Canine herpes induced retinal dysplasia and associated ocular anomalies

Newborn Beagle puppies (38 animals from 8 litters) of a specific pathogen free colony maintained in isolation were inoculated with canine herpesvirus. Pups were killed between one and 30 days after inoculation. Histopathologic studies were carried out on the eyes and other tissues in conjunction with fluorescent antibody and viral isolation studies. Evidence of ocular inflammation manifested by panuveitis with the presence of intranuclear inclusion bodies was usually seen by the fourth day after infection. Eyes with severe inflammation showed peripheral anterior synechiae, cataract, and keratitis. The presence of the virus was confirmed by viral isolation from ocular tissues and fluorescent antibody studies. Developmental anomalies included retinal dysplasia with fold and tube formation of the neural retina, retardation of retinal maturation, and areas of necrosis and reorganization was seen. The retinal pigment epithelium showed initially patchy depigmentation and vacuolization and, subsequently, folding hypertrophy and duplication as well as areas of widespread atrophy and patchy loss. In some animals ectopic retina was found within cystic spaces of the optic nerve. These experiments confirm the ability of canine herpes infection in neonatal pups to produce severe ocular inflammation with subsequent retinal dysplasia and associated ocular anomalies.