RENAL ULTRASONOGRAPHIC AND COMPUTED TOMOGRAPHIC APPEARANCE, VOLUME, AND FUNCTION OF CATS WITH AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

The purpose of this study was to describe the ultrasonographic (US) and computed tomographic (CT) appearance of autosomal dominant polycystic kidney disease (ADPKD) in cats; to compare renal volume in cats with ADPKD (n = 5; mean age 59 +/- 10 months)) and normal cats (n = 5; mean age 66 +/- 10 months) using 2 imaging modalities, US and CT; and to calculate cyst volume using CT. Glomerular filtration rate (GFR) was determined by 2 methods: 99mTc-diethylene-triaminepentaacetic acid (99mTc-DPTA) scintigraphic uptake and 99-Tc-DTPA plasma clearance. Sonographically, ADPKD affected kidneys were characterized by multiple anechoic to hypoechoic, round to irregularly shaped structures with variation in size. Affected kidneys had indistinct corticomedullary junctions and foci of mineralization. Intravenous (IV) contrast medium administration allowed more definitive identification of cysts with CT, and identification of distortion of renal pelves by cysts. A significant difference (Welch ANOVA, P = 0.05) was detected between the US-estimated renal volumes of normal and affected cats. No statistically significant differences were detected in CT volume (between the normal and affected cats, or between US and CT volume measurements) or the 2 GFR methods. In this group of clinically normal, middle-aged ADPKD cats, renal function was within normal limits and not significantly different than normal.     

Vestibular, vaginal, and urethral relations in spayed dogs with and without lower urinary tract signs

The purpose of this study was to evaluate the urogenital anatomy in female spayed dogs with and without signs of lower urinary tract disease by using conventional vaginourethrography, computed tomography (CT) vaginourethrography, and uroendoscopy. Nineteen dogs with lower urinary tract disease and 12 normal dogs were evaluated prospectively. Measurements made included vaginal length, vaginal height, vaginal width, vestibule length, vestibule height, vestibule width, vestibulovaginal ratios, cingulum height, cingulum width, cingulum area, urethral length, urethral height, urethral width, angle of urethra to vestibule, and angle of vaginal to vestibule. Group comparisons were made between dogs with and without lower urinary tract disease. Comparisons between conventional vaginourethrography and CT vaginourethrography were made when the same anatomical measurement was made by the 2 imaging modalities. There was no significant difference in all of the measurements (P > .01), including vestibulovaginal ratios and cingulum areas, between dogs with and without lower urinary tract disease. There was a larger proportion of dogs with a vestibulovaginal ratio <0.33 in normal dogs (8 of 12) compared with the clinical dogs (8 of 16). A significant difference between vestibulovaginal ratios or cingulum areas between dogs with and without lower urinary tract disease could not be identified. This suggests that a vestibulovaginal ratio of <0.33 may only be an incidental finding and the term "vestibulovaginal stenosis" may need to be redefined.     

Bilateral renal hypoplasia in four young horses

Three horses less than or equal to 3 years old were evaluated because of stunted growth, weight loss, anorexia, depression, and lethargy of at least 1 month's duration. A neonatal foal was examined after its death. In each case, gross and microscopic renal lesions were compatible with bilateral renal hypoplasia (ie, cortical hypoplasia with severe medullary hypoplasia). In young horses with renal failure, bilateral renal hypoplasia should be considered in the differential diagnosis, and may represent a congenital lesion.     

Cystinuria in a cat

A 10-month-old male Siamese cat with dysuria was determined to have cystine crystalluria. Many small calculi composed entirely of cystine were found in the urinary bladder. Measurement of serum and urine amino acids and calculation of fractional reabsorption of amino acids indicated reabsorption defects for cystine, ornithine, lysine, and arginine. Urinary acidification, fractional reabsorption of glucose, and fractional reabsorption of electrolytes were normal. Diagnoses of cystinuria and cystine urolithiasis were made on the basis of low fractional reabsorption of cystine and dibasic amino acids and the detection of cystine calculi in the urinary bladder.     

Determination of extrarenal plasma clearance and hepatic uptake of technetium-99m-mercaptoacetyltriglycine in cats

