EQUINE | CPD Article
is no/little hair cover and where flies feed without
hindrance.
• It has been suggested that sarcoid lesions tend to
occur on areas of skin prone to traumatic insult.
• Wounds are a common site for sarcoid
transformation - wound healing is delayed/
inhibited and complexes with granulation tissue
and sarcoid admixtures are common. Sarcoid
should be considered whenever there is incipient
and unexplained wound healing failure - there
is little clinical difference between granulation
tissue (proud flesh) and sarcoid.
Pathophysiology
• Occasional tumors exacerbate rapidly, especially
after traumatic damage, including biopsy. This
may be because incomplete excision activated
latent BPV which stimulates sarcoid growth.
• Epidemiology
• Flies have been suggested to be involved in the
transmission of an etiologic agent.
• This corresponds with the concept that sarcoids
multiply on an individual horse over the summer
and grow over the winter to become visible in the
following spring and summer.
Diagnosis
Client history
• Locally invasive, non-metastasizing, fibroblastic
tumors of the skin with a spectrum of clinical
presentations.
• Capacity for infiltrative expansion in the dermis
and subcutis.
• Metastatic spread does not occur, but some
reports of multiple small lesions occurring after
incomplete surgical removal of one sarcoid or
after autogenous vaccine usage.
• Malevolent form shares some characteristics with
aggressive, locally invasive neoplasms.
• Fibroblastic types have long sinuous pegs of tumor
tissue extending beneath the intact epidermis.
• High tendency for sarcoids to recur.
• Six distinguishable types (see under clinical signs).
• Lesions commonly seen on head (periorbital,
lips and muzzle), ventral abdomen and thorax,
especially paragenital area and axillae, and less
frequently on the limbs and upper body trunk/
dorsum.
• Lesions may worsen following iatrogenic or other
trauma, including biopsy.
• Sarcoid transformation of wounds may interfere
with wound healing.
• Horses with sarcoids require special sound
management procedures to avoid sarcoid
transformation and subsequent incipient wound
healing failure.
Clinical signs
Timecourse
• Lesions tend to persist; some static, some worsen
over time.
• Spontaneous resolution is very rare (<1%).
• May recur years after apparently successful
removal.
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Type I - Occult sarcoid
• Common around the mouth, eyes, neck and other
relatively hairless areas of the body, including the
eyelids, face, inside of antebrachium, axilla and
thigh.
• Well defined, commonly roughly circular, area
of alopecia or altered hair density and character
• Equine Health Update •