Nuclear scanning with 99mTc-HDP for the initial evaluation of osseous metastasis in canine osteosarcoma.

The purpose of this retrospective analysis was to evaluate the use of nuclear scintigraphy in determining the rate of secondary sites of osseous malignancy at initial presentation in dogs with osteosarcoma. Radiographs of suspicious secondary lesions were reviewed and placed into four separate categories: benign lesions; no lesion seen on radiographs; subtle radiographic changes suggestive of, but not conclusive for, metastasis; and metastatic lesions highly suspected on radiographs. Three hundred and ninety-nine dogs were evaluated by technetium nuclear scanning for suspected osteosarcoma. Three hundred and twenty-six of 399 dogs (82%) had only one apparent site on the nuclear scan, whereas 72 dogs (18%) had more than one suspicious site on the nuclear scans. Highly suspected secondary metastatic lesions were detected by nuclear scans in 7.8% of cases. Although interpretation of nuclear scans is subjective, this study showed a 7.8% chance of detecting unsuspected osseous metastasis with nuclear scans in canine osteosarcoma patients on initial presentation.

Evaluation of esophageal transit of tablets and capsules in 30 cats.

We have reported tablet-induced focal esophagitis and esophageal stricture formation in cats. The proposed mechanism is thought to be abnormal esophageal tablet retention resulting in focal esophagitis with subsequent stricture formation. The objective of this study was to evaluate the passage of tablets and capsules when given alone (dry swallow) and when followed by a water bolus (wet swallow) to determine if this could, in part, explain the esophageal stricture formation we have observed in cats. Fluoroscopy was used to evaluate tablet or capsule passage after administration. The percentage of dry tablet swallows that successfully passed into the stomach was 0.0% at 30 and 60 seconds, 6.7% at 90 seconds, 13.3% at 120 seconds, 26.7% at 180 and 240 seconds, and 36.7% at 300 seconds. Wet tablet swallows successfully passed 90.0% of the time at 30 seconds, 93.3% of the time at 60 seconds, and 100.0% of the time thereafter. The percentage of dry capsule swallows that successfully passed was 16.7% at each time interval. Wet capsule swallows successfully passed 96.7% of the time at 30 seconds and 100% of the time thereafter. For each time interval, wet swallows achieved significantly greater percentage passage into the stomach when compared to dry swallows (P < .05). This study shows that tablets or capsules given by dry swallow have prolonged retention in the esophagus compared to those given by wet swallow. On the basis of this study, we recommend the routine administration of a water bolus to cats receiving tablets or capsules PO to facilitate esophageal clearance. This practice may help prevent medication-associated esophagitis or stricture formation.

Radiographic interpretation of normal skeletal variations and pseudolesions in the equine foot.

Effective radiographic interpretation requires a veterinarian who is knowledgeable of equine limb anatomy and the various principles that affect the resulting image. The normal and its variations must be recognized and understood before the abnormal can be confidently identified as pathologic. Proper patient positioning and sound radiographic technique are mandatory if reliable diagnostic radiographs are to be produced. This review emphasizes equine foot radiographic variations of normal and pseudolesions that occur with commonly used radiographic views performed in equine practice.

Accuracy of radiography, nuclear scintigraphy, and histopathology for determining the proximal extent of distal radius osteosarcoma in dogs.

