Sarcoid in Horses: The Ultimate Treatment Guide (2023)

Author: Andrew McNiel   Title: DVM, MBA    Jan. 11th, 2023

What are Sarcoids on a Horse?

Horse sarcoid are the most frequent skin tumours.

Account for approximately 40% of all equine cancers.

They can affect breeds of any age and both sexes.

They usually appear in the abdominal area, inside the hind legs, around the eyes, ears and even on the horse’s limbs, and also affect places where there are healed wounds.

In general, it does not always mean that they are malignant tumors.

However, they do run the risk of spreading and multiplying to different areas of the horse’s body if not treated early and properly.

How Serious are Sarcoids on Horses?

Equine sarcoids, unlike other cancers, does not usually spread to other organs of the body, so the chances of the horse’s life being in danger are almost nil, but those strange lumpy presences on the horse’s skin should not be ignored.

Although equine sarcoids is not malignant, attention must be paid to diagnosis once detected, because as they increase in size they become problematic to treat.

When one sarcoid appears, there is a risk that other sarcoids will appear in other areas of the horse’s body.

This is why early treatment is usually the most feasible thing to do, to prevent it from spreading or increasing in size and becoming a more difficult task to remove.

So, if you notice a foreign lump on your horse’s body, see a veterinarian as soon as possible for treatment.

What do Early Sarcoids Look Like?

The first sarcoids usually appear on the skin as hairless areas, generally circular in appearance.

They are very subtle in their initial development and sometimes complicated to detect, because they are often confused with “ringworm” or chafing.

Therefore, if you detect something strange on your horse’s skin that does not go away and has little hair, it may be the growth of a sarcoid and you should not overlook it to prevent its development and growth.

My rule of thumb is that if he has any skin lesion on his body that shows no hair, then it is sarcoid, until a medical diagnosis proves otherwise.

If you begin to suspect that your horse has sarcoid, the first thing you should do is call your veterinarian.

As he will be able to give you a more accurate and experienced conclusion about the situation and, if necessary, recommend a biopsy.

Types of Sarcoids Found in Horses

There are different types of sarcoids, so they vary in size and appearance.
In order to know what equine sarcoids look like, I’m going to show pictures of sarcoids on horses.


This is the most common and superficial type, and they are slow growing.

They usually appear in areas with little hair, such as the neck, face, groin, hind legs, etc.

They have the appearance of a kind of flat, slightly scaly and thickened spot, which can cause total hair loss in the affected areas.


Causes multiple warty lesions in which the skin becomes dry, scaly and causes hair loss.

They are slow growing, but can become invasive when treated abruptly,

as well as worsen for no apparent reason.


These are lumps under the skin.

They vary in size and usually grow on the eyelids, foreskin and groin.


It is a combination of several types of sarcoid at the same time and is produced by the consequence of lesions that remain for a long time.


It is the most aggressive and invasive type of sarcoid, and due to its large size, it can be complicated to treat.

They tend to spread rapidly in the skin, causing lesions in the lymphatic vessels. They present as nodules and secondary ulcers.

What Causes Sarcoids in Horses

There are many studies that support the view that sarcoids are caused by a type of viral infection.

Currently, bovine papillomavirus (BPV) types 1 and 2 are considered to be the main etiological agent for equine sarcoids.

However, not all breeds of horses are susceptible to contracting sarcoids.

The reason being that in order for the virus to develop the horse must be genetically fit.

In other words, all horses can be exposed to the virus, but not all are at risk of developing sarcoids

And there are also genetic families that are much more susceptible to sarcoids than other breeds.

Can Horses Get Sarcoids Twice?

Horses that have been successfully treated for sarcoids are very likely to get sarcoids again.

The reason for this is that the virus is incorporated into the DNA of infected skin cells, thus transforming them into tumor cells.

However, this type of virus does not only affect horses, but also other species,

such as humans, a common example of papillomavirus is cervical cancer that occurs in women.

Can Sarcoids Spread from Horse to Horse?

There is no indication that horses with sarcoids pose a risk to other.

Although it is a cause of concern and alert for some people.

It has not been scientifically proven that this virus has the ability to be transmitted by direct contact between horses or even indirectly by flies.

In fact, the concern of some is so great that many owners of horses suffering from sarcoids have also been affected.

They isolate the horse in the stables, for fear of transmitting the virus to other horses.

However, there is no convincing evidence that horses with sarcoids are a contagious danger to others.

