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Background: Computed tomography (CT) is considered to be the reference method to evaluate middle ear structures., Objectives: To evaluate the presence and severity of CT changes in the middle ear and establish if any specific clinical presentations are associated with otitis media., Animals: Medical records of animals referred for CT with history and clinical signs consistent with middle ear disease., Methods: Retrospective evaluation of CT examinations of tympanic bullae performed over a six year period. Medical records were reviewed for signalment, clinical signs and cytological evaluation of the external ear canal. Dogs were divided into three clinical groups: chronic otitis externa (Group 1), peripheral vestibular disorder (Group 2) and other clinical presentations (Group 3)., Results: Group 1 - Of 214 ears, 87 (40.7%) had CT abnormalities: 38 of 87 (17.7%) had material-filled bullae, 42 of 87 (19.6%) had thickened bullae walls and seven of 87 (3.2%) had lysis of the bulla. Abnormalities were significantly more frequent in dogs with suppurative otitis than in erythemato-ceruminous otitis (57% and 23%, respectively; P = 0.003). Proliferative otitis, particularly in French bulldogs, was associated with severe otitis media. Group 2 - Of the 106 ears, 91 (85.8%) had normal tympanic bullae. Group 3 - Of the 26 ears from deaf dogs, 17 had filled bullae; all nine affected dogs were Cavalier King Charles spaniels. All dogs with Claude Bernard Horner syndrome or head tilt had normal tympanic bullae., Clinical Significance: CT is useful for canine chronic otitis externa, particularly in suppurative or proliferative otitis, even in the absence of associated neurological signs., (© 2017 ESVD and ACVD.)

Few reports have been published regarding the use of scintigraphy in the diagnosis of elbow joint lameness in dogs. Some authors have speculated about the potential use of bone scintigraphy and its suspected high sensitivity for the early diagnosis of abnormalities of the medial coronoid process (MCP) in dogs. Scintigraphy is used routinely in our institution in dogs presented for thoracic limb lameness and/or suspected of abnormalities of the MCP when radiographic findings were equivocal. Radiographic, scintigraphic, and surgical findings of the elbow joints of 17 dogs with elbow joint lameness were compared with radiographic, scintigraphic, and necropsy findings of the elbow joints of 12 clinically healthy Labrador Retrievers. Quantitative evaluation of scintigraphic images was performed to determine relative radiopharmaceutical uptake in the region of the MCP. Maximum relative uptake of the coronoid process in the normal dogs was taken as a threshold value to classify elbows as positive or negative for an abnormal MCP after all 24 elbows of the 12 healthy dogs were confirmed as being normal at necropsy. All 17 elbows from lame dogs were positive on scintigraphy and confirmed as having chondromalacia, a fissure, or fragmentation of the MCP. Based on our results, bone scintigraphy may be a valuable diagnostic tool for the diagnosis of abnormalities of the MCP in dogs, and particularly in older dogs where clinical and radiographic changes may be ambiguous.

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.

We describe the magnetic resonance (MR) imaging aspects of normal canine optic nerve, the diameter of the optic nerve as measured on MR images, and optimal MR sequences for the evaluation of the optic nerve using a 0.2T MR unit. Three millimeter contiguous slides of the normal canine orbital region were acquired in transverse and dorsal oblique planes using a variety of tissue weighting sequences. It was apparent that detailed anatomic assessment of the optic nerve can be performed with low-field MR imaging, but none of the sequences provided unequivocal superior image quality of the optic nerve. The mean diameter of the optic nerve sheath complex was 3.7mm and of the optic nerve 1.7 mm. The intraorbital and intracanalicular parts of the optic nerve are consistently visible and differentiation between the optic nerve and optic nerve sheath complex is possible using low-field MR systems.

