Background: Equine herpesviruses (EHV) are among the most diagnosed infectious diseases of equids. The type and clinical presentation of herpesvirus infection in donkeys can differ to that of horses. There is especially limited donkey-specific literature regarding gamma herpes viruses.
Objectives: The aim of this study was to retrospectively review positive herpesvirus cases in equids across 10 sanctuary sites in the south of England, examine the type of viruses identified and associated clinical manifestations.
Study design: Retrospective case review.
Methods: Identification of herpesvirus positive q-PCR results over a 15-month period from January 2023 to March 2024 through laboratory records. All descriptive statistical analysis was performed using R v4.2.1 and RStudio v2023.06.1.
Results: A total of 21 positive test results from 20 individual cases were examined. The population consisted of 19 donkeys and 1 pony, with ages ranging from 7 to 31. Sample types included nasopharyngeal, nasal, and ocular swabs, eye tissues and cerebrospinal fluid (CSF). EHV-2 was identified most frequently (12/21), including once in CSF, followed by EHV-8, formerly known as asinine herpesvirus-3, (8/21) and then EHV-5 (1/21). Overall, 43% (9/21) of positive cases were associated with outbreaks of disease. Serous nasal discharge was the most reported presenting sign across all positive cases (9/21), found also in 88% (7/8) of EHV-8 cases. Ultimately 70% of all positive cases resolved, 30% were euthanised, and of those 83% (5/6) had concurrent or chronic illness.
Main limitations: Due to the study design, the dataset available for analysis is limited. Consequently, only descriptive statistics are included.
Conclusion: Herpesvirus positive cases in donkeys and ponies at The Donkey Sanctuary, UK are often associated with outbreaks and a variety of clinical manifestations, from mild respiratory signs to severe neurological, respiratory, and ophthalmic disease. Screening for EHV-1 and EHV-4 in acutely unwell donkeys may overlook virus types associated with severe and infectious disease.