Equine herpesvirus 2-associated granulomatous dermatitis in a horse.

This study identifies Equine Herpesvirus 2 as a likely cause of a case of repeated granulomatous dermatitis, a type of skin inflammation, in a horse. The virus was detected within infected cells and cellular giants in the deeper layers of the skin, indicated by areas of cellular death and immune cell invasion.

Introduction to Granulomatous Dermatitis in Horses

• Granulomatous dermatitis refers to a type of skin inflammation in horses. It has been associated with multiple causes including various parasites, fungi, and bacteria.
• There are also instances where the cause of these inflammation-producing diseases in horses is unknown, and these cases are referred to as idiopathic.

Identification of Equine Herpesvirus 2 as a Potential Cause

• In this particular study, a recurring case of equine granulomatous skin disease was investigated.
• The researchers found that certain changes typically associated with viral infection were primarily observed in the deeper layer of the skin, the dermis. These changes included areas of cellular death together with an invasion of immune cells, namely histiocytic cells and so-called giant cells.
• Further investigation with electron microscopy revealed the presence of viral particles not only within but also outside the cell nuclei – these particles were identified as resembling herpesvirus.

Confirmation of Herpesvirus as the Causative Agent

• The researchers then used a molecular biology technique known as polymerase chain reaction (PCR), which is used to amplify specific DNA sequences, to further identify the virus.
• The sequence results from the PCR product matched with Equine Herpesvirus 2, therefore adding this virus to the list of potential causes of equine granulomatous skin disease.

Significance of the Study

• This study contributes to the understanding of the causes of granulomatous dermatitis in horses, revealing that in addition to parasites, fungi, and bacteria, Equine Herpesvirus 2 can also lead to this disease.
• This provides a new perspective that might help in the diagnosis, treatment, and prevention of this skin inflammation in horses in the future.