Field diagnosis: Based on clinical symptoms and lesions. But these are not very characteristic hence, it should be confirmed by laboratory diagnostic tests.
Clinical materials: Oro-pharyngeal fluid, nasal fluid (swabs) or tonsil biopsies are the ideal clinical materials from live animals. From dead animals samples of brain and tonsil are the preferred specimens. In latently infected pigs, the trigeminal ganglion is the most consistent site for virus isolation, although latent virus is usually difficult to culture.
Systems for isolation: Cell culture (Pig kidney PK-15 cell line), embryonated eggs (CAM route) and rabbits (subcutaneous or intracerebellar
Lesions / CPE: As mentioned under cultivation for each system. Since latent viruses are difficult to isolate, negative results in isolation does not rule out freedom from PR.
Direct identification of PRV from clinical specimens: The polymerase chain reaction (PCR) can be used to identify PRV genomes in secretions or organ samples.
Virus neutralization test and ELISA are routinely done to identify antibodies against PR in pigs. The VN and ELISA tests detect pseudorabies antibodies in serum of pigs that have been infected with the virus. These antibodies appears in the serum about day 7 of infection and may persist for years. The presence of pseudorabies antibodies is evidence that the pig has been infected with the virus in the past or has been vaccinated. Absence of antibodies indicates that the animal has probably not been infected or that it may be in the early stages of the disease. The VN and ELISA are extremely reliable tests. While these tests accurately detect antibodies to pseudorabies, they do not differentiate between antibodies resulting from natural disease and those resulting from vaccination. Both VN and ELISA tests are approved tests for international trade.
Differential diagnosis: The infection has to be differentiated from following infections