Electrochemotherapy Successful in Treating Equine Sarcoids

Electrochemotherapy Successful in Treating Equine Sarcoids

The four-year nonrecurrence rate was 97.9% for individual animals and 99.5% for individual tumors when sarcoids were treated with cisplatin electrochemotherapy.

Photo: Anne M. Eberhardt/The Horse

Sarcoids, the most common form of skin tumors in equids, are not only unsightly, but they also can be a frustrating condition to treat, as they often reoccur after the initial treatment. While some sarcoid treatment methods such as cryosurgery (freezing), laser therapy, light therapy, radiation, Bacillus Calmette-Guerin (BCG) injections, chemotherapy, and various topical medications have proved successful, none have been universally effective. However, a team of researchers recently examined electrochemotherapy as a treatment method with promising results.

Electrochemotherapy (ECT) combines chemotherapy and electrical field pulses, which allows for the penetration of an anti-cancer drug (cisplatin in this case) at a much higher concentration than when injected directly into the tumor. While veterinarians have used ECT on horses in the past, the treatment's efficacy for reducing sarcoids in a large number of horses had not been evaluated. A team of researchers led by Youssef Tamzali, DVM, PhD, Dipl. ECEIM, a veterinary professor at Toulouse Veterinary School (TVS) in France, completed a retrospective study to evaluate the success of cisplatin ECT treatments for sarcoids.

The researchers reviewed veterinary records of 34 horses, two ponies, 11 donkeys, and one mule that were examined at the TVS Equine Teaching Hospital from October 1999 to December 2004. The animals had a total of 194 non-malignant sarcoids in various areas of their bodies. Of those, 75 were either recurrences of previously reduced sarcoids or those that had not responded to other treatments.

The ECT was used either alone or in conjunction with tumor debulking surgery (in which as much of the tumor is removed as possible). Treatments were performed every two weeks for as long as was deemed necessary (anywhere from two to 14 weeks in this particular study). Veterinarians administered general anesthesia before each procedure as ECT treatments are not performed on conscious or sedated horses.

Upon reviewing the results, the team concluded that cisplatin ECT treatments were successful in treating equine sarcoids. Key findings included:

  • The four-year nonrecurrence rate was 97.9% for individual animals (47/48) and 99.5% (193/194) for individual tumors (Tamzali added that the one relapse most likely could have been prevented if the tumor had been debulked before the ECT treatment due to the large sarcoid size);
  • During treatment, the team noted that all 48 animals tolerated the ECT well with the most common side effect being edema (fluid swelling) in the tumor area that lasted an average of one to five days;
  • The number of treatments ranged from one to seven depending on the size of the tumor; and
  • In cases of larger sarcoids, debulking seemed to reduce the number of required treatments.

The team concluded by saying, "notwithstanding the need for repeated anesthesia, the method is simple and cost of an electropulsator is affordable for a specialized equine veterinary facility."

The study, "Successful treatment of equine sarcoids with cisplatin electrochemotherapy: A retrospective study of 48 cases," was published in July 2011 in Equine Veterinary Journal. The article can be viewed online.

About the Author

Casie Bazay, NBCAAM

Casie Bazay holds a bachelor of science degree in education from Oklahoma State University. She taught middle school for ten years, but now is a nationally certified equine acupressure practitioner and freelance writer. She has owned Quarter Horses nearly her entire life and has participated in a variety of horse events including Western and English pleasure, trail riding, and speed events. She was a competitive barrel racer for many years and hopes to pursue the sport again soon.

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