Understanding the Symptoms of Heartworm in Dogs

Heartworms are found almost around the world, with the most problematic regions being the warmer, more southern climates including most of the United States. Heartworms can infect dogs, cats, wolves, coyotes, foxes and other animals and this is what makes treating this condition so difficult.

Life Cycle

The heartworm starts its active life in the larva stage in a mosquito. The mosquito acts as both the host and the carrier for the parasite as it pulls the larva up when it draws blood from an infected animal and then deposits into a healthy dog or animal when it bites again. Once the larva is in the new animal, they burrow into the dog, seeking a blood vessel. They enter the blood vessels and travel to the right side of the heart by blood movement through the veins. Once in the heart the heartworms anchor themselves and grow. They can reach lengths of up to twelve inches and look like cooked spaghetti in the dog’s heart. They restrict the movement of blood through the heart as well as cause respiratory and other circulatory problems.

When the heartworms mature in the heart they then begin to produce eggs. This maturation process takes about six to eight months. A single female heartworm can produce thousands of live larva a day. These larva are then released into the arteries and carried to the outer areas of the body where they remain dormant for up to three years. They simply sit in the body and wait to be drawn up by a mosquito, where they in turn become active again and infest another dog when the mosquito bites.

Since there are so many wild animals and untreated domestic pets it is hard to control the spread of the parasite.

The Treatment

Thankfully there are several monthly pills or topical applications that can be given to dogs to prevent heartworms from living in the body, even if the dog is bitten by an infected mosquito. The treatments can also cure heartworms infestations in dogs provided the animal is otherwise healthy and the infestation is not severe.

A vet will blood test the dog to check for the presence of larva in the blood. Some dogs may carry the larva but may not have active infestations, whereas other dogs may have minor infestations but have very serious symptoms.

Generally the symptoms of heartworm infestation include:

· Coughing

· Inability to exercise without wheezing, coughing or retching

· Abnormal lung sounds

· Loss of consciousness

Generally if the symptoms are noted the infestation is already severe. It is always best to keep the dog on heartworm treatment from about the age of seven months on through their life to prevent the condition from developing.

If you live in an area where heartworms are not a problem and you are planning to travel to an area where they are with the dog be sure to start the dog on treatment at least one to two months in advance. Talk to your vet and determine which option for treatment is best for your dog.