Veterinary Medicine - February 2009 - (Page 86) Nonobstructive iFLUTD PEER-REVIEWED TABLE 1 Differential Diagnoses and Diagnostic Tests to Consider in Cats with LUTS Differential Diagnoses Idiopathic Behavioral Urolithiasis Urethral plugs Urinary tract infection Neoplasia Trauma Congenital abnormalities Diagnostic Tests History and physical examination Urinalysis Urine bacterial culture Complete blood count Serum chemistry profile Radiography Ultrasonography Double-contrast cystourethrography Cystoscopy of cats, while iFLUTD accounted for 63% of cases.6 Other studies have reported ranges of 13% to 28% for urolithiasis and 55% to 69% for iFLUTD.5 DIAGNOSTIC EVALUATION Keeping in mind that FLUTD is a constellation of diseases and that iFLUTD is a diagnosis of exclusion, each cat presenting with stranguria, pollakiuria, hematuria, periuria, or partial or complete urethral obstruction should be approached similarly. In addition to a history and physical examination, a typical work-up includes a urinalysis, urine bacterial culture, complete blood count, serum chemistry pro le, and radiographic examination. Ultrasonography, double-contrast cystourethrography, and cystoscopy are included as needed. In addition, consider evaluating platelets and, in rare cases, clotting factors when hematuria is present. Clotting factor assays, such as prothrombin time and activated partial thromboplastin time, are necessary if there is evidence of bleeding elsewhere or systemic illness, such as hepatic disease or neoplasia.30 chronic, recurrent history. On physical examination, affected cats appear normal and active unless they have a urethral obstruction or are in extreme pain. It is important to assess bladder size in cats with a history of stranguria that have become depressed or obtunded or that have other systemic signs such as vomiting and anorexia. Palpation may reveal a large, turgid bladder that cannot be expressed. Steps must be taken to relieve the obstruction as quickly as possible. In contrast, the bladders of cats with nonobstructive iFLUTD are small. Even minimal palpation can result in urination because of the irritated, in amed bladder wall. Often, no other relevant physical examination ndings related to the urinary signs will be present. the introduction of a new cat or other pet, arrival of a new baby or household member, a recent move or change to the living environment (e.g. new carpeting, a new addition), or a change in litter or food. The roles of environment and stress in iFLUTD will be discussed later. Hematuria Hematuria can be caused by UTIs, urolithiasis, neoplasia, thrombocytopenia, clotting disorders, and trauma.25 UTIs are uncommon in cats < 10 years old ( 10 years of age are more likely to develop UTIs.6 Since dilute urine increases the susceptibility of animals to UTIs, concurrent illness, such as chronic renal failure, may be responsible.26,27 This age group is also more likely to have bladder tumors such as transitional cell carcinoma that can serve as a nidus of infection.6 Inherited coagulopathies are uncommon in cats.28,29 Factor XII de ciency (Hageman trait) in cats rarely results in clinical hemorrhage. Urinalysis Cystocentesis is preferred to obtain a urine sample but may be dif cult to perform because affected cats often have small, irritated bladders. A comparison of samples obtained free-catch and by cystocentesis may be useful in cases of urethral disease. With urethral transitional cell carcinoma, for example, there may be few cytologic abnormalities in a sample obtained by cystocentesis, but transitional cells may be present in a free-catch sample. The mean urine speci c gravity in cats with iFLUTD is 1.052, urine pH is usually acidic, and microscopic hematuria is present in 95% of cases.24 Pyuria may be present if in ammation is severe, but bacteriuria is uncommon.24 CLINICAL SIGNS The LUTS that are present with iFLUTD can be attributed to other causes (Table 1), so a thorough work-up is imperative. These possible causes of LUTS, urolithiasis in particular, should guide the work-up of cats suspected of having iFLUTD. Pollakiuria and stranguria Pollakiuria and stranguria are reported in 79% and 70% of iFLUTD cases, respectively.24 These signs can result from UTIs, urethral plugs, cystic or urethral stones, neoplasia, and iFLUTD. In one large retrospective study, urolithiasis and urethral plugs accounted for LUTS in 10% Periuria Periuria is a common clinical sign, occurring in 93% of cats with iFLUTD.24 However, periuria can also be purely behavioral and should prompt questioning about the cat’s environment, such as Urine bacterial culture UTIs occur most commonly in cats > 10 years of age.6 Urolithiasis, neoplasia, previous urethral catheterizations, 86 February 2009 VETERINARY MEDICINE
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