Why you shouldn’t let your dog play with snails: it end up with a serious infection

No one understands why the parasite Angiostrongylus vasorum is still referred to as a heartworm, as it damages the lungs. It also spreads in a completely different way: via snails.

A French heartworm (Angiostrongylus vasorum), more specifically lungworm is much smaller than the classical heartworm Dirofilaria immitis. Females of the former can grow up to 30 (!) cm, while the French variety grows up to 1-2 cm and is translucent, not white like Dirofilaria immitis. But as small as it is, it is dangerous.

Infection also occurs under different conditions to normal heartworm, which enters the dog’s body through a mosquito bite. The intermediate hosts of Angiostrongylus vasorum are usually snails or frogs, and it can also be contracted by dogs licking up snail shells left behind, or eating infected faeces. Although most dogs don’t eat snails deliberately, they can accidentally put them in their mouths and get into trouble.

How does French heartworm damage the dog’s body?

After ingestion, the microscopic worm larvae enter the stomach of the dog and, once in the intestine, burrow through the intestinal wall and migrate to the lymph nodes in the intestinal fundus. From there, after a certain developmental period, they travel as stage 5 larvae to the liver and then to the heart, where they can settle, before reaching their final destination, the lungs.

They grow up in the dog’s respiratory veins and begin to reproduce: the female lays her eggs in the blood, which hatch in the capillaries of the lungs.

They then burrow into the alveoli, severely damaging the tissue. This can happen within 6-10 weeks of infection. The dog will return the parasite larvae to the outside world by coughing or, after regurgitation and digestion, by defecating, which may then be reintroduced to the public host or another dog. Angiostrongylus vasorum is not dangerous to humans, at least no documented cases of infection have been recorded so far.

Symptoms of French heartworm disease

If there are only a few worms in the dog’s body, the animal may cough very little, but if there are many, you may witness a persistent coughing. In addition, a large part of the surface of the lungs can be damaged and the animal becomes tired due to lack of oxygen.

Doctors can only speculate as to the cause, but the French heartworm can also cause blood clotting disorders. Signs include wounds that are difficult to heal, bruising and blood clots in the body cavities, which can sometimes lead to death.

What to do if your dog is suspected of having lungworm?

The doctor will detect the worm larvae in the animal’s faeces or sputum, and may also test the blood to confirm infection. If the diagnosis of French heartworm disease is successful, the dog is given an antidote in the form of a drip or tablet. The treatment is very long, taking 1-2 months to kill all the worms. Without treatment, it can live for years in the host’s body.

Relief from symptoms can only be expected if the lung surface is not yet damaged enough to cause permanent deterioration. Unfortunately, the disease is sometimes fatal. Prevention is of course possible in the form of spot-on solutions or tablets. The tablets fortunately also protect against the classic heartworm.