Administration of carbetocin-a long-acting oxytocin analogue-before sperm collection by transrectal ultrasound-guided massage of the accessory sex glands in bucks (Capra hircus) and ibexes (Capra pyrenaica).

Transrectal ultrasonic-guided massage of the accessory sex glands (TUMASG) is a technique that allows collecting semen requiring few electrical stimuli or even no pulse. A long-acting analogue of oxytocin (carbetocin, 0.1 mg) was i.v. administered before TUMASG in 10 conscious bucks (Experiment 1) and 10 anaesthetized Iberian ibexes (Experiment 2) to shorten the time of semen collection, decrease the number of electrical stimuli and/or improve the semen quality. The ejaculated volume, concentration, quality parameters and kinetics variables of the sperm were determined in fresh semen. The time length of the procedures and the number of electric pulses applied were recorded. Furthermore, stress response indicators (number of vocalizations in Experiment 1; heart and respiratory rates, rectal temperature, cortisol levels, totals proteins and neutrophil-to-lymphocyte ratio in Experiment 2) were documented. In bucks, the administration of carbetocin tended to shorten the time needed for semen collection but no-showed differences in the fresh seminal quality. In the Iberian ibexes, there were no significant differences between groups in the time length of procedures or in the number of animals that ejaculated. Carbetocin administration only reduced the respiratory rate, did it modify fresh semen characteristics in ibexes. In conclusion, the administration of carbetocin did not appear as a useful tool to improve welfare during semen collection with TUMASG or semen quality in conscious bucks and anaesthetized ibexes, having only slight advantages related to the procedure.

Using transrectal ultrasound-guided massage of the accessory sex glands for buck semen collection yields semen with greater cryoresistance than electroejaculation alone during the breeding season.

The cryoresistance of bucks' semen collected by transrectal ultrasound-guided massage of the accessory sex glands (TUMASG) and electroejaculation (EE) was compared during the breeding season (Study 1) or the late non-breeding season (Study 2). Semen was collected from 10 Gabon bucks with both methods in each season and then frozen according to a standardized protocol. The time required for ejaculation, the number of electrical pulses applied, the sum of the electrical pulses applied∗voltage and the total number of vocalizations emitted during the collection by each animal were recorded. In Study 1, TUMASG required a longer time (P = 0.0006) but fewer electrical pulses and a lower sum of pulses∗voltage than EE (P < 0.0001 for both comparisons). Bucks vocalized fewer times during TUMASG than during EE (P < 0001). Semen collected with TUMASG had greater sperm concentration, sperm mass motility, total number of motile sperm and of sperm with progressive motility, and tended to have greater total number of sperm with functional membrane than semen collected with EE (P = 0.02; P = 0.003; P = 0.02; P = 0.02; P = 0.06, respectively). After the freezing-thawing process, sperm collected with TUMASG had a greater quality of the motility, a total number of motile sperm and sperm with progressive motility, a greater percentage of motile sperm and sperm with functional membrane, and tended to have a greater total number of sperm with normal morphology than semen collected with EE (P = 0.04; P = 0.04; P = 0.03; P = 0.02; P = 0.04; P = 0.06, respectively). In Study 1 sperm collected with TUMASG had greater cryoresistance for almost all the variables considered than when it was collected with EE. In Study 2, the number of electrical pulses and the sum of pulses∗voltage were greater with EE than with TUMASG (P < 0001; P = 0.0002, respectively). There were no differences in any sperm variable in fresh or thawed samples collected with TUMASG or EE. However, the other seminal characteristics evaluated did not differ according to the method, and there were no differences in the cryoresistance of any variable. Overall, TUMASG affected animal welfare less than EE and was suitable for collecting semen of good quality with high cryoresistance during the breeding season in buck.

Cadaveric comparison of the accuracy of ultrasound-guided versus 'blind' perineural injection of the tibial nerve in horses.

