Effect of infection with bovine respiratory syncytial virus on pulmonary clearance of an inhaled antigen in calves.

OBJECTIVE: To evaluate the effect of infection with bovine respiratory syncytial virus (BRSV) on clearance of inhaled antigens from the lungs of calves. ANIMALS: Eleven 6- to 8-week-old Holstein bull calves. PROCEDURES: Aerosolized (99m)technetium ((99m)Tc)-labeled diethylene triamine pentacetate (DTPA; 3 calves), commonly used to measure integrity of the pulmonary epithelium, and (99m)Tc-labeled ovalbumin (OA; 8 calves), commonly used as a prototype allergen, were used to evaluate pulmonary clearance before, during, and after experimentally induced infection with BRSV or sham inoculation with BRSV. Uptake in plasma (6 calves) and lung-efferent lymph (1 calf) was examined. RESULTS: Clearance of (99m)Tc-DTPA was significantly increased during BRSV infection; clearance of (99m)Tc-OA was decreased on day 7 after inoculation. Clearance time was correlated with severity of clinical disease, and amounts of (99m)Tc-OA in plasma and lymph were inversely correlated with clearance time. Minimum amounts of (99m)Tc-OA were detected at time points when pulmonary clearance of (99m)Tc-OA was most delayed. CONCLUSIONS AND CLINICAL RELEVANCE: BRSV caused infection of the respiratory tract with peak signs of clinical disease at 7 or 8 days after inoculation. Concurrently, there was a diminished ability to move inhaled protein antigen out of the lungs. Prolonged exposure to inhaled antigens during BRSV infection may enhance antigen presentation with consequent allergic sensitization and development of chronic inflammatory lung disease. IMPACT FOR HUMAN MEDICINE: Infection of humans with respiratory syncytial virus early after birth is associated with subsequent development of allergic asthma. Results for BRSV infection in these calves suggested a supportive mechanism for this scenario.

Measurement of equine laminar blood flow and vascular permeability by use of dynamic contrast-enhanced computed tomography.

OBJECTIVE: To define the reference range for laminar blood flow (BF) and vascular permeability (VPM) in horses without laminitis by use of dynamic contrast-enhanced computed tomography (CT). ANIMALS: 9 adult horses that were not lame and had no abnormalities of the laminae or phalanges detectable via radiographic examination. PROCEDURES: Each horse was anesthetized by use of a routine protocol. Horses were placed in right or left lateral recumbency with the dependent forelimb in the CT gantry; only 1 limb of each horse was scanned. Serial 10-mm collimated transverse CT images were acquired at the same location every other second for 90 seconds during infusion of ionic, iodinated contrast medium. Custom software was used to estimate BF, VPM, and fractional vascular volume (FVV) in the dorsal, dorsomedial, and dorsolateral laminar regions. RESULTS: Among the 9 horses' forelimbs, mean +/- SD dorsal laminar BF was 0.43 +/- 0.21 mL*min(1)*mL(1). Mean dorsomedial and dorsolateral laminar BFs were 0.26 +/- 0.16 mL*min(1)*mL(1) and 0.24 +/- 0.16 mL*min(1)*mL(1), respectively. Mean dorsal laminar VPM was 0.09 +/- 0.03 mL*min(1)*mL(1). Mean dorsomedial and dorsolateral laminar VPMs were 0.16 +/- 0.06 mL*min(1)*mL(1) and 0.12 +/- 0.06 mL*min(1)*mL(1), respectively. Mean dorsal laminar FVV was 0.63 +/- 0.20 and dorsomedial and dorsolateral laminar FVV were 0.37 +/- 0.14 and 0.34 +/- 0.17, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, laminar BF, VPM, and FVV can be non-invasively measured by use of dynamic contrast-enhanced CT.

Comparison of arthroscopic and radiographic abnormalities in the hip joints of juvenile dogs with hip dysplasia.