OBJECTIVE: To determine maximum extrarenal plasma clearance of technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) and maximum extrarenal hepatic uptake of 99mTc-MAG3 in cats. ANIMALS: 6 clinically normal adult cats. PROCEDURES: Simultaneously, baseline plasma clearance and camera-based uptake of 99mTc-MAG3 were determined in anesthetized cats. Double exponential curves were fitted to plasma clearance data. Injected dose was divided by area under the curve and body weight to determine 99mTc-MAG3 clearance. Regions of interest were drawn around kidneys and liver, and percentage dose uptake was determined 1 to 3 minutes after injection. After bilateral nephrectomy, simultaneous extrarenal plasma clearance and camera-based hepatic uptake of 99mTc-MAG3 were evaluated in each cat. RESULTS: Mean +/- SD baseline plasma clearance and extrarenal clearance were 5.29 +/- 0.77 and 0.84 +/- 0.47 mL/min/kg, respectively. Mean extrarenal clearance (as a percentage of baseline plasma clearance) was 16.06 +/- 7.64%. For right, left, and both kidneys, mean percentage dose uptake was 9.42 +/- 2.58, 9.37 +/- 0.86, and 18.79 +/- 2.47%, respectively. Mean hepatic percentage dose uptake before and after nephrectomy was 12.95 +/- 0.93 and 21.47 +/- 2.00%, respectively. Mean percentage change of hepatic uptake after nephrectomy was 166.89 +/- 23.19%. CONCLUSIONS AND CLINICAL RELEVANCE: In cats, extrarenal clearance of 99mTc-MAG3 is higher than that of other species; therefore, 99mTc-MAG3 is not useful for estimation of renal function in felids. Evaluation of renal function in cats may be more accurate via camera-based versus plasma clearance-based methods because camera-based studies can discriminate specific organs.     

The Effects of Cyclosporine Versus Standard Care in Dogs With Naturally Occurring Glomerulonephritis

Glomerulonephritis (GN) is a leading cause of chronic renal failure in dogs. However, little is known about the efficacy of available treatment options for GN in this species. The purpose of this study was to determine the effects of cyclosporine (Cy) administration on the outcome of naturally occurring GN in dogs. Thirteen dogs from 4 institutions were included in the study. Randomization of dogs into placeboversus Cy-treated groups was stratified according to initial morphological diagnosis and contributing institution. Seven and 6 dogs were assigned to be given placebo or Cy, respectively. The initial Cy dose of 10 mg/kg every 24 hours was adjusted to maintain 24-hour trough, whole blood Cy concentrations between 250 and 400 ng/mL. There were no statistically significant differences between placebo-and Cy-treated groups with respect to serum total protein, albumin, urea nitrogen and creatinine, and plasma protein concentrations; platelet count; urine protein-creatinine ratio; endogenous creatinine clearance; 24-hour urine protein concentrations; or 24-hour urine protein—endogenous creatinine clearance ratio. However, PCV was significantly lower in the Cy-treated group. Decreased appetite, diarrhea, vomiting, weight loss, involuntary shaking, and thrombocytopenia were noted in both treatment groups; however, clinical signs in Cy-treated dogs subjectively were more severe. One Cy-treated dog developed gingival hyperplasia. After entry into the study, the median survival times for placebo-and Cy-treated dogs were 16 and 11 months, respectively. Considering the expense and the frequency of adverse effects related to Cy administration, the use of Cy in the treatment of dogs with GN does not seem warranted.     

Ureteral obstruction after ureteroneocystostomy in dogs assessed by technetium TC 99m diethylenetriamine pentaacetic acid (DTPA) scintigraphy

OBJECTIVE: To use technetium Tc 99m diethylenetriamine pentaacetic acid (99mTc-DTPA) renal scintigraphy to monitor ureteral obstruction after ureteroneocystostomy in a canine model of partial ureteral obstruction. STUDY DESIGN: Experimental study. ANIMALS: Eight normal adult dogs. METHODS: Partial ureteral obstruction was created in 8 dogs by incomplete ligation of the terminal right ureter. Two weeks later, ureteroneocystostomy was performed in 7 dogs with unilateral partial ureteral obstruction and in 1 dog that had developed bilateral partial ureteral obstruction. 99mTc-DTPA scintigraphy was performed intermittently for 2 weeks after ureteroneocystostomy. Renal transit time of each kidney, as assessed by the time to maximal uptake (time of peak), and glomerular filtration rate, as assessed by percentage of kidney uptake of the radiopharmaceutical between 1 and 3 minutes, were estimated. Comparison between affected and nonaffected kidneys was performed with the Wilcoxon rank sum test. RESULTS: Unilateral partial ureteral obstruction was induced successfully in 7 dogs. In 1 dog, bilateral partial obstruction was induced inadvertently. After ureteroneocystostomy, percentage of kidney uptake of 99mTc-DTPA was low in 4 affected kidneys. The uptake returned to within normal limits in 2 of the kidneys during the observation period. The time activity curve had a more rounded appearance or was increasing continuously for all affected kidneys. A significant increase in renal transit time was observed 2 and 4 days after ureteroneocystostomy. Transit time progressively returned to normal by 4 to 11 days for all affected kidneys except 1. CONCLUSION: Ureteroneocystostomy resulted in persistent partial ureteral obstruction for 4 to 11 days as determined by 99mTc-DTPA scintigraphy. CLINICAL RELEVANCE: 99mTc-DTPA scintigraphy may be a useful procedure for monitoring renal function and ureteral obstruction after ureteroneocystostomy. Persistent partial ureteral obstruction may be seen 1 to 2 weeks after ureteral reimplantation in dogs with previously existing dilated ureters.