Diagnosis of heartworms is done by examining under the microscope a sample of the dog's blood for heartworm offspring, called microfilaria. Another blood test looks for the adults by detecting antigens made by the female adult heartworm. However, this antigen test can be falsely negative if there are too few heartworms and thus not enough antigen is
Another useful diagnostic test, a chest x-ray, determines the severity of the illness and will show changes that reflect heartworm disease such as heart enlargement, pulmonary artery enlargement, as well any lung changes. A urinalysis may reveal any damage that has been done to the kidneys. Blood work can indicate if the dog is anemic from the disease, and it will help determine the overall health of the animal.
