JPC SYSTEMIC PATHOLOGY
SPECIAL SENSES
MAY 2018
S-P02

Signalment (JPC# 1754374):  Unknown age and gender New Zealand white rabbit 

HISTORY:  A New Zealand white rabbit had crusting, erythema and intense pruritus in both ears.

MORPHOLOGIC DESCRIPTION:  Haired skin, pinna:  Diffusely, the epidermis is hyperplastic and covered by a thick, up to 3 mm crust consisting of loosely arranged lamellations of orthokeratotic and parakeratotic hyperkeratosis, entrapped degenerative inflammatory cells (serocellular crust), numerous arthropod adults and eggs and colonies of 1-2 µm diameter basophilic cocci.  Mites are approximately 300 µm wide with a chitinous exoskeleton, few spines, striated musculature, jointed appendages, a digestive tract and ovary.  Within the ovary is a large, developing egg characterized by numerous eosinophilic globules.  Eggs are oval, 60 µm in diameter with a thin, 2-3 µm, pale eosinophilic shell and contain numerous 2-3 µm basophilic, round and variably-sized eosinophilic globules (yolk material).  Diffusely, the epidermis is moderately hyperplastic with acanthosis, spongiosis and prominent anastomosing rete ridges.  Multifocally, the underlying superficial dermis is infiltrated by low numbers of heterophils and macrophages.  Diffusely, apocrine glands are ectatic.  

MORPHOLOGIC DIAGNOSIS:  Haired skin, pinna:  Hyperkeratosis, orthokeratotic and parakeratotic, diffuse, severe, with mild heterophilic dermatitis, epidermal hyperplasia, and numerous superficial intracorneal adult mites and eggs, etiology consistent with Psoroptes cuniculi, New Zealand white rabbit, lagomorph.

ETIOLOGIC DIAGNOSIS: Psoroptic otitis externa; psoroptic otoascariasis

CAUSE:  Psoroptes cuniculi

CONDITION:  Ear canker; psoroptic mange; psoroptic scabies; ear mange

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: John Wiley & Sons; 2016:303.
  2. Bowman DD. In: Bowman DD, ed. Georgis’ Parasitology for Veterinarians. 10th ed. St. Louis, MO: Saunders Elsevier; 2013:392.
  3. Gardiner CH, Poynton SL. Morphological characteristics of arthropods in tissue section. In: Gardiner CH, Poynton SL, eds. An Atlas of Metazoan Parasites in Animal Tissues. Washington, DC: Armed Forces Institute of Pathology; 1999:56-58.
  4. Hargis AM, Myers S. Integumentary system. In: Zachary JF, Pathologic basis of Veterinary Disease. 6th ed. St. Louis, MO: Mosby Inc; 2016:1247. 
  5. Mauldin EA, Peters-Kennedy J. Integumentary Systems. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. Philadelphia, PA: Elsevier; 2016:675-676.
  6. Miller WH, Griffin CE, Campbell KL. Dermatoses of exotic small mammals. In: Miller WH, Griffin CE, Campbell KL, eds. Muller and Kirk's Small Animal Dermatology. 7th ed. St. Louis, MO: Elsevier Mosby; 2013:858.


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