Perhaps the main and constant concern of people who live with dogs is deworming, both internal and external. And we say main and constant because parasites are going to affect all dogs, at all stages of their life and throughout the year. To combat them, it is essential to know them and apply the necessary preventive measures.
In this article on our site we are going to focus on a parasite that is becoming more and more common, but which is still unknown to a large part of animal keepers: theThelazia in dogs Keep reading to find out what it is, how it manifests and what treatment it requires.
What is Thelazia and how is it spread in dogs?
Thelazia in dogs is an eye parasite, a nematode worm that lodges inside the eye and can cause discomfort, for it is also known as the "dog eye worm". It is native to Asian countries, in fact it was previously called "oriental worm", but it has already reached the entire Peninsula and several European countries.
This worm, which is usually Thelazia callipaeda, is transmitted by the characteristic small fruit tree flies, present during the warmer months (Depending on areas but usually from May to November, while the activity of these flies lasts). The flies look for the eye secretions of our dogs and it is by accessing them that the parasite reaches the eye from the fly. Once installed in it, the worm causes an irritation that can cause the symptoms, although, sometimes, its presence goes completely unnoticed.
Thelazia life cycle
The biological cycle of Thelazia includes a definitive host, in this case, the dog, and an intermediary which is the fruit fly; transmission is known to be by the male. In the dog, the adults of the parasite are located in different ocular structures, such as under the third eyelid or in the nasolacrimal ducts. The females will lay larvae in the eyes of the dogs and, in this way, when the flies feed on the eye secretions, they will ingest them. Inside, and within about three weeks, these larvae will mature into their infectious form, at which point they move to the fly's mouthparts (proboscis) and thus restart the cycle when the fly feeds on the eye secretions of another dog, where it reaches maturity within a month.
Is Thelazia in dogs contagious to humans?
Yes, thelaziosis, which is the name given to the pathology caused by this eye worm, is a zoonosis, that is, a disease transmissible to humansIn addition, it is an emerging disease, which means that it is expanding and, therefore, more and more dogs are affected. We talk more about this expansion in this other article: "GUSOCs: Eye and Heartworms in Dogs."
Thelazia symptoms in dogs and diagnosis
Thelazia diagnosis in dogs is made by direct observation of the parasite inside the eye Its appearance is threadlike and whitish from about 6-17 mm in length and 0.3-0.8 mm in diameter, with females being larger. Even so, it is not always possible to see it and the diagnosis will be made taking into account the symptoms or environmental factors such as the time of year (probably in the warm months) or the dog's habitat (life or access to an exterior with the presence of fruit trees). In other words, if the treatment that we will see in the next section works, it is because it was Thelazia even though no specimen had been observed. Among the symptoms of Thelazia that we can detect in our dogs, the following stand out, in one or both eyes:
- Conjunctivitis.
- Tearing.
- Serous discharge which may become purulent if a secondary bacterial infection occurs.
- Itching, the dog scratches, and can even cause injuries such as corneal ulcers.
- Periocular alopecia, as a result of scratching there is a loss of hair around the eye(s).
In the face of any of these symptoms, a visit to the vet is pertinent. Although they do not seem to be serious, not treating them can cause more important problems, such as the ulcer that we have named. The symptomatology usually manifests itself 7-15 days after the entry of the parasites in the eye.
Treatment of Thelazia in dogs
As we have seen, Thelazia in dogs lodges inside the eye. The first measure will be to manually eliminate the parasites that are observed, an operation that must be carried out by the veterinarian. It is not always permissible, because sometimes, even if these worms are present, it is not possible to locate them.
The most recommended treatment of choice today is milbemycin, a safe product that is also used for internal deworming. eye! We should never medicate our dog on our own. Even the most commonly used compounds can be life-threatening for some dogs. For this reason, it will always be the veterinarian who must indicate the treatment and the appropriate dose.
How to prevent Thelazia in dogs?
As with other parasites, prevention is complicated. In this case, it is impossible to control the presence of flies in the trees during the hottest months and, likewise, it will not be possible to prevent them from accessing our dogs. So, even being aware that they cannot be followed in all dogs, these would be some recommendations aimed, basically, at avoiding contact with flies:
- Keep dogs indoors during the months that the presence of flies lasts, generally the warmest, although the length of this period will depend on the geographical situation.
- Avoid or reduce going out during daylight hours, when flies are active.
- Remove as far as possible organic matter such as cut grass, fruit that has fallen from the trees, leaves, etc., so as not to favor the increase of the fly population.
- Try to use sunglasses for dogs or any device that prevents or hinders the access of flies to the eyes, since, remember, it is this contact that transmits Thelazia to dogs.
- R check the condition of the eyes frequently and go to the vet in case of any symptoms.
- According to recent studies, a monthly dose of milbemycin can be maintained during the problem months[1]. Of course, it should be the veterinarian who prescribes this prevention method.
