JPC SYSTEMIC PATHOLOGY
URINARY SYSTEM
January 2018
U-T18

Slide A: Signalment (AFIP # 2948647):  One-year-old mixed breed dog

HISTORY:  The dog had clinical signs of gradual weight loss, vomiting, and anorexia.

HISTOPATHOLOGIC DESCRIPTION:  Kidney:  Multifocally, cortical and medullary tubules are filled and expanded by 10-80 um diameter, round, green-brown, birefringent crystals, occasionally arranged in concentric circles.  Tubular lumina also multifocally contain: basophilic granular material (mineral), sloughed necrotic epithelial cells, necrotic debris and/or granular eosinophilic material (protein).  Tubular epithelial cells multifocally exhibit the following changes: pale with swollen vacuolated cytoplasm (degeneration), or hypereosinophilic, shrunken angular cytoplasm with pyknotic nuclei (necrosis).  There is loss of tubular architecture, tubulorrhexis and tubular basement membranes are multifocally lined or replaced by a basophilic smooth band of mineral.  The interstitium is multifocally, mildly to moderately expanded and replaced by fibrous connective tissue and edema. The renal capsule is thickened 2-3x normal by fibrous connective tissue and is mildly pitted/undulating. 

MORPHOLOGIC DIAGNOSIS:  Kidney, tubules:  Degeneration, necrosis and regeneration, diffuse, moderate, with intratubular melamine/cyanuric acid crystals, interstitial fibrosis, and multifocal mineralization, mixed-breed, canine.

CAUSE:  Melamine/cyanuric acid toxicosis

ETIOLOGIC DIAGNOSIS:  Toxic nephropathy 

GENERAL DISCUSSION: 

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ADDITONAL DIAGNOSTIC TESTS:

STAIN Melamine-Containing Calcium Oxalate Calcium Phosphate

Oil Red O

Positive

Negative

Negative

Von Kossa

Negative

Positive

Positive

Alizarin Red S (pH 4.1-4.3)

Negative

Negative

Positive

H & E

Pale brown

Colorless, prismatic effect

Basophilic

Thompson ME, et al. (2008)

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Breshears MA, Confer AW. The Urinary System. In: Zachary JF, ed.  Pathologic basis of veterinary disease. 6th ed. St. Louis, MO: Elsevier. 2017; 679.
  2. Brown CA, Jeong KS, Poppenga RH, et al. Outbreaks of renal failure associated with melamine and cyanuric acid in dogs and cats in 2004 and 2007. J Vet Diagn Invest. 2007; 19:525-531.
  3. Cianciolo RE, Bischoff K, Ebel JG, et al. Clinicopathologic, histologic, and toxicologic findings in 70 cats inadvertently exposed to pet food contaminated with melamine and cyanuric acid. J Am Vet Med Assoc. 2008; 233:729-737.
  4. Cianciolo RE, Mohr FC. Urinary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer's Pathology of Domestic Animals. 6th ed. Vol 2. Philadelphia, PA: Elsevier Saunders;2016:426.
  5. Pirarat N, Katagiri T, Chansue N et al. The pathological effects of melamine and cyanuric acid in the diets of walking catfish (Clarius batrachus). J. Comp. Pathol. 2012; 147: 259-266
  6. Thompson ME, Lewin-Smith MR, Kalasinsky VF, et al. Characterization of melamine-containing and calcium oxalate crystals in three dogs with suspected pet food-induced nephrotoxicosis. Vet Pathol. 2008; 45:417-426.


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