Objective—To evaluate results of SDS-agarose gel
electrophoresis (AGE) of urinary proteins for use in
defining glomerular and tubulointerstitial derangements,
investigate patterns of high-molecular-weight
(HMW) proteins for differentiating among glomerular
disorders, and assess low-molecular-weight (LMW) proteins
as markers of severity of tubulointerstitial disease
Animals—49 dogs with increased serum creatinine
concentrations or abnormal renal protein loss.
Procedure—Urinary proteins were examined by use
of SDS-AGE and differentiated on the basis of molecular
weight. The HMW proteins (≥ 69 kd) were considered
indicative of glomerular origin, whereas LMW
proteins (< 69 kd) were of tubular origin. Renal specimens
were examined by use of light microscopy.
Glomerular and tubulointerstitial lesions were differentiated
by use of the classification for the World
Health Organization and semiquantitative grading,
Results—Sensitivity of SDS-AGE was 100% for
detection of glomerular lesions and 92.6% for tubulointerstitial
lesions; specificity was 40% and 62.5%,
respectively. Although HMW urinary proteins were
not significantly associated with the type of glomerular
lesion, LMW urinary proteins were significantly
associated with the grade of tubulointerstitial damage.
Detection of 12- or 15-kd proteins or both was
highly indicative of a severe tubulointerstitial lesion.
Conclusions and Clinical Relevance—SDS-AGE of
urinary proteins in dogs represents a noninvasive test
with high sensitivity for identifying glomerular and
tubulointerstitial damage, but low specificity limits its
validity as a stand-alone test to differentiate between
glomerular and tubulointerstitial lesions. The test is
particularly useful for identifying dogs with advanced
tubulointerstitial disease but cannot be used to characterize
glomerular disorders. ( Am J Vet Res 2004;65:964–971)
Objective—To evaluate a urine dipstick test as a possible replacement for urine protein-tocreatinine (UPC) ratio for identifying proteinuria in dogs.
Sample Population—507 urine samples from adult dogs.
Procedures—Urine dipstick, UPC ratio, specific gravity (USG), and sediment testing were performed on 507 samples. With UPC ratio as the reference criterion, diagnostic accuracy of the urine dipstick test was calculated for the entire data set and for urine samples grouped by USG (≤ 1.012 or > 1.012; < 1.030 or ≥ 1.030). A UPC ratio < 0.2 was used to indicate absence of proteinuria.
Results—The sensitivity of the urine dipstick test for detection of proteinuria was > 90% when 0 mg of protein/dL (a 0+ result) was used to indicate a negative test result, and the specificity ranged from 40% to 60%, depending on the USG. Sensitivity decreased to a range of 56% to 81% when 30 mg of protein/dL (a 1+ result) was used as the cutoff, depending on the USG, but the specificity increased to > 90%. The likelihood of correctly identifying nonproteinuric dogs was low when the USG was ≤ 1.012, particularly when samples with a 1+ result were considered negative.
Conclusions and Clinical Relevance—For dogs with a dipstick-test result of 1+ and USG ≤ 1.012, proteinuria should be assessed by use of the UPC ratio; dogs with a USG value > 1.012 are likely nonproteinuric. When used together, the urine dipstick test and USG measurement were reliable as a rapid alternative to UPC ratio determination in dogs in this study.
Objective—To determine whether preanalytic and analytic factors affect evaluation of the urinary protein-to-creatinine (UPC) ratio in dogs.
Sample—50 canine urine samples.
Procedures—The UPC ratio was measured to assess the intra-assay imprecision (20 measurements within a single session), the influence of predilution (1:10, 1:20, and 1:100) for urine creatinine concentration measurement, and the effect of storage at room temperature (approx 20°C), 4°C, and −20°C.
Results—The coefficient of variation at room temperature determined with the 1:20 predilution was < 10.0%, with the highest coefficients of variation found in samples with a low protein concentration or low urine specific gravity. This variability could result in misclassification of samples with UPC ratios close to the thresholds defined by the International Renal Interest Society to classify dogs as nonproteinuric (0.2), borderline proteinuric (0.21 to 0.50), or proteinuric (> 0.51). A proportional bias was found in samples prediluted 1:10, compared with samples prediluted 1:20 or 1:100. At room temperature, the UPC ratio did not significantly increase after 2 and 4 hours. After 12 hours at room temperature and at 4°C, the UPC ratio significantly increased. The UPC ratio did not significantly change during 3 months of storage at −20°C.
Conclusions and Clinical Relevance—The intra-assay precision of the UPC ratio was sufficiently low to avoid misclassification of samples, except for values close to 0.2 or 0.5. The optimal predilution ratio for urine creatinine concentration measurement was 1:20. A 1:100 predilution is recommended in samples with a urine specific gravity > 1.030. The UPC ratio must be measured as soon as samples are collected. Alternatively, samples should be immediately frozen to increase their stability and minimize the risk of misclassification of proteinuria.
