Cedar's Year-Long Sarcoid Saga

Dr. Erin Lane was surprised when her normally easy-going warmblood gelding, Cedar, uncharacteristically took off bucking during a ride. A few days later, her instructor noticed a lesion on his inner thigh. Thus began a year-long saga, and extended stay at UC Davis, to rid Cedar of sarcoids.

Lane, a life-long equestrian and owner of Occidental Veterinary Hospital in Sonoma County, bought Cedar in 2020 during the COVID-19 lockdown. She found that the former Grand Prix jumper quickly took to dressage as a second career. Cedar and Lane had only been partners for a year when the sarcoids were discovered.

Sarcoids are commonly diagnosed skin tumors. They are generally not life-threatening. However, they can become aggressive locally, causing irritation and discomfort and limiting performance if they are in high motion areas or in contact with tack.

In Cedar’s case, the sarcoid on the inside of one hind leg rubbed against the inside of the opposite leg, inoculating it with tumor cells. He ended up with adjacent tumors that continued to irritate each other and further spread the sarcoid cells. The repetitive trauma also made it harder for the sites to heal.

“Sarcoids are notorious for having microscopic tumor cells that extend far beyond the edge of what we can see,” said Dr. Emily Berryhill, a UC Davis equine internal medicine specialist who was part of the team that managed Cedar’s case. “This means that we must treat a wide area. Cedar ended up having large areas to treat that were hard to access.”

Treatment involved a combination of surgery, chemotherapy, and radiation therapy. Initially, the mass on the right thigh was removed surgically. Both the left and right-side lesions subsequently underwent rounds of chemotherapy and radiation treatments.

“Even though Cedar was a model patient, the location of the sarcoids required general anesthesia for accessibility,” said Berryhill. “His case is an example of using an aggressive, multimodal approach that we are privileged to be able to provide at UC Davis.”

Cedar experienced some local recurrence of the sarcoids, which was addressed with laser surgery and additional chemotherapy. He resided at the Center for Equine Health (CEH) for the duration of his treatments – nearly 13 months.

“He is a very sweet, kind horse,” said Lane. “He is so much fun to ride, but I really just wanted to save his life – whether he ended up being rideable or not.”

Cedar has been back at home with Lane for a year. They have been to a show and clinics and have been practicing some upper-level movements. She checks the former sarcoid sites periodically. He has some scar tissue, but no new lumps.

“His attitude is great,” reported Lane. “It is just taking a long time. We kept going with procedures because he recovered so well and was so easy to handle. He is a unicorn.”

The staff and students at CEH and the veterinary hospital agree with that mythological comparison. We love to get updates on our beloved former patient who beat the odds thanks to a dedicated owner, advanced treatment options, skilled clinicians, and the healing power of time.

How to Determine the Right Sarcoid Treatment

• Take a thorough history - how long the mass has been there, if it is changing (and how fast), and what treatments have been done. By the time cases are seen at UC Davis, some treatments have usually been attempted.
• Determine the location, size, and depth of the mass. Small and superficial sarcoids may be treated with topical therapies at home with the help of a veterinarian. Larger or more extensive tumors may be removed surgically, eliminating the need for further treatment provided there is enough extra skin in the area to close the incision.
• Many sarcoids are in locations where a wide surgical excision is not possible, such as around the eye, on the ear, or inside of the hind leg. In these cases, smaller surgical margins are taken to ensure that there is enough skin to close the surgery site. Follow up treatment may include chemotherapy or radiation therapy.
• For large areas or if the mass continues to regrow, external beam radiation therapy, a specialty procedure available at UC Davis, may be considered. The horse is anesthetized and positioned very specifically under the radiation beam, so there are specific requirements related to the treatment area for this to be an option.
• The main goals of treatment are to manage the tumor while minimizing damage to surrounding tissues. This can be challenging as there are pros and cons to each treatment.