An outbreak of foal perinatal mortality due to equid herpesvirus type 1: pathological observations.

The research paper discusses an outbreak of the equid herpesvirus type 1 (EHV1) infection in foals, examining physical and microscopic indications of the disease in affected young horses.

Overview of the Outbreak

• Twenty-nine cases of equid herpesvirus type 1 (EHV1) infection occurred on a single property, mostly impacting full-term foals.
• Some foals were stillborn, others were born weak and passed away soon after, while others appeared healthy at birth but fell ill and died within three days.

Pathological Observations

• No evident gross lesions were found apart from significant oedema (fluid accumulation) and atelectic lungs (collapsed air sacs in the lungs).

Microscopic Observations in Lungs

• Under microscopic examination, indications of the disease in the lungs were more prominent, with findings of oedema, pneumonitis (inflammation of lung tissue), and bronchiolitis (inflammation of the small airways).
• Additional intranuclear inclusions (abnormal structures in cell nuclei) were observed, suggesting viral infection.
• Many foals that survived for more than 6 hours also exhibited hyaline membrane formation, another indicator of a severe lung disease.

Observations in Other Organs

• Microscopic lesions were observed in the liver, adrenal glands, thymus, and spleen of some of the foals, signalling that the infection could have spread to various parts of the body.

The paper provides valuable insights into the pathological progression of EHV1 infection in foals and could inform future prevention and treatment strategies for this potentially fatal disease.