Electron microscopy does not distinguish between cowpox, smallpox, vaccinia and the molluscum viruses, so clinical information is critical. Virus may be grown from lesional skin in cell culture and then studied by electron microscopy. Growth on chick chorioallantoic membrane produces characteristic hemorrhagic pocks. Serologic tests to detect antibodies to cowpox virus are not routinely available in hospital laboratories, but may be performed in research laboratories. Previous vaccination with vaccinia may cause false positive results, but these can be eliminated by the use of specific IgM tests.
Immunohistochemistry detects cowpox antigens in feline cases.
Using electron microscopy, biopsy material may reveal viral particles. As cowpox is generally a self-limited disease, treatment is largely supportive. Patients often feel unwell and require bed rest or occasionally hospitalization. Antiviral medications are not helpful, nor are antibiotics unless the patient has developed a secondary bacterial infection. In severe cases, anti-vaccinia gammaglobulin may be given.