Impact of arthroscopy on post-procedure intra-articular elbow injections: A cadaveric study.

OBJECTIVE: To determine the influence of arthroscopy and injection volume on post-procedure intra-articular (IA) injection extravasation. STUDY DESIGN: Ex vivo prospective study. SAMPLE POPULATION: A total of 40 paired canine cadaver forelimbs. METHODS: After radiographs and computed tomography (CT) scans with three-dimensional (3D) digital bone model reconstructions, elbows were randomly assigned to the arthroscopy or control group and randomly assigned to receive an IA injection of 2 or 4 mL of contrast. Elbow arthroscopy was performed on assigned specimens, followed by IA injections of contrast in all elbows, and imaging was repeated. 3D digital model volumes were compared. Images were interpreted and scored for extravasation by a radiologist unaware of treatment and volume assignments. RESULTS: Based on CT images and regardless of treatment group, IA injections of 4 mL resulted in a mean extravasation score of 2.25 (SD 0.97) versus 1.55 (SD 1.05) (p = .02) for 2 mL IA injections. The change in 3D model volumes after IA injections was a mean of 13.2 cm3 (SD 5.85) after 4 mL injections, compared to 6.97 cm3 (SD 6.28) (p = .003) after 2 mL injections. On radiographic evaluation, but not CT, the mean extravasation scores were 2.45 (SD 1.15) for the arthroscopy group and 1.25 (SD 0.79) for the control group (p < .001). CONCLUSION: A larger volume of IA injection resulted in higher CT extravasation scores and larger 3D volumes regardless of arthroscopic treatment. CLINICAL SIGNIFICANCE: IA injections performed immediately after arthroscopy resulted in 50% or less extravasation, especially with a smaller IA injection volume.

Veterinary radiologic error rate as determined by necropsy.

A large-scale postmortem auditing of antemortem imaging diagnoses has yet to be accomplished in veterinary medicine. For this retrospective, observational, single-center, diagnostic accuracy study, necropsy reports for patients of The Schwarzman Animal Medical Center were collected over a 1-year period. Each necropsy diagnosis was determined to be either correctly diagnosed or discrepant with its corresponding antemortem diagnostic imaging, and discrepancies were categorized. The radiologic error rate was calculated to include only clinically significant missed diagnoses (lesion was not reported but was retrospectively visible on the image) and misinterpretations (lesion was noted but was incorrectly diagnosed). Nonerror discrepancies, such as temporal indeterminacy, microscopic limitations, sensitivity limitations, and study-type limitations were not included in the error rate. A total of 1099 necropsy diagnoses had corresponding antemortem imaging; 440 diagnoses were classified as major diagnoses, of which 176 were discrepant, for a major discrepancy rate of 40%, similar to reports in people. Seventeen major discrepancies were diagnoses that were missed or misinterpreted by the radiologist, for a calculated radiologic error rate of 4.6%, comparable with error rates of 3%-5% reported in people. From 2020 to 2021, nearly half of all clinically significant abnormalities noted at necropsy went undetected by antemortem imaging, though most discrepancies owed to factors other than radiologic error. Identifying common patterns of misdiagnosis and discrepancy will help radiologists refine their analysis of imaging studies to potentially reduce interpretive error.

Canine intrahepatic portosystemic shunts: Interlobar and intralobar classifications.

This two-part study design showed that a canine congenital intrahepatic portosystemic shunt (IPSS) may be classified by its location within a liver fissure (interlobar) or lobe (intralobar). A prospective anatomic study reviewed normal canine liver morphology and showed the CT angiography (CTA) appearance of the normal canine ductus venosus (DV), which was confirmed via dissection and literature review to be between the papillary process and left-lateral liver lobe (in the fissure for ligamentum venosum). A retrospective multi-institutional case series documented the frequency of imaging findings in 56 dogs with a single IPSS that underwent portal CTA at Cornell University or the Schwarzman Animal Medical Center between June 2008 and August 2022. An interlobar IPSS was seen in 24 of 56 (43%) dogs, all arose from the left portal branch except one. These shunts were typically near the median plane, remained interlobar throughout the course, and were nearly always (96%) craniodorsal to the porta hepatis. Four types were distinguished: patent DV (11 dogs), left interlobar (11 dogs), right interlobar (1 dog), and ventral interlobar (1 dog). Only about half (46%) were in the fissure for ligamentum venosum and therefore classified as a patent DV. An intralobar IPSS was seen in 32 of 56 (57%) dogs, most (88%) originated from the right portal branch and were in the right-lateral liver lobe (21 dogs) or caudate process (7 dogs). During canine portal CTA, documenting the interlobar or intralobar location of an IPSS might increase the consistency and validity of IPSS description.

