February 2018

Signalment (JPC # 1917806):  Cat, age, breed and sex unspecified

HISTORY:  This cat was weak, depressed, anorexic, and had severe halitosis upon presentation to the veterinary hospital.  Radiographs demonstrated enlarged kidneys.

HISTOPATHOLOGIC DESCRIPTION:  Kidney:  Diffusely affecting small and medium caliber venules, there is loss of the endothelium within the tunica intima and expansion and effacement of the tunica media and expansion of the tunica adventitia with many viable and degenerate neutrophils; fewer lymphocytes, histiocytes and plasma cells; necrotic cellular debris; fibrin and edema (phlebitis). This cellular infiltrate also expands the capsule up to 2 mm; separates, surrounds, and replaces glomeruli and tubules; and is admixed with plump fibroblasts, fibrous connective tissue, and abundant fibrin, hemorrhage, and edema. Rare venules within affected areas are occluded by an eosinophilic hyalinized fibrin with entrapped erythrocytes and leukocytes (fibrin thrombi). Multifocally within the cortex and medulla there are many ectatic tubules, lined by attenuated epithelium, which contain variable amounts of eosinophilic proteinaceous material, sloughed epithelial cells, necrotic debris, granular basophilic material (mineral), and variably sized anisotropic crystals (oxalate).   

MORPHOLOGIC DIAGNOSIS:  Kidney:  Phlebitis and interstitial nephritis, pyogranulomatous, multifocal, moderate with fibrin thrombi, tubular and glomerular loss, fibrinosuppurative capsulitis, and tubular oxalate crystals breed not specified, feline.

ETIOLOGIC DIAGNOSIS:  Coronaviral nephritis

CAUSE:  Mutated feline enteric coronavirus (feline infectious peritonitis virus)




Effusive (wet form):  Weight loss, dyspnea, tachypnea, mild pyrexia, icterus, scrotal enlargement, palpable abdominal masses (from adhesions)

Noneffusive (dry form): Typically granulomatous inflammation, localized in the lymph nodes, kidneys, uvea, meninges, ependyma, and choroid plexus of the brain and spinal cord with vague signs of dullness, weight loss and anorexia and CNS signs (ataxia, nystagmus, seizures) in 12.5% of cases


Effusive form – Pleural effusion (40%) and effusive peritonitis (60‑70%)

Noneffusive form – Granulomatous lesions in various organs (on surface and throughout)







  1. Addie DD. Feline coronavirus infections. In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 4th ed. Philadelphia, PA: Saunders Elsevier; 2012:92-108.
  2. Fujii Y, Tochitani T, Kouchi M, et al. Glomerulonephritis in a ferret with feline coronavirus infection. J Vet Diagn Invest. 2015;27(5):637-640.
  3. Garner MM, Ramsell K, Morera N, et al. Clinicopathologic features of a systemic coronavirus-associated disease resembling feline infectious peritonitis in the domestic ferret (Mustela putorius). Vet Pathol. 2008;45:236-246.
  4. Graham E, Lamm C, Denk D, Stidworthy MF, Carrasco DC, Kubiak M. Systemic coronavirus-associated disease resembling feline infectious peritonitis in ferrets in the UK. Vet Rec. 2012;171(8):200-201.
  5. Hartmann K. Coronavirus infections (canine and feline), including feline infectious peritonitis. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. Vol 1. 8th ed. Philadelphia, PA: Elsevier Saunders; 2017:984-991.
  6. Kipar A, Kohler K, Leukert W, Reinacher M. Comparison of lymphatic tissues from cats with spontaneous feline infectious peritonitis (FIP), cats with FIP virus infection but no FIP, and cats with no infection. J Comp Pathol. 2001:125:182-191.
  7. Kipar A, May H, Menger S, Weber M, Leukert W, Reinacher M. Morphologic features and development of granulomatous vasculitis in feline infectious peritonitis. Vet Pathol. 2005;42:321-330.
  8. Kipar A, Meli ML. Feline Infectious Peritonitis: Still an Enigma? Vet Pathol. 2014;(51):505-526.
  9. Labelle P. The eye. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2016:1317-1318.
  10. MacLachlan NJ, Dubovi EJ. Coronaviridae. In: MacLachlan NJ, Dubovi EJ, eds. Fenner’s Veterinary Virology. 4th ed. Oxford, UK: Elsevier Academic Press; 2011:402-404.
  11. Mwase M, Shimada K, Mumba C, et al. Positive immunolabelling for feline infectious peritonitis in an African lion (Panthera leo) with bilateral panuveitis. J Comp Pathol. 2015;152(2-3):265-268.
  12. Miller AD, Zachary JF. Nervous system. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2016:896-897.
  13. Oliveira LB, Susta L, Rech RR, et al. Vet med today: pathology in practice. 2014; 245(8):899-901.
  14. Pesavento PA, Murphy BG. Reviews: Common and Emerging Infectious Diseases in the Animal Shelter. Vet Pathol. 2014;(51):478-491.
  15. Poncelet L, Coppens A, Peeters D, Bianchi E, Grant CK, Kadhim H. Detection of antigenic heterogeneity in feline coronavirus nucleocapsid in feline pyogranulomatous meningoencephalitis.Vet Pathol. 2008;45:140-153.
  16. Stranieri A, Paltrinieri S, Giordano A. Diagnosing feline infectious peritonitis using sysmex XT-2000iV based on frozen supernatants from cavitary effusions. J Vet Diagn Invest. 2017; 29(3):321-324.
  17. 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 Saunders; 2016:253-255.
  18. Zachary JF. Mechanisms of microbial infections. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2016:217-218.
  19. Ziolkowska N, Pazdzior-Czapula K, Lewczuk B, et al. Feline infectious peritonitis: immunohistochemical features of ocular inflammation and the distribution of viral antigens in structures of the eye. Vet Pathol. 2017;54(6):933-944.

Click the slide to view.

Click on image for diagnostic series.

Back | Home | Contact Us | Links | Help |