The efficacy of intratumoural 5-fluorouracil for the treatment of equine sarcoids.

The research investigates the effectiveness of 5-fluorouracil injections given directly into tumours for treating equine (horse) sarcoids, a type of skin tumour found in horses. The study conducted over several years concludes that this treatment method has a long term success rate of 61.5%, proving it to be a worthy comparative to other treatment methods.

Study Design and Methodology

• The research was carried out prospectively on 13 horses and a donkey. All animals had sarcoids, which were confirmed via histological examination.
• The animals were treated with an anti-cancer drug known as 5-fluorouracil, administered directly into the tumours (intratumoural) every 2 weeks.
• If sarcoids did not disappear after seven such treatments, the treatment was deemed unsuccessful for that particular case.

Outcomes and Observations

• Post-treatment, the animals were re-evaluated after 6 months. Plus, three years post the start of the treatment, the owners were contacted to report about the condition of the tumours.
• The research noted that smaller sarcoids (less than 13.5 cm3) were significantly more likely (P = 0.032) to resolve with the treatment than those larger in size.
• Sarcoids that had proven resistant to previous treatments were more likely to return (P = 0.007) three years after this study than those that had not been treated previously.
• The rates of tumour resolution were comparable in animals with multiple tumours versus those with a single one – 66.6% versus 60%, respectively.
• The small number of participants in the study meant that an accurate evaluation of the impact of tumour location on treatment success was not feasible.
• Overall, 9 out of the 13 cases (61.5%) had demonstrated resolution of sarcoids as per the owners’ report three years after the initial treatment.

Conclusions

• The research concludes that using intratumoural 5-fluorouracil compares positively with other sarcoid treatments, given its 61.5% long term success rate.
• However, the study also warns owners that sarcoids resistant to other treatments and those larger than 13.5 cm3 carry a poorer prognosis for cure, and might require more aggressive treatment approaches.