Differential Diagnosis: Proteinuria in Cats

Barry Hedgespeth, BVSc, North Carolina State University

Karyn Harrell, DVM, DACVIM (SAIM), North Carolina State University

ArticleLast Updated April 20211 min readPeer Reviewed
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A gray British Shorthair cat is lying on a windowsill, with its front paw extended and a calm expression on its face. The soft natural light from the window highlights the cat's plush fur and striking amber eyes.

Following are differential diagnoses for cats presented with proteinuria.

Prerenal

  • Hemoglobinuria

  • Myoglobinuria 

  • Light chain immunoglobulins (multiple myeloma, lymphoma)

Renal

  • Functional or physiologic

    • Congestive heart failure

    • Strenuous exercise

    • Fever

    • Seizure

    • Exposure to extreme temperatures

  • Glomerular

    • Infectious

      • Bacterial (eg, chronic bacterial infection, mycoplasmal polyarthritis, endocarditis)

      • Viral (eg, FIV, feline infectious peritonitis, FeLV)

      • Protozoal (eg, toxoplasmosis) 

      • Fungal (eg, cryptococcosis, other systemic fungal infection)

    • Inflammatory

      • Acute pancreatitis

      • Cholangiohepatitis

      • Chronic progressive polyarthritis

      • Systemic lupus erythematosus

      • Other immune-mediated diseases

    • Neoplastic

      • Leukemia

      • Lymphoma

      • Mastocytosis

    • Miscellaneous

      • Acromegaly

      • Drug reactions

      • Diabetes mellitus

      • Corticosteroids (endogenous/spontaneous hyperadrenocorticism and exogenous)

      • Hyperthyroidism

      • Systemic hypertension

    • Familial

      • Membranous nephropathy

      • Amyloidosis (Abyssinian, Siamese)

  • Tubulointerstitial

    • Chronic kidney disease

    • Acute kidney injury

      • Toxins (eg, NSAIDs, acetaminophen, ethylene glycol, lilies [Lilium and Hemerocallis spp], heavy metal ingestion [eg, lead, mercury, arsenic, thallium], insect or snake bite)

      • Hypotension

Postrenal

  • Bacterial cystitis

  • Idiopathic cystitis/FLUTD

  • Urolithiasis

  • Neoplasia (eg, urothelial carcinoma, other)

  • Prostatitis (rare in cats)

  • Vaginitis

  • Pyometra