Today's Veterinary Practice

SEP-OCT 2015

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

Issue link: http://todaysveterinarypractice.epubxp.com/i/561362

Contents of this Issue

Navigation

Page 17 of 83

Today's VeTerinary PracTice | september/october 2015 | tvpjournal.com Feline sTruViTe & calcium oxalaTe uroliThiasis Peer reviewed 16 CLINICAL SIGNS Clinical signs of urolithiasis in cats depend on urolith number, location, and physical characteristics. Solitary, smooth uroliths in the bladder or renal pelvis may be less irritating than multiple uroliths or uroliths with irregular or sharp borders. Urolithiasis complicated by bacterial UTI is more likely to cause tissue infammation than sterile urolithiasis. Nephroliths Nephroliths are often asymptomatic but can be associated with microscopic or gross hematuria. All nephroliths have potential to damage renal tissue and cause chronic infammation; this chronic infammation may decrease normal host defense mechanisms and increase the risk for ascending bacterial pyelonephritis in cats with lower UTIs. Larger nephroliths can cause hydronephrosis associated with pelvic and/or ureteral obstruction. Smaller nephroliths may pass through the ureter asymptomatically; however, hydroureter and hydronephrosis may be secondary to urolith-induced ureteral obstruction or stricture. Ureteroliths Ureteroliths may be asymptomatic or associated with varying degrees of abdominal pain and decreased appetite. In cats with pre-existing CKD, partial or complete ureteral obstruction will often result in an "acute-on-chronic" decompensation of renal function that may include hyperkalemia and/or acidemia. Ureteral obstruction in a cat with previously normal renal function may not be associated with any clinicopathologic abnormalities, especially if it is unilateral, but renal asymmetry may be palpated due to hydronephrosis. Cystoliths Cystoliths may be asymptomatic or, instead, irritate the uroepithelium, resulting in hematuria, pollakiuria, and dysuria/stranguria. Struvite cystoliths can result from urease-producing bacterial UTI; however, any urocystolith can irritate the uroepithelium, compromise host defense mechanisms, and predispose the patient to a complicated bacterial UTI. Urethral Uroliths Urethral uroliths are common causes of partial or complete urethral obstruction in males, leading to an altered or absent urine stream, hematuria, or dysuria/stranguria. In cases of complete urethral obstruction, postrenal azotemia and uremia develop within 24 to 36 hours. DIAGNOSIS Imaging The number, mineral composition, size, and location in the urinary tract affect the radiographic and ultrasonographic appearance of uroliths. • Calcium oxalate uroliths are typically the most radio-opaque of all uroliths, and usually are easily observed on plain film radiographs. • Struvite uroliths are less radio-opaque than calcium oxalate uroliths. • Small uroliths (< 3 mm) of any composition may be difficult to visualize on survey radiographs. • Calcium oxalate nephroliths can be difficult to differentiate from renal soft tissue mineralization on survey radiographs. Indications for imaging besides radiography include: • Ultrasonography: For detection of radiolucent uroliths, as well as obstructive uropathy resulting in renal pelvic or ureteral dilatation (Figure 3). • Combination of radiography and ultrasonography: Recommended to diagnose FIGURE 2. Lateral radiograph of a 9-year-old castrated male domestic longhair cat with calcium oxalate cystoliths (A); 100% calcium oxalate monohydrate cystoliths were removed from this cat (B). (Scale, 1 division = 1 mm). Types of Uroliths Nephrolith: Calculus formed or retained in the kidney Ureterolith: Calculus located in the ureter Cystolith: Calculus formed or retained in the bladder; also called vesical calculus Urethral urolith: Calculus located in the urethra B A

Articles in this issue

Links on this page

Archives of this issue

view archives of Today's Veterinary Practice - SEP-OCT 2015