During diagnostic evaluation of hindlimb lameness in horses the tibial nerve block is traditionally performed based on anatomical reference points, but it can be difficult to achieve effective local anaesthesia using this blind technique. Ultrasound (US)-guided injection could increase the accuracy of injection. The aim of this study was to compare the accuracy of both techniques. Twenty-one paired sets of cadaver hindlimbs were injected with 1 mL methylene blue using the blind or US-guided technique. There was no significant difference in stain width and length and in coloured nerve length between techniques. However, the successful rate of nerve staining was 85.7% and 47.6% for the US-guided and blind technique, respectively (P = 0.02; odds ratio 6.6; 95% confidence interval, 1.5-29.4). This study suggests that the US-guided technique is more accurate than the blind technique. However, in the treated sample, a single US-guided injection did not consistently result in nerve staining.

Financial impact of ultrasound-guided lumbar plexus and sciatic nerve blocks with electrostimulation for tibial plateau leveling osteotomy surgery in dogs.

OBJECTIVE: To determine the anesthesia cost from ultrasound-guided lumbar plexus and sciatic nerve blocks confirmed with electrostimulation for unilateral tibial plateau leveling osteotomy (TPLO) surgery in dogs. STUDY DESIGN: Prospective, randomized, blinded clinical trial. ANIMALS: A group of 20 dogs weighing 33.9 ± 6.0 kg (mean ± standard deviation). METHODS: All dogs were administered hydromorphone and atropine, propofol for induction of anesthesia and isoflurane for maintenance. Hydromorphone and carprofen were administered for recovery. The dogs were randomly assigned to one of two groups, lumbar plexus and sciatic nerve blocks with ropivacaine [regional anesthesia (RA)] or sham blocks with saline [control (CON)]. Fentanyl was administered for rescue analgesia intraoperatively and postoperatively. The cost to manage anesthesia was divided into fixed and variable costs using the micro-costing method. The variable costs were compared using Student's t test or Mann-Whitney U test. RESULTS: The fixed anesthesia costs were equal between groups at US$354.00 per case. The variable anesthesia cost range was US$27.90-100.10 for RA and US$21.00-180.50 for CON. Overall, cost per dog in CON was from -US$6.9 to US$80.4 compared with RA. For 160 TPLO cases per year, hospital cost when RA is performed decreased the cost by $12,864 per year up to increased cost by $1104 per year, depending on the requirements for systemic drugs and incidence/severity of anesthesia complications. The estimated fee charge per case for service necessary to reimburse the cost of a new ultrasound (US$25,000.00) and nerve locator (US$925.00) over their life span of 6 and 10 years, respectively, is US$26.62. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided lumbar plexus and sciatic nerve blocks with electrostimulation confirmation can increase the anesthesia cost through use of specific equipment. However, in most cases, the anesthesia cost decreased as a result of decreased costs for pain management and treatment of complications.

Locoregional Anesthesia in Exotic Pets.

Locoregional techniques are used in exotic pets to improve perioperative analgesia as well as decrease the requirement of systemic analgesics during and after invasive surgeries. This article focuses on the techniques that have been described for exotic mammals, birds, and reptiles, focusing on those that rely on ultrasonographic or nerve stimulator guidance.

Two-point ultrasound-guided transversus abdominis plane injection in canine cadavers - a pilot study.

OBJECTIVE: This study evaluated the spread of a two-point transversus abdominis plane (TAP) injection in canine cadavers. Compared with previous techniques, the two-point TAP injection was developed to increase the consistency of local anaesthetic spread to the nerve segments T11, T12, L1, L2 and L3. STUDY DESIGN: Prospective experimental trial. ANIMALS: Five fresh canine cadavers. METHODS: Two-point TAP injections were performed under ultrasound guidance by a single trained individual in canine cadavers (15.7-43.0 kg). Each hemi-abdomen was infiltrated and evaluated independently for a total of 10 evaluations of the technique. The first injection was performed at the level of the costo-chondral junction of the thirteenth rib, and the second injection was performed cranial to the tuber coxae. Each injection comprised 0.3 mL kg-1 methylene blue solution (0.0015 mg mL-1). Ten minutes after the injections, abdominal wall dissection was performed, and any nerves stained for a minimum of 10 mm along their long axis were identified and recorded. RESULTS: During all injections, separation of the internal oblique and transversus abdominis muscles was observed on ultrasound. On dissection, branches of T12, T13, L1, L2 and L3 were adequately stained in 30%, 100%, 100%, 90% and 90% of injections, respectively. No staining of branches of T11 occurred in any of the cadavers. In one hemi-abdomen, branches of L1 and L3, but not L2, were stained. CONCLUSIONS AND CLINICAL RELEVANCE: This study indicates that the two-point TAP injection delivers consistent dye dispersion to adequately stain branches of T13, L1, L2 and L3, with no coverage of T11 and poor coverage of T12, in fresh canine cadavers. An in vivo study using local anaesthetic should be performed to evaluate the analgesic efficacy of this technique in mid to caudal abdominal surgeries.

