Almost every horse owner has had to deal with equine sarcoids at least once. In fact, sarcoids account for nearly 40% of all equine cancers.1 Even if you haven’t dealt with them yet, chances are you’ll come across the topic sooner or later. Persistent and locally aggressive, these skin lesions and tumors can appear just about anywhere on a horse’s body. Once they appear, they rarely disappear on their own.
Often developing as wounds, they pose an even greater challenge to less-experienced horse owners. Many, for example, confuse them with proud flesh.
But the reality is that equine sarcoidosis is more frustrating and challenging to deal with. Understanding sarcoidosis, including how and where they appear, how to treat them, and what to expect, is the key to managing your horse’s long-term well-being and quality of life.
What Causes Sarcoids in Horses?
The most common cause behind equine sarcoids is the bovine papillomavirus. However, not every horse exposed to the virus will develop sarcoids. Only genetically susceptible horses will trigger the tumor to grow.2
To make matters worse, the virus can embed itself into the DNA of skin cells and permanently alter them. As a result, even after successful treatment, horses are at risk of relapse, making sarcoids one of the most persistent problems for horse owners.3
Throughout the article, we will examine treatment options for sarcoids and ideas on how to prevent them from coming back.
Are Sarcoids a Contagious Disease?
This is a long debate within the equine community. There is currently no conclusive scientific evidence proving that sarcoids are contagious. However, there is a growing suspicion that they spread through direct horse-to-horse contact or by flies as potential carriers.
Findings link flies with part of the virus, including its DNA and protein. However, the complete virus has yet to be isolated in flies.
Despite the uncertainty, the fear of transmission is real. Many livery yards and boarding facilities hesitate to accept horses with visible sarcoids. Despite the lack of definitive proof, owners face challenges and often have to accept the rejection.
Types of Sarcoids
There are five types of equine sarcoids, each with distinct characteristics, behaviors, and treatment challenges. Understanding how they are different is crucial for accurate diagnosis and treatment for your horse.4
Verrucose Sarcoids
Verrucose sarcoids are among the least aggressive types, often resembling scar-like lesions. They grow slowly into wart-like, scaly growths. While they are typically superficial, verrucose sarcoids can extend deeper into the horse’s skin compared to occult sarcoids. Often, they appear as multiple irregularly shaped lesions.
Occult Sarcoids
Occult sarcoids appear as smooth, flat patches of hair loss with a grey and scaly surface. Considered mild and non-invasive, horse owners often confuse them with ringworms due to their circular shape. Horse owners will likely notice them on the horse’s nose, the side of the face, and the inner thigh.
Nodular Sarcoids
Nodular sarcoids develop as firm lumps beneath thin, shiny skin. They often have a spherical shape and can attach to the skin with either a flat base or a narrower, stalk-like stem. While they grow at a moderate rate, their behavior can change unpredictably. In some cases, they become more invasive.
Fibroblastic Sarcoids
Fibroblastic sarcoids are more aggressive, often appearing at the site of a wound. From there, they quickly expand, becoming ulcerated and inflamed. These are often mistaken for proud flesh in horses, especially by less experienced owners. While they are locally invasive, fibroblastic sarcoids can invade the area beneath the skin and cause discomfort for horses.
Mixed Sarcoids
As the name suggests, mixed sarcoids are a combination of different types. Horses can have multiple sarcoids in one area, each with different features. At the same time, they can develop different sarcoids across the entire body. The variability poses a challenge to treating and managing.
Malevolent Sarcoids
Malevolent sarcoids are the rarest, but the most aggressive form of sarcoids in horses. They spread rapidly through the skin and can travel through lymphatic vessels. They can develop spontaneously, but more often, they emerge after failed treatments. Once they appear, they pose a challenge to treatment and carry a serious prognosis.
Where Do Sarcoids Appear?
Equine sarcoids can be one of the most frustrating horse skin conditions for horse owners to handle. They can develop anywhere on the body, however, in most cases, they appear on:
- Ventral thorax
- Abdomen
- Head
- Paragenital region
How to Identify Sarcoids in Horses
The appearance of sarcoids can vary depending on the type and stage. Initially, they appear innocuous and can be easily overlooked. Some types of sarcoids can be concealed within the horse’s coat, making them harder for horse owners to recognize.
In the early stages, they often look like smooth, nodular skin lumps. However, others can have irregular shapes from the beginning. Lumps may grow over time, and the speed depends on the type of sarcoidosis.
If you suspect that your horse has sarcoids, it is best that you take them to the vet for a checkup. Veterinarians can often make the diagnosis by appearance, but sometimes, they may need to take a sample to confirm. To do so, they’ll use a fine needle aspirate or perform a biopsy to determine the condition.
What Increases a Horse’s Risk of Developing Sarcoids?
While exposure to the bovine papillomavirus is a known trigger, several other factors may increase a horse’s likelihood of developing sarcoidosis:
- Genetics: Horses with a family history of sarcoids are more likely to develop them.
- Age: Young adult horses, ages 3-6, are most commonly affected, though all ages can be at risk.
- Injury or Skin Trauma: Open wounds or repeated irritation can create opportunities for viral entry and infection.
- Environment: Horses in high-fly zones or communal turnout situations may be more exposed to potential virus carriers like flies.
Knowing these risk factors allows owners to take more proactive steps toward prevention and monitoring.5
Common Treatment Options for Sarcoids
The best treatment for sarcoids varies depending on the type and your horse’s condition. Over the years, various treatments have been used to help horses cope with this skin condition. Factors like types of sarcoids, location, extent, treatment cost, and temperament of the horse can all determine the type of treatment. However, it’s important to note that even with treatment, sarcoids tend to recur, further increasing the cost of managing the condition. With that in mind, let’s take a look at the available treatment options.
