Depending on prevalence, the positive predictive value of the heartworm antigen test ranged from 15 to 54% and negative predictive value from 99 to 99.9%. For a hospital testing 1,000 dogs per year, false-positive test results may vary from 24 to 27 dogs.
Can heartworm tests be wrong?
What is a false negative test? This happens when your dog is infected with adult heartworms and the test fails to detect their presence. Early infestations, very low numbers of parasites, and infestation with mostly male worms are the most common causes of false negatives. False negative heartworm tests are rare.
How common is a false negative heartworm test?
Blocked Antigen Causes False-Negative Heartworm Test Results The antigen test is generally considered the more sensitive test, but studies estimate that 6.0% to 38.7% of microfilaria-positive samples produce negative antigen test results.
What are the chances of a false positive heartworm test?
Recent studies have documented that antigen tests may not test positive in up to 7% of dogs due to the occurrence of “antigen-antibody complexes” that are formed in the dog's blood. These complexes bind the circulating antigen so that it is “unavailable” to react on the antigen tests.
Can a dog have a false negative heartworm test?
False-negative antigen tests occur most often in heartworm-infected animals when the host immune response traps circulating D immitis antigen in antigen—antibody complexes, preventing it from reacting with commercial assays.
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