Pathological changes associated with equine arteritis virus infection of the reproductive tract in prepubertal and peripubertal colts.

The research investigates the severity of infection caused by Equine Arteritis Virus (EAV) in the reproductive tract of prepubertal and peripubertal colts and the relationship it has with the stage of maturity of the reproductive tract.

Overview of the Research

• The research involves a study of 21 prepubertal and 15 peripubertal colts that were infected with EAV via an intranasal challenge using a field isolate of EAV.
• All colts developed symptoms of Equine Viral Arteritis following the challenge, the symptoms of which included fever, ocular, and nasal discharge, edema of limbs and reproductive organs, and behavior changes.

Observations and Findings

• Post-Necropsy observations showed excessive fluid accumulation in the thoracic and abdominal cavities, lymph node enlargement, and reproductive tract edema.
• Pathological changes included acute necrotizing vasculitis (inflammation of blood vessels) involving the testes and other reproductive organs. This condition was characterized by fibrinoid necrosis (death of arterial muscle tissue) coupled with red blood cell and protein leakage into surrounding tissues.
• Colts that were examined on the 28th to the 180th day post-challenge showed lymphocytic and plasmacytic infiltrates in the reproductive organs, pointing towards a chronic immune response against the EAV infection.
• The pathological findings during the acute phase of EAV infection were markedly different from those noticed during chronic phase, which showed the presence of specific types of immune cells.

Persistence of Infection

• Out of the peripubertal colts, one was found to be persistently infected with EAV even 15 months after the challenge. It presented significant lympho-plasmacytic infiltrates in the ampullae of the reproductive tract.
• This study throws light on the persistent nature of the EAV infection in colts and how the maturity state of the reproductive tract could influence the susceptibility to a persistent EAV infection. Understanding these findings can help develop effective therapies and preventive strategies in equine health management.