Topographical anatomy and desensitization of the pudendal nerve in adult male dromedary camels.

The objectives of this study were to describe the topographical anatomy of the pudendal nerve and to develop techniques of its blocking in adult male dromedary camels. Two cadavers and 30 adult male dromedary camels were used for the description of topographical anatomy and pudendal nerve block techniques, respectively. Results revealed that the pudendal nerve arises from the ventral branches of the 2(nd) and 3(rd) sacral spinal nerves. The nerve had three divisions; dorsal, middle, and ventral. The caudal rectal nerve was a branch of the dorsal division. Three blocking techniques were developed according to the results of topographical anatomy. The first technique was 15 cm cranial to the tail base and 7 cm lateral to the midline. The second was 12 cm cranial to the tail base and 7 cm lateral to the midline. The third was about 3 cm on either sides of the anus. Details and complications of each technique were reported. In conclusion, the anatomy of the pudendal nerve was different from that of cattle and horse. The second technique (12 cm cranial to the tail base and 7 cm lateral to the midline) for pudendal nerve block was superior among the three methods. Duration of nerve blocking was suitable for examination and for performing some surgical procedures in male dromedary camels.

Plasma lidocaine concentrations in conscious horses after cervicothoracic (stellate) ganglion block with 1% lidocaine HCl solution.

Arterial and/or central venous plasma concentrations of lidocaine were determined in 12 nonmedicated adult horses (422 +/- 59 kg of body weight, mean +/- SD) after injecting a 1% lidocaine HCl solution into the cervicothoracic ganglion (CTG). A mean dosage of 2.9 +/- 0.5 mg of lidocaine/kg of body weight was used to induce unilateral CTG blockade in 8 horses and 4.8 +/- 0.8 mg was used to induce bilateral CTG blockade in 4 horses. Blood samples were collected before and at 5, 15, 30, 45, 60, 75, 90, 105, and 120 minutes after injection. The plasma lidocaine concentrations were determined by use of gas chromatography (sensitivity less than 0.01 microgram/ml). Cervicothoracic sympathetic blockade was characterized by Horner's syndrome and by profuse sweating over the face, neck, and thoracic limbs. Mean maximal venous concentrations of lidocaine were 0.86 +/- 0.33 microgram/ml at 26.3 +/- 6.9 minutes after unilateral CTG blockade, and 1.14 +/- 0.25 micrograms/ml at 31.2 +/- 18.9 minutes after bilateral CTG blockade. The mean venous and arterial concentrations of lidocaine were not significantly different at 45 and 120 minutes after injection. Venous concentrations of lidocaine were consistently higher than were concentrations in simultaneously collected arterial blood samples in 2 horses in which the right CTG and brachial plexus were temporarily anesthetized after repeated administration of 100 ml of lidocaine into the right CTG.(ABSTRACT TRUNCATED AT 250 WORDS)

Cervicothoracic (stellate) ganglion block in conscious horses.

Seven adult horses were used to compare the cardiovascular and respiratory effects of unilateral (right side) and bilateral cervicothoracic ganglion (CTG) blockade. An 18-gauge, 25-cm needle was placed midventrally between articulations of the 1st and 2nd ribs from a cranial and paratracheal site. One gram of lidocaine HCl in aqueous solution (100 ml) was used to infiltrate the CTG. Cervicothoracic sympathetic blockade was characterized by Horner's syndrome, increased skin temperature and profuse sweating over the face, neck, and thoracic limb. Comparison of base-line data with data obtained during unilateral and bilateral CTG blockades indicated a significant (P less than 0.05) decrease in respiratory rate, significant (P less than 0.05) increases in arterial oxygen, and carbon dioxide tensions, and a significant increase in subcutaneous temperature at the neck and shoulder. Systolic, diastolic, and mean aortic blood pressures, pulse pressure, rectal temperature, arterial pH, bicarbonate, PVC, and total solid concentration did not change significantly from base-line values. Arterial O2 tension was significantly (P less than 0.05) less in horses with bilateral CTG blockade than in horses with unilateral CTG blockade. In 4 horses without cervicothoracic sympathetic blockade that were given lidocaine (1 g in 100 ml) in the right cervicothoracic region, cardiovascular and respiratory values did not change significantly from base-line values. The nonsedated healthy horse tolerated unilateral CTG blockade well. Bilateral and unilateral injections of 100 ml of 1% lidocaine into the CTG at intervals of less than 2 hours induced bilateral recurrent nerve paralysis and airway obstruction.

Technique for reversible vagal blockade in the standing conscious pony.

A surgical technique is described for preparation of chronic cervical vagal loops in ponies. Vagal blockade was induced by circulating methanol (-2 C) through coils which enclosed the loops. Vagal blockade increased tidal volume, heart rate, and systemic blood pressure and decreased respiratory rate. Atropine, given at a dose of 0.04 mg/kg IV, increased heart rate and systemic pressure but did not alter respiratory variables, indicating that vagal cooling caused both afferent and efferent blockade. The effects of vagal blockade were rapidly reversed when refrigerated coils were removed.