OBJECTIVE: To compare radiographic and arthroscopic abnormalities in juvenile dogs with clinically apparent hip dysplasia. DESIGN: Case series. ANIMALS: 52 dogs (70 hip joints) with clinical signs of hip dysplasia scheduled to undergo triple pelvic osteotomy. PROCEDURE: A ventrodorsal radiographic projection of the pelvis was evaluated by a radiologist unaware of clinical and arthroscopic findings, and radiographic osteoarthritic abnormalities were judged and scored as absent (0), mild (1), moderate (2), or severe (3). Arthroscopy was performed by a surgeon unaware of clinical and radiographic findings, and arthroscopic abnormalities were graded from 0 (normal) to 5 (exposed, eburnated subchondral bone). RESULTS: In 30 of the 70 (43%) hip joints, no radiographic osteoarthritic abnormalities were seen. Severe, full-thickness articular cartilage lesions (grade 4) of the femoral head or acetabulum were seen arthroscopically in 14 (20%) joints. Lesions > or = grade 2 were seen in 60 (86%) joints. Partial tearing of the ligament of the femoral head was present in 57 (81%) joints, and complete rupture was seen in 5 (7%). Radiographic abnormalities were seen in 13 of the 14 (93%; 95% confidence interval, 66% to 99.8%) joints with grade 4 arthroscopic abnormalities but in only 23 of the 46 (50%; 95% confidence interval, 35% to 65%) joints with grade 2 or 3 arthroscopic abnormalities. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that radiography is not a sensitive method for identifying moderate cartilage lesions in juvenile dogs with hip dysplasia. If moderate cartilage lesions are an important prognostic indicator for the success of triple pelvic osteotomy, then methods other than radiography should be used to detect these lesions.

On the ultrasonic properties of tendon.

The strong dependence of tendon echogenicity on insonation angle is explored by analyzing echo spectra. Combining echo spectra with high-resolution images from several modalities reveals that fluid spaces surrounding fascicles and bundles are likely sources of ultrasonic scatter. Mathematical models of tendon structure are proposed to explain how the anisotropic microstructure of tendon gives rise to angle-dependent echogenicity. Echo spectra from spontaneously damaged equine tendon samples were compared with normal equine tendon and found to exhibit a dramatic decrease in anisotropic properties that appears to be related to the spatial organization and type of collagen generated during repair. Variation in echo spectra with insonation angle is a robust indicator of mechanical damage.

Use of computed tomography angiography to evaluate the vascular anatomy of the distal portion of the forelimb of horses.

OBJECTIVE: To provide a detailed description of the vascular anatomy of the distal portion of the forelimbs of horses by use of computed tomography angiography (CTA). SAMPLE POPULATION: 6 forelimbs of 5 horses and 1 forelimb from an equine cadaver; none of the horses had orthopedic or vascular disease. PROCEDURE: Horses were anesthetized and CTA was conducted on the dependent forelimb. A catheter was inserted in the median artery, and contrast medium was infused at a rate of 3 mL/s. A computed tomography (CT) scanner was used to obtain contiguous slices from the region of the proximal sesamoid bones to the toe. All horses were allowed to recover from anesthesia. To help identify vessel patterns in the distal portion of the forelimb, the median artery and lateral palmar digital vein of a heparinized forelimb obtained from an equine cadaver were infused with red and blue polymethylmethacrylate and the distal portion of that forelimb was then sectioned to correspond to CTA images. RESULTS: Vessel patterns in CTA images matched vascular anatomic structures of the cadaver forelimb and were consistent with published anatomic structures. Major and minor vessels were consistently visible in CTA images of all horses. There were no complications reported in any horses. CONCLUSIONS AND CLINICAL RELEVANCE: Use of CTA provided a highly detailed depiction of the vasculature of the distal portion of the equine forelimb. This was a safe technique and should be useful in the evaluation of the blood supply to the distal portion of the forelimb.

Inheritance of cricopharyngeal dysfunction in Golden Retrievers.