Treatment for Sarcoids on Horses

Although there are different types of treatments for sarcoids, there is always the risky possibility that the horse will relapse.

Treatment is variable, depending on the position, size and amount of sarcoids.

In general, the prognosis is not very encouraging, as it tends to recur regardless of treatment, which can be very costly.

The choice of treatment will depend on the following factors:

  • Number and size of existing sarcoid
  • Areas of skin affected on the horse

  • Necessary facilities and availability of drugs

  • Financial situation to cover the costs

Horse Sarcoids Treatment Options

Surgical removal

It is usually highly feasible to remove a sarcoid by simply cutting into the surrounding area.

Applying local anesthesia and then suturing the wound.

It is a low-risk procedure if only a solitary tumor is found or there is a small number of sarcoids present.

As there is enough skin left free to close the wound.

There is also the option of removing tiny sarcoids and leaving a small open wound to encourage healing by granulation.

However, 50% of sarcoids reappear despite being treated in this way.

Applying ligatures or rubber rings

The most commonly used system is the application of strong rubber rings (elastrator rings) with a special applicator.

It may cause swelling after application, but when the sarcoid disappears this also decreases.

It is possible to remove most of some sarcoids, specifically those with a short root.

This ligature cuts off the blood supply to the tumor, causing it to detach in an estimated two weeks and 10 days.

It is a useful and common method that can help control the virus in the short term.

However, it does not completely solve the problem in the long term since it can reappear.

Freezing (Cryosurgery)

There is the option of freezing the sarcoid using liquid nitrogen or some other suitable freezing agent, which causes tissue death.

If the sarcoid is large in size, most of it can be cut away first, leaving only the base frozen.

This method is usually more effective in preventing the sarcoid from reappearing.

Although it can often result in the appearance of white patches of hair due to damage to the hair follicles.

Laser surgery

Laser surgical treatment allows removal of a large portion of the sarcoid and weakening of the base in a single step or after removal of the main mass.

There is minimal bleeding because the tissues are cauterized, however, healing may be delayed.

Although scarring from the surgical process does not disappear, hair color is usually not affected.

Radioactive beads or wires

For this technique special permissions are needed to perform it, since despite being a specialized technique it is not so widespread.

However, it is effective mainly in palpebral sarcoids, those where the eyelid is affected and needs intervention.

Radioactive treatment reduces the size of the tumor although it may leave the eyelid disfigured.

BCG vaccine

BCG is a vaccine created from a bacterium known as Mycobacterium Bovis, for immunization against tuberculosis.

It can also be injected into the sarcoid tumor(s) and good results can be obtained.

However, several injections may be needed gradually over a period of weeks or months.

Its purpose is to activate the immune system of the horse’s body so that it is able to fight the tumor, or even reject its tissue.

It is most commonly used for eyelid tumors, because if it works, there is a chance that the eyelid will be saved.

Although it takes several weeks after the first injection to get good results and can produce noticeable inflammation which can cause skin damage.

There have been a few cases where injections have caused death due to anaphylactic shock from the vaccine, so horses should be given anti-inflammatory drugs before each injection.

Equine sarcoid topical treatment

Cytotoxic creams have been used specifically to treat sarcoid tumors, as they attack the sarcoid tumor cells and are highly effective.

They should be used with caution mainly on sensitive areas, such as bony areas, blood vessels or nerves.

These types of creams should only be administered by someone experienced in the veterinary field.

Horse sarcoid cream

We highly recommend PetACS cream, a topical cream for veterinary use, and it is an herbal paste that

stimulates the immune system to function as an antigen and provoke a rejection reaction by the body to the sarcoid.

PetACS Herbal Paste Cream is also used as immunotherapy, meaning that the immune system will be stimulated to reduce tumor cells and susceptibility to viruses.

It is an herbal formulation created from bloodroot powder, together with a zinc chloride solution.

PetACS cream with bloodroot powder

Bloodroot is a natural herbal plant that has important skin properties, such as salicylic acid, and is collected in the eastern United States, where it was commonly used by American Indian tribes to treat any type of skin condition.

Bloodroot achieved a great reach in the 19th century, so because of its fame it began to be used as a topical medicine against skin cancer, polyps and warts.

Bloodroot also contains other antibiotic properties.

Also, chelaratin and protopopin, all of them alkaloids.

These alkaloids are known to be chemotherapeutic agents and in addition, bloodroot is made to act on cancer cells when used as a topical treatment, and for that reason, it will help the sarcoid to heal quickly without so many complications.

