Introduction
Sarcoids are locally aggressive fibroblastic tumours that are the most
common neoplasm in equids, reportedly accounting for up to 67% of all
neoplasms (Ragland et al. 1970; Cotchin 1977; Marti et al. 1993; Sullins
et al.1986). The tumours are non-metastatic but can be very aggressive
locally. Although metastatic dissemination does not occur, the tendency
for exacerbation means that treatment is usually recommended, especially
whilst the lesions are small and manageable (Knottenbelt et al. 2015).
Currently no treatment is available which produces repeatable resolution
in all cases and the prognosis is always guarded because of the high
risk of recurrence and development of new lesions (Knottenbelt et al.
2015). Numerous different treatment modalities are available, but none
are universally effective, and none can be applied in all cases. The
choice of which treatment to use in an individual horse will be affected
by factors such as the type, location, extent and duration of the
sarcoids, as well as cost. Treatment options include ligation, sharp
surgical excision, laser excision and ablation, cryosurgery,
hyperthermia, electrocautery, immunomodulation, autogenous vaccines,
anti-viral drugs, radiotherapy and topical / intralesional chemotherapy
(including electrochemotherapy). For practical reasons, topical and
intralesional treatments are commonly employed in equine practice to
treat sarcoids. Topical drugs include chemotherapy agents such as
5-fluorouracil, and compounds containing heavy metals, such as arsenic
trioxide, mercuric chloride and antimony sulphate. One compound commonly
used in the UK is AW5-LUDES cream1(sometimes referred
to as the “Liverpool cream”, sourced from Equine Medical solutions),
which is a formulation containing fluorouracil (an anti-metabolite
chemotherapy agent) and heavy metals. The cream is strongly caustic, and
there is a significant risk of spread / run-off where the material
causes damage to adjacent normal tissues. This case presents a
previously undocumented complication of AW5-LUDES cream treatment.