Macroscopical and histopathological changes in regressing primary and recurrent equine sarcoids during active specific bio-immunotherapy.

The article examines how sarcoids in horses, either primary or recurrent, regress during bio-immunotherapy. The treatment involves debulking the tumours and then immunizing the horses with an autogenous vaccine made from the excised part of the tumour. Regular inspections and biopsies are part of the follow-up procedure. The study found that most histopathological features typical of equine sarcoid significantly diminished with the onset of visibly normal epithelisation, though the changes were more evident in primary tumours than recurrent ones.

Methodology

• The researchers observed the healing sarcoids in 18 horses, which were part of earlier clinical studies involving 29 horses with either primary or recurrent sarcoids.
• The tumours in these horses were surgically debulked, leaving the base in the skin.
• Post-surgery, the horses were immunized at 2- to 4-week intervals. The immunization process used an autogenous vaccine developed from the excised part of the tumour. The immunizations were done regularly until the tumour base visibly regressed.
• Healing progress was tracked through regular inspections and serial biopsies from the base. These biopsies were then studied under a light microscope.

Results and Observations

• As the healing process commenced, visibly normal epithelisation first occurred at the margin of the tumour’s base and gradually progressed to the centre. The rate of this epithelisation was reported to be almost equal to that of normal horse skin.
• Most of the histopathological features typical of equine sarcoid, such as abnormal cell growth, significantly diminished during the follow-up biopsies, typically when the first signs of normal epithelisation appeared.
• The healing and regression changes were more prominently visible in primary tumours than in recurrent ones.

Conclusions

• No leucocyte infiltration, lysis, or apoptosis were observed during the regression process, suggesting no additional damage or cell death was caused by the treatment.
• The results from this bio-immunotherapy treatment seem to simulate a spontaneous healing process, providing encouraging prospects for the treatment of equine sarcoids.