Heartworm—Canine

Heartworm is transmitted to dogs by the bite of an infected mosquito. Dogs typically do not have clinical signs in the early stages of infection, but if infection remains undiagnosed, heartworm infection can cause severe illness and in some situations can be fatal. Therefore, prevention and routine screening for heartworm infection are critical components of the canine health plan.
Canine Heartworm
Diagnosis
Treatment

In the early stages, heartworm has no clinical signs and it may not be detectable via laboratory tests for up to six months.

Clinical signs and physical examination findings that can develop include:

  • Persistent cough
  • Exercise intolerance
  • Dyspnea
  • Abnormal lung sounds
  • Hepatomegaly
  • Syncope
  • Ascites
  • Abnormal heart sounds
  • Death

After the prepatent period, the adult stage of the infection can be determine by detecting heartworm antigen in the blood. A less sensitive means of diagnosis is to identify microfilariae in the dog’s blood.

Radiography of the chest and electro- or echocardiography may also be helpful in making a diagnosis, and may indicate the severity of the infection.

Canine Heartworm Algorith

View/print the Canine heartworm algorithm (PDF)