The equine sarcoid is by far the most common skin tumour of horses, and we still have much to learn about the factors which lead to its development. It affects horses of all ages, although most cases are first presented between 2 and 9 years of age.
Sarcoids can appear anywhere on the body. The most susceptible regions seem to be the armpit, groin, ventral midline, face and ears. . One interesting feature of the disease is that it often occurs at wound sites and where the skin has been damaged.
There are 6 different forms of sarcoids :
It is important to point out that individual lesions of different sarcoid types often require very different treatments.
Early veterinary intervention will help ensure the condition is held in check and not allowed to spread through the skin. Biopsy is usually not recommended for sarcoids as trauma may cause them to transform into a more aggressive tumour.
Sarcoids generally have a high capacity to invade local tissues and surrounding structures. The correct treatment method is critical and advice should only be taken from a veterinarian. Inappropriate treatment can transform an otherwise ‘quiet’ lesion into a very aggressive tumour.
Factors that influence the choice of treatment of the equine sarcoid.
- 1. Sarcoid type
- 2. Sarcoid location
- 3. Sarcoid extent
- 4. Sarcoid duration
- 5.Previous interference?
- 6. Prognosis
- 7. Logistics of treatment
- 8. Relative value of horse
- 9. Relative cost of treatment
- 10. Duration of treatment
- a. Management of treatment process
- b. Time to return to work
- 11. Animal compliance
- 12. Owner compliance
Sarcoids in different locations seem to have different clinicopathologic characteristics.
- Sarcoids around the eye tend to be very invasive with penetration into the underlying tissue.
- Sarcoids occurring on the ear tend to remain firmly localized.
- One of the most dangerous of all sites for sarcoid development are the point of the elbow and the side of the face; for some reason there is a much greater tendency for local invasion and transformation to malignant sarcoid in these locations
More than 40 different treatment options and treatment combinations are described but can be broadly broken down into the following categories : surgery, chemotherapy, immunotherapy, gene therapy, radiotherapy, phototherapy.
The wrong choice of the wrong treatment at the wrong time in the wrong place can have catastrophic outcomes.
Treatments often need to be modified and combined therapies need to be chosen. What works on the flank is unlikely to be tolerated on the eyelid. Similarly, what works on an eyelid could be too weak for a lesion on the sheath or medial thigh.
A standard principle of cancer therapy is that it is easier, and more effective, to treat small isolated early tumors. Unfortunately this concept is not widely understood by horse owners, who usually consult the Internet long before they consult a veterinarian. Not every treatment is available, practicable, or affordable in every case. This disease demands careful consideration because the wrong decision can result in a catastrophic outcome. Therapy has to be directed first at destroying the tumor in its entirety.
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