Intrahepatic venous collaterals in dogs with congenital intrahepatic portosystemic shunts are associated with focal shunt or hepatic vein narrowing.

Dogs with congenital intrahepatic portosystemic shunts (IHPSS) occasionally have multiple smaller intrahepatic, tortuous blood vessels surrounding the primary shunt. This study was a retrospective, observational design that was also descriptive and anatomic in nature. Objectives were to characterize vascular morphology in IHPSS dogs presenting with intrahepatic venous collaterals (IVCs) relative to IHPSS dogs without IVCs, and to propose reasons for IVC development. The authors hypothesized that (a) IVCs develop secondary to flow resistance around a focal area of a shunt or draining hepatic vein narrowing and (b) the presence of IVC is associated with portal vessel development before intervention. Anonymized CT angiograms (CTA) and fluoroscopic portovenograms (FPV) of dogs with IHPSS were evaluated for the presence of IVCs, focal narrowing within the IHPSS, and intrahepatic portal vessels >5 mm long. Eleven of 47 (23%) dogs had IVCs identified. IVCs were significantly associated with focal narrowing in the shunt or draining hepatic vein on CTA (P = 0.039) and FPV (P = 0.021). IVCs were not associated with the presence of intrahepatic portal branches >5 mm long on portovenography (P = 0.42) or CTA (P = 0.49). Focal narrowing in the shunt (circumferential soft tissue narrowing >20% of the shunt diameter) was significantly associated with intrahepatic portal branches >5 mm long on both modalities (P < 0.001). IVCs are associated with focal narrowing of the shunt or draining hepatic vein in dogs with IHPSS. IVC should be distinguished from other conditions when evaluating a CTA for canine IHPSS.

Comparison of artificial intelligence to the veterinary radiologist's diagnosis of canine cardiogenic pulmonary edema.

Application of artificial intelligence (AI) to improve clinical diagnosis is a burgeoning field in human and veterinary medicine. The objective of this prospective, diagnostic accuracy study was to determine the accuracy, sensitivity, and specificity of an AI-based software for diagnosing canine cardiogenic pulmonary edema from thoracic radiographs, using an American College of Veterinary Radiology-certified veterinary radiologist's interpretation as the reference standard. Five hundred consecutive canine thoracic radiographs made after-hours by a veterinary Emergency Department were retrieved. A total of 481 of 500 cases were technically analyzable. Based on the radiologist's assessment, 46 (10.4%) of these 481 dogs were diagnosed with cardiogenic pulmonary edema (CPE+). Of these cases, the AI software designated 42 of 46 as CPE+ and four of 46 as cardiogenic pulmonary edema negative (CPE-). Accuracy, sensitivity, and specificity of the AI-based software compared to radiologist diagnosis were 92.3%, 91.3%, and 92.4%, respectively (positive predictive value, 56%; negative predictive value, 99%). Findings supported using AI software screening for thoracic radiographs of dogs with suspected cardiogenic pulmonary edema to assist with short-term decision-making when a radiologist is unavailable.

Radiographic features of suspected suture-associated cystic calculi in dogs.

This retrospective case series describes the radiographic features of suspected suture-associated cystic calculi in six dogs with a history of at least one or multiple prior cystotomies. One of the dogs presented twice. Suspected suture-associated cystic calculi were multifocal, short, predominantly linear mineral opacities localized in the center of the urinary bladder on abdominal radiographs. One patient (n = 1) presented with multifocal round, pin point, and linear radiopaque calculi. The calculi were all calcium oxalate in composition. On gross examination, the calculi had a hollow center. Six cystotomies used monofilament absorbable suture material (polydioxanone [n = 4] or poliglecaprone 25 [n = 1]) in prior cystotomies. Suture material in two of the cases was unknown. Suspected suture-associated cystic calculi are a rare occurrence in veterinary medicine but should be considered in dogs that have a history of prior cystotomy, hollow core on gross analysis, and radiographic evidence of mineral opaque, predominantly linear, cystic calculi.

Radial torsion in dogs with medial compartment disease.

