EDITION: June - August 2011

FILARIOSIS. The Heart Worm

Texto: Lic. Silvina Guerrini (Col. 689)

In this issue of our magazine we wanted to address one of the illnesses which concerns us most at this time of year, since it can affect our most beloved pets: dogs, and sometimes cats. Filariasis is a heart and lung disease caused by a worm (Dirofilaria Immitis), which can sometimes be fatal. Many different types of mosquitoes transmit this disease.
In Ibiza there are indeed sources of risk: stagnant waters where the mosquitoes can breed. Due to climate change, it is quite likely that these sorts of places will multiply.
How can my pet dog or cat become infected?
Infection happens through mosquito bites, as the latter pick up the microscopic worm larva from the blood of another animal that is already infected. The worm matures inside the mosquito itself. When it bites another animal it passes on the parasite, which migrates towards various organs before settling for good in the pulmonary arteries and the heart.
The intermediate step between pet-mosquito-pet is essential, since it is within the insect that the infectious stage develops; which is why it is unlikely for dogs to infect other dogs or cats. Incidentally, while cats can sometimes cure spontaneously, dogs cannot.
What are the symptoms of Filariasis?
Around six months after infection, the worms reach adult stage and produce what is known as microfilaremia (a massive outburst of microscopic worms into the bloodstream). As the number of adult worms increases, they move faster towards the lungs and heart, where they create an irreversible cardiovascular dilation.
As the disease advances, we will notice that our pet coughs, is listless, loses weight, does not play like it used to or wants to return home from its walk earlier than usual. As well as these symptoms, infected animals can present others that are related to the specific area where the worm has concentrated (for example: liver, kidney, skin, spleen, eyes and brain).
Can this disease be treated?
The development of filariasis is progressive and takes a long time. For this reason, the sooner the illness is diagnosed the better our pet’s chances are, allowing even for a full recovery. Fortunately, nowadays there are effective treatments to cure this illness, but success will depend on how advanced the condition is. Therefore, dogs who present a much-advanced case of filariasis cannot be treated, as they risk dying.
What can I do to prevent it?
The mosquito season extends between March and November, although in the Balearics it can be even longer than that. In order to prevent infection, there are products available that are 100% effective: there is a vaccine that lasts twelve months and also tablets that come as tasty treats that are administered monthly, with the additional advantage that they protect against intestinal worms.
It is important to be aware of the fact that, in order to prevent the illness from developing in dogs that are more than eight months old, a test must be carried out to rule out the possibility of infection already being present from previous summers. We can only protect our pet completely if we are certain that it does not already carry Dirofilaria Immitis. Speak with your vet to find the best prevention strategy for your pet.