Serial abdominal radiographs do not significantly increase accuracy of diagnosis of gastrointestinal mechanical obstruction due to occult foreign bodies in dogs and cats.

Abdominal radiographs are commonly used in dogs and cats that present with gastrointestinal signs. When initial abdominal radiographs are equivocal for the presence or absence of gastrointestinal mechanical obstruction, follow-up abdominal radiographs may be recommended. Based on our review of the literature, no published study has been performed to evaluate the clinical utility of serial abdominal radiographs in such cases. The purpose of this study is to determine whether follow-up abdominal radiographs increase diagnostic accuracy for mechanical obstruction. A prospective cohort study was performed on client-owned dogs and cats with clinical concern for gastrointestinal mechanical obstruction and initial abdominal radiographs inconclusive for the presence of obstruction. Follow-up abdominal radiographs were performed between 7 and 28 h of the initial radiographs; an abdominal ultrasound performed within 3 h of the follow-up study served as the gold standard. A total of 57 patients (40 dogs and 17 cats) were recruited; 19 of 57 cases (11 dogs; 8 cats) were mechanically obstructed, all with nonradiopaque foreign bodies. Four blinded reviewers (2 radiologists, 1 radiology resident, 1 criticalist) separately assessed the initial and the combined initial/follow-up radiographic studies for diagnosis of mechanical obstruction; for each observer, there was no significant change in accuracy (P = .058-.87) for the diagnosis of mechanical obstruction. Given the lack of significant increase in diagnostic accuracy using follow-up radiographs in cases of occult gastrointestinal mechanical obstruction, other diagnostic options (eg, abdominal ultrasonography) could be considered when survey abdominal radiographs are inconclusive for the diagnosis of mechanical obstruction in dogs and cats.

A technique for ultrasound-guided paravertebral brachial plexus injections in dogs.

Using cadaveric dogs, we established the ultrasonographic landmarks for performing paravertebral injections around the brachial plexus nerve roots in the dog, and assessed the accuracy and regional spread of the aliquots. A mixture of methylene blue dye and an iodinated contrast medium was used as the injectate. A 0.3 ml volume was used to assess accuracy and a 3.0 ml volume was used to assess regional spread. Accuracy and regional spread were assessed from computed tomography (CT) images acquired after injection by measuring the distance from each foramen to the nearest edge of contrast medium, and the dimensions of spread of contrast medium in each anatomic plane, respectively. The mean distance of small volume injections from each foramen was 0.9 cm (standard deviation [SD] 0.56 cm). The mean spread of contrast medium for the small volume injections measured 1.7 cm (SD 0.6 cm) cranial-to-caudal, 1.2 cm (SD 0.4 cm) dorsal-to-ventral and 7.4 cm (SD 0.4 cm) medial-to-lateral. The mean spread of contrast medium for the combined three large volume injections measured 7.4 cm (SD 1.7 cm) cranial-to-caudal, 3.1 cm (SD 0.8 cm) medial-to-lateral, and 2.8 cm (SD 0.5 cm) dorsal-to-ventral. After the CT studies, staining of each nerve root and any other regional structure was assessed grossly. Based on our results, ultrasound can be used to guide injections around the nerve roots of the brachial plexus in dogs.