JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

November 2016

I-P10

 

Signalment (JPC #1618600):  Rabbit, age and breed not specified

HISTORY:  This rabbit presented with crusty ears and a head tilt.

HISTOPATHOLOGIC DESCRIPTION:  External auditory meatus:  A large segment of the canal lumen is filled with a dense coagulum of keratin, granular eosinophilic debris, and few aggregates of heterophils, which surround numerous, often fragmented, sections of arthropod adults and eggs.  The arthropods are oval and measure approximately 350 X 500 um.  They have a striated chitinous exoskeleton, jointed appendages, striated musculature, a haemocoel, a digestive and reproductive tract, and contain an anisotropic, yellowish‑brown granular excretory material.  The eggs are oval and measure 50 X 70 um, with a 5‑8 um anisotropic shell.  The epidermis of the auditory meatus is hyperplastic and multifocally forms rete ridges.  There is multifocal parakeratotic and orthokeratotic hyperkeratosis.  Moderate numbers of plasma cells, lymphocytes, fewer heterophils, eosinophils, and macrophages diffusely infiltrate the dermis.  Lymphocytes and heterophils occasionally transmigrate the epidermis.  There is focal sebaceous gland hyperplasia.

MORPHOLOGIC DIAGNOSIS:  External auditory meatus:  Otitis externa, heterophilic, eosinophilic and lymphoplasmacytic, diffuse, moderate, with acanthosis, marked hyperkeratosis, and intraluminal adult mites and eggs, rabbit, lagomorph.

ETIOLOGIC DIAGNOSIS:  Psoroptic otitis

ETIOLOGY:  Psoroptes cuniculi

CONDITION:  Psoroptic mange

CONDITION SYNONYMS:  Ear canker; ear mange; psoroptic scabies

GENERAL:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

 COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits, 4th ed. Ames, IA: Iowa State University Press; 2016:303.
  2. Bleich VC, Johnson CK, Torres SG, Davis JH, Ramsey JM, Villepique JT, Gonzzlea BJ. Psoroptes infestation and treatment in an isolated population of bighorn sheep (Ovis canadensis), J Zoo Wildl Med, 2015;461(3): 491-7.
  3. Ginn P, Mansell J, Rakich P. Skin and appendages. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, 5th ed. Philadelphia, Pennsylvania: Elsevier; 2007:721-722.
  4. Kraus AL. Arthropod parasites. In: Weisbroth SH, Flatt RE, Kraus AL, eds. The Biology of the Laboratory Rabbit, New York, NY: Academic Press Inc; 1974:288-290.
  5. Mauldin EA, Peters-Kennedy J. Integumentary Systems. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, 6th ed. Philadelphia, Pennsylvania: Elsevier; 2016:656-657.
  6. Scott DW, Miller WH, Griffin CE. Muller and Kirk's Small Animal Dermatology, 6th ed. Philadelphia, PA: WB Saunders Company; 2001:1448-1449.


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