Objective—To histologically identify glomerular
lesions in dogs infected with Leishmania organisms.
Animals—41 dogs (17 sexually intact males and 14
sexually intact and 10 ovariohysterectomized females)
that had positive results when tested for leishmaniosis
as determined by use of serologic evaluation (indirect
fluorescent antibody test, titers of 1:80 to 1:640)
and direct microscopic identification of the protozoal
Procedure—Urine samples were collected by use of
cystocentesis and examined by qualitative SDSagarose
gel electrophoresis (AGE). All dogs had nonselective
(glomerular) or mixed (glomerular and tubular)
proteinemia. Specimens were obtained from each
dog during ultrasound-assisted renal biopsy and used
for histologic examination. Each specimen was
stained with H&E, periodic acid–Schiff, Goldner's
trichrome, methenamine silver, and Congo Red
stains. Specimens were adequate for evaluation
when they contained at least 5 glomeruli/section,
except for specimens stained with Congo Red in
which 1 glomerulus/section was adequate.
Results—Examination of renal biopsy specimens
revealed various glomerular lesions in all dogs and
interstitial or tubular (or both) lesions in 23 of 41
Conclusions and Clinical Relevance—Glomerular
lesions that develop in dogs during infection with
Leishmania organisms can be classified histologically
as mesangial glomerulonephritis, membranous
glomerulonephritis, membranoproliferative glomerulonephritis,
and focal segmental glomerulonephritis.
Tubulointerstitial histopathologic conditions were not
observed as the primary lesion, despite being evident
in 23 of 41 (55%) dogs. Use of SDS-AGE for qualitative
evaluation of proteinuria and successive collection
of specimens during renal biopsies following
diagnosis of nonselective glomerular proteinuria provides
the possibility for early identification of renal
lesions. (Am J Vet Res 2003;64:558–561)
Objective—To determine results of cytologic examination of fine-needle aspirates and impression smears of gastrointestinal tract tumors in dogs and cats.
Design—Retrospective case series.
Animals—38 dogs and 44 cats with histologically confirmed gastrointestinal tract tumors.
Procedures—Results of cytologic examination of fine-needle aspirates (n = 67) or impression smears (31) were compared with the histologic diagnosis, and extent of agreement was classified as complete, partial, none, or undetermined.
Results—For 48 of the 67 (72%) fine-needle aspirates, there was complete or partial agreement between the cytologic and histologic diagnoses. For 12 (18%) aspirates, the extent of agreement could not be determined because the cytologic specimen was considered unsatisfactory. For 29 of the 31 (94%) impression smears, there was complete agreement between the cytologic and histologic diagnoses, and for 2 (6%), there was partial agreement. None of the impression smears were considered unsatisfactory. Proportion of samples with complete agreement and proportion of samples with complete or partial agreement were significantly higher for impression smears than for fine-needle aspirates.
Conclusions and Clinical Relevance—Results suggest that there was moderate agreement between results of cytologic examination of fine-needle aspirates from dogs and cats with gastrointestinal tract neoplasia and the definitive histologic diagnosis. The agreement between results of cytologic examination of impression smears and the histologic diagnosis appeared to be higher.
Objective—To assess whether urine protein-to-creatinine (UPC) ratios determined in urine samples collected by cystocentesis versus those collected by free catch provide similar diagnostic information for dogs.
Animals—115 client-owned dogs evaluated because of various health problems requiring urinalysis or to screen for proteinuria in an area endemic for leishmaniasis.
Procedures—230 paired urine samples, 1 collected by cystocentesis and 1 by free catch, were collected from the 115 dogs. The UPC ratio was determined in paired urine samples (n = 162) from 81 dogs with no indication of active inflammation according to urine sediment analysis. On the basis of the UPC ratio of urine sample collected by cystocentesis, dogs were classified as nonproteinuric (UPC ratio < 0.2), borderline proteinuric (UPC ratio of 0.2 to 0.5), or proteinuric (UPC ratio > 0.5), according to the International Renal Interest Society (IRIS).
Results—The correlation between UPC ratio in urine samples collected by cystocentesis and by free catch was strong (r2 = 0.90); 75 of 81 (92.6%) dogs had UPC ratios from both urine samples that resulted in classification in the same IRIS substage with a kappa coefficient of 0.83.
Conclusions and Clinical Relevance—The UPC ratio in dogs was minimally affected in urine samples collected by free catch, thus allowing correct grading of proteinuria with this method. The high reliability of the UPC ratio in free-catch urine samples coupled with the ease of collection should increase the use of this value for assessment of proteinuria.