OBJECTIVE: To characterize a genetic component to cricopharyngeal dysfunction (CD) in Golden Retrievers. ANIMALS: 117 dogs. PROCEDURE: The CD phenotype was determined by videofluoroscopy, and dogs were classified as affected if the upper esophageal sphincter (UES) did not open, if there were morphologic abnormalities of the UES, or if opening of the UES was delayed for > or = 6 videofluoroscopic frames (0.2 seconds) after closure of the epiglottis. All survey radiographic and videofluoroscopic studies were reviewed by the same radiologist. RESULTS: Of the 117 dogs (47 males and 70 females) with a CD phenotype determined via videofluoroscopy, 21 dogs (18.0%) had abnormalities of the UES (affected). Of these 21 dogs, 9 were males (19.1% of all males) and 12 were females (17.1% of all females). The heritability of CD in a threshold model was estimated as 0.61, which established that CD could be passed from parent to offspring. Results of complex segregation analysis suggested that a single recessive allele of large effect contributed to the expression of this disease in Golden Retrievers. CONCLUSIONS AND CLINICAL RELEVANCE: The determination that CD is inherited in Golden Retrievers is an important step in providing information for veterinarians attending dogs with this disorder. Breeders also require this information to make informed breeding decisions.

Percutaneous ultrasound-guided radiofrequency heat ablation for treatment of hyperthyroidism in cats.

OBJECTIVE: To determine efficacy and safety of percutaneous radiofrequency heat ablation for treatment of hyperthyroidism in cats. DESIGN: Prospective study. ANIMALS: 9 cats. PROCEDURE: Hyperthyroidism was diagnosed via clinical signs and high serum total (TT4) and free thyroxine (fT4) concentrations. One or 2 hyperfunctional cervical thyroid nodules were detected by use of scintigraphy and ultrasonography. If cats had 1 abnormal thyroid lobe, heat ablation was performed on that lobe; if cats had 2 abnormal lobes, heat ablation was applied to the larger lobe. Overall, heat ablation was performed 14 times in the 9 cats. Clinical signs and serum TT4, fT4, and calcium concentrations were monitored daily for 2 days after the procedure, weekly for the first month, and then monthly. Laryngeal function was evaluated and cervical ultrasonography and thyroid scintigraphy were also performed. Monitoring continued for as long as 9 months after heat ablation if a cat became euthyroid or until an owner chose an alternative treatment because of recurrence of hyperthyroidism. RESULTS: Serum TT4 and fT4 concentrations transiently decreased after all 14 heat ablation procedures (< or = reference range after 10 of 14 treatments) within 2 days after the procedure. Cats were euthyroid for 0 to 18 months (mean, 4 months). Hyperthyroidism recurred in all cats. Adverse effects included transient Horner's syndrome (2 cats) and laryngeal paralysis without clinical signs (1 cat). CONCLUSIONS AND CLINICAL RELEVANCE: Percutaneous heat ablation as a treatment for hyperthyroidism in cats is effective transiently but not permanently.

Postoperative assessment of surgical clip position in 16 dogs with cancer: a pilot study.

Metallic hemoclips or surgical staples were inserted in 16 tumor-bearing dogs at the time of surgical resection of the tumor. Orthogonal radiographs were taken immediately postoperatively and after wound healing to visualize the location and number of hemoclips or metallic staples. A shift in hemoclip/staple position was identified in nine dogs, mainly from positioning during radiography. In three dogs, an absolute shift in marker position was identified. Based on this study, it appears that the placement of surgical clips is potentially useful in identifying the tumor bed, which may be of benefit in establishing radiation treatment fields.

Multiscale image processing and antiscatter grids in digital radiography.

Scatter radiation is a source of noise and results in decreased signal-to-noise ratio and thus decreased image quality in digital radiography. We determined subjectively whether a digitally processed image made without a grid would be of similar quality to an image made with a grid but without image processing. Additionally the effects of exposure dose and of a using a grid with digital radiography on overall image quality were studied. Thoracic and abdominal radiographs of five dogs of various sizes were made. Four acquisition techniques were included (1) with a grid, standard exposure dose, digital image processing; (2) without a grid, standard exposure dose, digital image processing; (3) without a grid, half the exposure dose, digital image processing; and (4) with a grid, standard exposure dose, no digital image processing (to mimic a film-screen radiograph). Full-size radiographs as well as magnified images of specific anatomic regions were generated. Nine reviewers rated the overall image quality subjectively using a five-point scale. All digitally processed radiographs had higher overall scores than nondigitally processed radiographs regardless of patient size, exposure dose, or use of a grid. The images made at half the exposure dose had a slightly lower quality than those made at full dose, but this was only statistically significant in magnified images. Using a grid with digital image processing led to a slight but statistically significant increase in overall quality when compared with digitally processed images made without a grid but whether this increase in quality is clinically significant is unknown.

