Oriental Eye Worm – A New Threat

The PETS Passports scheme in combination with the illegal import of thousands of puppies to fuel the online trade in dogs, has led to a huge rise in diseases and infections that were not previously seen in dogs the UK. One recent problem is the spread of the thelazia parasitic worm. A survey in 1978 found that 40% of examined in a Surrey abattoir two year previously were infected by the thelazia parasite. It has now started to affect dogs. usually found in the Far East, Russia and other parts of Europe and also known as Oriental Eye Worm, the species found here is Thelazia callipaeda. If only a few worms are present, dogs can be asymptomatic but, as they multiply, signs include conjunctivitis and excessive watering, keratitis and light sensitivity, spreading to visual impairment and ulcers or scarring of the cornea. if not treated, an infected dog can go blind. Thelazia callipaeda affects cats and humans as well.

The parasite is not transmitted directly on contact but requires an intermediate vector, usually the common housefly (Musca domestica) or blow flies (Calliphora vomitoria) and crane flies (Tipulidae). Adult females release larvae into the tears of the infected animal and are ingested by flies. Infected flies transmit the next stage of the larvae via the eyes or surrounding tissues where they complete development to adult worms in 3 – 9 weeks. Adult worms can live for up to a year in their final host.
Aural ivermectin, milbemycin oxime, moxidectin, injectable moxidectin and spot-on selamectin have been found to be effective in dogs. However, some treatments (not just ivermectin) can be toxic to genetically-prone dogs, particularly collies, so veterinary advice is essential. There is no vaccine available currently.

Although house flies are beginning to die off, it is still very mild for the time of year and peak season for crane flies.

My dog has been infected twice recently by irresponsible owners who have not treated conjunctivitis and let their dogs run freely in the park. Luckily, on both occasions it was just a mild case of conjunctivitis, although the effect on my budget was not so light. It is vital that any eye problem that do not clear up with saline flushing within a few hours are treated by a vet and that the dog is isolated from other dogs until the eyes are clear and/or a course of medication is completed.

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