There are no specific tests which are reliable in all cases. Although organ biopsy is the most reliable, this requires major surgery. For obvious reasons, surgery may not be advisable in a sick cat. The following tests are usually used on cats with suspicious clinical signs. This test detects antibodies to any coronavirus.
Antibodies are the circulating defense agents of the immune system.
If positive, this test indicates that one or both of those viruses WAS or IS present in the cat. We do not know which virus is reacting to the test. Since antibodies may persist even if the virus is no longer present, a positive test can be misleading in some cases. This can result in a false negative test result. This test must be interpreted in conjunction with results of other tests.