Podotrochlear bursa endoscopy in the horse: a cadaver study.

OBJECTIVES: To evaluate podotrochlear bursa (navicular bursa) endoscopy as a diagnostic technique in horses and to correlate observations to radiographic and pathologic findings. STUDY DESIGN: Descriptive study. SAMPLE POPULATION: Seventeen equine cadaver forelimbs. METHODS: Five standard radiographic views of the navicular region and a bursographic study with lateromedial and caudal tangential radiographic views were taken of each forelimb. Radiographic scoring of the navicular bone (0, excellent; 1, good; 2, fair; 3, poor) was performed using a previously reported technique. Endoscopic examination was performed using a 30 degrees wide-angle forward oblique-viewing, 4-mm outside diameter (OD), arthroscope. Four examiners using recorded videotapes made independent evaluations of bursal endoscopy. The specimens were then dissected and examined to verify radiographic and endoscopic findings. RESULTS: The distribution of radiographic scores (RS) were 0 (5 limbs), 1 (7), 2 (2), and 3 (3). Abnormal endoscopic findings (fibrillation of the deep digital flexor tendon, a defect in the navicular bone fibrocartilage, and synovial hyperplasia) were identified in 3 limbs (2 with an RS of 1, and 1 with an RS of 3). The endoscopic observations made in the two RS 1 bursae were not confirmed on gross examination, whereas they were in the RS 3 specimen, which also had the only abnormal bursogram. Evaluation of the bursa on the side ipsilateral to the arthroscope portal was difficult. Complications of the technique included inadvertent penetration of the distal interphalangeal joint and the digital sheath, and superficial scoring of the navicular bone fibrocartilage. CONCLUSIONS: Podotrochlear bursa endoscopy is feasible and may be a useful technique in identifying early abnormalities associated with podotrochleosis. CLINICAL RELEVANCE: In horses with podotrochleosis, endoscopic examination of the podotrochlear bursa may improve identification of pathologic changes within the bursa.

Excretory urography by intraosseous injection of contrast media in a rabbit model.

There are many indications for an intravenous excretory urogram. However, where intravenous access is not available, the intraosseous route to the circulation may be an alternative. We found that safe and diagnostic excretory urograms could be obtained in rabbits following the injection of different contrast media via the intraosseous route. In fact, these excretory urograms were indistinguishable from ones obtained by the conventional intravenous route. While the rabbits did not develop any abnormal clinical signs following the procedure, there were postmortem histologic lesions of osteochondrosis in 5 of 22 (22.7%) tibias receiving an intraosseous needle, but in none of the 14 tibias that did not receive an intraosseous needle. Further, the use of diatrizoate was associated with the development of osteochondrosis while the use of iopamidol was not.

MR imaging findings in a dog with lumbar ganglion cysts.

Intraspinal cysts of the L6-L7 and L7-S1 articular process joints in a six-year-old neutered female German Shepherd Dog were diagnosed using magnetic resonance (MR) imaging. Histopathology provided a diagnosis of ganglion cysts. Clinical, laboratory, radiographic and MR imaging findings are described. Briefly, radiographic findings revealed lumbarization of the first sacral vertebra, and fusion of the first caudal vertebra to the sacrum. In addition, spondylosis and articular process osteoarthrosis occurred at L6-L7 and L7-S1. MR imaging revealed multiple, well encapsulated structures ranging in size from 3-10 mm in diameter which were found to arise from the L6-L7 and L7-S1 articular process joints. These cysts had signal intensities that varied from hyperintense to the cerebrospinal fluid (CSF) on T1 weighted images to isointense to CSF on T2 weighted images. Decompressive surgery in conjunction with arthrodesis of these joints resulted in resolution of clinical signs. The dog remained pain-free 1 1/2 years following surgical therapy.

An assessment of the ability of diplomates, practitioners, and students to describe and interpret recordings of heart murmurs and arrhythmia.

The ability of clinicians, ie, 10 veterinary students, 10 general practitioners, and 10 board certified internists, to describe and interpret common normal and abnormal heart sounds was assessed. Recordings of heart sounds from 7 horses with a variety of normal and abnormal rhythms, heart sounds, and murmurs were analyzed by digital sonography. The perception of the presence or absence of the heart sounds S1, S2, and S4 was similar for clinicians irrespective of their level of training and was in agreement with the sonographic interpretation on 89, 82, and 78% of occasions, respectively. However, practitioners were less likely to correctly describe the presence of S3. The heart rhythm was correctly described as being regular or irregular on 89% of occasions, and this outcome was not affected by level of training. Differentiation of the type of irregularity was less reliable. The perception of the intensity of a heart murmur was accurate and correlated with the grade assigned in the living horses, R2 = .68, and with sonographic measurements of the murmur's intensity, R2 = .69. Clinicians overestimated the duration of cardiac murmurs, particularly that of the loud systolic murmur. Only diplomates could reliably differentiate systolic from diastolic murmurs. The ability to diagnose the underlying cardiac problem was significantly affected by training; diplomates, practitioners, and undergraduates made the correct diagnosis on 53, 33, and 29% of occasions, respectively. The poor diagnostic ability of practitioners and the lack of improvement in diagnostic skill after the 2nd year of veterinary school emphasizes the need for better teaching of these skills. Digital sonograms that combine sound files with synchronous visual interpretations may be useful in this regard.

