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Abstract

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.

Procedure—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. (Am J Vet Res 2003;64:1076–1080)

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To determine the effect of sedation and anesthesia on thyroid and salivary gland uptake of technetium Tc 99m pertechnetate (99mTcO4) in euthyroid cats.

Animals—6 euthyroid cats.

Procedures—Thyroid scintigraphy was performed by use of a high-resolution low-energy parallel-hole collimator after IV injection of 117 to 133 MBq (3.16 to 3.59 mCi) of 99mTcO4 . The procedure was performed 4 times on each cat during different sedative and anesthetic protocols in a rotating schedule as follows: propofol, ketamine-midazolam-atropine, ketaminemidazolam, and medetomidine. Regions of interest were drawn around thyroid and salivary glands and counts corrected for background and decay. Percentage of 99mTcO4 uptake in salivary and thyroid glands and thyroid-to-salivary gland 99mTcO4 uptake ratio were calculated at 20 and 40 minutes. Relative effects of anesthesia and sedation on salivary and thyroid gland 99mTcO4 uptake were compared.

Results—Significant differences among sedativeanesthetic protocols were found for thyroid gland 99mTcO4 uptake, salivary gland 99mTcO4 uptake, and thyroid-to-salivary gland 99mTcO4 uptake ratio. Thyroid gland 99mTcO4 uptake for the ketamine-midazolam protocol at 20 and 40 minutes after 99mTcO4 administration was significantly higher than for the propofol protocol. A significant difference in salivary gland99m TcO4 uptake was found between ketamine-midazolam and ketamine-midazolam-atropine protocols at 40 minutes. The thyroid-to-salivary gland 99mTcO4 uptake ratio for the ketamine-midazolam protocol was significantly higher at 40 minutes than for propofol or ketamine-midazolam-atropine protocols.

Conclusions and Clinical Relevance—Sedation and anesthesia have a significant effect on thyroid and salivary gland 99mTcO4 uptake in euthyroid cats that may interfere with thyroid scintigraphic image interpretation.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To use scintigraphy to determine the effects of partial ureteral obstruction on renal transit time and induction of diuresis in dogs.

Animals

8 adult dogs.

Procedure

Scintigraphy was performed, using technetium Tc 99m diethylenetriaminepentacetic acid (Tc 99m-DTPA), before and within 2 weeks after surgical induction of unilateral partial ureteral obstruction. Time of peak (TOP) for the parenchyma (pTOP) and whole kidney (wTOP) and mean-transit time (MTT) for the parenchyma (pMTT) and whole kidney (wMTT) were determined by evaluation of renal time-activity curves before and after deconvolution analysis. Percentage uptake for each kidney between 1 and 3 minutes after injection of Tc 99m-DTPA was determined and used to indicate glomerular filtration rate. The effect of diuresis was determined by measuring the slope of decrease in activity after IV administration of furosemide. Obstruction was documented by direct inspection of the ureter.

Results

There was a concomitant increase in pTOP, wTOP, pMTT, and wMTT of the kidney with the partially obstructed ureter in all dogs at various times between 2 and 9 days after surgery. Concurrently, renal time-activity curves changed shape. Percentage renal uptake of the affected kidney was decreased in 2 dogs. Response to furosemide injection was inconsistent for kidneys before surgery and for kidneys with obstructed and nonobstructed ureters after surgery.

Conclusions and Clinical Relevance

Scintigraphy may be a useful procedure for the evaluation of renal function in dogs with ureteral obstruction. Induction of diuresis appears to be of little value for differentiating renal function in dogs with obstructed and nonobstructed ureters. (Am J Vet Res 1999;60:1383–1389)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of number of blood samples and sampling times on plasma clearance of technetium Tc 99m pentetate (Tc99mP) and orthoiodohippurate sodium I 131(OIH).

Animals—20 dogs and 14 cats.

Procedure—Plasma clearances of OIH and Tc99mP were calculated by use of a 2-compartment model, on the basis of a 12-point curve as a reference method. Plasma clearance was calculated by use of all possible combinations of 4 to 11 samples. Time schedule yielding the smallest difference from the reference method was considered to be optimal. Regression analysis was performed between the 12-point model and models using a reduced number of samples.

Results—SD of the difference between the 12-point clearance and the models with reduced numbers of samples increased when the number of samples decreased. The SD of the difference between 12-point clearance and 4-point clearance was 4.17 ml/min for OIH and 0.94 ml/min for Tc99mP in dogs and 0.45 ml/min for OIH and 0.11 ml/min for Tc99mP in cats. Optimal schedules were distributed logarithmically and included an early sample at 5 or 10 minutes, a late sample at 2.5, 3, 4, or 5 hours for OIH, and a late sample at 4 or 5 hours for Tc99mP.

Conclusions and Clinical Relevance—Plasma clearances of OIH and Tc99mP can be accurately calculated in dogs and cats by use of a single-injection 2-compartment pharmacologic model with a reduced number of blood samples, resulting in an acceptable margin of error. (Am J Vet Res 2000;61:280–285)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To describe clinical, ultrasonographic, and computed tomographic (CT) features of confirmed neoplastic and nonneoplastic disease in dogs with unilateral orbital diseases, determine criteria to differentiate between the 2 conditions, and assess the relative value of ultrasonography and CT for the differential diagnosis of these 2 conditions.

Design—Prospective study.

Animals—29 dogs with unilateral neoplastic orbital disease and 16 dogs with unilateral nonneoplastic orbital disease.

