Pathology of the urinary system

Feline Urologic Syndrome

 (FUS) (= Feline Lower Urinary Tract Disease) 

   ∙ 

a common condition of male cats characterized by dysuria, hematuria, pollakiuria, and obstruction of 

the urethra by an urethral plug. 

 

   ∙ 

of considerably more importance than the formation of discrete calculi are the accumulations of 

protein, cellular debris, and struvite crystals that form sabulous (sand-like) urethral plugs; the material 

obstructing the urethra may be either struvite sand or rubber-like protein matrix, or a mixture of the 

two; 

 

   ∙ 

the pathogenesis is complex and likely multifactorial; some predisposing factors include: 

   - 

bladder infection by some viruses (herpesvirus, calicivirus) -  exudate or necrotic cells derived 

from the infection may act as a nidus for the formation and aggregation of crystals of minerals 

or may contribute directly to the formation of urethral plugs; 

   - 

inhibition of urethral growth, including its diameter, by early castration; 

   - 

large amounts of magnesium and phosphate in the diet; the introduction of low-ash and 

acidifying types of cat food has resulted in an overall decrease in incidence of FUS; 

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paradoxically, however, these types of food may also promote the formation of calcium 

oxalate uroliths; 

   - 

alkaline urine pH, e.g. resulting from production of urease in bacterial infection; 

   - 

cold winter months: decreased fluid consumption or increased intervals between urination. 

 

  ∙ 

grossly, the bladder is distended, hemorrhagic and inflamed; the obstructed portion of urethra is also 

hemorrhagic and inflamed.