Digital radiography artifacts.

Radiographic artifacts may mimic a clinical feature, impair image quality, or obscure abnormalities. With the development of digital radiography (DR), a new set of artifacts is introduced. Regardless of the technology, the classic technical errors that occur with film screen radiography still occur using DR. Artifacts created using computed radiography, DR, and incorrect image processing are discussed. Methods for correction of the artifacts are presented.

Intraarterial contrast-enhanced computed tomography of the equine distal extremity.

A technique for regional delivery of contrast medium to the foot of the horse to increase the diagnostic utility of computed tomography (CT) for the characterization of soft tissue structures within the hoof capsule was developed. An intraarterial catheter was placed under ultrasound guidance into the medial palmar artery at the level of the carpus to facilitate a steady-state infusion of iodinated contrast medium. Two 5 mm collimated contiguous acquisition CT scans were performed in 10 horses without lameness or radiographic evidence of distal sesamoid bone degeneration. CT examination was performed before and during regional arterial infusion of iodinated contrast medium administered at a rate of 2 ml/s. Cross-sectional area and mean pre- and post-contrast attenuation of the deep digital flexor tendon and the collateral ligaments of the distal interphalangeal joint were quantified from CT images. Soft tissue anatomy of the foot was also qualitatively characterized from pre- and postcontrast images. Catheterization was successful and without complication in all horses. The evaluated tendons and ligaments were clearly visible and had a small (8-20 Hounsfield Unit) but significant (P < 0.05, paired t-test) increase in attenuation during the steady-state infusion of contrast medium. This study should enhance the diagnostic potential of CT by providing baseline quantitative data for comparison with horses affected with soft tissue injuries in the distal extremity causing lameness that is alleviated with a palmar digital nerve block.

Self-retaining braces for canine arthroscopy.

OBJECTIVE: To describe self-retaining braces for canine shoulder, elbow, hip, and stifle arthroscopy. STUDY DESIGN: Clinical design and application. SAMPLE POPULATION: Clinical patients admitted for elective arthroscopy. METHODS: Self-retaining braces were designed and constructed from commercially available products, steel tubing, and upholstery. The design efficacy was determined by clinical use. RESULTS: A shoulder/hip retraction device was constructed from a heavy-duty Mayo stand and a steel T frame. An elbow brace and a stifle brace were constructed from a commercially available positioning arm and steel tubing. These devices were used successfully in clinical canine arthroscopy and provided consistent stability for arthroscopic surgery without the need of a surgical assistant. CONCLUSIONS: Arthroscopic self-retaining braces can be constructed from commercially available products and other simple materials to provide reliable patient positioning without the need for a surgical assistant. CLINICAL RELEVANCE: Self-retaining braces may provide improved patient stabilization and eliminate the need for a surgical assistant in most cases of canine arthroscopy.

Ultrasonographic diagnosis-small bowel infarction in a cat.

An 8-year-old, domestic short hair cat with a known history of hypertrophic cardiomyopathy and previous aortic thromboembolism was presented for 24 h of vomiting and pyrexia. Initial abdominal radiographs were unremarkable. On an upper gastrointestinal series, delayed gastric emptying and prolonged small intestinal transit time were found. An initial abdominal ultrasound revealed a focal region of aperistaltic small intestine with mild wall thickening, however, intestinal wall layering in this area appeared normal. By 72 h, there was a diffusely hypoechoic portion of thickened small bowel (0.51 cm) with loss of the normal layering and hyperechoic mesentery surrounding this segment of bowel. A small bowel infarction and focal peritonitis were suspected and confirmed at surgery.

