Pathology of the urinary system

CYSTITIS

 

 

   ∙ 

inflammation of the urinary bladder is generally due to bacterial infections, formation and 

accumulation of uroliths, and, to a lesser extent, exposure to toxic compounds. 

 

   ∙ 

normal voiding of the urine usually maintains sterility of the bladder; in addition, the normal urine of 

domestic animals, especially dogs and cats, has natural antibacterial activity; this activity is related to 

its low pH (a result of the high concentration of undissociated organic acids) and, particularly, its 

high osmolality (a result of the high concentration of urea and other solutes). 

 

   ∙ 

factors predisposing to infection of the bladder are often not obvious; there is a higher incidence in 

females, probably because of their shorter and wider urethra. 

   ∙ 

the bacteria involved in cystitis are similar to those causing pyelonephritis: 

Corynebacterium renale 

in cattle; 

Eubacterium suis

 in pigs; 

E. coli

, 

Proteus

 species, 

Enterobacter

 species, 

Pseudomonas 

aeruginosa

 (mostly members of the normal rectal flora) in dogs and cats. 

   ∙ 

mycotic cystitis (e.g. 

Candida

 sp., 

Aspergillus

 sp.) is seen sporadically. 

   ∙ 

examples of toxic compounds that can cause cystitis: 

   - 

ingestion of blister beetle (

Epicauta

 species), containing the toxic compound cantharidin, in 

horses; may also cause necrosis and ulceration of the gastric mucosa, enterocolitis, and even 

myocardial necrosis. 

   - 

ingestion of bracken fern in cattle 

➝

 “enzootic hematuria”, which can progress from acute to 

chronic / proliferative to neoplastic; persistent hematuria results from the development of 

nodular hemangiomatous lesions. 

   - 

treatment with cyclophosphamide in dogs and cats with neoplastic or immunologic diseases. 

 

   ∙ 

acute cystitis may result in mucosal hemorrhage and ulceration, and production of fibrinopurulent 

exudate. 

   ∙ 

chronic cystitis is often accompanied by mucous metaplasia of the transitional epithelium (with 

production of mucus), formation of lymphoid follicles (follicular cystitis), and formation of mucosal 

polyps (polypoid cystitis). 

   ∙ 

“emphysematous cystitis” develops in some dogs and cats with diabetes mellitus: thought to be 

caused by fermentation of the excess sugar in the urine by glucose-fermenting bacteria. 

 

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