OBJECTIVE: To compare the accuracy of radiography, nuclear scintigraphy, and histopathology for determining the proximal extent of distal radius osteosarcoma in dogs. STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Twenty client-owned dogs taken to Colorado State University with osteosarcoma of the distal radius. METHODS: Medical records of 20 dogs with confirmed osteosarcoma that underwent a limb-salvage procedure were reviewed. Measurements were performed directly from the lateral view of each radius, from both the scintigram and the radiograph, to determine the length of the radius and the distance from the proximal extent of the tumor to the distal radiographic or scintographic extent of the radius. The ratio of distal radial involvement to total radius length was calculated. A similar ratio was also determined using the macroslide, which included the entire portion of bone that was excised during the limb-salvage procedure. All 3 methods of measurement were compared. RESULTS: Nuclear scintigraphy significantly overestimated tumor length when compared with macroslide specimen measurements. Radiography also overestimated tumor length, but these results were not significantly different from macroslide specimen measurements. CONCLUSIONS: Both radiography and nuclear scintigraphy overestimate the extent of distal radius osteosarcoma in dogs when compared with histopathologic macroslides of the same lesions. Nuclear scintigraphy overestimated tumor extent to a larger degree than did radiography. CLINICAL RELEVANCE: Although radiography is a more accurate method of measurement of the extent of distal radius osteosarcoma, because nuclear scintigraphy overestimates tumor length to a greater degree, scintigraphy may provide a larger margin of safety for determining the site of proximal osteotomy during a limb-salvage procedure. However, caution should be taken when utilizing scintigraphy, because this method may overestimate length of radius involved to such an extent as to cause the surgeon to believe that a patient is not a suitable limb-salvage candidate.

Effect of a static magnetic field on blood flow to the metacarpus in horses.

OBJECTIVE: To determine the effect of a static magnetic field on relative blood flow to the metacarpus of horses. DESIGN: Randomized controlled clinical trial. ANIMALS: 6 healthy adult horses. PROCEDURE: Red blood cells were radiolabeled in vivo by administration of technetium Tc 99m (pyro- and trimeta-) phosphates, and scintigraphic images were obtained 30 minutes later. A magnetic wrap that emitted a static magnetic field was applied to 1 metacarpus and a control wrap was applied to the contralateral metacarpus. Forty-eight hours later, the wraps were removed, and scintigraphy was repeated. Relative perfusion ratios were calculated by dividing mean count per pixel for the portion of the metacarpus under the wrap by mean count per pixel for a portion of the distal aspect of the antebrachium that was not in the magnetic field. RESULTS: The difference between the relative perfusion ratio prior to application of the wrap and the ratio after application of the wrap for limbs that received the magnetic wrap was not significantly different from the difference in ratio for limbs that received the control wrap. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses, the static magnetic field associated with application of commercially available magnetic wraps for 48 hours does not increase blood flow to the portion of the metacarpus underneath the wrap.

The application of technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled white blood cells for the diagnosis of right dorsal ulcerative colitis in two horses.

The application of 99mTc-HMPAO labeled white blood cells to support the diagnosis of right dorsal ulcerative colitis was studied in two horses with a history and clinical signs consistent with phenylbutazone toxicity. These images were compared to a reference horse unaffected by right dorsal ulcerative colitis. Blood was collected aseptically in heparinized syringes from the patients for in vitro white blood cell (WBC) radiolabeling. The buffy coat was separated out and radiolabeled with 99mTc-HMPAO. The radiolabeled blood was re-injected i.v. and four images of the right and left side of the patient's abdomen were acquired at 4 hours and 20 hours post-injection. Results of the nuclear study revealed no abnormal findings in the abdomen at the four-hour post-injection images in any horse. Images obtained 20 hours post-injection revealed a linear uptake of radiolabeled WBCs in the right cranioventral abdomen in the region of the right dorsal colon in both horses with right dorsal ulcerative colitis. The reference horse had no radiopharmaceutical uptake in this region. This nuclear imaging study was a rapid, non-invasive method to identify right dorsal colon inflammation. These findings not only supported the diagnosis of right dorsal ulcerative colitis, but also facilitated appropriate medical management of each horse.

Mammary gland uptake of sodium Tc-pertechnetate in a cat with a drug-induced gynecomastia.

Sodium Tc-pertechnetate accumulated in the mammary glands of a male cat. It was determined that the uptake was attributable to gynecomastia induced by medroxyprogesterone acetate injections. Gynecomastia and pertechnetate uptake resolved following cessation of medroxyprogesterone acetate treatment.

