Equine herpesvirus 2 is a virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 of the family Herpesviridae

Herpesviridae

The Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...

, originally known as equine cytomegalovirus due to its slow replication in tissue culture. However, complete sequencing of the EHV-2 genome has demonstrated that it is a member of the subfamily Gammaherpesvirinae, in the genus Rhadinovirus .
. It has an uncertain role in respiratory disease in horse

Horse

The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

s, but EHV-2 has been isolated from cases exhibiting symptoms such as coughing, conjunctivitis

Conjunctivitis

Conjunctivitis refers to inflammation of the conjunctiva...

, and swollen submaxillary and parotid lymph node

Lymph node

A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...

s.