November 2016



Signalment (JPC Accession #1497357):  California sea lion (Zalophus californianus)

HISTORY:  This sea lion presented with multiple vesicular and ulcerated skin lesions over various parts of the body.

HISTOPATHOLOGIC DESCRIPTION:  Haired skin:  There are multifocal intracorneal vesicopustules, up to 3 mm in diameter, filled with degenerate and non-degenerate neutrophils, cellular and karyorrhectic necrotic debris, fibrin and granular to amorphous, eosinophilic proteinaceous fluid. The epidermis is hyperplastic with acanthosis, prominent rete ridges, orthokeratotic hyperkeratosis, pigment in all layers (hyperpigmentation), and moderate spongiosis (intercellular edema).  Within the superficial dermis, there are low numbers of perivascular lymphocytes, plasma cells, and macrophages. Lymphatics are mildly dilated (edema), and the endothelium of superficial small vessels is reactive.

HISTOPATHOLOGIC DESCRIPTION:  Haired skin, pinna:  There is a focally extensive 1.5 cm diameter ruptured, ulcerated vesicle with replacement of the epidermis by a serocellular crust of fibrin, necrotic debris, degenerate neutrophils, macrophages, lymphocytes, and plasma cells.  The epithelium adjacent to the ulcer is hyperplastic with spongiosis and moderate orthokeratotic hyperkeratosis, and is undermined forming 2 overhanging flaps. The underlying dermis contains low numbers of previously described inflammatory cells, granulation tissue (characterized by numerous small caliber vessels that are oriented perpendicular to the ulcer) and edema (characterized by clear space between dermal collagen and ectatic lymphatics).

MORPHOLOGIC DIAGNOSIS:  1. Haired skin:  Dermatitis, vesiculopustular, subacute, multifocal, mild, with orthokeratotic hyperkeratosis, California sea lion (Zalophus califonianus), pinniped. 

  1. Haired skin, pinna: Dermatitis, ulcerative, subacute, focally extensive, mild, with orthokeratotic hyperkeratosis.

ETIOLOGY:  San Miguel sea lion virus (SMSV) (calicivirus)

ETIOLOGIC DIAGNOSIS:  Caliciviral dermatitis










Caliciviridae viruses:


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