Skin tumours – neoplasms – are a potentially worrying topic and imply a life threatening condition. However the proportion of cancerous (malignant) tumours is relatively low the vast majority of tumours being sarcoids.
Sarcoids are not one particular type of tumour. Although described as “locally aggressive, non-metastatic fibroblastic nodular neoplastic lesions” (Yu, 2007), there are 4 non-malignant forms, and one malignant, as well as combinations (Szcserba et al. 2009)
Sarcoids are more often noted in donkeys & mules than horses. Most affected individuals tend to be geldings with an age of onset between 1 to 7 years of age. Of the horses Thoroughbreds, Warmbloods, and those horses that often work cattle such as Appaloosas, Arabians, Quarter horses appear predisposed to sarcoid formation.
Multiple lesions are noted in 14-84% of affected individuals. Equine sarcoids tend to occur in areas of previous trauma or irritation by insects or tack, including the chest, legs, girth, and base of the ears, along with areas of thin skin such as the periocular, muzzle and ventral abdomen. Geographical variation seems to result in differing distribution.
It is the irritation of insect attack and geographical variation that supports the theory that a large percentage of sarcoids are caused by infection of the bovine papillomaviruses. These viruses are currently categorized into 6 subtypes and 2 groups (A+B). Subgroup A – transform fibroblast and epithelial cells, while Subgroup B – transform epithelial cells only. It is believed that BPV types 1 and 2, subgroup A are associated with the genesis of sarcoids. Where it starts to get complicated is that the less aggressive forms (the epithelial forms, such as occult and verrucous) can become fibroblastic when traumatised.
Other forms of tumour include squamous cell carcinoma, melanomas and basal cell tumours, which although technically not sarcoids are usually included in general description.
Veterinary treatment of sarcoids broadly falls into surgical and adjunctive therapy (Palmer, 2004). Surgical techniques include excision, cryotherapy (freezing) and CO2 (evaporation), but all this treatments have limited effect in avoiding recurrence (Borzacchiello & Corteggio, 2009).
Adjunctive therapy, usually contemporary with surgery is based on intralesional injections, topical preparations and even oral loading, and all of these therapies are based on chemotherapy or immunomodulation.
In the case of immunomodulation direct injections of attenuated mycobacterium (BCG) have been shown to permanently reduce the targeted sarcoid. Similarly commercial preparations of Propionibacterium acnes have been shown to reduce sarcoids. These products act through massive stimulation of the host immunity system so that it “recognises” the tumours as invasive and attacks them through the production of lymphocyte and natural killer cells in the case of BCG and non-specifically producing Macrophages in the latter case. Both routes generate Tumour Necrotising Factors (TNF-?), which reduce the sarcoid.
Topical applications will act through the same medium. Research has shown that bloodroot (Sanguinaria Canadensis) in a commercial preparation (Passino et al 2005) and a non-specific immunostimulator – Baypamun P (Studer et al 1997) both reduced tumour size and induced tumour regression, although it was noted that this is more likely to occur in recent rather than long established sarcoids. Aldera cream is an immonomodulator that also has had significant effects (Royal Dick Veterinary School. Sarcoid Factsheet . 2014).
In all instances the mode of action is believed be, as in the case of injections, mediated through macrophage phagocytosis – the “eating” of tumour cells by stimulated immune system. Such common themes mean that other known phytochemicals that act as immunostimulants can potentially aid in the reduction of sarcoids and anecdotal evidence of the success of functional plants, such as chasteberry, supports this theory.
It would make sense that the largest organ in the immune system, the gastro intestinal tract, would also have a role in the control of sarcoids. Oral dosing of ivomectin (an equine wormer) had positive effects on papillomas (Orac et al, 2010) and enhancement of the mammalian immune system by Cimetidine impacted on melanomas (Goetz et al, 1990).
Stimulation of the immune system is an area of interest to research and commercial enterprises that manufacture products to help with the maintenance of “condition” and many products have been shown to have a positive effect.
As well as phytochemical components of plants such as bloodroot and chasteberry, curcumin (turmeric) and garlic are powerful immunostimulants, as well as having antibacterial and antiviral properties, and so it would be logical to infer they also have an impact.
Likewise cell wall fractions, mannan oligosaccharides, fructo-oligosaccharides, pectins and ?-glucans all have ro9les in stimulating the gut immunity system at the site of the Peyers Patches, where they have been shown to promote beneficial bacteria that colonise the Peyers Parch, or directly stimulate the production of lymphocytes and macrophages.
Anecdotal evidence has shown that these products can reduce the incidence of sarcoids, particularly the occult and verrucous types.
Although it would be irresponsible to claim that functional nutrients such as prebiotics (oligosaccharides) and functional fibres in the diet (pectins and glucans), and orally or topically applied phytochemicals from herbs, can treat sarcoids. They can support immune function and improve macrophage activity. Sarcoid reduction could be the end result.
Borzacchiello G, Corteggio A. Equine sarcoid: state of the art. Ippologia 2009. 4. 7-14.
Goetz TE, Ogilvie GK, Keegan KG. Cimetidine for treatment of melanomas in three horses. J. Am. Vet. Med. Ass. 1990. 196(3). 449-452.
Palmer SE. Skin tumour management. The North American Veterinary Conference Proceedings 2004. 179-180
Passino ES, Mulas D, Careddu GM, Manunta ML, Masala G, Muzzetto P. Clinical experiences in the treatment of equine sarcoid with XX terra. Ippologia. 2005. 16(2). 11-19
Royal Dick Veterinary School. Sarcoid Factsheet . 2014
Studer U, Marli E, Stornetta D, Lazary S, Gerber H. The therapy of equine sarcoid with a non-specific immunostimulator – the epidemiology and spontaneous regression of sarcoids. Schweiser Archiv fur Tierheilkunde. 1997. 139(9). 385-391.
Szczerba-Turek A, Siemionek J, Ras A, Platt-Samoraj A, Schuszler L, Mikulska-Skupien E, Bnacerz-Kisiel A, Szweda W. Clinical types of equine sarcoids. Medycyna Weterynaryjna. 2009. 65 (12). 827-829.
Yu AA. Sufferin Sarcoid Succotash. OVMA Conference Proceedings 2007. 358-363