What is toxocariasis?
Toxocariasis is a very common canine parasitic disease caused by infestation by roundworms of the roundworm family called Toxocara canis.
How can my dog get toxocariasis?
Toxocara canis, the parasite in question
Toxocara canis is a white to dew colored long nematode whose definitive host is the dog. Being able to measure up to 20cm, it lives freely in the intestinal lumen of the animal where it feeds on chyme (the intestinal contents). The eggs of the parasite are eliminated in the animal's stool and thus contaminate the environment.They become infesting in 10 to 15 days if the temperature is between 15 and 30°C and if humidity and oxygenation are favourable. Eggs can remain infesting for 2 years if conditions are right.
When the infesting eggs are ingested by the animal, the larvae they contain pass through the liver, lungs and trachea to end up in the digestive tract. Some larvae can encyst in the breast tissue, uterus or muscles to resume their cycle later.
Oral or transplacental contamination
Contamination of the dog is done by ingesting the eggs of the parasite present in the environment or if the dog eats a prey infested by the worm (rodent, for example).
But it is common for puppies to be infected in utero through the transplacental route.
Can toxocarosis be transmitted to humans?
There is no direct contagion from an infested dog to humans because the eggs must become infective in 1 to 3 weeks for them to infect humans. On the other hand, a human being can become infested by consuming plants soiled by infesting eggs of the worm present in the environment. Contamination of children is very common when they play in sandboxes containing canine or feline droppings because it is a favorable environment for the development of eggs. Human infestation by Toxocara canis can lead to larval migrations in the eyes or in various organs.
What are the symptoms of toxocariasis in dogs?
Toxocara canis has a fairly low infestation power so that the animal manages to completely get rid of the worm in most cases and its infestation often goes unnoticed.
On the other hand, the infestation is where it originated:
- weight loss or growth curve abnormalities,
- a dull coat,
- fatigue,
- abdominal distension,
- vomiting,
- and diarrhoea.
During a massive infestation, the parasite - large in size - can form veritable pellets in the animal's digestive tract and create an intestinal obstruction.
How is the diagnosis made?
To find out if an animal is suffering from toxocariasis, the veterinarian uses a parasitic coproscopy. He collects some of the animal's stools, which he then observes under the microscope in order to highlight the parasite eggs or the adult worm directly.
Additional examinations can be carried out such as blood tests in the event of a massive infestation.
What is the treatment for toxocariasis?
The treatment of the infested dog is based on the use of anthelmintics, in other words effective dewormers against the family of worms to which Toxocara canis belongs.
A second treatment may be necessary 2 to 3 weeks after the first intake in order to eliminate all the worms present in the dog.
At the same time, it will be necessary to pick up the dog's droppings in order to limit the presence of the parasite in the environment. If it is a puppy and it still relieves itself inside the house, then it is necessary to clean the floor with high pressure steam in order to eliminate the eggs.
How to prevent toxocariasis?
In order to prevent the infestation of dogs and humans by these worms, it is recommended to deworm adult dogs every 3 months as a preventive measure and in particular the dogs most at risk such as dogs of hunting or coprophagous dogs (which eat their own excrement or that of other animals).
Puppies should be dewormed from the age of 2 weeks then every 15 days until two weeks after weaning then once a month until they are 6 months old.