Transesophageal ultrasonography of the normal canine mediastinum.

The mediastinum of eight normal research dogs was examined by transesophageal ultrasonography with a 5 MHz frequency transducer to establish a baseline for future use of this new imaging modality as a diagnostic tool. Each examination consisted of 360 degree scans in both transverse and sagittal planes from the thoracic inlet to the esophageal hiatus. Dissections of four of these research dogs were then performed to confirm transesophageal ultrasonography findings. Transesophageal ultrasonography of the mediastinum was a good imaging modality for the evaluation of the heartbase, the major cranial mediastinal vessels, the descending aorta, and occasionally part of the azygos vein. Anatomic orientation was best obtained by beginning the examination at the heart base. Lymph nodes and smaller caliber vessels could not be distinguished from surrounding tissues; however, Doppler ultrasound was useful for identifying the smaller vessels. Although a 5 MHz frequency transducer is preferred for transesophageal echocardiography, a higher frequency transducer would improve the resolution of the images of small near-field structures and may be more appropriate for mediastinal imaging.

Deep hypothermic low flow cardiopulmonary bypass in small dogs.

OBJECTIVE: To evaluate the feasibility of and morbidity and mortality associated with cardiopulmonary bypass (CPB) using deep hypothermia and low flow perfusion in adult dogs weighing less than 10 kg. STUDY DESIGN: Prospective, descriptive study. ANIMALS: Two groups of three dogs underwent CPB. Group 1 dogs underwent deep hypothermia (15 to 18 degrees C), 45 minutes of low perfusion flow (20 mL/kg/min) and 1 hour of aortic cross clamp time. In group 2, ultrafiltration of perfusate before discontinuation of bypass was added to the standard treatment. Complete blood counts, serum biochemistry, urine output, ejection fraction, and cardiac output were monitored before and for 7 days after surgery. RESULTS: All dogs were successfully weaned from bypass. Four of six dogs survived, three without major complications. One dog developed and recovered from septic pleuritis. Two dogs died or were euthanatized after surgery because of respiratory or gastrointestinal complications. Minor complications included anemia, hypoproteinemia, and electrolyte disturbances. Transfusion requirements and edema formation were reduced by ultrafiltration. CONCLUSIONS: The observations in this study support the feasibility of low flow hypothermic CPB. Meticulous tissue handling, precise equipment, ultrafiltration, and aggressive postoperative potassium supplementation are recommended for smaller patients. CLINICAL RELEVANCE: Increased sensitivity to adverse sequelae of CPB may be associated with small patient size. Further evaluation is necessary before routine clinical application of low flow hypothermic CPB in this patient population.

Ocular and orbital porcupine quills in the dog: a review and case series.

A retrospective evaluation of 5 cases of orbital or intraocular porcupine quills in the dog and a literature review from MEDLINE (1983-1995) is presented. This paper reviews the diagnosis, therapy, and visual prognosis of ocular and orbital quills in the dog. Distinguishing penetration and perforation of the eye and intraocular structures is paramount in establishing a visual prognosis and appropriate therapy. Perforation of the cornea or sclera, lens, or the uvea and retina necessitates prompt specialized surgical therapy to save vision. The diagnosis of orbital quills can be readily confirmed with ultrasonography. The characteristic sonographic appearance of a double-banded, linear, hyperechoic object allows accurate localization of the quill, which aids surgical removal.

Fetal growth in muskoxen determined by transabdominal ultrasonography.

A 5 MHz commercial sector scanner was used to monitor 13 muskox pregnancies and establish normal fetal growth curves. Examinations were carried out between 40 and 197 days of gestation and pregnancy could be detected throughout the period. Early pregnancies were found by scanning lateral to the udder but as pregnancy progressed the fetus was found closer to the dam's umbilicus. Measurements of cranial and abdominal diameters taken at about two week intervals in seven uncomplicated pregnancies in four cows were used to construct fetal growth curves. These can be reliably used in the reproductive management of muskoxen. In addition a series of regressions based on measurements of the fetuses of muskoxen killed in the Arctic are provided. These allow cranial and abdominal diameters to be related to fetal weight and crown-rump length.

Removal of a retropharyngeal foreign body in a horse, with the aid of ultrasonography during surgery.

Diagnostic ultrasonography was used during surgery to assist in the removal of a piece of wire from the retropharyngeal region. A 3-year-old Quarter Horse mare was referred with dysphagia of 2 days' duration. Radiography revealed a 9-cm piece of wire located caudodorsal to the larynx. A ventral surgical approach was performed, dissecting along the right side of the larynx and trachea. The surgical field was filled with 0.85% sterile physiologic saline solution. A 5 MHz-mm sector scanner probe immersed in the fluid was able to locate the wire and facilitate the direction and depth of dissection to where the wire was identified and removed.

