Topical Ganciclovir Reduces Viral Excretion in Mares With Equine Coital Exanthema.

The study investigates how a topical application of the antiviral medication Ganciclovir can reduce the replication of Equid alphaherpesvirus 3 (EHV-3) in horses, leading to less severe symptoms and decreased viral shedding.

Study Background

• Equid alphaherpesvirus 3 (EHV-3) is responsible for equine coital exanthema (ECE), a disease that can disrupt the usual horse breeding cycles due to its inclination to appear during mating.
• The practical ways to prevent ECE revolve around clinical examination before mating and brief breaks from breeding when lesions appear since there are no vaccines or antiviral therapies available.
• Current prevention methods are limited as they can’t detect subclinical infections.
• Ganciclovir, an antiviral compound known for its strong effectiveness against EHV-3, was the focus of the research, designed to assess its efficacy when applied topically to infected animals.

Study Design and Implementation

• The study employed a double-blind, completely randomized design with twenty mares split randomly into five groups – three groups were treated with varying dosages of Ganciclovir, one with a placebo, and one group received no treatment.
• The horses were purposefully infected with EHV-3 and subsequent changes in rectal temperature, clinical signs, and lesion development were consistently monitored.
• Swabs were taken daily for virus detection, using a quantitative polymerase chain reaction. In addition, serum samples were collected weekly for antibody response assessment through the virus neutralization test.

Study Results

• Mares treated with Ganciclovir demonstrated fewer symptoms and viral excretions.
• The period of viral shedding was halved from 18 down to 9 days in comparison to the untreated group.
• It was concluded that when Ganciclovir is applied to mares showing signs of ECE, the antiviral impact against EHV-3 replication is recognizable.
• Further studies are suggested in order to determine the optimal dosing of the antiviral before a definitive formulation can be established.