A physician will perform a complete physical examination and compile a thorough medical history in diagnosing cat scratch disease. During the exam, the physician will look for a characteristic scratch or injury and the presence of an enlarged spleen (splenomegaly). In many cases, cat scratch disease can be diagnosed solely on the basis of a patient’s report of being bitten or scratched by a cat.

Blood tests may be ordered to look for the presence of the Bartonella henselae bacteria. In addition, a Bartonella henselae immunofluorescent antibody (IFA) test may allow the physician to examine fluid or tissue from a lymph node. In some cases, a lymph node biopsy may be performed to rule out other causes of swollen glands.