November 2016



Signalment (JPC # 1823588):  Age and breed unspecified, horse

HISTORY:  This horse had generalized dermatitis.  Several randomly scattered nodular cutaneous lesions were also present in and around the cervical region

MICROSCOPIC DESCRIPTION:  Haired skin, site not specified:  Within the superficial and deep dermis, predominantly surrounding blood vessels and adnexa, there are variably sized, nodular, aggregates of high numbers of eosinophils, fewer lymphocytes, plasma cells, mast cells, and occasional melanomacrophages (pigmentary incontinence).  There are numerous tangential and longitudinal sections of 3-4um wide microfilaria scattered throughout areas of dermal inflammation.  The overlying epidermis is mildly hyperplastic with mild orthokeratotic hyperkeratosis.

MORPHOLOGIC DIAGNOSIS:  Haired skin, site not specified:  Dermatitis, perivascular and periadnexal, eosinophilic, subacute, multifocal, moderate, with numerous microfilariae, breed unspecified, equine

ETIOLOGY:  Onchocerca cervicalis

ETIOLOGIC DIAGNOSIS:  Cutaneous onchocerciasis






Cutaneous lesions:

Ocular lesions (caused by microfilaria):


For gross findings:



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