The purpose of this study was to determine if variation in the ultrasound beam angle would affect cartilage thickness measurement performed with B-mode ultrasonography. Transverse sections of six fresh equine middle phalanges were obtained from necropsy. Ultrasonographic images of the proximal articular cartilage were obtained in a water bath, in a plane parallel and adjacent to the section plane using a 5-10 MHz linear transducer. Static images were acquired for all six bone specimens with an ultrasound beam angle of 0 degree, 30 degrees, 45 degrees, and 60 degrees. Proximal articular cartilage thickness was measured on ultrasonographic images and on the bone specimen at the same level. A linear mixed-effects model was used to compare articular cartilage thickness measured on specimen and on ultrasonographic images using different ultrasound beam angle. Mean +/- SD cartilage thickness was 1.82 +/- 0.35 mm on bone specimens, 1.72 +/- 0.29 with a 0 degrees angle, 1.99 +/- 0.34 with 30 degrees, 2.06 +/- 0.34 with 45 degrees, and 2.3 +/- 0.38 with 60 degrees. There was a significant difference between macroscopic measurements and ultrasonographic measurements performed with ultrasound angles at 30 degrees, 45 degrees, and 60 degrees. There was a significant increase in cartilage thickness when the ultrasound beam angle decreased (P = 0.0157; R2 = 0.969). Cartilage thickeness measured on ultrasonographic images varies with the ultrasound beam angle and may not be accurate because ultrasound speed in cartilage may be different than the speed used by the ultrasonographic unit for distance calculation.

Either in research or in clinical practice, the exploration of renal oxidative metabolism is limited by the lack of noninvasive measurement. Positron-emission tomography using carbon-11 acetate may estimate tissue oxidative metabolism by measuring acetate turnover in the Krebs cycle. Although extensively studied in cardiology, this method has never been validated for renal oxidative metabolism measurement. The aim of this study is the validation of acetate turnover compared with the invasive renal oxygen consumption measurement. Renal oxygen consumption and tubular sodium reabsorption were measured invasively in 10 anesthetized pigs. Simultaneously, acetate turnover was estimated by the clearance of carbon-11 acetate in the renal cortex, after a 166-MBq injection of carbon-11 acetate. Renal oxidative metabolism was measured under various conditions induced by mechanical and pharmacological interventions. Renal oxygen consumption and acetate turnover varied on a wide range from 0.05 to 0.29 mmol min(-1) (>5-fold) and from 0.025 to 0.188 minutes(-1) (>7-fold), respectively. Acetate turnover was very significantly correlated with renal oxygen consumption (P<0.0001; R=0.82) and tubular sodium reabsorption (P=0.001; R=0.67). This study demonstrates that acetate turnover measures renal oxidative metabolism noninvasively and quantitatively, consistent with changes in tubular sodium reabsorption. This method may be applied to assess oxidative metabolism in animal models and in humans.

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.

The purpose of this study was to determine the optimal window level and width for accurate measurement of pituitary gland height in a phantom. A phantom, mimicking the appearance of the pituitary gland, was made by using the base of a canine skull immersed in buttermilk. Seven different-sized cylindrical pieces of cheese were made and the real diameter of each sample was measured by using a caliper. The cheese was then placed in the pituitary fossa, and 2-mm thick contiguous computed tomography (CT) slices were acquired. The height of the cheese was measured using electronic calipers with different window width and level (WW-WL) settings. The mean difference between CT and manual caliper measurements and concordance correlation coefficients were calculated for all settings. CT measurements underestimated manual caliper measurements with all settings, but the smallest difference (0.5 mm) was obtained with a 250-80 window. Concordance coefficients ranged from 0.699 to 0.820, with the maximum concordance coefficient obtained with a 250-80 window. A second series of measurements using a different window setting for the brain-pituitary gland edge (WW-WL: 250-80) and for the bone-pituitary gland edge (WW-WL: 250-240) resulted in a reduction in the mean difference (0.1 mm) and an increase in the concordance coefficient (0.836). It was concluded that underestimation of the height of the pituitary gland on CT images is most likely due to erroneous placement of the edge of the basisphenoid bone using a low level and a narrow window.

