Another skin cancer commonly seen in the horse is squamous cell carcinoma (abbreviated as SCC). It is usually found at the muco-cutaneous junctions e.g. the corner of the eye/eyelids, vulva and penile sheath; Basically areas were skin is less pigmented. The condition has been associated with equine papilloma virus 2 with transition from warts into skin cancer and sunlight. Initial skin abnormalities can appear as warts but later become more irregular with a tendency to bleed. In more advanced stages they tend to infiltrate the local surrounding tissue and cause problems due to interfering with mechanical function (eyelids, penile sheath) and local lymph flow. A variety of treatments is available but depends on the stage (early vs. late, extend, infiltration in the region and location). Treatments can include surgery, cryotherapy (freezing), injection as well topical application with cytostatic drugs). Obviously early treatment will likely be more successful.
Picture of two early stage penile SCC. The primary complaints were failure to drop the penis (picture one with a “wartlike growth on the penile shaft) and bloody spots on the hind legs (picture 2 from a bleeding SCC on the tip of the penis).
A skin disorder that quite commonly is seen is the equine sarcoid. It probably is best to classify a sarcoid as a tumour like skin condition although the exact cause is still unclear. There is some support for possible viral involvement by an aberrant bovine fibropapilloma infection and possibly some underlying genetic predisposition. Sarcoids are often found on certain locations on the body such as close to the eye, under the abdomen and chest as well inguinal area and the axilla but other locations are possible too. Potential spread by insects has been implicated partly based on these locations (there were flies like to bite) and small predisposing wounds could also be a risk factor. Six different presentation forms are generally recognized but intermediate forms exists. A large percentage of sarcoids can be treated by “immune-stimulating creams” which basically blister the sarcoid off (and it does look ugly when this happens). However the best approach and success depends eventually on the type of sarcoid, it’s location, size etc. Success is not always guaranteed and treatment will take time as it often is taken in stages. Also while sarcoids may successfully be treated it is not a guarantee either that new ones will occur in the future. That is of course not a reasons for not treating them as over time they eventually become more aggressive and can cause problems and at that stage will be harder and more costly to treat.
Picture 1: Example of a occult sarcoid type in the lower flank area.
Picture 2: Example of a nodular sarcoid type near the (medial) corner of the eye.