Medical Treatment
Medical treatments for equine sarcoids include the immune stimulant Bacillus Calmette Guerin (BCG), a vaccine originally used to prevent tuberculosis. Medical professionals inject it into the tumor to reduce the symptoms, stimulate the immune system, and eventually, eliminate the tumor. This treatment is partially effective and often requires multiple sessions. During the procedure, horses need to be under heavy sedation.6
Other medical treatments include chemotherapy drugs, topical chemotherapy cream, and ointments with extracts of the bloodroot plant.
Surgical Treatments
Surgical removal of sarcoids has had a very poor success rate, with local recurrence often reported. The challenge with surgery is that it is not possible to visually identify the margin between the tumor and normal tissue. To maximize the success rate, surgery should include different options, including surgical excision, cryosurgery, and laser surgery. Following the surgery, additional therapy for wounds is recommended to reduce the chance of recurrence.7
Ligation
For this method, medical professionals apply a tight band around the base of the tumor. While it is efficient for some horses, there is a high risk of leaving residual tumor cells behind. Eventually, they can regrow and cause additional discomfort to the animal.
Electrochemotherapy (ECT)
This method for treating equine sarcoids involves injecting chemotherapeutic drugs into the sarcoid and applying high-voltage electric pulses. The idea is to increase the drug concentration in the cells, thereby enhancing its effectiveness.
Topical Treatments
There are plenty of special animal wound care products that help smaller superficial lesions. The equine world continues to work on developing successful topical treatments.
Radiation Therapy
Radiation therapy has shown great success in treating sarcoids in horses. However, the method requires general anesthesia and can easily pile up costs. Because of technical difficulties, only specialized medical centers offer this option.8
Laser Removal
A relatively novel treatment for equine sarcoids, laser therapy can remove the tumor along with a margin of healthy tissue. The belief is that the laser will reduce the chance of leaving behind any potential cancerous cells. Unlike other methods, laser therapy offers the least invasive method. Medical professionals can perform it with standing sedation and local anesthesia. As the least discomforting method to horses, laser removal is gaining popularity in the equine world.
Follow-up Treatment
Whatever treatment options for equine sarcoids owners and their veterinarians select, it is essential that they continue until they reach an effective response. Stopping treatment before the sarcoid has been eliminated increases the risk of recurrence, often with a worse lesion than the original.
Final Words for Horse Owners
While no solution fits all for equine sarcoids, supportive equine care is essential. There are three keys to increasing the success rate for sarcoid treatment: early intervention, consistency, and the right products.
Vetericyn animal skin care and wound care products help protect, moisturize, and provide relief to wounds and topical skin issues. Our formula can clean hard-to-reach areas on your horse and help ease the discomfort of your horse.
No matter which treatment for sarcoids you choose, the aftercare is just as important. Our antimicrobial wound care products help to clean, flush, and moisturize wounds. Remember to always consult with a certified veterinarian for the best plan for your horse and see how Vetericyn can play a role in helping your animal have a higher quality of life.
Reviewed by C. Scott Van Winkle
Scott has been with Innovacyn for the past 11 years and has been working within the Burlingame portfolio of companies for the past 23 years. Scott brings a diverse background to Innovacyn. With an upbringing as the 5th generation on his families cattle ranch, Scott has a passion for animal health and the continuous improvement surrounding agricultural practices. Scott earned marketing and business management degrees from the University of Idaho and holds an Executive MBA from Pepperdine University.
Sources:
- “Royal Veterinary College. Sarcoids.” Royal Veterinary College, www.rvc.ac.uk/equine-vet/information-and-advice/fact-files/sarcoids
- Chambers, G., et al. “Analysis of Bovine Papillomavirus Type 1 Variant Isolates and Development of a Real-Time PCR Assay.” Journal of General Virology, vol. 84, no. 4, 2003, pp. 1051–1060. Microbiology Society, https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.18947-0
- Genetic Studies of Equine Sarcoid Tumors.” Cornell University College of Veterinary Medicine, Baker Institute for Animal Health, www.vet.cornell.edu/departments-centers-and-institutes/baker-institute/research/genetic-studies-equine-sarcoid-tumors
- Knottenbelt, Derek C. Sarcoids. University of Liverpool, www.liverpool.ac.uk/media/livacuk/equine/equinepractice/Sarcoids.pdf
- MSD Veterinary Manual. “Equine Sarcoids.” MSD Veterinary Manual, www.msdvetmanual.com/integumentary-system/tumors-of-the-skin-and-soft-tissues/equine-sarcoids.
- Otten, N., et al. “Clinical, Histopathological and Immunohistochemical Investigations of Equine Sarcoids: A Study on 17 Cases.” Veterinary Record, vol. 122, no. 4, 1988, pp. 95–99. PubMed, https://pubmed.ncbi.nlm.nih.gov/3215172/
- “Surgical Management of Sarcoids.” UK Vet Equine, www.ukvetequine.com/content/clinical/surgical-management-of-sarcoids/
- Bogaert, D., et al. “Therapeutic Management of Equine Sarcoids: 445 Cases (2002–2017).” Equine Veterinary Education, vol. 32, no. 11, 2020, pp. 546–552. Wiley Online Library, https://beva.onlinelibrary.wiley.com/doi/10.1111/eve.13038