99mTc-pertechnetate is excreted in humans by the thyroid glands, gastric mucosa, salivary glands, choroid plexus, and sweat glands. Uptake attributed to the zygomatic and molar salivary glands is used commonly as a reference to assess thyroid uptake and differentiate euthyroid from hyperthyroid cats. However, the exact location and origin of uptake of 99mTc-pertechnetate in the head during thyroid scintigraphy in cats remains uncertain. The purpose of this study was to localize uptake of 99mTc-pertechnetate in the head of the cat using multimodality image fusion. Computed tomography (CT), magnetic resonance (MR), and single photon emission tomography (SPECT) imaging were performed successively in two cats during the same anesthesia procedure. Transverse, dorsal, and sagittal images were reconstructed for each modality. Images were rescaled and fused manually. The anatomic location of focal 99mTc activity in SPECT images was identified in CT and MR images. Four major and four minor focal areas of uptakes were identified in the head in both cats. A rostral conical-shaped activity was identified in the nasal cavity. Two symmetric focal areas of uptakes seen in the soft tissues in the ventro-caudal retro-bulbar region, and rostro-medial to the vertical ramus of the mandible were attributed to zygomatic salivary glands. A central focal activity located ventral and caudal to the zygomatic uptake was located in the nasopharynx and soft palate. Minor symmetric areas of uptake identified in the retromandibular region were attributed to parotid and mandibular salivary glands. Minor symmetric areas of uptake identified in the region of the mandible were attributed to molar salivary glands. No focal area of uptake was identified in the brain.

Objectives: To determine the effect of sedation and anesthesia on thyroid and salivary gland uptake of technetium Tc 99m pertechnetate ((99m)TcO(4)) 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 (99m)TcO(4)(-). 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 (99m)TcO(4)(-) uptake in salivary and thyroid glands and thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio were calculated at 20 and 40 minutes. Relative effects of anesthesia and sedation on salivary and thyroid gland (99m)TcO(4)(-) uptake were compared., Results: Significant differences among sedativeanesthetic protocols were found for thyroid gland (99m)TcO(4)(-) uptake, salivary gland (99m)TcO(4)(-) uptake, and thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio. Thyroid gland (99m)TcO(4)(-) uptake for the ketamine-midazolam protocol at 20 and 40 minutes after (99m)TcO(4)(-) administration was significantly higher than for the propofol protocol. A significant difference in salivary gland(99m) TcO(4)(-) uptake was found between ketamine-midazolam and ketamine-midazolam-atropine protocols at 40 minutes. The thyroid-to-salivary gland (99m)TcO(4)(-) 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 (99m)TcO(4) uptake in euthyroid cats that may interfere with thyroid scintigraphic image interpretation.

Iohexol plasma clearance as a measure of glomerular filtration was determined in 31 dogs and 19 cats after an intravenous (i.v.) bolus injection. All animals were healthy and privately owned. Serial blood samples were taken before and up to 4 h after tracer injection. Iohexol plasma concentration was determined using X-ray fluorescence. A plasma tracer elimination curve was generated and clearance was calculated by dividing the injected dose by the area under the curve estimated using a two-compartment pharmacological model. Clearance was normalized to body weight (BW), body surface area (BSA), and extracellular fluid volume (ECFV). Mean, SD, and coefficient of variation of plasma clearance, before and after normalization, were calculated. Linear regression analyses were performed between body size and normalized plasma clearances. No significant linear relation was found between BSA and clearance normalized to BSA in dogs, and between BSA, BW, ECFV and clearance normalized to BSA, BW, and ECFV in cats. The optimal method for normalization of iohexol plasma clearance in dogs was by using BSA. In cats, all three methods tested were considered satisfactory. Normalization to BSA appears to be superior to normalization to BW and ECFV in dogs, and can be recommended for clinical use.

The purpose of this study was to evaluate simplified methods for iohexol plasma clearance estimation in dogs and cats. Serial blood samples were taken before and 5, 20, 40, 60, 80, 100, 120, 150, 180, and 240 minutes after a bolus injection of iohexol in 51 dogs and 25 cats. Iohexol plasma concentration was determined with X-ray fluorescence. Clearance was calculated by dividing the injected dose by the area under the plasma tracer elimination curve estimated with a 2-compartment pharmacologic model. Clearance was normalized to body surface area (BSA). The 10-point clearance was used as a reference for the evaluation of simplified methods. A 2-sample method based on a single exponential fit and a single-sample method based on a linear quadratic model were investigated. Simplified methods were evaluated by calculating the standard deviation of the difference (SDD) between the clearances obtained with the simplified methods and the 10-point reference method. All combinations of sampling times were evaluated. The best sampling times were chosen for dogs and cats as the ones yielding the lowest SDD. Linear regression analysis was performed between the reference method and the optimized simplified methods. The best combination of time for the 2-sample method was 5 and 120 minutes in dogs and 20 and 180 minutes in cats. The best time for sampling in the single-sample method was 120 minutes in dogs and 80 minutes in cats. Plasma clearance of iohexol can be estimated in dogs and cats from 1 or 2 blood samples with a reasonable margin of error.

