Balanced Eco Solutions

Acyclovir is considered a safe, topical option for equine sarcoids with few side effects, such as no significant inflammatory response. However, its effectiveness is debated, with some studies finding it has limited to no benefit over placebo and a potential problem with penetration to the sarcoid's deep layers. The primary downside for owners is the need for daily, long-term application over several months to potentially achieve results. [1, 2, 3, 4, 5]  

• Minimal to no inflammation: Acyclovir cream is known for not causing the significant inflammatory reaction that other topicals, like imiquimod or bloodroot extract, can induce. This makes it a preferred choice for owners. 
• No pain: The cream is generally well-tolerated by horses, with no pain or resentment from the application process. 

• Unclear mechanism of action: Acyclovir is an anti-viral medication, but bovine papillomaviruses (BPVs), which cause sarcoids, lack the enzyme (thymidine kinase) needed to activate acyclovir. [3, 6]  
• Limited deep penetration: Studies indicate that acyclovir penetrates less into the deep layers of sarcoid-affected skin compared to normal skin. [5]  
• Variable and questioned efficacy: Some studies have shown good response rates, while more recent, larger placebo-controlled studies found no better results than placebo treatment. [3, 4, 7]  

• Long-term, daily application: The main downside from an owner's viewpoint is the necessity for daily application for several months to achieve full resolution. 
• Best for small, flat lesions: Acyclovir is generally considered more suitable for smaller, flatter sarcoids rather than rapidly growing or thicker ones.