JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
September 2018
D-M21 (NP)

HISTORY (JPC #3134054): Tissue from a six month old spayed, female, Labrador retriever.  One month prior to euthanasia the dog presented with bilateral dropped eyelids and mild prolapse of both third eyelids.  This was followed by vomiting and diarrhea.  Complete blood count, clinical chemistry, thoracic radiographs and blood lead data were within normal limits.  A barium study of the gastrointestinal tract revealed a dilated, non-motile, stomach and small intestine.  A clonic-tonic head motion was noted.

MICROSCOPIC DESCRIPTION: Stomach, small intestine, large intestine:  Diffusely affecting the small and large intestine are variably dense aggregates of lymphocytes, plasma cells, and fewer macrophages that separate shrunken, atrophied smooth muscle fibers.  Within the muscular tunics there is small amounts of basophilic to eosinophilic karryorhectic debris, swollen and vacuolated smooth myofibers (degeneration), shrunken myofibers that have pyknotic nuclei (necrosis), and small amounts of basophilic granular material (mineral).  Inflammatory infiltrates extend throughout muscle layers and into nerve plexi, frequently surrounding neurons of the myenteric plexi.  Neurons within the myenteric and submucosal plexi frequently have peripheralized Nissl substance and nuclei with central pallor (central chromatolysis), decreased density of neurons and vacuolation of the ganglion.  The serosa is moderately expanded by clear space (edema).

The stomach is less affected with approximately 40% of the tunica muscularis infiltrated by multifocal to coalescing, streaming aggregates of lymphocytes, plasma cells, and fewer macrophages that separate smooth muscle fibers.

MORPHOLOGIC DIAGNOSIS:  Stomach, small intestine, large intestine: Leiomyositis, lymphoplasmacytic, multifocal to diffuse, marked, with necrosis, smooth muscle atropy and loss, and myenteric plexi degeneration, Labrador Retriever, canine.

CONDITION: Intestinal pseudo-obstruction

GENERAL:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIAGNOSIS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Cooper BJ, Valentine BA. Muscle and tendon. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals, Vol 1, 6th ed. St. Louis, USA: Elsevier; 2016:227-228.
  2. Gelberg HB. Alimentary system and the peritoneum, omentum, mesentery, and peritoneal cavity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:333,361-362,370.
  3. Hall EJ, Day MJ. Diseases of the small intestine. In: Ettinger SJ, Feldman EC, Cote, E. eds. Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat. Vol 2. 8th ed. St. Louis, MO: Elsevier; 2017:1562-1563.
  4. Harvey AM, Hall EJ, Day MJ, Moore AH, Battersby IA, Tasker S. Chronic intestinal pseudo-obstruction in a cat caused by visceral myopathy. J Vet Intern Med. 2005;19:111-114.
  5. Johnson CS, Fales-Williams AJ, Reimer SB, Lotsikas PJ, Haynes JS. Fibrosing gastrointestinal leiomyositis as a cause of chronic intestinal pseudo-obstruction in an 8-month-old dog. Vet Pathol. 2007 Jan;44(1):106-109.
  6. Miller AD, Zachary JF. Nervous system. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:900-901.
  7. Schmidt RE, Reavill DR, Phalen DN. Gastrointestinal system and pancreas. In: Pathology of Pet and Aviary Birds. 2nd ed. Ames, IA: John Wiley & Sons, Inc.; 2015:69.
  8. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier Saunders; 2016:77-78.
  9. Zacuto AC, Pesavento PA, Hill S, McAlister A, Rosenthal K, Cherbinsky O, Marks SL. Intestinal leiomyositis: a cause of chronic intestinal pseudo-obstruction in 6 dogs. J Vet Intern Med. 2016 Jan-Feb;30(1):132-140.


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