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.

Four dogs with ureteral fibroepithelial polyps, ranging from 9-12 years of age, are presented in this report. The patients presented with urinary incontinence, urinary tract infection, and/or polydypsia and pollakiuria. All dogs were intact at the time of diagnosis or for the majority of their lives and three were male. Various diagnostic procedures were performed including ultrasonography, contrast radiography, and nuclear scintigraphy. Not all procedures were performed in all patients. Findings included ureteral dilation proximal to the level of an intraluminal mass and ipsilateral hydronephrosis. Unilateral ureteronephrectomy was performed in three dogs with masses in the proximal ureter; ureteral resection and anastamosis was performed in the remaining patient with a mass located in the distal ureter. The same pathologist (RAP) reviewed all four lesions. The lesions appeared polypoid and were attached to the ureteral wall by a thin stalk. Histopathologically, they contained a superficial layer of well-differentiated transitional epithelial cells overlying a prominent fibrovascular stroma with a mild (three dogs) or marked (one dog) degree of lymphoplasmacytic inflammation. This disease may represent a benign neoplasm or a chronic inflammatory reaction and has a good prognosis with surgical removal. Its histopathological characteristics, higher incidence in males, and location more commonly within the upper third of the ureter is remarkably similar to the disease in humans.

Background: Positron emission tomography (PET) is a functional imaging device that allows dynamic regional blood flow measurements. We performed a study to test whether PET could detect acute changes in renal blood flow (RBF) in patients with chronic renal failure (CRF)., Methods: RBF was measured by means of PET (PET-RBF) using oxygen 15-labeled water (H2(15)O) in eight men with hypertension and moderate CRF before and 5, 40, 80, and 120 minutes after the injection of quinaprilat (10 mg intravenously). Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were measured simultaneously by para-aminohippuric acid (PAH-ERPF) and inulin clearances before and 20, 60, 100, and 140 minutes after quinaprilat injection., Results: Baseline RBF and ERPF were decreased in all patients (221 +/- 20 mL/min/100 g and 225 +/- 38 mL/min/1.73 m2, respectively). PET-RBF increased significantly after quinaprilat injection (+15%, +26%, +19%, and +23% versus baseline; P < 0.003). PAH-ERPF did not increase significantly (-6%, +12%, +20%, and +15% versus baseline; P = 0.15). GFR (50.1 +/- 8.9 mL/min/1.73 m2 at baseline) did not change significantly after quinaprilat injection; however, filtration fraction (GFR-ERPF ratio) decreased significantly from 0.23% +/- 0.02% to 0.20% +/- 0.02% (P = 0.0004). Mean arterial pressure decreased significantly after quinaprilat injection (P < 0.005)., Conclusion: This study dynamically measured RBF by means of PET in patients with CRF for the first time. It showed that RBF rapidly increased after quinaprilat injection. PET using H2(15)O is a powerful method for the noninvasive measurement of dynamic changes in RBF that remain undetected by PAH clearance., (Copyright 2002 by the National Kidney Foundation, Inc.)

