Contributors: Melissa Wallace, Penny Watson, Julien Bazelle

 Species: Feline   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • Inflammation of the bladder due to bacterial lower urinary tract infection.
  • Cause: usually an ascending bacterial infection; predisposing factors are generally necessary for this opportunistic infection, ie rarely the initial cause in cats.
  • Signs: stranguria, dysuria, increased frequency of urination (pollakiuria) and small amounts of urine, hematuria.
  • Diagnosis: urine cytology and culture.
  • Treatment: antibiotics, supportive care (ie pain relief when appropriate).
  • Prognosis: generally good.
    Print off the owner factsheet Cystitis (bladder inflammation) Cystitis (bladder inflammation)  to give to your client.

Presenting Signs

  • Dysuria.
  • Stranguria.
  • Pollakiuria.
  • Hematuria.
  • Asymptomatic (in 0.6 to 29% of cats with positive urine culture).



Predisposing Factors


Causes of lower urinary tract infection and/or inflammation

  • Trauma.
  • Iatrogenic - catheterization.
  • Glucocorticoids (iatrogenic, hyperadrenocorticism).
  • Glucosuria (diabetes mellitus, Fanconi's syndrome).
  • Bladder distension (neurological or polyuria) increases binding sites for bacteria and reduces blood flow in bladder wall.
  • Decreased urethral function.
  • Neoplasia Bladder: neoplasia.



  • It is usually an ascending bacterial infection, less likely a hematogenous infection, and generally requires a predisposing factor in cats (different from dogs).
  • Predisposing factors + opportunistic microbes  →  ascending into bladder  →  cystitis  →  pyelonephritis Pyelonephritis.


Presenting Problems

  • Stranguria/dysuria.
  • Hematuria Hematuria.
  • Pain (caudal abdominal or lumbar).

Client History

  • Stranguria.
  • Pollakiuria.
  • Hematuria.
  • Asymptomatic.

Clinical Signs

  • Small, empty bladder on abdominal palpation is most common.
  • Thickened bladder wall on abdominal palpation.

Diagnostic Investigation



  • Considered to assess size and position of bladder and kidneys.
  • Important to check for calculi  Bladder: calculi - cystogram and exposure factors before giving contrast radiography.

Contrast radiography

  • Double contrast urography Radiography: double contrast cystography shows thickened and irregular bladder wall in chronic cases  Bladder: cystitis - double contrast cystogram (lateral) .
  • Small bladder in most cases, unless animal is polyuric or has a distal urinary tract obstruction or neurologic urine retention.
  • Bladder wall irregularities on double contrast study.
  • Urolithiasis Urolithiasis.
  • Bladder diverticulum Bladder: diverticulum on positive or double contrast study.
  • Bladder neoplasia Bladder: neoplasia, most common in the bladder trigone area, visible on double or positive contrast study.
  • Emphysematous cystitis.


  • Thickened bladder wall  Bladder: normal - ultrasound .
  • Echogenic sediment in bladder.
  • Diverticulum (can only be accurately evaluated with a full bladder).
  • Urolithiasis causing acoustic shadowing.
  • Irregular bladder wall due to polyps, neoplasia  Bladder: neoplasia - ultrasound .
  • Intraluminal gas in case of emphysematous cystitis. 



  • Leucocytosis (uncommon) Hematology: leucocyte (WBC), indicating severe infection, inflammation or even sepsis. Uncomplicated cystitis does not cause leukocytosis.


  • Bladder wall biopsy shows evidence of neutrophilic inflammation and the possibility to assess severity of the disease.
  • Culture biopsy to find infectious cause.
  • May be necessary to rule out neoplasia but rarely indicated.

Gross Autopsy Findings

  • Thickened bladder wall.
  • Evidence of underlying cause  Bladder: transitional cell carcinoma - pathology .

Histopathology Findings

  • Inflammatory cell infiltrate in bladder wall.
  • Follicular proliferation of lymphoid tissue in bladder wall in chronic cases.
  • Formation of chronic inflammatory polyps.
  • Bladder wall fibrosis.

Differential Diagnosis

Feline idiopathic cystitis

Secondary cystitis




Initial Symptomatic Treatment

  • Antibiosis for 3-5 days for uncomplicated urinary tract infection Therapeutics: urinary system.
  • 7-14 days for persistent or relapsing urinary tract infections. 
  • 10 to 14 days for pyelonephritis. 
  • Follow treatment with second urine culture in chronic or recurrent cases.
  • May need analgesics if some patients. 

Standard Treatment

  • Treat underlying cause.
  • Antibiosis based on urine culture and sensitivity ideally.
    Best given late at night (urine storage overnight).
  • Encourage frequent voiding of urine.
  • Induction of polyuria (increase water intake).
  • Urinary antiseptics (methenamine mandelate, methenamine hippurate Methenamine hippurate) not recommended for uncomplicated urinary tract infections and evidence is lacking for management of recurrent non-responsive cases.

Subsequent Management


  • Resolution of clinical signs.
  • In persistent urinary tract infection, the urine should be cultured before the discontinuation of the antibiotic treatment. If the culture is still positive, antibiotics should be changed on the basis of sensitivity.
  • In recurrent urinary tract infection, the urine should be recultured 7 days after finishing antibiotic therapy and then on a monthly basis (3 times) to monitor recurrence.
  • Prophylactic antibiotherapy is not recommended. 
  • Recurrence should stimulate another careful search for underlying cause.



  • Good: If uncomplicated primary cystitis and underlying cause identified and removed.
  • Guarded: If cannot remove underlying cause, or if complications.
  • Poor: If underlying malignant neoplasia.

Expected Response to Treatment

  • Resolution of clinical signs usually within days of starting appropriate treatment.

Reasons for Treatment Failure

  • Inappropriate antibiotic (not based on urine culture/sensitivity).
  • Underlying cause not identified.
  • Complications have occurred, eg pyelonephritis.
  • Candidal urinary tract infection in immunocompromized animal or after long-term antibiotic therapy.
  • Imbedded bacterial infections 'hidden' in kidney/bladder wall.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Dorsch R, Teichmann-Knorrn S, Sjetne Lund H (2019) Urinary tract infection and subclinical bacteriuria in cats: A clinical update. J Feline Med Surg 21(11), 1023-1038 PubMed
  • Weese J S, Blondeau J, Boothe D et al (2019) International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J 247, 8-25 PubMed
  • Teichmann-Knorrn S, Reese S, Wolf G et al (2018) Prevalence of feline urinary tract pathogens and antimicrobial resistance over five years. Vet Rec 183(1), 21 PubMed
  • Lees G E (1996) Bacterial urinary tract infections. Vet Clin North Am Small Anim Pract 26 (2), 297-304 PubMed.
  • Low D A, Braaten B A, Ling G V et al (1988) Isolation and comparison of Escherichia coli strains from canine and human patients with urinary tract infections. Infect Immunol 56 (10), 2601-2609 PubMed.

Other Sources of Information