PetACS cream with zinc chloride

On the other hand, zinc also plays a very important role for the immune system to function properly.

Zinc is present in all the cells of the body; therefore, it helps the immune system to fight against bacteria or viruses that try to attack the body.

It also promotes wound healing, the release of vitamin A from the liver, the production of proteins, etc.

Zinc chloride has been shown to work in promoting inflammation of the sarcoid surface, since in the company of alkaloids, it produces an alteration of the sarcoid cells so that they become antigenic to the host, or in this case, the affected horse.

The sarcoid can re-appear

Statistically, less than 20% of sarcoids are likely to reappear within 60 days of complete removal, but a second treatment with PetACS is usually more effective.

And less than 2% of those that recur for a third time recur after a final treatment.

The efficacy of bloodroot has been studied for a long time.

Therefore, treatment trials were conducted for 15 sarcoids with this herbal cream, and it has a success rate of over 90%.

And the response to treatment was sarcoid shrinkage, complete regression and almost no side effects.

Fast equine skin treatment

Treatment with PetACS is very easy to apply and is known for its speed.

The paste can be applied to the sarcoid and affected tissue daily for 5 to 7 days.

The immune system of the horse’s body will eventually take over and begin to reject the cancerous cells, resulting in a detachment of the sarcoid.

The tissue will begin to heal, and a full recovery should be expected within 20 to 30 days, often leaving no mark at all.

Other types of treatment methods require surgical intervention and multiple treatments with a lower success rate.

Should I Buy a Horse with Sarcoids?

There are approximately 8% of horses that over their lifetime may be at risk for sarcoids, and although it can rarely lead to death,

what can be complicated is the high cost of treatment and the wear and tear on the owner.

We do a lot of extensive testing prior to the sale and purchase of horses and one thing that can be a major reason

for abandoning the purchase of a horse is the discovery that it has sarcoids.

Simply put, clients look to us for guidance and help in making the decision to buy a horse.

So, without further ado, here are some of the things to consider before offering any advice.

First thing: location of the sarcoid

The first thing I will take into consideration is the location of the sarcoid.

Because depending on the area where it is located, the treatment will also depend, and so you can know with more certainty what type of treatment can or cannot be applied.

And if the sarcoid interferes with the approach increasing the risk of the sarcoid having abrupt changes and also the amount of time you have to be on sick leave after finishing the treatment, which means economic losses.

Sarcoids around the eyes are very limiting in terms of treatment options, because in that particular area, treatment has high costs.

Second thing: type of sarcoid

The second thing I have analyzed is the type of sarcoid we are dealing with.

There are 6 different types, and some can be mild and others more aggressive and complicated to cure.

For example, some sarcoids, such as occult sarcoids, are very difficult to treat.

But the malignant ones are extremely aggressive.

Third thing: how much would it cost

Now, a question of utmost importance. How much will it cost the customer to treat these sarcoids if he decides to buy the horse?

You have to take into account the cost, especially when it comes to sarcoids located in the area of the eyes and muzzle, since treatments for this type of area usually involve a high cost much higher than the value of the horse.

On the other hand, you should also take into account that sarcoids are not covered by your insurance policy.

Therefore, you should have enough savings to be able to cover all the expenses that the treatment requires and also cover any complications that may arise.

Last thing: what about resale

The horse may be your dream horse and you may be willing to offer it a home for life.

But I always analyze the client’s circumstances, as they may have unexpected changes where they have to sell their horse, or in the case of children’s ponies, they outgrow them.

You may find it very difficult to sell a horse with sarcoids, as it may have developed more tumors and may not pass the check-up period.

These aspects must be taken into account.

Should I Buy a Horse with Sarcoids will depend on the following factors:

  • Do I have the financial capabilities to afford the costs of treating a sarcoid and others if they develop?

  • Am I willing to exclude sarcoids from my insurance policy?

  • Will I make the decision to sell the horse in the future?
  • Am I prepared to sell it for a lower cost than when I first purchased it?

Andrew McNiel
Andrew McNielDVM, MBA
The author of this post: Dr. Andrew is a highly experienced equine veterinarian with a passion for promoting the health and well-being of horses. With over 20 years of practice, he has become a trusted figure in the equestrian community, known for his expertise in equine medicine and surgery. Dr. Andrew’s dedication to his profession and his patients has earned him a reputation as one of the most respected equine veterinarians in the region.