Occult osseous metastasis of a colonic adenocarcinoma visualized with technetium tc 99m hydroxymethylene diphosphate scintigraphy in a horse.

A 5-year-old Arabian horse was admitted with a 5-day history of undulant pyrexia of unknown origin, inappetence, obtundation, and acute collapse. Physical examination results were unremarkable except for a grade II/VI left-sided systolic cardiac murmur and abdominal splinting. Mild chronic inflammatory changes were evident on clinicopathologic evaluation. Echocardiography revealed moderate aortic insufficiency. A solitary soft tissue opacity was found on thoracic radiography but not on ultrasonography. Palliative treatment was ineffective. Nuclear scintigraphy with WBC labeled with technetium Tc 99m hexamethylpropyleneamine oxime did not identify abnormalities, but a second nuclear scan with technetium Tc 99m hydroxymethylene diphosphate identified polyostotic disease. Examination of a biopsy specimen from an affected rib revealed disseminated adenocarcinoma. The horse was euthanatized. Necropsy and histologic examination revealed a colonic adenocarcinoma with osseous metaplasia that had disseminated to multiple parenchymal organs, muscle, and bone.

Comparison of gonioscopy and ultrasound biomicroscopy for evaluating the iridocorneal angle in dogs.

OBJECTIVE: To compare iridocorneal angle grading systems on the basis of gonioscopy and ultrasound biomicroscopy (UBM). DESIGN: Original cross-sectional observational study. ANIMALS: 22 dogs. PROCEDURE: Gonioscopy, goniophotography, and UBM were performed on 38 eyes from dogs without clinical evidence of glaucoma in the eyes examined. RESULTS: Predominant gonioscopic grades derived from goniophotographs were considered normal (n = 26) and mild (12). Ultrasound biomicroscopy angle measurements ranged from 16 to 38 degrees (mean +/- SD, 26.2 +/- 4.5 degrees). Ciliary clefts depicted on UBM images were graded as open (n = 4), compact/narrow (23), and closed (11). Significant differences were not found between UBM-derived ciliary cleft grades and goniophotography-derived dysgenesis grades, nor between UBM-derived ciliary cleft grades and subjective gonioscopic grades. CLINICAL IMPLICATIONS: Because gonioscopy allows evaluation of the anterior face of the ciliary cleft, whereas UBM provides cross-sectional information of the iridocorneal filtration angle, UBM may yield more information regarding pathogenesis and prognosis of, and preferred management approaches to, glaucoma. Ultrasound biomicroscopy may also be useful as a predictor of glaucoma or to diagnose early stages of glaucoma.

The effect of intravenous diazepam on solid phase gastric emptying in normal cats.

Intravenous diazepam has been advocated as an appetite stimulant in anorexic cats. Diazepam has also been used to stimulate the intake of radiographic contrast medium-food mixture to determine the gastric emptying time of a solid meal. Diazepam has been suspected to delay gastric emptying in cats. One study found diazepam combined with valium to have little effect on gastric transit times in cats while diazepam alone accelerates gastric emptying in humans. The purpose of this study was to determine if diazepam influences gastric emptying times in normal cats. The gastric emptying half-time of solid food in normal, non-diazepam treated cats has been previously determined using a scintigraphic technique using 99mTc-sulfur colloid to radiolabel solid dry food. The median gastric emptying half-time was 2.3 hours and the mean meal size was 16.1 grams. Gastric emptying half-times were determined in this study using diazepam as an appetite stimulant. The median gastric emptying half-times of diazepam treatment groups given both a 16.1 gram meal and a large meal were both significantly longer than the normal non-treated group (P < 0.05). Solid phase gastric emptying is therefore significantly delayed when diazepam is used as an appetite stimulant, irrespective of the volume of the meal.

Development of subchondral cystic lesions after articular cartilage and subchondral bone damage in young horses.