The purpose of this study was to compare characteristics and performances between single-phase (SP) and high-frequency (HF) generators for x-ray units dedicated to veterinary radiology practice. A 30-kW SP and a 30-kW high HF generator connected to a rotating anode x-ray tube were used for the study. Source-film distance, screen/film combination, and film processing were kept the same during the experiment. The mAs value yielding a similar film optical density of a stair step phantom, as assessed by a densitometer and a similar dose, as assessed by a solid state detector, was estimated for different kVp values. The ratio of the mAs used with the SP generator to the equivalent mAs used with the HF generator to produce similar film density or radiation dose was calculated. Subject contrast was measured for different kVp values as the relative difference in film optical density between two steps of the phantom. The waveform of the tube current was recorded for the two generators using an oscilloscope. Motion artifact was produced on a lateral radiograph of a canine tarsus using the two generators. Reproducibility was assessed by comparing the variances of film density measurements made on the central step of the phantom on 10 consecutive images produced with the two generators. mAs ratios (SP/HF) to obtain similar film optical density ranged from 2 (for 90kVp) to 2.5 (for 70 kVp), and mAs ratios to obtain similar radiation dose ranged from 1.2 (for 100 kVp) to 1.4 (for 70 kVp). Image contrast was slightly higher for the SP than for the HF generator. Current waveform for the SP generator was half-sinusoidal and it was almost continuous for the HF generator. Motion artifact appeared as blur for the HF generator and as several regularly placed images of the subject for the SP generator. Reproducibility was significantly better for the HF than for the SP generator (P = 0.047). It was concluded that the HF generator was approximately two times more efficient, had a better reproducibility, and produced images with a lower contrast than the SP generator. Motion artifact appears differently due to different current waveform.

The purpose of this study was to evaluate simplified methods for estimation of Technetium Tc 99m (99mTc)-pentetate and orthoiodohippurate I 131 (131I-OIH) plasma clearance in dogs and cats with 1 and 2 blood samples. Plasma clearances were calculated after a bolus injection of 1.85-11.1 MBq of 99mTc-pentetate and 131I-OIH with a 2-compartment model based on a 12-point curve as a reference method in 21 dogs and 18 cats. Three 2-sample and 3 single-sample methods were investigated. The method yielding the smallest standard deviation of the difference between the reference method and the simplified method was selected as the optimal one. Linear regression analysis was performed between the reference method and the simplified method and coefficient of determination (R2) was calculated. For 99mTc-pentetate plasma clearance, the optimal 2-sample method was the one with a mono-compartment model with samples taken at specific times. For 131I-OIH plasma clearance, the estimation was improved slightly by raising the clearance calculated with a mono-compartment model to the power of an empirically determined parameter. The optimal single-sample method was the one with a linear quadratic regression between the volume of distribution of the tracer at a specific time and the clearance calculated with 12 samples. Two-sample methods performed significantly better than did single-sample methods. The conclusion is made that 99mTc-pentetate and 131I-OIH plasma clearances can be estimated in dogs and cats with 1 or 2 blood samples with a reasonable margin of error compared to plasma clearances calculated with a 2-compartment model and 12 blood samples.

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.

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.

The transit time of 99mTc-DTPA in the kidneys is an indicator of renal function that has been used in humans for the diagnosis of renal obstruction, renal artery stenosis, and rejection of renal transplants. Its use, however, has not been reported in the dog. 99mTc-DTPA scintigraphy was performed in 8 normal dogs and the time of peak was calculated as the time between the injection and the maximum renal uptake. Deconvolution analysis was performed to estimate the renal retention function using 3 different techniques, i.e. the matrix method, the fast Fourier transform (FFT) method, and the constrained least square method. The parenchymal and whole kidney mean transit times were calculated from the deconvolved renogram using alternatively the thorax and the aorta as the input function. Average mean transit times ranged from 137 to 184 seconds. Parenchymal mean transit time was significantly shorter than whole kidney mean transit time (P<0.03). Mean transit time calculated with the thorax as the input function was significantly longer than mean transit time calculated with the aorta (P<0.001). No differences were observed between mean transit time calculated with the matrix, FFT and constrained least square methods.

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 i.v. 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.

Computed tomography (CT) excretory urography was performed in five adult female dogs after intravenous injection of a bolus of four different doses of water-soluble iodinated contrast medium (100, 200, 400, and 800 mgI/kg). CT images centered over the urinary bladder were performed before injection and 1, 3, 5, 7, 9, 11, 15, 20, 25, 30, 40, 50, and 60 minutes after injection. Opacification of both ureters was evaluated by measuring maximum CT number of individual ureters at each time. Time opacification curves were generated for each dose. Best opacification of the ureters was obtained with 400 and 800 mgI/kg, with a constant peak at 3 minutes and durable opacification for 1 hour. Insufficient opacification was obtained with lower dose of 100 and 200 mgI/kg.

