treatments

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AT-HOME CARE

An Elizabethan collar (cone) may be used at home to prevent pawing or rubbing of the eye(s).
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SUPPORTIVE CARE

Administer all medications are prescribed.
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MEDICATIONS

Anti-parasitic medications including ivermectin, moxidectin, imidacloprid, and selamectin which may be prescribed to cure infestations. Topical or systemic anti-inflammatory medications may also be used to decrease any swelling, redness, and irritation caused by the parasite. Antibiotics may also be prescribed to treat or prevent and treat secondary bacterial infections.
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DEVICES

None
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SURGERY

None
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SPECIALISTS

A general practitioner veterinarian typically manages eyeworm infection and a specialist is not needed.

Cost Of Treatment

Uncomplicated cases of Thelaziasis can be diagnosed and treated for less than $500.

Recovery

Most cats respond well to treatment and make a full recovery within a few weeks. If left untreated, there is a risk of permanent blindness.

Monitoring

Cats should be monitored closely during recovery for resolution of clinical signs. A follow-up eye examination may be necessary to ensure the condition has completely resolved.

Prevention

Keeping pets indoors and controlling the fly population is a helpful method in reducing the spread of eyeworms. Keeping the environment clean and free of garbage and fecal material will also help decrease the population of flies. If avoidance is not possible, the use of a fly repellent is recommended, especially in areas with a high fly population.

Questions about Eyeworms
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I have a cat that as a kitten was very ill. We got him from 7 months old. We knew he’d had cat flu prior to him coming here. He is now nearly 5 yrs old. He picks huge fights with our other cat. He keeps urinating and scratching at doors and windows around the house. We allow him to go out via the cat flap unlimited. What is happening to him

I'm glad to see that Pippin has been neutered because this eliminates that possibility of hormone-fueled behavioral changes and aggression. Behavioral changes in cats can occur at any point in time, and could be related to anxiety or stressful situations (even rearranging furniture or introducing new people to the home can be stressful to cats). Without a lot more information and observing Pippin's behaviors, I can't precisely tell you why these changes are occurring. It may be best to consult a veterinary behaviorist in your home so that they can observe everything firsthand. You can also try using calming pheromone collars or diffusers (Feliway is one example), and discussing the use of anxiety medication with Pippin's vet. I hope that all goes well!

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Hi! My cat was recently diagnosed with diabetes. He’s taking insulin and taking antibiotics for a Uti. It’s been 4 weeks and he wobles when he’s walking. He can’t jump up on the bed like he used to.He’s blood sugar is 250 it’s better than it used to. I don’t understand why he’s so wobbly.

Cats can develop what's called diabetic neuropathy, where their hindlegs become progressively weak. The best thing to do is try to get his diabetes under control as quickly as possible. Here is a link describing the conditon: http://www.diabeticcatcare.com/DCCCOK/Neuropathy.htm

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My senior cat has metastized cancer.17 yrs old. My vet gave her predizone1 and one half tabs a day.i wanted to know if i can just stop the meds.

Is there a reason you want to stop the prednisone? I would recommend not stopping it and if you feel it is better to stop the prednisone then I would recommend weaning off of the prednisone. I would discuss how to wean the prednisone with your veterinarian. Thank you for using Boop by Petco.

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My 3 year old long haired tuxedo female pees just fine in the litter box, but she preferred to poop on the bathroom rug or on the carpet behind the sofa. Then, she will go weeks and everything is fine only start pooping outside the box again. I have 4 litter boxes and 3 cats. I clean all several times a day. She is the youngest. I've put wee wee pads down and she lifts them up and poops under them. Any ideas to help? Thanks!

A good first step, if you haven't already, is to rule out any health issues with your vet such as arthritis that may be causing the accidents. Secondly, making sure none of the other cats are bullying her away from the litter box may also alert you to any issues. Thirdly, a good enzymatic cleaner may help reduce the smell/discourage use of these areas in the future. That said, if you've done the above and the issue is still happening, it's probably time to call in a veterinary or animal behaviorist that can visit in person to see what may be going on. They may be able to check for stressors that could be causing the accidents where they are, look for issues with refusal to defecate in the box, or see if there is a cycle that is happening that is triggering this reaction. From there they may be able to set up a more tailored plan to help reduce the accidents and encourage use of the litter box at all times. If you're in the US, you can use this website to help find someone available in your area: https://www.dacvb.org/page/about

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My dogs are experiencing a bad flea outbreak. We used a generic for Frontline (fipronil) two weeks ago, with no results. I have purchased a generic for Advantix II (Imidacloprid, Permethrin, and Pyriproxyfen) and am wondering if I need to wait the full 4 weeks to use this, or if I can treat with the second medication now.

In severe outbreaks, 2 weeks between different drugs is ok. You will also need to use a household flea treatment in order to break the cycle, only 5% of the flea population are adults and actually present on pets, tge remaining 95% are eggs/large and will continue to hatch, develop and reinvest your pets. All in contact animals should be treated together and also given a tapeworm treatment because tapeworms are also transmitted by fleas

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There seems to be two wounds underneath my cat’s ear. There is not one on the other side. Does it look like ringworm or caused by fleas? What can I use to help her? It was smaller a week ago.

Thank you for contacting Boop by Petco with your question about Tor and for providing pictures, they are very helpful. Yes, I see the two wounds, and they could be caused by her scratching at her ear. While that could be due to fleas, it may be she has an ear infection causing her to scratch at her ears. Continually scratching at them would cause the wounds to get bigger. This does need to be checked out by a vet, as if she does have an ear infection, it could be caused by ear mites, yeast, or bacteria. In addition, the ear drum needs to be visualized through an otoscope to make sure it's still intact before any medication is given. Ear problems can be considered an emergency as leaving them untreated can lead to hearing loss. Given that these wounds are getting bigger, I'd see if you can get her into her vet asap. I hope this helps!

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Disclaimer

The information contained on this page is for educational purposes only. Treatment should only be provided under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.