Procedures—Clinical history and results of physical and ophthalmologic examinations were recorded. Ultrasonographic and CT images were evaluated, and discriminating factors were identified to differentiate neoplastic from nonneoplastic diseases. Diagnostic value of ultrasonography and CT was assessed.

Results—Dogs with neoplastic disease were significantly older; had clinical signs for a longer time before initial examination; had more progressive onset of clinical signs; and more frequently had protrusion of the nictitating membrane, fever, and anorexia. The most discriminating factor for both imaging modalities was delineation of the margins (odds ratio was 41.7 for ultrasonography and 45 for CT), with neoplastic lesions clearly delineated more often. Ultrasonographically, neoplastic lesions were more frequently hypoechoic and homogeneous, with indentation of the globe and bone involvement evident more frequently than for nonneoplastic lesions. Mineralization was detected only with neoplasia. Fluctuant fluid was seen more frequently in dogs with nonneoplastic disease. Computed tomography more frequently revealed extraorbital involvement. Diagnostic value was similar for both imaging modalities.

Conclusions and Clinical Relevance—Ultrasonography and CT are valuable imaging modalities to assist in differentiating neoplastic from nonneoplastic unilateral orbital disease in dogs.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the results of computed tomography (CT) and magnetic resonance imaging (MRI) of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism (PDH) caused by histologically confirmed pituitary adenoma.

Design—Retrospective case series.

Animals—11 dogs with PDH that underwent transsphenoidal hypophysectomy.

Procedures—Medical records of dogs examined between January 2001 and March 2003 were reviewed. Dogs were included in this study if they had clinical signs of hypercortisolism at the time of admission (for which PDH was diagnosed) and underwent transsphenoidal hypophysectomy. Pre- and postcontrast CT and low-field MRI (0.2-Tesla magnet) were performed on the same day as surgery for each dog.

Results—An abnormal pituitary gland was found in 7 dogs by use of MRI and in the same 7 dogs by use of CT. Significant differences were found between postcontrast CT and MR images for height, width, and length of the pituitary gland; brain area; and thickness of the sphenoid bone. However, the pituitary gland height-to-brain area ratio determined from postcontrast CT and MR images was not significantly different. The signal-to-noise ratio and contrast-to-noise ratio of pre- and postcontrast MR images were significantly higher than those of the CT images.

Conclusions and Clinical Relevance—Low-field MRI and dynamic CT imaging of the pituitary gland provided comparable information on the presence of pituitary adenomas in dogs with PDH.

Full access
in Journal of the American Veterinary Medical Association

  • Intermittent incontinence can be associated with incomplete urethral duplication in dogs.

  • Urethral duplication in dogs can be diagnosed by urethrography, voiding cystourethrography, or radiography after direct administration of positive contrast medium into cystic structures, if present.

  • Surgical removal of the urethral duplication and cysts can be curative in dogs.

Free access
in Journal of the American Veterinary Medical Association

Summary

Five radiographic protocols for detecting pulmonary metastases in dogs were compared by analyzing receiver operating characteristic curves for the protocols. Protocols compared were a right lateral view only, a left lateral view only, right lateral and dorso- ventral views, both lateral views, and all 3 views. Three radiologists used each of the protocols to evaluate 99 sets of thoracic radiographs. Fifty-two sets of radiographs were from dogs confirmed histologically to have pulmonary metastases and 47 were from dogs proven at necropsy to be free of pulmonary metastases. Results of the 5 protocols were not statistically different. We concluded that a third view is not necessary when routinely screening dogs with cancer for pulmonary metastases and that the standard 2-view thoracic examination should be adequate. However, in individual cases, a third view may be the determining factor in establishing a radiographic diagnosis and should be obtained if any suspicious areas are seen.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—

To determine normal adrenal gland size by means of ultrasonography in dogs and to determine the value of ultrasonography in the diagnosis of pituitary-de-pendent hyperadrenocorticism (PDH) in dogs.

Design—

Prospective observational study.

Animals—

62 dogs: 20 healthy dogs, 20 dogs with non-endocrine disease, and 22 dogs with untreated PDH.

Procedure—

Length and maximum and minimum diameter of the adrenal glands were measured ultrasonographically. Multiple regression and correlation analyses were used to determine whether body weight, kidney length, aortic diameter, or age was related to adrenal gland size. Two-tailed t-tests and multiple linear regression analysis were used to compare values between groups. Sensitivity and specificity of using ultrasonographic measurement of adrenal gland size as a diagnostic test for PDH were determined.

Results—

There was a significant linear relationship between adrenal gland length, but not maximum and minimum diameters, and body weight, aortic diameter, and kidney length in healthy dogs and in dogs with nonenocrine diseases. Length, maximum diameter, and minimum diameter of the right adrenal gland and maximum and minimum diameters of the left adrenal gland were significantly greater in dogs with PDH than in healthy dogs and dogs with nonendocrine diseases. As a diagnostic test for pdh, ultrasonographic measurement of maximum or minimum diameter of the left adrenal gland gave the best combination of sensitivity and specificity. For maximum diameter of the left adrenal gland, sensitivity was 77% and specificity was 80%. For minimum diameter of the left adrenal gland, sensitivity was 73% and specificity was 85%.

Clinical Implication—

Ultrasonography of the adrenal glands is a valuable diagnostic procedure in dogs suspected of having pituitary-dependent hyperadrenocorticism.

Free access
in Journal of the American Veterinary Medical Association