OBJECTIVE: To evaluate the magnitude and direction of radial torsion (RT) in dogs with medial compartment disease (MCD). STUDY DESIGN: Case-control study. SAMPLE POPULATION: Twenty-eight healthy dogs and 28 dogs with confirmed MCD. METHODS: Computed tomography images of each dog's antebrachium were evaluated. Radial torsion was measured by using previously described landmarks on the proximal and distal radius. Differences between groups were tested with Student's t tests and Wilcoxon rank-sum tests. RESULTS: Healthy dogs had a mean RT angle of 3.44° (range, 1.28°-5.44°). Dogs with MCD had a mean RT angle of 11.84° (range, 2.31°-26.55°). Both groups included similar proportions of dogs with external (76% vs 77%) and internal (24% vs 23%) torsion. The direction of torsion (P = .21 and P = .69) did not appear to affect the magnitude of the RT angle. CONCLUSION: Dogs with MCD had an increased RT angle compared with healthy controls. The direction of torsion varied similarly between groups regardless of the disease status of dogs in this study. CLINICAL SIGNIFICANCE: The fourfold increase in the RT seen in dogs with MCD may contribute to the rotational overload proposed recently, potentially modifying the orientation of the elliptical radial head and the ligaments crossing the elbow joint.

STANDING COMPUTED TOMOGRAPHY IN NONANESTHETIZED LITTLE PENGUINS (EUDYPTULA MINOR) TO ASSESS RESPIRATORY SYSTEM ANATOMY AND MONITOR DISEASE.

Multidetector computed tomography (MDCT) scans were performed in clinically healthy, nonanesthetized, standing little penguins (Eudyptula minor) to determine reference ranges for air-sac and lung volumes, as well as lung density. Five of 15 clinically healthy birds were diagnosed with pulmonary granulomas on initial MDCT scans. Granulomas were not readily apparent on radiographs, even in cases where the entire normal pulmonary parenchymal architecture was effaced on the MDCT scan. Serial MDCT scans after antifungal and antimycobacterial therapies demonstrated a response to treatment. MDCT scanning in nonanesthetized little penguins proved to be a well-tolerated, non-invasive imaging modality for respiratory diseases that are otherwise difficult to diagnose, including aspergillosis and mycobacteriosis.

Academic and private practice partnerships in veterinary radiology residency training.

As veterinary radiologists devote greater time to telemedicine consultation, residency training must evolve to reflect the skills of these services. The contribution of private practice/consultant radiologists to residency training has traditionally been minimal but academic and private practice partnerships in education and research can provide the framework for a well-rounded residency. These partnerships can also lessen the impact of workforce shortages in academia and provide financial compensation to academicians through external consultation. The purpose of this commentary is to review existing collaborative interactions between academic and private practice veterinary radiologists; with a focus on ways to sustain, improve, and cautiously increase the number of veterinary radiology training programs.

Evaluation of thoracic radiographs as a screening test for dogs and cats admitted to a tertiary-care veterinary hospital for noncardiopulmonary disease.

Thoracic radiographs are used as a screening tool for dogs and cats with a variety of disorders that have no clinical signs associated with thoracic structures. However, this practice has never been supported by an evidence-based study. The objective of this retrospective observational study was to determine if certain canine and feline populations have a higher proportion of radiographic abnormalities, and whether any of these abnormalities are associated with patient hospitalization and outcome. Patients were excluded if current or previous examinations revealed evidence of primary respiratory or cardiac disease, malignant neoplasia, or an abnormal breathing pattern consistent with pulmonary pathology. Any notable thoracic change in the radiology report was considered important and evaluated in this study. One hundred and sixty-six of these included patients were dogs and 65 were cats. Of the 166 dog radiographs evaluated, 120 (72.3%) had normal thoracic radiographs, while 46 (27.7%) had radiographic abnormalities. Of the sixty-five cats included, 36 (55.4%) had normal radiographs, while 29 (44.6%) had abnormal radiographs. Canine patients with abnormal radiographs had a significantly higher lactate level (P-value 0.0348) and feline patients with abnormal radiographs had a significantly lower packed cell volume (P-value 0.012). A large proportion of patients that had screening thoracic radiographs (32.5%) had documented abnormalities, but a relatively low percentage (6.5%) of our total population had their clinical plan changed as a consequence of detection of these abnormalities. Findings indicated that abnormal screening thoracic radiographs are more likely in dogs with an elevated lactate and cats with anemia, or a low normal hematocrit.

