JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
October 2018
D-T10 (NP)

Signalment (JPC# 2339016):  18-year-old quarter horse gelding

HISTORY:  This horse had mild to moderate colic for about 48 hours.  The veterinarian administered 500 mg flunixin meglumine; this same dose was administered three times over a ten hour period.  Despite supportive therapy, the horse died two days after admission.

HISTOPATHOLOGIC DESCRIPTION:  Colon:  Focally there is a well-demarcated, 1 cm wide ulcer characterized by loss of the mucosal epithelium, lamina propria, muscularis mucosa, and superficial submucosa with replacement by abundant necrotic debris, fibrin, numerous viable and degenerate neutrophils, fewer eosinophils, macrophages, and hemorrhage.  The inflammatory infiltrate extends into and expands the adjacent submucosa, submucsoal fibroblasts are often hypertrophed and there is submucosal edema. Within several submucosal small vessels, there is loss of the endothelium in the tunica intima and the tunica media is hypereosinophilic and both the tunica media and tunica externa are infiltrated by low numbers of neutrophils and and are expanded by variable amounts of fibrin, edema and karyorrhectic debris (fibrinonecrotizing vasculitis).  Affected vessels often contain luminal fibrin thrombi.  Remaining submucosal vessels are markedly congested. Focally within the central portion of the ulcer, there is a small portion of mucosa with retention of normal tissue architecture and loss of differential staining (coagulative necrosis).

MORPHOLOGIC DIAGNOSIS:  Colon:  Colitis, ulcerative, acute, focally extensive, severe, with fibrinonecrotizing vasculitis and thrombosis, quarter horse, equine.

ETIOLOGIC DIAGNOSIS:  Toxic colonic ulceration

CAUSE:  Non-steroidal anti-inflammatory drugs (NSAIDs)

GENERAL DISCUSSION: 

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

 

TYPICAL GROSS FINDINGS: 

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY: 

REFERENCES:

  1. Geldberg 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; 2017:374.
  2. Jones SL, Smith BP. Diseases of the alimentary tract. In: Smith BP, ed. Large Animal Internal Medicine. 4th ed. St. Louis, MO: Elsevier Mosby; 2015:693,732-734,874,1046.
  3. Constable PD, Hinchcliff KW, Done SH, Grunberg W. Veterinary Medicine:  a Textbook of the Diseases of Cattle, Horses, Sheep, Pigs, and Goats. 11th ed. St. Louis, MO: Elsevier; 2017:267-268.
  4. 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. Philadelphia, PA: Elsevier; 2016:55-57, 85
  5. D’Arcy-Moskwa E, Noble GK, Weston LA. Effects of meloxicam and phenylbutazone on equine gastric mucosal permeability. J Vet Intern Med. 2012; 26(6):1494-1499.


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