Treatment of equine sarcoid with the mistletoe extract ISCADOR(R) P (viscum album austriacus) : a double-blind placebo controlled study

Summary

Background: The Equine Sarcoid (ES) is the most common skin tumour in horses. It is difficult to treat: recurrence rate is high and no single universally effective treatment for ES is known. Viscum album extracts (VAE) are used as adjunct in the treatment of some human cancers without known side effects.
Hypothesis: We hypothesized that the long-term therapy with VAE (Iscador® P) is effective in Equine Sarcoids as a single treatment or as an adjunct treatment to selective surgical excision.
Material and methods: Of 53 horses with ES, 42 were treated solely with VAE as monotherapy and 11 were treated after selective excision of ES. Horses were randomly assigned to the treatment group (VAE; n=32) or control group (Placebo; n=21). The horses received rising concentrations of Iscador® P extract from 0.1 mg per ml to 20 mg per ml or physiological NaCl solution 3 times a week over 105 days s.c. Number, localization, size and type of the ES were documented over 12 months. Horses were grouped in 3 classes: individuals with <3 ES, 3 to 9 ES and >9ES. Statistical analysis of effects was divided in horse level and sarcoid level analysis. In horse level analysis effects were assessed considering the development of all 3
tumours found in the horse. Outcome of this analysis was cure, improvement (decrease of tumour size by 50% or more in at least half of the tumours), unchanged status or deterioration, respectively. Sarcoid level assessment included analysis of 1 to 7 clinically relevant sarcoids per horse comparing parameters of size and quality of single tumours in both treatment groups. All analyses were performed using statistical package STATA ver.9.2. Significance level was set at p<0.05.
Results: Horse level: In the VAE group, 13 horses (40.6%) showed an improvement. Of these, 9 patients showed complete remission (28.1%). In the control group only 3 cases (14%), all showing complete remission, were classified as improved. Significantly better results were observed after VAE treatment in horses with 3 to 9 ES compared to those with <3 ES or >9 ES. Sarcoid level: After one year observation time in the VAE group 27 ES showed complete remission (37.5%) and there was an improvement in 48 (66.7%) ES. In contrast, in the control group 9 ES with complete remission (13.2%; n.s.) and 17 ES (39.5%; p=0.005) with improvement were found. The only side effects observed after VAE were slight oedema at the injection site in 5 of 32 cases, which disappeared spontaneously within two to three days.
Conclusions: VAE (Iscador® P) represent a safe and effective treatment for ES, particularly in cases with multiple sarcoids.