Page 789 - Small Animal Clinical Nutrition 5th Edition

Introduction to Canine Urolithiasis 819

tion(s), 3) physical characteristics of uroliths (size, shape, num- Table 38-2. Clinical signs of uroliths that may be associated
VetBooks.ir ber), 4) secondary urinary tract infection (UTI) and virulence with urinary system dysfunction.
of infecting organism(s) and 5) presence of concomitant dis-
eases in the urinary tract and other body systems. After a diag-
Urethroliths
nosis of urolithiasis has been confirmed, the history and physi- Asymptomatic
Dysuria, pollakiuria, urge incontinence and/or periuria
cal examination should focus on detection of any underlying ill- Gross hematuria
ness that may predispose the dog to urolith formation. Palpable urethral uroliths
A dietary history should also be obtained for all patients with Spontaneous voiding of small uroliths
Partial or complete urine outflow obstruction
urolithiasis, with the objective of identifying risk factors that Overflow incontinence
predispose the patient to specific mineral types. Likewise, own- Anuria
ers should be questioned about vitamin-mineral supplements, Palpation of an overdistended and painful urinary bladder
Urinary bladder rupture, abdominal distention and
previous illnesses and medications that may predispose the abdominal pain
patient to various types of uroliths. Signs of postrenal azotemia (anorexia, depression, vomiting
Signs typical of lower urinary tract disease include dysuria, and diarrhea)
Signs associated with concurrent urocystoliths, ureteroliths
pollakiuria, hematuria, urge incontinence, paradoxical inconti- and/or renoliths
nence and voiding small uroliths during micturition. Signs of Urocystoliths
uremia may occur if urine flow has been obstructed for a suffi- Asymptomatic
Dysuria, pollakiuria and urge incontinence
cient period, or if there is extravasation of urine into the peri- Gross hematuria
toneal cavity due to rupture of the excretory pathways. Palpable bladder uroliths
Signs of upper tract disease include painless hematuria and Palpably thickened urinary bladder wall
Partial or complete urine outflow obstruction of bladder neck
polyuria if sufficient nephrons have impaired function. Ab- (See Urethroliths.)
dominal pain may occur if there is overdistention of the renal Other signs associated with concurrent urethroliths, ureteroliths
pelvis with urine due to outflow obstruction (Table 38-2). and/or renoliths
Ureteroliths
Many patients with uroliths have no clinical signs. Absence of Asymptomatic
signs is especially common in patients with nephroliths. Gross hematuria
If gross hematuria is present, determining when during the Constant abdominal pain
Unilateral or bilateral urine outflow obstruction
process of micturition it is most severe may be of value in local- Palpably enlarged kidney(s)
izing its source. If hematuria occurs throughout micturition, Signs of postrenal azotemia (See Urethroliths.)
lesions (including uroliths) may be present in the kidneys, May have other signs associated with concurrent urethroliths,
urocystoliths and/or nephroliths
ureters, urinary bladder, prostate gland and/or urethra. If hema- Nephroliths
turia occurs primarily at the end of micturition, lesions of the Asymptomatic
ventral bladder wall or intermittent renal hematuria should be Gross hematuria
Constant abdominal pain
suspected. If hematuria occurs at the beginning or is independ- Signs of systemic illness if generalized renal infection is present
ent of micturition, lesions in the urethra or genital tract should (anorexia, depression, fever and polyuria)
be suspected. Palpably enlarged kidney(s)
Signs of postrenal azotemia (See Urethroliths.)
Digital palpation of the entire urethra, including evaluation Other signs associated with concurrent urethroliths, urocys-
by rectal examination, may reveal urethroliths or uroliths toliths and/or ureteroliths
lodged in the bladder neck. A firm, non-yielding mass may be
palpated in the urinary bladder if a solitary urolith is present; a
grating sensation confined to the bladder may be detected if
multiple uroliths are present. It may be impossible to palpate in the area of the kidneys and/or palpable enlargement of the
small or solitary urocystoliths if the bladder wall is contracted affected kidney(s). Concomitant bacterial pyelonephritis may
and/or thickened due to inflammation. Likewise, it may be be associated with polysystemic signs due to sepsis.
impossible to palpate uroliths in a distended or overdistended
bladder. In this situation, the bladder should be repalpated after Diagnostic Studies
urine has been eliminated by voiding, manual compression of Urinalysis
the bladder, cystocentesis or catheterization. One should sus- Results of urinalysis are usually characterized by abnormalities
pect urethroliths when urethral catheters cannot be advanced typical of inflammation (pyuria, proteinuria, hematuria and
into the bladder. However, inability to advance a catheter increased numbers of epithelial cells), which may or may not be
through the urethra may also be associated with urethral stric- associated with infection. Whereas urease-producing microbes
tures or space occupying lesions that partially or totally occlude (staphylococci, Proteus spp., ureaplasmas) may cause infection-
the urethral lumen. induced struvite (magnesium ammonium phosphate) uroliths
In the absence of infection or outflow obstruction, abnormal- to form, opportunistic bacteria that are not lithogenic (e.g.,
ities are usually not associated with nephroliths unless bilateral Escherichia coli and streptococci) may colonize the urinary tract
nephroliths are associated with sufficient renal damage to cause as a result of urolith-induced alterations in local host defenses.
uremia. If infection or obstruction is present, there may be pain Quantitative urine culture of all patients with uroliths is recom-