FILARCHECK

Pathogen

Dirofilaria immitis

Pathology

Filariasis is caused by Dirofilaria immitis, a nematode whose immature stages are transmitted by common and tiger mosquitoes to dogs and cats.

The Dirofilaria immitis larvae enter the circulatory system and, once they become adult worms, reside near the heart and lungs, causing heart and respiratory disorders. They grow and spread so massively that, if the disease is not diagnosed and treated in time, this can result in death of the animal.

Filariasis is generally widespread throughout Italy, but is more present in the Po Valley and surrounding areas. It affects dogs of any breed, gender and age. A greater prevalence of the disease has been reported in male dogs. The animal’s behaviour is related the probability of developing the disease: large-sized breeds living outdoor are more likely to develop heartworm.

Clinical signs

Clinical signs of cardiopulmonary filariasis are ambiguous and not always easily visible; it takes about four months before the parasites colonizes the heart and the pulmonary arteries of the animal; it takes much longer before the number of parasites is large enough to cause clear symptoms.

Clear symptoms:

• Weakness, poor appetite, difficulty breathing under stress;
• sometimes, intermittent chronic vomiting.

At an advanced stage, the following symptoms may occur:

• Loss of weight,
• Increase in the breathing rate,
• Coughing,
• Erythrocytopenia (reduction in the number of red blood cells),
• Abdominal swelling,
• Right heart failure,
• Epistaxis (nosebleeds),
• Thromboembolism,
• Alteration of lung function.