Cystitis

Cystitis

Cystitis is inflammation of the bladder. Under normal conditions, the bladder is resistant to bacterial infection. Anything that disrupts normal passage of urine can damage and lead to irritation of the bladder wall lining, predisposing to inflammation and infection.

• Predisposing factors include:
  • urine stasis
  • incomplete voiding of urine
  • bladder trauma
  • glycosuria
  • dilute or alkaline urine
  • anatomy - females are more prone to bacterial cystitis due to ease of entry through the urethra. In males, the relatively long urethra protects against ascending infection.
• Causes include:
  • ascending infections - examples included metritis, vaginitis, balanopsthitis
  • urolithiasis
  • infected catheters or trauma due to catheters
  • prolonged administration of some anticancer drugs such as cyclophosphamide
  • bacterial pathogens include Escherichia coli, Staphylococcus, Streptococcus in small animals, Corynebacterium renale in cattle and Eubacterium suis in pigs, Haemophilus haemoglobinophilus

Acute cystitis

• Is a catarrhal inflammation initially.
• May be haemorrhagic depending upon the cause of trauma or virulence of the infection organism.
• Mild cases usually resolve completely whereas others will lead to chronic cystitis.

Gross pathology

• cloudy urine
• hyperaemic and oedematous mucosa
• haemorrhages and blood clots
• catarrhal exudate on the mucosal surface in severe inflammation

Histopathology

• epithelial degeneration and necrosis
• leukocyte infilatration
• dilation of submucosal vessels

Chronic cystitis

• Urolithiasis is the most common cause of chronic cystitis.
• Follicular cystitis - chronic cystitis of unknown aetiology common in the dog.

Gross pathology - Grey/white nodular lesions cover the surface of the bladder.

Histopathology - Clumps of lymphocytes just beneath the epithelial layer which may be normal or ulcerated.

• Polypoid cystitis - chronic cystitis seen in most species.

Gross pathology - Polyp like projections from the mucosa that resemble neoplasms.

Histopathology - The mucous membrane has villous projections covered by epithelium.

Gross pathology

• Thickening of the entire bladder wall due to fibrosis and hypertrophy of the muscle layers.
• Mucosa appears corrugated and dark red in colour.

Histopathology

• Erosion and hyperplasia of the epithelium.
• Increased cellularity of the mucosa with mostly lymphocytes.
• Increased smooth muscle componen.
• Fibrosis

Emphysematous cystitis

• Occurs in some dogs and cats with diabetes mellitus. The cause is likely related to the fermentation of sugar by glucose-fermenting bacteria.