The heartworm disease is a deadly infection which can seriously affect your dog so make sure you give him/her heartworm prevention throughout his/her life to protect him/her.
Dirofilaria immitis is the parasite round worm that is spread from dog to dog through the bites of mosquitoes. The heartworm is a type of filaria, a small thread-like worm, that causes filariasis.
It is hard to know which dog might be infected because there might not be symptoms as such.
Your veterinarian can do an antigen test to check and detect infections of heartworm, usually these start appearing from five months onwards of the heartworms being present. Heartworm prevention should only be given to dogs not infected. The treatment should then be repeated regularly which your veterinarian can confirm.
Always make sure heartworm prevention has been administered to your dog in a timely manner.