Contributors: Phil Nicholls, Melissa Wallace, Julien Bazelle

 Species: Canine   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • Inflammation of the bladder.
  • Causes: usually an ascending bacterial infection; predisposing factors are necessary for this opportunistic infection. Rarer causes include cyclophosphamide toxicity, eosinophilic cystitis, polypoid cystitis, foreign bodies. 
  • Signs: stranguria, dysuria, increased frequency of urination (pollakiuria) and small amounts of urine, hematuria, abnormal smell/turbidity of the urine, more rarely abdominal discomfort, excessive licking, attracting male dogs.
  • Treatment: antibiotics, pain killers.
  • Sequelae: ascending urinary tract infections (pyelonephritis), diskospondylitis (rarely), prostatitis, sepsis, endocarditis, urolithiasis.
  • Prognosis: good if uncomplicated; guarded if chronic; poor if secondary to malignant neoplasia.
Print off the owner factsheet Cystitis (bladder inflammation) to give to your client.

Presenting Signs

  • Dysuria.
  • Stranguria.
  • Pollakiuria.
  • Hematuria, discolored urine. 
  • Abdominal pain. 
  • Excessive licking. 
  • Attracting male dogs. 
  • Asymptomatic.

Age Predisposition

  • <2 years old.
  • >6 years old.



Predisposing Factors

Causes of lower urinary tract infection and/or inflammation

  • Bladder distension (neurological or polyuria) increases binding sites for bacteria and reduces blood flow in bladder wall.
  • Decreased urethral function.



  • Days to weeks.


Presenting Problems

  • Stranguria/dysuria.
  • Hematuria Hematuria.
  • Pain (caudal abdominal or lumbar).
  • Excessive licking. 
  • Attracting male dogs. 

Client History

  • Stranguria.
  • Pollakiuria.
  • Hematuria.
  • Discolored peri-vulvar coat due to licking. 
  • Asymptomatic.

Clinical Signs

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

Diagnostic Investigation


  • Cystocentesis Cystocentesis preferred to avoid contamination by bacteria from distal urinary/genital tract​.
  • Hematuria Hematuria Urinalysis: blood.
  • Active sediment examination Urinalysis: centrifuge sediment with more than 5 WBC/high power field Urinalysis: white blood cell. In cases of excess glucocorticosteroids the sediment examination is often non-inflammatory and culture is necessary. Bacteria on sediment examination may originate from kidney, ureter, bladder or prostate.
  • Proteinuria Urinalysis: protein. UPC as high as 40 was seen in experimental cystitis, although cystitis most often is associated with only mild proteinuria Proteinuria
  • Positive urine culture Urinalysis: bacteriology. Cut-off of more than (10*^5) bacteria/mL was suggested but depends on technique of collection and should be interpreted in light of clinical signs and urine sediment as asymptomatic bacteriuria can be present in healthy individuals. 
  • Sensitivity testing based on urine concentrations of antibiotics, rather than serum concentrations.
  • Evidence of crystalluria Urolithiasis Urinalysis calcium oxalate crystal Urinalysis cysteine crystal Urinalysis struvite crystal Urinalysis urate crystals.

Contrast radiography

  • Positive contrast Radiography: cystography and double contrast cystography Radiography: double contrast cystography required.
  • Bladder cystitis Bladder cystitis - double contrast cystogram :
    • Small bladder in most cases, unless animal is polyuric or has a distal urinary tract obstruction or neurologic urine retention.
    • Thickened bladder wall, especially in cranio-ventral area of the bladder on double contrast study.
    • Bladder wall irregularities on double contrast study, rarely polypoid cystitis Bladder: polypoid cystitis.
    • Urolithiasis Bladder calculi - cystogram.
    • 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 Bladder emphysematous cystitis - radiograph lateral abdomen.

2-D Ultrasonography

  • Thickened bladder wall Bladder severe cystitis - ultrasound. The thickness of the bladder wall does vary depending on filling of the bladder.
  • Echogenic sediment in bladder.
  • Diverticulum (can only be accurately evaluated with a full bladder).
  • Urolithiasis causing acoustic shadowing Bladder calculus - ultrasound.
  • Irregular bladder wall due to polyps, neoplasia Bladder neoplasia - ultrasound.



  • Leukocytosis Hematology: leukocyte (WBC) , indicating severe infection, inflammation or even sepsis. Simple cystitis does not cause leukocytosis.