Unsuccessful surgical repair of a short soft palate in a dog.

An 8-week-old male Miniature Schnauzer had nasal discharge of milk, food, and water since birth, especially during eating. Examination of the oral cavity revealed a short soft palate. Numerous unsuccessful surgical procedures were performed to construct a shelf of tissue to prevent oronasal reflux. The dog was euthanatized.

The radiographic and histologic appearance of controlled surgical manipulation of the equine periosteum.

This study documented the normal histologic features of the equine metacarpal and metatarsal periosteum and characterized its osteogenic response to surgical manipulation. Two periosteal flaps were elevated from the dorsomedial matacarpal and metatarsal diaphysis in each of three limbs of four yearling and four adult lightbreed horses. The superficial metacarpal cortex under the flap was resected with a bone chisel in one-half of the horses and was undisturbed in the remainder. One periosteal flap in each limb was excised and the other flap was replaced and secured by sutures. All limbs in the horses were radiographed at regular intervals postoperatively. Horses were killed either 30 or 120 days after surgery. Periosteal bone production occurred only at treatment sites of young horses treated by periosteal flap replacement and was limited to approximately 50% of these sites, as determined by radiography and microradiography. Cortical abrasion resulted in an increased incidence of bone production in the periosteum adjacent to the flap perimeter. The histologic features of the periosteum were similar to those reported in other species; young horses had active osteogenesis referable to appositional growth and adults had an inactive periosteum. Histologically, osteogenesis induced by surgery resembled accentuated appositional growth in both yearlings and adults. In the horse, the cambial (osteogenic) layer is included in sharply elevated periosteal flaps. It should be removed in surgical procedures where bone production is to be avoided, and preserved where osteogenesis is desired.

Bilateral carpus valgus with cranial bowing of the distal radius in a foal.

Bilateral carpus valgus with concomitant outward rotation and cranial bowing of the distal radii was diagnosed in a crossbred foal. The foal was not lame on admission and showed no radiographic evidence of carpal bone abnormalities. Surgery was limited to the most severely affected leg, and consisted of a combination of growth promotion (periosteal transection and stripping) and temporary physeal retardation (transphyseal bridging) procedures. Correction of the valgus deformity was nearly complete in the operated limb and substantial improvement was observed in the cranial bowing and outward rotation in both limbs, five months postoperatively.

Periorbital skull fractures in five horses.

Periorbital skull fractures were diagnosed in 5 horses, and were associated with ophthalmic complications including corneal ulceration, uveitis, and entrapment of the eye by retrobulbar bone fragments. Physical examination was of greater diagnostic use than radiography. Surgical repair was performed on all horses and was associated with a more favorable postoperative appearance in horses treated acutely; however, the cosmetic results were considered acceptable in all horses. Major postoperative complications were not observed.

Microsurgical management of tetralogy of Fallot in a cat.

A modified Blalock-Taussig shunt was performed on a cat with tetralogy of Fallot. Previous attempts at such palliative surgery in the cat have failed, due to small vessel size. The use of microvascular instrumentation and technique resulted in a patent shunt in this case.

Ancillary diagnostic imaging. Angiography, ultrasonography, scintigraphy, and xeroradiography.

Veterinary medical imaging is now accepted as including a number of imaging modalities other than conventional radiography. Although the wide availability and relatively low cost of conventional radiography will keep it in the forefront of veterinary medical imaging, other imaging modalities or techniques such as those discussed in this article will, where available, be of significant value in selected cases of bovine lameness.

Quantitative analysis of long-bone growth in the horse.

Long-bone growth at the distal ends of the radial bones, the distal ends of the 3rd metacarpal bones, the distal ends of the 3rd metatarsal bones, and the proximal ends of the proximal phalangeal bones (of thoracic and pelvic limbs) was quantitatively analyzed in 9 Thoroughbred-Quarter Horse foals from birth to 2 years of age. Metal growth markers were surgically implanted in the bones of the animals at 2 to 4 days of age. Radiographs of the bones were made on the day of surgical manipulation, the next day, and then once a week for 8 months, and once a month thereafter for an additional 18 months. On each radiograph, the intervals between the growth markers were measured and plotted, and these accumulated growth data were subjected to statistical analyses. Growth curves, cumulative growth, and relative growth rates were determined. The ages of radiographic growth plate closure also were determined. Total bone growth observed in these foals was proportionately greater than that observed in a similar study of Shetland-Welsh ponies, probably indicating a breed difference. The most rapid growth rate at the 5 anatomic sites in the foals occurred from birth to 10 weeks of age; however, in the distal part of the radius, there was a continuous, though declining growth rate until 60 weeks of age, whereas in the distal ends of the 3rd metacarpal and metatarsal bones and the proximal end of the proximal phalanges growth ceased abruptly and nearly plateaued after 10 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Carpal bone lesions associated with angular limb deformities in foals.

Six foals with angular limb deformities present at birth or shortly after were examined. The limb deformities were caused by abnormalities of the carpal bones and included hypoplasia and osteochondritis dissecans. The 3rd carpal bone was affected most frequently.