OFF-SITE SMARTPHONE VS. STANDARD WORKSTATION IN THE RADIOGRAPHIC DIAGNOSIS OF SMALL INTESTINAL MECHANICAL OBSTRUCTION IN DOGS AND CATS.

Off-site consultations by board-certified veterinary radiologists benefit residents and emergency clinicians by providing immediate feedback and potentially improving patient outcome. Smartphone devices and compressed images transmitted by email or text greatly facilitate availability of these off-site consultations. Criticism of a smartphone interface for off-site consultation is mostly directed at image degradation relative to the standard radiographic viewing room and monitors. The purpose of this retrospective, cross-sectional, methods comparison study was to compare the accuracy of abdominal radiographs in two imaging interfaces (Joint Photographic Experts Group, off-site, smartphone vs. Digital Imaging and Communications in Medicine, on-site, standard workstation) for the diagnosis of small intestinal mechanical obstruction in vomiting dogs and cats. Two board-certified radiologists graded randomized abdominal radiographs using a five-point Likert scale for the presence of mechanical obstruction in 100 dogs or cats presenting for vomiting. The area under the receiver operator characteristic curves for both imaging interfaces was high. The accuracy of the smartphone and traditional workstation was not statistically significantly different for either reviewer (P = 0.384 and P = 0.536). Correlation coefficients were 0.821 and 0.705 for each reviewer when the same radiographic study was viewed in different formats. Accuracy differences between radiologists were potentially related to years of experience. We conclude that off-site expert consultation with a smartphone provides an acceptable interface for accurate diagnosis of small intestinal mechanical obstruction in dogs and cat.

IMAGING DIAGNOSIS--URINARY BLADDER DUPLICATION IN A CAT.

A female kitten presented for chronic, intermittent, antibiotic-responsive urinary incontinence and chronic kidney disease. Abdominal ultrasound identified bilateral pelvic/ureteral dilation and three closely apposed thin-walled fluid-filled structures in the caudal abdomen, extending toward the pelvic inlet. Excretory urography and negative contrast cystography identified contrast medium accumulation from the dilated ureters into two tubular soft tissue masses of the caudal abdomen, with subsequent gradual filling of a more cranially located urinary bladder. A retrograde vaginocystourethrogram identified a normal uterus, normal vagina, and a single urethra continuous with the cranially located urinary bladder. Antemortem diagnosis was suspicious for bilateral ectopic ureteroceles. Postmortem diagnosis, 35 months following initial presentation, determined the fluid-filled masses to have abundant smooth muscle in the wall, including a muscularis mucosa connected by a common ostium, consistent with urinary bladder duplication. Urinary bladder duplication should be included as a differential diagnosis in cats with these clinical and imaging characteristics. In this case, differentiation of ectopic ureterocele from urinary bladder duplication required histological confirmation.

Preoperative parameters (signalment, digital radiography, urinalysis, urine microbiological culture) and novel algorithm improve prediction of canine urocystolith composition.

OBJECTIVE: To determine the accuracy of 4 preoperative parameters (signalment, urinalysis, urine microbiological culture, and digital radiography) in predicting urocystolith composition, compare accuracy between evaluators of varying clinical experience and a mobile application, and propose a novel algorithm to improve accuracy. ANIMALS: 175 client-owned dogs with quantitative analyses of urocystoliths between January 1, 2012, and July 31, 2020. METHODS: Prospective experimental study. Canine urocystolith cases were randomly presented to 6 blinded "stone evaluators" (rotating interns, radiologists, internists) in 3 rounds, each separated by 2 weeks: case data alone, case data with a urolith teaching lecture, and case data with a novel algorithm. Case data were also entered into the Minnesota Urolith Center mobile application. Prediction accuracy was determined by comparison to quantitative laboratory stone analysis results. RESULTS: Prediction accuracy of evaluators varied with experience when shown case data alone (accuracy, 57% to 82%) but improved with a teaching lecture (accuracy, 76% to 89%) and further improved with a novel algorithm (accuracy, 93% to 96%). Mixed stone compositions were the most incorrectly predicted type. Mobile application accuracy was 74%. CLINICAL RELEVANCE: Use of the 4 preoperative parameters resulted in variable accuracy of urocystolith composition predictions among evaluators. The proposed novel algorithm improves accuracy for all clinicians, surpassing accuracy of the mobile application, and may help guide patient management.

