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Read-Only Case Details Reviewed: Jan 2009

December 2017

Signalment (JPC # 1290759): Dog

HISTORY: Tissue from a sick dog

HISTOPATHOLOGIC DISCRIPTION: Kidney and ureter: There is a diffuse inflammatory infiltrate composed of moderate numbers of lymphocytes, plasma cells, and macrophages with fewer neutrophils infiltrating within the subepithelial connective tissue of the ureter and renal pelvis, subjacent to the urothelium, which extends into the interstitium of the medulla, and is also present multifocally in the cortex.  This inflammation is confluent with multiple tertiary lymphoid nodules, which have pale germinal centers, and are underlying the urothelium. Diffusely the urothelium of the ureter and pelvis is either swollen with cytoplasmic pallor and vacuolation (degeneration), is transmigrated by moderate numbers of neutrophils that often form microabscesses, is hyperplastic, or is multifocally ulcerated and replaced by the similar inflammatory population. Extending from the medulla to the cortex in broad linear bands, abundant fibrous connective tissue admixed with the previously described inflammation, expands the interstitium and surrounds, separates and replaces medullary rays and occasionally glomeruli. Multifocally remaining tubules are ectatic, lined by attenuated epithelium, and contain eosinophilic proteinaceous material (proteinosis) or scattered cellular debris, are degenerate with vacuolated epithelial cytoplasm, or are shrunken and atrophic. Multifocally, glomeruli have one or more of the following changes: mild segmental to global expansion of the basement membranes and mesangium by eosinophilic matrix; adherence of the hyperplastic parietal and visceral epithelium of Bowman’s capsule (synechia); loss of glomerular architecture and marked expansion of the mesangium by collagen (glomerulosclerosis); are surrounded by periglomerular fibrosis, or are shrunken, hyalinized, avascular and hypocellular (obsolescence).  Multifocally Bowman’s capsule is  markedly dilated with atrophy of the glomerular tuft (glomerulocystic change), or multifocally thickened and surrounded by periglomerular fibrosis. The capsular surface is irregularly undulant and moderately thickened by collagenous connective tissue (fibrosis).

MORPHOLOGIC DIAGNOSIS: Kidney: Pyelonephritis, lymphohistiocytic, chronic, diffuse, marked with interstitial fibrosis, glomerulosclerosis, and capsular fibrosis, breed unspecified, canine.

ETIOLOGIC DIAGNOSIS: Bacterial pyelonephritis






ADDITIONAL DIAGNOSTIC TESTS: Urinalysis, urine culture, and radiographs

DIFFERENTIAL DIAGNOSIS: Bacteria that most commonly cause pyelonephritis in dogs

COMPARATIVE PATHOLOGY: Bacterial etiologic agents commonly isolated: 


  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Wiley-Blackwell; 2016:145.
  2. Breshears MA, Confer AW. The urinary system. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:659-667.
  3. Cianciolo RE, Mohr FC. Urinary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. Vol 2. St. Louis, MO: Elsevier; 2016:439-441.
  4. Jones TC, Hunt RD. The urinary system. In: Jones TC, King NW, eds. Veterinary Pathology. 6th ed. Baltimore, MD: Williams & Wilkins; 1997:1129-1131.

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