The objective of this study was to determine if damage to the articular cartilage alone or articular cartilage plus subchondral bone of the distal medial femoral condyle of young, exercised horses resulted in the formation of subchondral cystic lesions. Twelve Quarter Horses (age 1-2 years), free of clinical and radiographic signs of osteochondrosis and lameness were used. In 6 horses (Group 1), a 15 times 1 mm linear full thickness defect in the articular cartilage was made arthroscopically on the weightbearing surface of the distal aspect of the medial femoral condyle. In the other 6 horses (Group 2), a 15 times 3 mm full thickness elliptical cartilage defect was made, followed by burring a 5 mm diameter, 4 mm deep hole into the subchondral bone. Three weeks after surgery, all horses were hand walked and trotted for 2 weeks and then exercised for 6 min daily, 5 days a week for the next 14 weeks on a treadmill. They were then turned onto a small paddock for 6 weeks (6 months total). The development of subchondral cystic lesions was determined using radiography. Bone activity in the femoral condyle was monitored with nuclear scintigraphy. All horses that developed subchondral cystic lesions radiographically were subjected to euthanasia for gross and histological examination of the lesions. No subchondral cystic lesions and no clinical abnormalities were detected in the horses in Group 1. Subchondral cystic lesions developed radiographically in 5 of 6 horses in (Group 2). Scintigraphic findings of horses with subchondral cystic lesions were inconsistent. Histological examination of lesions revealed variable quantities of fibrous connective tissue, fibrocartilage and bone, with evidence of bone remodelling adjacent to the subchondral cystic lesion. The results suggest that damage to articular cartilage plus subchondral bone, but not articular cartilage alone, of the distal medial femoral condyle may lead to the development of subchondral cystic lesions. These findings indicate that all subchondral cystic lesions in horses may not be osteochondrosis-type lesions and that trauma to weightbearing articular surfaces of young horses may be a predisposing factor.

Dynamic cardiomyoplasty for treatment of idiopathic dilatative cardiomyopathy in a dog.

In a dog with advanced dilatative cardiomyopathy, dynamic cardiomyoplasty resulted in improvement in clinical status and systolic function. Dynamic cardiomyoplasty involved surgical isolation of the right latissimus dorsi muscle on its neurovascular pedicle, transposition of the muscle into the thoracic cavity, wrapping the ventricles with the muscle, and implantation of a myostimulator for cardiosynchronous stimulation of the muscle. After a 2-week period, the latissimus muscle underwent a 50-day period of progressive burst stimulation to transform the muscle to a fatigue resistant phenotype. Thereafter, the muscle received cardiosynchronous stimulation at a 3:1 R-wave-to-burst ratio. This procedure may offer hope for long-term treatment of dilatative cardiomyopathy in dogs.

Biological half-life of aerosolized 99mTc-diethylenetriaminepentaacetate in various lung regions of clinically normal beagles.

The biological half-life (TB) of aerosolized 99mTc-diethylenetriaminepentaacetate was determined in 14 lung regions of 18 clinically normal Beagles. Three groups of lung regions or volumes were identified on the basis of significantly (P < 0.05) different TB. Group A (mean +/- SD TB, 82 +/- 21 minutes) included the transversely oriented cranial and caudal nonperihilar regions. Group B (mean +/- SD, 61 +/- 15 minutes) represented all sagittally oriented lung regions and the entire lung field. Group C (mean +/- SD, 49 +/- 11 minutes) included the transversely oriented cranial and caudal perihilar regions. Clearance of 99mTc-diethylenetriaminepentaacetate is considered a function of transepithelial transport into the blood, as well as bronchial transport via the mucociliary transport mechanism.

Radiographic anatomy and technique for arthrography of the cubital joint in clinically normal dogs.

