JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

November 2016

I-P18

 

Signalment (JPC #2416085):  Adult female African clawed frog (Xenopus laevis)

HISTORY:  This frog was submitted for necropsy.  The frog had become thin and lethargic and had an area of brown discoloration on its dorsum.

MICROSCOPIC DESCRIPTION:  Skin:  The epidermis is diffusely thickened up to four times normal with acanthosis and spongiosis.   Multifocally within the epidermis there are numerous adult aphasmid nematodes, which measure up to 100 um in diameter with a thin cuticle, a stichosome, inapparent musculature and bacillary bands, a uterus containing many eggs, and an intestine lined by multiple cuboidal cells.  Frequently, the epidermis is expanded by a cystic space (tunnel) that contains degenerating nematodes and cellular debris.  Occasionally basal keratinocytes are swollen with a clear vacuole (hydropic degeneration) and rarely cells within the stratum spinosum are rounded with intensely eosinophilic cytoplasm (dyskeratosis).  Occasionally, granulocytes transmigrate the epidermis, and there are a few lymphocytes and plasma cells in the dermis.  There is orthokeratotic hyperkeratosis with few degenerateing nematode fragments within the stratum corneum.  There is a focal area of sub-basilar erosion where the epidermis has lifted off of the basement membrane, and the remaining cleft contains a moderate amount of homogenous eosinophilic to fibrillar fluid (serum, fibrin).

MORPHOLOGIC DIAGNOSIS: Skin:  Hyperplasia, epidermal, diffuse, moderate, with viable and degenerating intraepithelial aphasmid nematodes, and orthokeratotic hyperkeratosis, African clawed frog (Xenopus laevis), amphibian.

ETIOLOGIC DIAGNOSIS:  Cutaneous capillariasis

ETIOLOGY:  Pseudocapillaroides xenopi

ETIOLOGY SYNONYMS:  Capillaria xenopodis

CONDITION:  Capillariasis

CONDITION SYNONYMS: Flaky skin disease, gray skin disease

GENERAL:

LIFE CYCLE:

PATHOGENESIS:

TYPICAL CLINICAL AND GROSS FINDINGS:

TYPICAL MICROSCOPIC FINDINGS:

Granular degeneration of dermal glands in severe cases

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

Gross:

Histologic:

None (Pseudocapillaroides xenopi is the only epidermal nematode of South African clawed frogs)

COMPARATIVE PATHOLOGY:

Other nematodes that localize in the epithelium include:

REFERENCES:

  1. Cunningham AA, Sainsbury AW, Cooper JE. Diagnosis and treatment of a parasitic dermatitis in a laboratory colony of African clawed frogs (Xenopus laevis). Vet Rec.138:640-642.
  2. Feldman SH, Ramirez MP. Molecular phylogeny of Pseudocapillaroides xenopi (Moravec et Cosgrove 1982) and development of a quantitative PCR assay for its detection in aquarium sediment.  Jour Am Assoc Lab Animal Science 2014; 53(6): 668-674.
  3. Wright KM, Whitaker BR. Amphibian Medicine and Captive Husbandry. 1st ed. Malabar, FL: Krieger Publishing Company; 2001:210, 436-437.


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