  • Biopsy bladder wall, ideally through cystoscopy Cystoscopy: transurethral cystoscopy/vaginoscopy, less commonly surgical biopsies or ultrasound-guided (risk of metastatic disease in case of transitional cell carcinoma):
    • Evidence of inflammation and the possibility to assess severity of the disease.
    • Culture biopsy to find infectious cause. Tissue culture may differ from urine culture.
    • May be necessary to rule out neoplasia.

Gross Autopsy Findings

  • Bladder wall may appear thickened.
    Check if it can be stretched manually, since a contracted empty bladder can appear thickened.
  • Fibrosis will prevent stretching.
  • Acute cystitis may be hemorrhagic, fibrinopurulent exudate, necrotizing, ulcerative or a combination of these.
  • Urine may be cloudy and discolored, eg red tinged with ammoniacal odor.

Histopathology Findings

  • Mucosa may show focal erosion or ulceration with inflammatory exudate, necrotic debris and adherent blood clots.
  • Bacterial colonies may be seen.
  • Lamina propria may be edematous, with neutrophilic inflammation.
  • Muscular layers may have perivascular inflammation.

Differential Diagnosis

Secondary cystitis




Initial Symptomatic Treatment

  • Antimicrobials for 3-5 days for sporadic uncomplicated bacterial cystitis. Although ideally antibiotic choice should be guided by results of culture and sensitivity, amoxicillin Amoxicillin (+/- clavulanic acid Clavulanate) and trimethoprim-sulfonamides Trimethoprim are considered reasonable first choice in most areas.  
  • Non-steroidal anti-inflammatory drugs Therapeutics: urinary.

Standard Treatment

  • Treat underlying cause.
  • Antibiotics for 3-5 days for sporadic uncomplicated bacterial cystitis to 7-14 days in complicated/recurrent/relapsing bacterial cystitis, based on urine culture and sensitivity Urinalysis: bacteriology.
    Best given after dog has emptied bladder and late at night (urine storage overnight).
  • Encourage frequent voiding of urine.
  • Induction of polyuria (increase water intake).
  • Urinary antiseptics (methenamine mandelate, methenamine hippurate) or alternative treatment (eg cranberries extracts Cranberry extract containing proanthocyanidins for urinary health) have been used sporadically but insufficient evidence is present to support their use, even in recurrent cystitis.

Subsequent Management


  • Resolution of clinical signs.
  • Urinary cytology. 
  • In persistent urinary tract infection, the urine should be cultured 7 days after starting 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.



  • Good: if uncomplicated primary cystitis and underlying cause identified and removed.
  • Guarded: if cannot remove underlying cause, or if complications, eg severe prostatitis, diskospondylitis, sepsis, pyelonephritis.
  • 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).
  • Poor drug compliance. 
  • Underlying cause not identified.
  • Complications have occurred, eg prostatitis, diskospondylitis, septicemia, pyelonephritis.
  • Candidal urinary tract infection in immunocompromised animal or after long-term antibiotic therapy.
  • Imbedded bacterial infections 'hidden' in kidney/prostate/bladder wall.
  • Antibiotic resistance. 

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Llido M, Vachon C, Dickinson M et al (2020) Transurethral cystoscopy  in dogs with recurrent urinary tract infections: Retrospective study (2011-2018). J Vet Intern Med 34(2), 790-796 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 ofbacterial urinary tract infections in dogs and cats. Vet J 247, 8-25 PubMed.
  • Clare S, Hartmann F A, Jooss M et al (2014) Short- and long-term cure rates of short-duration trimethoprim-sulfamethoxazole treatment in female dogs with uncomplicated bacterial cystitis. J Vet Intern Med 28(3), 818-826 PubMed.
  • Ling G V et al (2001) Interrelations of organism prevalence, specimen collection method, and host age, sex, and breed among 8534 canine urinary tract infections (1969-1995). JVIM 15 (4), 341-347 PubMed.
  • Norris C R, Williams B J et al (2000) Recurrent and persistent urinary tract infections in dogs - 383 cases (1969-1995). JAAHA 36 (6), 484-492 PubMed.
  • Low D A, Braaten B A, Ling G V, Johnson D L & Ruby A L (1988) Isolation and comparison of Escherichia coli strains from canine and human patients with urinary tract infections. Infect Immun 56 (10), 2601-2609 PubMed.
  • Thomsen M K, Svane L C & Poulsen P H (1986) Canine urinary tract infection. Detection, prevalence and therapeutic consequences of bacteriuria. Nord Vet Med 38 (6), 394-402 PubMed.
  • Ginder D R (1974) Urinary tract infection and pyelonephritis due to Escherichia coli in dogs infected with canine adenovirus. J Infect Dis 129 (6), 715-719 PubMed.

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