Heartworm is spread by mosquitoes.  Biting mosquitoes transfer heartworm larvae from infected dogs to healthy dogs.  Within six months these larvae grow into adult worms in the right side of the heart.  Left untreated adult worms grow and multiply causing blockage of the right side of the heart and inflammation of the lungs.  Symptoms may include exercise intolerance, lethargy, coughing and weight loss.  Severe symptoms may develop with rapid breathing, abdominal swelling, collapse, blue gums and sudden death.

Vets diagnose heartworm with a blood test which is effective provided the heartworm infection is more than 6 months old.  Chest x-rays and general health profile may be necessary before starting treatment.  Treatment is difficult and risky so prevention is always better than cure.

However, prevention is easy with either a monthly tablet or spot on often combined with other flea and tick preventative or your vet can administer a yearly injection as a part of your pet’s Annual Health Check.  Many dog owners manage the risk of heartworm infection with a yearly injection as this removes the risk of forgetting.  Prevention needs to be year-round to be effective.