Chemotherapeutic Options for Cutaneous Neoplasia

Skin tumours are a frequently encountered challenge in equine practice. The most common tumours on the skin of the horse are sarcoids, squamous cell carcinomas and melanomas, but other types of cancer are also possible. For the purpose of this presentation the chemotherapeutic options available will be divided into topical, intralesional or systemic.

Topical application
Drugs do not diffuse more than 5 mm in normal or tumour tissues before they are absorbed into the bloodstream. For this reason this form of treatment is restricted to superficial tumours; otherwise, application of topical chemotherapeutic agent will result in a tumour-free surface followed by tumour recurrence from the deeper margins of the mass. Examples of topical application of antineoplastic drugs for the treatment of superficial skin tumours in horses are 5-fluorouracil (Fortier and Macharg 1994; Paterson 1997), AW-4 LUDES (Knottenbelt and Kelly 2000), Imiquimod (Nogueira et al. 2006), aciclovir (Stadler et al. 2011), heavy metal compounds, bloodroot extract (Mair and Couto 2006), etc. [...]