Diagnosis

A combination of findings from history (including details related to behavior, the environment, husbandry practices), physical examination (including all body systems in addition to the lower urinary tract), urinaly­sis, serum biochemistry, and quantitative urine culture are often needed to establish a definitive diagnosis for the causes of lower urinary tract disease (LUTD).

A thorough diagnostic evaluation is indi­cated for all cats that fail to have spontaneous remission of clinical signs within one week or for those with recurrent episodes, urethral obstruction, a history or the presence of other health problems, or in older cats (>8 years of age).

In male and female cats with FIC, a varying degree of increased vessel number and tortu­osity, oedema, and glomerulations (submu­cosal petechial haemorrhages) are often visualized in the urinary bladder during cys­toscopy. An increase in the number and size of glomerulations often occurs in cats with FIC when higher bladder filling pressures (≥80cm water) are used during cystoscopy. This finding does not occur in normal uri­nary bladders and can serve as a provocative test for FIC (Chew et al. 1996). Female cats with FIC rarely have lesions in the urethra whereas urethral lesions (erosions, hemor­rhages, glomerulations) are observed in approximately 40% of male cats with FIC. It should be noted that lower urinary tract signs do not necessarily correlate with the degree or number of cystoscopic abnormalities iden­tified in cats with FIC (Chew et al. 1996).

Reliable diagnostic markers for FIC are cur­rently not yet clinically available. Urinary lev­els of antiproliferative factor, heparin-binding epidermal factor, and epidermal growth fac­tor distinguish human patients with intersti­tial cystitis from healthy controls, but have not been investigated in cats with FIC.

Differential Diagnosis

• Bacterial cystitis

• Urolithiasis

• Urethral strictures

• Urethral plugs

• Urinary tract trauma

• Urinary tract neoplasia