Interstitial Nephritis

Nonsuppurative

Introduction:

Nonsuppurative interstitial nephritis is a type of tubulointerstital disease that can be acute or chronic. Tubulointerstital nephritis is a type of inflammatory disease that involves the tubules and the interstitium.  The glomeruli may not be affected or affected only late in the course of infection.  Infectious agents infect the kidney tubule and cause an inflammatory response in the interstitium.

Pathophysiology:

The best known cause of acute suppurative interstitial nephritis is Leptospira canicola infection in dogs. Tubular epithelial cells degenerate and undergo necrosis due to the direct toxic effects of the infectious agent or due to the interstitial inflammation reaction. In nonsuppurative interstitial nephritis, the predominate infiltrating cells are monocytes, lymphocytes, and plasma cells. The outcome varies with the severity of the disease. In severe acute diseases, oliguric renal failure may occur, while polyuric failure may develop later.  Chronic nonsuppurative interstitial nephritis is usually a slowly progressive disease with no overt cause in the majority of animals. This disease occurs mostly in older dogs and cats. The clinical progression leads to polyuric renal failure.
 

Causes of nonsuppurative interstitial nephritis:

Gross Pathology:
The kidneys may be swollen and pale, with a random gray mottling on the capsular surface. The cut surface may bulge and the cortex may have coalescing gray infiltrates.
 

Chronic nephritis, Washington State University Vet Hospital Image database http://imagedb.vetmed.wsu.edu/Default.htm

For chronic cases, renal fibrosis may be severe.   Fibrotic kidneys are pale, shrunken, and firm.   A stippled pattern with fine pitting and a thin, granular cortex on the cut surface characterize diffuse interstitial fibrosis.

Histopathology:

Aggregates of lymphocytes, monocytes and plasma cells are concentrated throughout the interstitium. The epithelium of damaged tubules shows necrosis and degeneration.
 

For more information:

Carlton, W.W., and McGavin, M.D. 1995. Tubulointerstitial nephritis: Chapter 5: The Urinary System. In: Thompson's Special Veterinary Pathology. Mosby pp 231-225.

Pubmed:

chronic interstitial nephritis in dogs

 interstitial nephritis in cats

Interstitial Nephritis

Suppurative

This form of interstitial nephritis is characterized by the presence of neutrophils.  Bacteria are seeded in the kidney due to bacteremia or septic thromboembolism.  Bacteria or emboli may lodge in glomeruli and capillaries to produce small abscesses. The infections result in abscess formation usually  in the cortex. Healed lesions may be present, but animals usually succumb to the renal disease early.  Suppurative interstitial nephritis is caused by the following agents:

• Actinobacillus equui in foals

• Corynebacterium pseudotuberculosis in sheep and goats

• Actinomyces pyogenes in cattle

• Erysipelothrix rhusiopathiae in swine