Our tranquility is usually absolute because we believe that our cat, spending most of its time indoors, is exposed to much less parasites. We tend to think: “those who do face a great risk of contagion are canine pets, poor dogs! A trust that can betray us and lead us to misdiagnoses that will put our feline pet at risk.

The domestic cat is an atypical host for the Dirofilariasis imcites parasite, a worm from the nematode family, known as a heartworm because it enters the pulmonary system and tries to reach the heart. The incidence of heartworm disease in cats it is 10 times lower than the incidence of this in dogs; however, the diagnosis of infection in cats is more difficult and these incidences are likely to be higher. The propensity to develop parasites is lower, typically they acquire a smaller number of worms and of smaller size; and the infection period is shorter, around 2-4 years. However, in cats they cause more problematic infections which, due to their lower frequency of incidence, can lead to wrong diagnoses and pose a serious danger to the animal. The usual age of infected cats is between 3 and 6 years.

Heartworm infection begins with the bite of a mosquito that transmits larvae through its saliva. These migrate through the tissues until they reach the pulmonary vasculature 3-4 months after inoculation. The cat has a good immune response and therefore many larvae die when they enter the lung, so that only about 2-4 parasites develop into adult worms and can remain lodged in the pulmonary arteries. Although it can happen, it is rarer for cats to have heartworms.

Despite the above, the disease in cats can be more serious than in dogs. When the larvae enter the pulmonary vasculature, the cat can show respiratory disease, which can sometimes be severe. Later, the few larvae that survive and evolve into adult worms live in the pulmonary arteries without causing signs in cats; but, when these worms die over time, they again originate a process in the cat that can lead to its death, so that the death of even a single worm can kill the animal. There is also the fact that some cats can remain asymptomatic and never show signs of illness.

The clinical signs of parasitic heartworm infection are very unspecific. Diagnosis solely by clinical signs is therefore very difficult. These are generally respiratory and gastrointestinal signs and can be acute or chronic. We can stand out:

  • Exercise intolerance, lethargy, lack of energy, difficulty walking
  • Loss of appetite, weight loss, anorexia
  • Cough, shortness of breath, fast breathing
  • Intermittent vomiting, diarrhea
  • Tachycardia, seizures, shock, fainting
  • Anxiety, open mouth
  • Sudden deaths can also occur without other obvious signs

The treatment of feline heartworm is not easy, so for all these reasons, it is very important to prevent the disease in cats that live in areas where there is disease in dogs, even in indoor cats, since mosquitoes they can be introduced inside the houses. The ideal is to apply a good monthly prophylaxis, especially coinciding with the hot and humid times of greatest activity of mosquitoes. The plan will surely include the administration of the Double Monthly Protection against internal and external parasites, using the most appropriate antiphrastic.