Incomplete urethral duplication with cyst formation was diagnosed in a dog that had soft, fluctuant, subcutaneous swellings in the ventral perineal and penile areas and a history of nocturia and incontinence during recumbency that were unresponsive to treatment with antibiotics. Retrograde urethrocystography, voiding urethrography, double-contrast cystography, radiography after direct administration of contrast medium into cystic structures, and excretory urography were performed to evaluate the urinary tract. Communication between the cysts and the urethra was demonstrated radiographically only after intralesional injection of contrast medium. Nocturia and incontinence resolved after surgical removal of the urethral duplication and cysts. The dog was clinically normal 1 year after surgery.

The scintigraphically measured percentage dose uptake of 99mTc-DTPA by the kidneys and the plasma clearance of 99mTc-DTPA have been reported to correlate well with inulin clearance. These two parameters were evaluated in seven dogs with known or suspected naturally occurring renal disease and compared to simultaneously measured renal inulin clearance. Correlation between inulin clearance and the 99mTc-DTPA plasma clearance was better (p = .0016) than the correlation between the percentage DTPA uptake by the kidney. It was concluded that measurement of 99mTc-DTPA plasma clearance is a more accurate method to estimate global glomerular filtration rate (GFR) than the percentage kidney uptake.

Ultrasonography has become an important modality for imaging adrenal glands in small animals. Normal adrenal glands and structural abnormalities, such as changes in size, shape, and echogenicity, can be identified. In the case of adrenal tumors, ultrasonography is a valuable tool for identifying neoplastic masses with local and regional involvement, as well as potential abdominal metastases. When correlated with clinical findings and results of hematologic, serum biochemical and endocrine tests, ultrasonographic findings make a substantial contribution to the diagnosis of adrenal diseases in dogs, cats, and ferrets.

Ultrasonography of the gallbladder was performed in 3 groups of dogs: 30 clinically healthy dogs, 50 dogs with hepatobiliary disease, and 50 dogs with diseases other than hepatobiliary disease. The gallbladder was evaluated for the presence of sludge (echogenic material without acoustic shadowing). Maximal gallbladder length, width, height, and area were measured as well as the gallbladder wall thickness. The relative sludge area was calculated as the ratio of sludge area over gallbladder area on longitudinal images. No significant difference was found in the prevalence of gallbladder sludge among healthy dogs (53%), dogs with hepatobiliary diseases (62%), and dogs with other diseases (48%). The mean age of dogs with sludge was higher than the mean age of dogs without sludge in dogs with hepatobiliary disease and dogs with other diseases (p < 0.05). The mean relative sludge area did not differ significantly among the 3 groups. A trend to larger gallbladder dimensions in dogs with sludge compared to dogs without sludge was detected within the 3 groups. The gallbladder wall thickness was not different between dogs with and without sludge within the 3 groups. However, the gallbladder wall was more frequently isoechoic than hyperechoic to the liver in dogs with sludge than in dogs without sludge. The results of this study indicate that gallbladder sludge, in dogs, is not particularly associated with hepatobiliary disease and should be considered an incidental finding.

Sagittal and transverse ultrasonographic images of the prostate gland were obtained in 100 healthy adult intact male dogs. Prostatic length, width, and height on transverse and sagittal images as well as the presence of prostatic cysts were determined. Linear regression and correlation analysis were performed between prostatic parameters (length, width, height on sagittal and transverse images, and estimated volume) and parameters related to body size (body weight, body height, left kidney length and aortic diameter) and age of the dogs. Significant positive correlations were found between all prostatic parameters and parameters related to body size and age. Maximum predicted values for prostatic parameters for a given body weight and age were determined based on the upper limit of the 95% confidence interval of the mean predicted values. Such values should represent a useful tool for ultrasonographic evaluation of the prostate in the dog. Prostatic cysts were found in 14% of the dogs.

