EXPERIMENTAL TREATMENT OF EQUINE SARCOID USING A XANTHATE COMPOUND AND RECOMBINANT HUMAN TUMOR-NECROSIS-FACTOR-ALPHA

A xanthate compound with antiviral and antitumoural activities, tricyclodecan-9-yl-xanthogenate (D609) in combination with the potassium salt of the lauric acid (KC12) and, in a further investigation, the above mentioned substances together with recombinant human TNF alpha (rh-TNF alpha), were tested on equine sarcoid rumours for therapeutic efficacy. A pilot investigation on 5 healthy horses showed that the compounds were well-tolerated; apart from a local, temporary oedema at the injection site, no other clinical symptoms were observed after subcutaneous administration of volumes from 0.1 to 10 ml per injection. The tested concentrations of D609 and KC12 (5 mg/ml solution) and of rh-TNF alpha (50 mu g/ml) were used for the treatment experiments. The repeated injections of the compounds to 11 sarcoid affected horses were also well-tolerated, except by one horse. In this case the treatment had to be interrupted after two injections because of severe reaction, i.e. fever and lameness due to oedemas. Five horses (n = 6 sarcoids) were treated by local, subcutaneous injection of D609 and KC,, under the tumour at intervals of 3 weeks. On one periocular sarcoid the compounds were applied as an ointment. After a follow-up period of 18 months, 5 rumours did completely regress and one remained unchanged. The periocular tumour showed a reduction in size. Five horses (n = 9 sarcoids) were then treated with a combination of D609, KC12 and rhT-NF alpha. After a follow-up period of 13 months, one horse showed a complete regression of the treated tumour, 3 horses showed an important reduction (50 %) in size of the treated neoplasms (n = 4) and one of those also exhibited a complete regression of the other multiple, small untreated rumours. Two sarcoids (2 horses) did not change and one of the horses even showed continuous growth of two other treated sarcoids. These preliminary results may open a new way to conservative treatment of the equine sarcoid.