Heartworm Disease in Dogs

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Section: Follow-up

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical.

Administer all prescribed medications as directed. Alert your veterinarian if you are experiencing problems treating your dog.

STRICT EXERCISE RESTRICTION is the most important aspect of care at home after treatment for heartworm disease. This is imperative for the first four weeks after treatment. During this time, exercise or activity may result in an increased likelihood of pulmonary thromboembolism (PTE). PTE is interruption of blood flow to a portion of the lung due to blockage of a pulmonary artery with dead or dying worms, and associated blood clot and inflammation. The body can take care of the dying worms by breaking them down and absorbing them, but this takes time. Although PTE can occur in a dog that is being quiet, it is much more likely to occur in a dog who is exercising.

The PTE episodes can be very severe, even fatal.

Owners need to be very alert for the signs of PTE: coughing, fast or heavy breathing or fever. If these signs are noted, the dog should be presented for examination as soon as possible. If PTE is identified, it is usually treated with the administration of the anti-inflammatory drug prednisone. Oxygen may need to be administered until the dog is breathing more easily.

Some very mild coughing is to be expected after heartworm treatment. However, if the coughing is occurring frequently during the day, or if the dog coughs up blood, the dog should be examined. Any coughing should be reported to your veterinarian.

The heartworm tests need to be repeated after treatment, to ensure the treatment has been successful in eliminating the heartworms. The filarial test is done one month after the microfilaricide is given. If it is positive, microfilaricide is repeated. Cases with occult heartworm infection have repeat serology three months after treatment. If the serology is still positive, it should be repeated three months later. At that time, if it is still positive, the dog should be re-evaluated for repeat treatment. Luckily, adulticide treatment is usually successful the first time!

All dogs with heartworm disease should be started on heartworm prevention immediately after the adulticide for occult infections, and after successfully killing the microfilaria in the other cases.

In dogs determined to be medically unsuitable for heartworm treatment, an appropriate heartworm preventative will be prescribed by the veterinarian to prevent the dog from acquiring additional heartworms. Some of the heartworm preventatives available are dangerous to administer in dogs already infected with heartworms.

The American Heartworm Society (AHS) recommends that all dogs in areas endemic for heartworms should take a year-round preventative. Annual testing will ensure that an infection is caught in plenty of time to effectively manage it. Testing is also recommended when a pet owner switches between preventative medications.