sarcoids in horses

Sometimes it’s obvious your horse has a sarcoid—those noncancerous skin tumors with a classic nodular or verrucous (cauliflowerlike) appearance are difficult to miss. But what about that patch of rough-looking skin or that little warty lump? Are they sarcoids? Your veterinarian can run diagnostic tests for sarcoids in horses, but those techniques aren’t without their challenges. Gold-standard biopsies can aggravate the tumors and make the disease worse, and less-invasive swabbing techniques don’t detect all cases.

But researchers in Switzerland are working toward a new way to confirm sarcoids: They’ve tested an innovative blood test that looks for recently identified biomarkers indicative of sarcoids.

The focus is on microRNAs (miRNAs)—tiny RNAs that circulate freely in the blood without cells and don’t code for anything, but seem to target and silence messenger RNAs, said Lucia Unger, DrMedVet, Dipl. ECEIM, and Vinzenz Gerber, DrMedVet, PhD, Dipl. ACVIM, ECEIM, both of the University of Bern Vetsuisse Faculty Swiss Institute of Equine Medicine and Agroscope Bern.

Researchers know miRNAs are good biomarkers for detecting cancer in humans and other mammals. And while sarcoids aren’t a cancer per se, because they don’t metastasize, they are still invasive tumors with cancerlike qualities, Unger said.

In their recent study, Unger and colleagues ran miRNA whole blood and blood serum testing on five healthy horses and six horses with sarcoids. They found that sarcoid-affected horses had nine kinds of miRNA in their serum that were significantly different from those in the healthy horses’ serum, she said. When they tested the whole blood, they found 19 miRNAs that were expressed differently in horses with sarcoids than in healthy horses.

Unger said this gives them strong hope that they’ve identified a reliable sarcoid biomarker in the blood.

“In the future, it would be great to use circulating miRNA profiles as diagnostic or prognostic biomarkers for equine sarcoid disease in daily practice,” she said.

It’s too soon, however, to put this test into practice. First, the team must validate their results through further research. Then they need to make the testing “cheaper and easier,” because the next generation sequencing they used in the study is neither, Unger said.

The connection between miRNAs and diseases such as cancer and sarcoids is not always clear, said Unger. Researchers don’t know why the body expresses these tiny RNAs differently.

“For the moment, we can only speculate on the possible biological functions of circulating miRNAs (not only in veterinary medicine but also in human medicine),” she said. “This is a very interesting field of research, and research is ongoing.”

The study, “MicroRNA fingerprints in serum and whole blood of sarcoid-affected horses as potential non-invasive diagnostic biomarkers,” was published in Veterinary and Comparative Oncology.