Computed tomographic appearance of osteochondritis dissecans-like lesions of the proximal articular surface of the proximal phalanx in a horse.

A 6-year-old Thoroughbred gelding presented with a left forelimb lameness. The results of lameness examination, radiography, nuclear scintigraphy, and computed tomography are presented. Based on the diagnostic imaging, subchondral fractures and osteochondritis dissecans lesions of the proximal articular surface of the proximal phalanx were diagnosed. A brief discussion of osteochondritis dissecans is presented.

Accuracy of magnetic resonance imaging for estimating intramedullary osteosarcoma extent in pre-operative planning of canine limb-salvage procedures.

The objective of this work was to compare the accuracy of radiographs and magnetic resonance imaging (MRI) for estimating appendicular osteosarcoma margins. The accuracy of computed tomography (CT) and bone scintigraphy was also assessed when these studies were available. Eight dogs with appendicular osteosarcoma underwent radiographic and MRI of affected limbs. In addition, bone scintigraphy was performed in six dogs and CT examination was performed in five dogs. Two observers jointly measured tumor length on all imaging studies. Correlative gross and histologic evaluation of all affected limbs was performed to determine tumor extent as measured from the nearest articular surface. Results from imaging studies were compared to gross and microscopic morphometry findings to determine the accuracy of each modality for determining tumor boundaries. MRI images were accurate with a mean overestimation of actual tumor length of 3 +/- 13%. T1-weighted non-contrast images were superior in identifying intramedullary tumor margins in most instances whereas contrast-enhanced images provided supplemental information in two dogs. Lateromedial and craniocaudal radiographs overestimated tumor length by 17 +/- 28% and 4 +/- 26%, respectively. Scintigraphy and CT overestimated tumor margins by 14 +/- 28% and 27 +/- 36%, respectively. MRI appears to be an accurate diagnostic imaging modality in determining intramedullary osteosarcoma boundaries. MRI should be considered as part of a pre-operative assessment of appendicular osteosarcoma, particularly when a limb-sparing procedure is contemplated.

Sensitivity of radiographic evaluation of radio-ulnar incongruence in the dog in vitro.

OBJECTIVE: To determine the sensitivity and specificity of radiographic evaluation of radio-ulnar incongruence in canine elbow joints in vitro. STUDY DESIGN: Radiographic evaluation of induced radio-ulnar incongruence in canine cadaveric forelimbs by radiologists blinded to study design. SAMPLE POPULATION: Six cadaveric canine left forelimbs. METHODS: Extended lateral, 90 degrees flexed lateral, and cranio-caudal projections were taken of the elbow joint of six cadaveric canine forelimbs. A four-pin, type I external skeletal fixator (ESF) with a linear motor side bar was attached to the medial aspect of the radius, and a 2-cm segment of bone was removed from the mid-diaphysis. A 3.5-mm cortical bone screw placed from the medial to lateral styloid processes prevented relative movement between the distal radius and ulna during radial shortening. The ESF was used to progressively shorten the radius in increments of 0.5 mm to a total of 4 mm. The three radiographic projections were repeated after each incremental change of length. After the study, each elbow joint was disarticulated to confirm the presence of a step defect. The original radiographs and three copies were randomized and then evaluated by four radiologists blinded to the study design. Radiologists were asked to evaluate whether the joint was normal or abnormal and if there was evidence of radio-ulnar incongruence. The ability of each radiologist to correctly identify congruent elbows (specificity) and incongruent elbows (sensitivity) was calculated. RESULTS: The median specificity was 86% using the lateral projection and 82% using the cranio-caudal projection. The median sensitivities using the lateral and cranio-caudal radiographic projections were 78% and 79%, respectively. The degree of radial shortening required for individual radiologists to achieve a sensitivity of 90% ranged from 1.5 mm to greater than 4 mm. CLINICAL RELEVANCE: Standard radiographic evaluation for radio-ulnar incongruence in the dog may be associated with relatively poor sensitivity and specificity. Invasive surgical procedures and screening programs that rely on radiographic diagnosis of radio-ulnar incongruence should be discouraged until a more reliable method of diagnosis of this type of elbow joint incongruence is available.