Side lobes and grating lobes are both unwanted parts of the ultrasound beam emitted off axis that produce image artifacts due to error in positioning the returning echo. The purpose of this study was to reproduce artifacts associated with side lobes and grating lobes in vitro using different transducer types and recognize these artifacts in vivo. A phantom, composed of a water bath, a metallic wire, and a wooden tongue depressor, was imaged using a linear array, a curved linear a vector array, and a sector mechanical transducer. When imaging the metallic wire in a transverse plane, an echogenic artifact was constantly seen on each side of the wire, with a shape and intensity variable with the transducer type. The artifact was curvilinear and concave (linear and curved linear arrays), or curvilinear and convex (vector array and the mechanical transducer). When the tongue depressor was imaged in a longitudinal plane, the artifact was a straight line (linear array), a curved convex line (curved array), a series of convex curvilinear echo (vector array) or a small convex curvilinear echo (mechanical transducer). In vivo situations similar to the phantom experiment were investigated using clinical patients. Artifacts produced in vitro were recognized in vivo when a highly reflective object (urinary bladder wall) was imaged adjacent to an anechoic region (urine). These artifacts corresponded to the principle of secondary ultrasound lobes, and were therefore interpreted as such.

This report presents the clinical, laboratory, imaging, and pathologic findings in 61 dogs with pheochromocytoma by retrospective evaluation of medical records. Pheochromocytomas were diagnosed by histopathologic examination of tissue specimens in all dogs. Special stains (chromogranin A and synaptophysin) also were used to confirm the chromaffin cell origin of the tumors. Epidemiologic findings were in agreement with previous studies, indicating that pheochromocytomas affect middle-aged to older dogs with no apparent gender or breed predilection. The tumor was considered clinical in 21 dogs (34%), was responsible for abnormalities related to a space-occupying mass in 7 dogs (11%), and was an incidental finding in 35 dogs (57%). The hematologic and biochemical findings were nonspecific. Hypertension was detected in 10 of 23 (43%) dogs tested, but all hypertensive dogs had concurrent diseases that may have contributed to hypertension. Abdominal ultrasonography was the most commonly used imaging procedure, with a mass detected in the region of the adrenal glands in 20 of 40 (50%) dogs examined. In 4 of the 20 dogs (20%), invasion of the caudal vena cava was identified. Surgery was performed in 17 dogs (28%) with immediate death or euthanasia of 5 dogs. Survival after surgery ranged from 1 day to 3.25 years. Pheochromocytomas were locally invasive in 39% of affected dogs and produced metastases in 13% of the cases. Common sites for metastases included regional lymph nodes, liver, lung, kidney, spleen, and bone. A high frequency of concurrent neoplasia (54%), including endocrine neoplasia, was identified.

Three patients (1 dog, 2 horses) are described where myelography was complicated, purportedly by injection of contrast medium into the meninges superficial to the subarachnoid space. Contrast medium injected in this location in a cadaver tended to accumulate dorsally within the vertebral canal, deep to the dura mater but superficial to the subarachnoid space. The ventral margin of the pooled contrast medium had a wavy or undulating margin and the dorsal margin was smooth. Pooled contrast medium was believed to be sequestered within the structurally weak dural border cell layer between the dura mater and arachnoid membrane, or the so-called subdural space.

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-dependent 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 nonendocrine 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.

Nine dogs and 9 cats with ceruminous gland carcinoma were evaluated to determine whether they would receive radiation therapy. Tissue samples were reviewed to confirm the diagnosis and to assess completeness of resection in animals that had undergone surgery. Seven animals were excluded because surgical excision was determined histologically to have been complete (5) or because the owners did not wish to pursue treatment, because of advanced disease (2). The remaining 6 cats and 5 dogs, 6 of which had previously undergone surgery, were included in the study. The radiation therapy dose was 48 Gy, given in 12 fractions over 4 weeks. The product-limit estimate of mean progression-free survival time was 39.5 months. The estimate of 1-year progression-free survival rate was 56%. The tumor recurred in 4 animals, and metastases were observed in 3 animals. Radiation therapy was found to be safe and effective.

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 dorsoventral 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.