Development of an ultrasound-guided technique for retrobulbar nerve block in dromedary camels: a cadaveric study.

OBJECTIVE: Description of an ultrasound (US)-guided technique for retrobulbar nerve blockade in dromedary (Camelus dromedarius) cadavers. STUDY DESIGN: Prospective experimental cadaveric study that was carried out in three phases: phase I: anatomical dissection and development of US-guided technique; phase II: methylene blue (MB) injection; phase III: contrast medium (CM), US-guided injections with computed tomography (CT) control. ANIMALS: A total of 36 orbits from 18 heads were obtained from 18 dromedary cadavers. METHODS: Phase I: anatomical dissections were carried out bilaterally, using two heads to determine needle site placement. Phase II: a US-guided, lateral, in-plane approach using one of three volumes of MB (3, 6, or 9 mL) was evaluated in six heads (four orbits per volume tested) to establish the ideal injection volume. Injections of MB that strongly stained all retrobulbar nerves were considered successful, whereas insufficient MB volumes resulted in weak or no nerve staining. Phase III: US-guided retrobulbar injection with CM was carried out using 20 orbits. Computed tomography was performed after each injection trial to determine the accuracy of needle placement and CM dispersal. An injection was judged to be successful when the CT images revealed that the needle was located within the retractor bulbi muscle cone and the CM reached the target nerves at the orbitorotundum and the optic foramina. RESULTS: Only injection of 9 mL of MB stained the target nerves sufficiently, whereas there was no or only weak staining with 3 and 6 mL, respectively. Therefore, 9 mL of CM was used for the US-guided injections in phase III. Subsequent CT scans revealed satisfying CM distribution within the ocular muscle cone in 18 of 20 cases (90% success rate). CONCLUSIONS AND CLINICAL RELEVANCE: US-guided retrobulbar injection in dromedary cadavers is feasible. Further research is required to assess its practicality and usefulness in vivo.

Reference values and repeatability of the Schirmer tear tests I and II in domesticated, clinically normal dromedary camels (Camelus dromedarius).

OBJECTIVE: To determine the normal values and repeatability for Schirmer tear test (STT) in clinically normal dromedary camels and to analyze the influence of the age and gender on these values. ANIMALS STUDIED: Thirty clinically normal dromedary camels of different ages (calves, immature, and mature). PROCEDURES: Schirmer tear tests I and II were performed using commercial STT strips. Three measurements were obtained from each eye over three consecutive weeks, and the variance of these measurements was determined. RESULTS: Mean values and coefficient of variation of STT I and STT II for the right and left eyes varied significantly among camel groups (P < 0.05). For STT I, the most frequently recorded values were >14-18, > 22-26, and >30-34 mm/min in calves, immature camels, and mature camels, respectively. For STT II, however, the most frequently recorded values were 7-14, >10-18, and >26-30 mm/min, respectively. The interassay coefficients of variation were 1.7-14.4% and were significantly lower in mature camels than in calves and immature camels (P < 0.05). Age was positively correlated with STT I (r = 0.81) and STT II values (r = 0.88). No significant variations were found between genders. CONCLUSIONS: This preliminary study reports STT I and II values and repeatability in normal dromedary camels. This information may assist veterinary practitioners in complete ophthalmic examinations and in accurate diagnosis of ocular surface diseases affecting the tear film in this species.

Computed tomographic arthrography of the normal dromedary camel carpus.

The aim of this prospective cadaveric study was to provide a detailed computed tomographic (CT) reference of the carpal joint in healthy dromedary camels. Twelve forelimbs of six apparently healthy camels were used. Computed tomographic imaging of 12 normal cadaveric camel carpal joints was performed before and after intra-articular administration of iodinated contrast medium. Transverse CT images were reconstructed in dorsal and parasagittal planes. The six carpal bones, the radial trochlea, and the proximal articular surface of the metacarpal bones were clearly visible on CT images with the bone setting window. Radiocarpal, carpometacarpal, transverse intercarpal, medial and lateral palmer intercarpal, middle intercarpal, accessory carpoulnar and medial and lateral collateral ligaments, carpal canal, joint capsule, and the extensor and flexor tendons were identified on CT images with the soft-tissue setting window. Postcontrast CT images provided better delineation of intercarpal ligaments, the capsular compartments and recesses. Results indicated that the osseous and the clinically important soft tissue structures of the dromedary camel carpal joint could be identified using CT and CT arthrography. The CT data of this study will serve as a basis for diagnosis of carpal problems in camels.