A technique for arthrography of the cubital joint in clinically normal large-breed dogs was developed with the objective of improving visualization of the articular margin of the medial coronoid process. A lateral approach to the cubital joint for injection of contrast medium was selected. Arthrography of 24 cubital joints was performed by using 14 dogs. Twelve combinations of iodinated contrast medium, consisting of various concentrations (3) and volumes (4), were used. Two sets of arthrograms for each of the 12 combinations of contrast medium were obtained. Five radiographic views were used for each set. All arthrograms were examined by 3 evaluators, and each articular surface received a numerical rating for how well it could be seen in each view. Results of the evaluation indicated that low volumes of contrast medium were preferable to high volumes, with 2 ml providing the best visualization. Concentration of iodine seemed less important than did volume. The numerical ratings also indicated that the articular margin of the coronoid process was clearly observed a maximum of only 24% of the time on a slightly supinated mediolateral projection. The articular margins of the head of the radius, trochlea humeri, and trochlear notch were well visualized > 90% of the time. Arthrography of the cubital joint was technically easy to perform, and complications were not encountered, but arthrographic anatomy of the cubital joint is complex. Potential uses for arthrography of the cubital joint include diagnosis of osteochondrosis, intraarticular fragments, and joint capsule ruptures.

Comparison of radiologic imaging techniques for diagnosis of fragmented medial coronoid process of the cubital joint in dogs.

Thirty cubital joints from 16 dogs suspected of having a fragmented medial coronoid process were examined. Four breeds accounted for 87.5% of the cases: German Shepherd Dog (25%), Labrador Retriever (25%), Rottweiler (18.75%), and Golden Retriever (18.75%). Seventy-five percent of the dogs were male. Mean age of affected dogs was 13.6 months. Plain-film radiography, xeroradiography, linear tomography, arthrography, and computed tomography were performed on each cubital joint prior to surgical exploration of the joint. Three reviewers evaluated each diagnostic study and independently determined whether a fragment from the medial coronoid process could be seen. The consensus opinion was compared with the finding at surgery. Abnormalities of the medial coronoid process were detected in 25 of 30 joints at surgery. Fragmented coronoid process was found in 17 of 30 joints, and wear lesions were observed in 8 of 30 joints. Computed tomography had the highest accuracy (86.7%), sensitivity (88.2%), and negative-predictive value (84.6%) of the 5 imaging modalities evaluated (P < 0.05). Specificity and positive-predictive value of all imaging techniques were high. There was no significant difference between the diagnostic ability of plain-film radiography, xeroradiography, or linear tomography of the cubital joint. The combination of plain-film radiography and linear tomography provided an improvement in accuracy, approaching that of computed tomography.

Radiographic, epidemiologic, and clinical aspects of simultaneous pleural and peritoneal effusions in dogs and cats: 48 cases (1982-1991).

In this study, we found that the rate at which radiographically diagnosed simultaneous pleural and peritoneal effusions (double effusion [DE]) developed was highest in dogs and cats with infectious causes of pleuritis and/or peritonitis and in those with pancreatitis. However, DE were observed more frequently in dogs and cats with neoplastic and cardiovascular diseases. Nonneoplastic liver disease was also documented as a cause of DE in the population of this study. Frequency of DE was increased in males and in animals > 6 years old. The finding of simultaneous pleural and peritoneal effusions can be considered an indicator of disease severity, and warrants a poor to grave prognosis.

Lymphosarcoma with disseminated skeletal involvement in a pup.

Lymphoblastic lymphosarcoma with disseminated skeletal involvement was diagnosed in a 15-week-old Golden Retriever. The skeletal disease was characterized by diffuse, irregular areas of radiolucency most evident in the diaphyseal portion of long bones and was associated with gait abnormalities and signs of pain. Necropsy also revealed involvement of the spleen, liver, kidneys, and mesenteric lymph nodes.

The angiocardiographic diagnosis of a persistent truncus arteriosus in a foal.

Persistent truncus arteriosus is a relatively rare cardiac anomaly which is associated with a single large artery arising from the ventricles. An interventricular septal defect is invariably present. The vessel gives origin to the pulmonary trunk, aorta and coronary arteries. A description of the angiocardiographic diagnosis of this condition is given as well as a general review of the relative developmental anatomy.