Comparing diagnostic findings and cost of whole body computed tomography to traditional diagnostic imaging in polytrauma patients.

OBJECTIVE: To compare the diagnostic utility of traditional diagnostic tests (ie, radiographs and focused assessment using sonography for trauma [FAST] scans) to whole-body computed tomography (WBCT) for characterizing injuries in polytrauma patients. A secondary objective was to compare costs of traditional diagnostic tests to WBCT. DESIGN: Prospective, observational study. SETTING: Private, level 1 veterinary trauma center. ANIMALS: Convenience sample of 21 client-owned cats and dogs presenting with polytrauma. INTERVENTIONS: Abdominal and thoracic FAST were performed by the primary clinician, if indicated. Radiographs were performed on areas concerning for trauma at the primary clinician's discretion. A WBCT was performed on each patient within 24 h of presentation and was blindly interpreted by a board-certified radiologist. Patients were only placed under anesthesia if further procedures were planned. IV contrast administration was employed at the discretion of the primary clinician and radiologist. MEASUREMENTS AND MAIN RESULTS: Twenty-one patients (14 dogs and 7 cats) were enrolled. Sources of trauma included blunt force (80%), penetrating wounds (10%), and unknown sources (10%). Twelve injuries were missed on traditional diagnostics tests. Injuries missed on traditional diagnostic workup included pneumothorax, pneumomediastinum, pulmonary contusions, pleural effusion, traumatic bulla, peritoneal effusion, and an appendicular skeleton fracture. A distal metacarpal fracture was missed on WBCT. Traditional diagnostic tests misdiagnosed a diaphragmatic hernia and a ruptured urinary bladder, whereas WBCT was able to rule out these injuries. There were no adverse outcomes associated with missed injuries. The median cost of traditional diagnostic tests was significantly less than the cost of WBCT (P < 0.001). CONCLUSIONS: Although cost is higher, WBCT is a single test that can provide more comprehensive information and may help decrease the risk of missed injuries compared to traditional diagnostic tests. WBCT may be considered as a first-line diagnostic in severely traumatized patients.

Utilization of whole body computed tomography in polytrauma patients.

OBJECTIVE: To determine the safety, feasibility, and utility of whole body computed tomography (WBCT) in polytrauma patients. A second objective was to describe the utilization of the VetMouse Trap for sedated WBCT in polytrauma patients. METHODS: A prospective, observational study in a high-volume private practice. Any cat or dog weighing <20 kg that presented to the emergency department following a polytrauma was eligible. Patients were given analgesia and sedation prior to placement in the VetMouse Trap. A WBCT was then performed. RESULTS: A total of 16 patients (8 dogs and 8 cats) met inclusion criteria. All patients presented with blunt trauma; 3 also had evidence of penetrating wounds. Five (31.25%) patients met inclusion criteria for WBCT based on their neurological evaluation. Five (31.5%) were non-ambulatory with suspicion of orthopedic injury, and 37.5% met additional criteria for WBCT. The most common areas of injury were head (43.7%), lungs (25%), and pelvis (25%). Four patients (25%) had evidence of cavitary effusion that was not seen on focused assessment using sonography for trauma (FAST) scan. No patient had any adverse events during the CT. CONCLUSION: This study demonstrated successful WBCT imaging of the sedated small animal polytrauma patient with the VetMouse Trap.

Evaluation of surgically placed gastrojejunostomy feeding tubes in critically ill dogs.

OBJECTIVE: To evaluate complications and outcomes associated with surgical placement of gastrojejunostomy feeding tubes in dogs with naturally occurring disease. DESIGN: Prospective study. ANIMALS: 26 dogs. Multiple preoperative, intraoperative, and postoperative variables were evaluated. Daily postoperative abdominal radiographic examinations were performed to determine the presence of the following mechanical tube complications: kinking, coiling, knotting, and migration. Tube stoma abnormalities (erythema, cellulitis, and discharge) were observed daily and recorded by use of a standardized visual analog grading scale. Additionally, presence of complications was compared with median survival times. RESULTS: The most common indication for gastrojejunostomy tube placement was gastrointestinal disease (n = 11), with confirmed septic peritonitis in 8 of 11 dogs. Other indications for gastrojejunostomy tube placement included extrahepatic biliary surgery (n = 6) and pancreatic disease (9). Mean +/- SD surgical time required for tube placement was 26 +/- 14 minutes. Overall, mechanical tube complication rate was 46% (12/26), including coiling (7), migration (4), and kinking (2). Overall minor tube stoma complication rate was 77% (20/26) and included erythema (16), cellulitis (13), and discharge (17). Dislodgement or self-induced tube trauma resulted in accidental tube removal in 2 of 26 dogs, and inadvertent tube damage necessitated premature removal by the clinician in 1 of 26 dogs. Kaplan-Meier median survival time was 39 days with 13 of 26 dogs still alive. CONCLUSIONS AND CLINICAL RELEVANCE: Gastrojejunostomy tube placement affords flexibility in the postoperative nutritional regimen by allowing for postgastric feeding with simultaneous access to the stomach.

