Diagnosis of Feline Herpesvirus
FHV-1 is usually diagnosed on the basis of the cat's medical history and clinical symptoms. Laboratory tests that detect the virus in the cat's nasal or eye secretions can confirm the diagnosis.
Several different tests can identify FHV-1 in eye and nasal secretions.
An immunofluorescent assay of secretions from the nose or conjunctiva (membrane lining the eyelid) uses special proteins labeled with a fluorescent chemical to detect the presence of FHV-1 antibodies (proteins that the immune system makes to fight the virus).
The virus can be isolated with pharyngeal swab samples (the pharynx is the passageway that leads from the nose to the larynx, and from the mouth to the esophagus). Cotton or gauze is used to collect respiratory tract secretions from the pharynx.
Smears from the conjunctiva can be used to detect structures inside the nucleus of a viral-infected cell.
Feline Herpesvirus Differential Diagnosis
Clinical symptoms are similar to those of other feline upper respiratory infections. Cats with feline calicivirus infection do not sneeze as often and have less eye discharge and inflammation; they are also more likely to have pneumonia. Cats with chlamydiosis have more chronic conjunctivitis (discharge, pain, and swelling of the eye).
Bacterial infections usually do not involve the eyes and nose.