What Causes Canine Ocular Onchocerciasis? Can it lead to blindness?

What Causes Canine Ocular Onchocerciasis? Photo by Christian Domingues: https://www.pexels.com/photo/closeup-photography-of-adult-short-coated-tan-and-white-dog-sleeping-on-gray-textile-at-daytime-731022/

Canine ocular onchocerciasis, also known as canine onchocerciasis, is a parasitic infection of the eye caused by the Onchocerca volvulus roundworm.

Ocular onchocerciasis is an eye disease caused by the parasite Onchocerca volvulus. This parasite can be transmitted through fly bites, which is how it causes eye disease. The flies breed in stools and other excrements, so if you live in a country with poor sanitation, you may be exposed to the parasites that cause ocular onchocerciasis.

While this infection can affect both eyes, it is most often found in only one eye. The severity of symptoms depends on which stage of development the larvae are at when they enter a new host. 125 infected dogs were compared to 1255 dogs without any symptoms to determine their likelihood of being infected.

The common signs of ocular onchocerciasis include severe pain, redness, swelling of the eye, discharge from the eye, and blurry vision or blindness. These symptoms generally occur within three weeks after being bitten by an infected fly; however, they may not appear until several months later. 

The Parasite Is Transmitted Through Fly Bites

The parasite that causes ocular onchocerciasis is transmitted to dogs through fly bites. Flies are the primary mode of transmission, especially considering most cases of canine ocular onchocerciasis occur in areas where there are many flies.

The warble fly (Hypoderma bovis) has been identified as a carrier of the parasite and often bites dogs around their eyes, eyelids, or ears. Warble flies feed on blood and other fluids found in wounds caused by biting flies or ticks; this makes them prime carriers for pathogens such as O. volvulus, which can enter a dog's body when it comes into contact with these types of insects while grooming itself after being bitten by them, especially if they happen to be infected themselves! 

Symptoms Of Ocular Onchocerciasis

Symptoms of ocular onchocerciasis include:

? A red eye. Your dog's eye may be swollen, and the skin around it looks irritated.

? Discharge from the eye, although this is not a common symptom. This discharge can be mucous or pus-like, and it may have an odor to it. It will be thick, creamy in color, and have a yellowish tint to it. 

At times it is possible that your dog has been experiencing pain for a while before you noticed symptoms of ocular onchocerciasis. You can give your pet Prednisone for dogs to relieve the pain. 

Treatment Options For Ocular Onchocerciasis

Treatment options for ocular onchocerciasis include surgery, medication, laser therapy, topical dog eye drops, and other pet medications. However, some dogs with the disease have a poor response to treatment, or the infection can't be cured. Some treatments are more effective than others. 

In general, the severity of the infection determines which treatment is recommended. As part of treatment, you should also ensure the hygiene of your dog to avoid flea infestation to reduce the risk of infection. The vet may prescribe some dog flea pills like K9 Advantix and additionally use flea chews for dogs, flea collars for dogs, flea combs, etc. 

Ways Your Dog Can Contract Ocular Onchocerciasis

They can contract ocular onchocerciasis through a fly bite. If your dog is bitten by an infected fly, the worm may enter his body and eventually reach the eye. They can also contract ocular onchocerciasis through contact with other infected dogs.

A dog with ocular onchocerciasis will often have parasites living in its eye(s) that can be transmitted to other dogs who come into close contact with him, such as when they play together or share food bowls. 

In rare cases, humans can transmit this infection to their pets by touching a heavily infested area of their skin and then touching their pet's eyes or mouth before washing their hands thoroughly afterward. 


The causes of ocular onchocerciasis in dogs are not fully understood. However, the parasite is thought to be transmitted through the bite of an infected blackfly or tick. The biting insect then spreads the parasite when it feeds on another dog or other warm-blooded animal.

Was this article helpful?