Basic ultrasound beam formation and instrumentation.

This article is a brief review of ultrasound beam formation. Some detailed components of the ultrasound machine are discussed as a primer for the subsequent article on recent technological advances. The components of the ultrasound transducer responsible for broad bandwidth technology and electronic focusing are discussed in the context of optimizing resolution. Other aspects of ultrasound physics, including artifacts and interactions with matter, are not discussed.

Laparoscopic Resection of a Pancreatic ß Cell Tumor in a Dog.

Laparoscopic partial pancreatectomy has been performed in experimental canine studies and has been evaluated in human medicine but has not been reported in a clinical veterinary case. The authors present a 9 yr old field spaniel with weakness and hypoglycemia with insulin levels and Amended Insulin: Glucose Ratio results equivocal for a pancreatic insulinoma. Multiple abdominal ultrasounds did not detect the tumor, yet dual-phase computed tomographic angiography revealed the presence of a focal hypoattenuating nodule in the left lobe of the pancreas. A 3-port laparoscopic approach to the abdomen confirmed a 1.5-cm mass in the mid-left limb of the pancreas, and resection of the mass was performed with a bipolar vessel-sealing device. The surgery was performed without complication, and the dog became normoglycemic within 4 hr following surgery. Final histopathology results revealed pancreatic neuroendocrine carcinoma of the ß cells. Recurrence of hypoglycemia was noted 18 mo postoperatively; however, repeat computed tomographic angiography did not reveal pancreatic abnormalities and fine needle aspirates of liver nodules did not suggest metastatic disease. Medical management was elected and the patient was euthanized 28 mo after surgery due to refractory hypoglycemic seizures.

Symmetrical brachydactyly in a dog.

Congenital malformations of the canine manus and pes are infrequently reported in the veterinary literature. This includes brachydactyly which is a general term used to indicate the shortening of digits due to abnormal development of the phalanges, metacarpals, or metatarsals. This case report describes isolated brachydactyly in a one-year-old male Maremma Sheepdog affecting all of the phalanges, metacarpals, and metatarsals of digits two through five. This condition was confirmed by determining the length of each phalanx, metacarpal, and metatarsal of the affected dog as well as an unaffected littermate. The affected dog's metacarpal, metatarsal, and phalanx lengths ranged from 50% to 77% of that of the unaffected sibling. Other abnormalities found on physical examination as well as on radiographic imaging are discussed.

Comparison of glomerular filtration rate between greyhounds and non-Greyhound dogs.

Greyhounds have significantly higher serum creatinine (SCr) concentration than do non-Greyhound dogs that may be attributable to differences in glomerular filtration rate (GFR). By means of plasma clearance of technetium Tc 99m diethylenetriaminepentaacetic acid, GFR was measured in 10 Greyhounds and 10 non-Greyhound dogs with normal findings of physical examination, CBC, serum biochemical analysis, and urinalysis. Dogs were fed the same diet for a minimum of 6 weeks before GFR data collection. Greyhounds had significantly higher mean +/- SD GFR (3.0 +/- 0.1 vs 2.5 +/- 0.2 ml/min/ kg; P = .01) and SCr concentration (1.8 +/- 0.1 vs 1.5 +/- 0.1 mg/dL; P = .03) than did non-Greyhound dogs, but the serum urea nitrogen (SUN) concentration was not significantly different (18 +/- 1 vs 18 +/- 2 mg/dL; P = .8). Therefore, the higher SCr concentration in Greyhounds is not attributable to decreased GFR, and may be associated with the high muscle mass in the breed. Healthy Greyhounds have higher GFR than do non-Greyhound dogs.