Dirofilariasis – The Deadly Heartworm in Dogs

When a dog is suffering from heartworm, it means that they are infected with a roundworm commonly known as heart worm. The organism is actually Dirofilaria immitis, a parasite. This worm is transmitted by mosquitoes and will infect your dog’s blood, heart and lungs. Left untreated, the disease is fatal.

Causes

Heartworms are spread through mosquitos that carry the infective heartworm larvae. The larvae enter the dog’s body through the mosquito bite wound and travel through the dog’s body to the heart. This process will take approximately six months.

Once the heartworms are living inside your dog, the adults will release immature heartworms (microfilariae) into the bloodstream of the dog. When a mosquito bites an infected dog, it will become a carrier of these microfilariae and infect the next dog it bites.

If a dog lives in a high risk area for heartworm, without preventative treatment it will almost certainly contract heartworm disease. Although heartworm is mainly endemic in tropical and subtropical areas, it is not limited to these areas. Heartworm has been identified in all 50 US states and is found worldwide.

Symptoms of Heartworm

Heartworm disease can be diagnosed by your veterinarian through a blood test. There are three classes of heartworm, and the symptoms vary from no visible symptoms to extreme ill health. It is difficult for a dog owner to identify heartworm in their pet.

The symptoms of heartworm include but are not limited to an occasional or more regular coughing, reduced canine activity or an intolerance to exercise, anaemia, fainting, chronic heart failure, labored breathing and high blood pressure.

The severity of heartworm disease will depend on the severity of the infestation, the duration of the disease and the response of the dog. All dogs are different in the way their bodies cope with the heartworm infestation.

Diagnosis

If your vet suspects your dog may have heartworm they can conduct a blood test, carry out an electrocardiograph (can reveal heart rhythm disturbances), a urine analysis or x-rays. They are looking for damage to or enlargement of the heart and associated arteries.

Treatment

Initially your dog will be hospitalized, and receive a dose of adulticide which will kill the adult heartworms. Depending on the severity of the infestation your dog may need to be hospitalized for a longer period. In some cases surgery may also be required to remove adult worms from the heart and jugular vein.

After the adult worms have been killed, treatment must be ongoing with a monthly dose of prophylaxis to kill eggs and larvae which have not been killed by adulticide.

You should be aware that the treatment for heartworm can be deadly. Even mild to moderate cases of heartworm will have a considerable impact on your dog. It is not an easy treatment for your dog, and should not be considered light heartedly.

Prevention

Heartworm disease is completely preventable through a regular dose of prophylaxis which is a preventative heartworm medication. Your veterinarian will be able to assist you with the appropriate medication and dosage to suit your dog.

If your dog does contract heartworm and has been successfully treated, you should take care to administer the monthly dose of prophylaxis as advised by your vet – reinfestation can easily occur especially in high risk areas.