Ultrasound-guided lateral and subcostal transversus abdominis plane block in calves: a cadaveric study.

OBJECTIVE: To describe and assess the ultrasound-guided transversus abdominis plane (TAP) block feasibility in calf cadavers, to compare two injection volumes and to evaluate possible undesired solution spreads. STUDY DESIGN: Prospective, descriptive, anatomic study. ANIMALS: A group of 15 bovine cadavers weighing 47±11 kg (mean±standard deviation). METHODS: Lateral (n = 24) and subcostal (n = 12) TAP block approaches were assessed. For each approach, two volumes (0.2 or 0.4 mL kg-1) of toluidine blue and contrast medium were injected using both sides of the animals. Nerve staining was assessed by anatomical dissection and spread of injectate by contrast-enhanced computed tomography. Objective and subjective technique feasibility was evaluated by a specific score (poor, good, excellent). RESULTS: Using the lateral approach, 58%, 92% and 25% and 75%, 83% and 25% of the thirteenth thoracic, first and second lumbar nerves were stained by 0.2 and 0.4 mL kg-1, respectively. Craniocaudal and dorsoventral solution spread and number of blocks that adequately stained an individual nerve were not significantly different between the volumes. Using the subcostal approach, 67%, 83%, 67%, 67% and 50%, and 83%, 100%, 83%, 83% and 50% of the eighth, ninth, tenth, eleventh, twelfth thoracic nerves were stained by 0.2 and 0.4 mL kg-1, respectively. With both techniques, no intraspinal and one intraperitoneal spread were observed. Objective and subjective feasibility score was excellent for both approaches in the majority of the cases. CONCLUSIONS AND CLINICAL RELEVANCE: TAP injections were easy to perform with both techniques in calf cadavers. The volume of injectate did not influence spread. The authors conclude that a combination of the two approaches is necessary, but perhaps not sufficient, to stain all of the nerves innervating the ventral abdominal wall. Further studies are required to refine the technique and evaluate its efficacy in preventing nociception in calves.

Transversus abdominis plane block in ponies: a preliminary anatomical study.

OBJECTIVE: To describe a single-site transversus abdominis plane (TAP) block technique in horses. STUDY DESIGN: Prospective, descriptive, experimental anatomical study. ANIMALS: Four adult pony cadavers. METHODS: Freshly euthanized ponies were positioned in dorsal recumbency. A 6-13 MHz linear ultrasonic probe was used to scan the abdominal wall bilaterally midway between the last rib and iliac crest in search of the TAP location. By modifying the technique to accommodate the equine anatomy, the TAP was successfully visualized with the transducer positioned in a transverse plane with its side indicator over the intercept of two lines, one connecting the most cranial aspect of the iliac crest and the most caudal extent of the last rib and another originating just caudal to the umbilicus and extending laterally. Each hemiabdomen was injected with 0.5 mL kg-1 of a 1:1 solution of 1% methylene blue and 0.5% bupivacaine via a 21 gauge 10 cm stimulating needle inserted ventral-dorsally and in plane with the ultrasound beam. Approximately 3 hours after injection, the abdomen was dissected and nerves stained over 1 cm in length were identified. RESULTS: Staining was evident from the fourteenth thoracic (T14) to the third lumbar (L3) nerves. The ventral branches of the fifteenth to the eighteenth thoracic nerves (T15-T18) and first and second lumbar nerves (L1 and L2) were stained in three, six, eight, eight, eight and seven of eight injections, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Nerves T16-L2 had over 75% success rate in staining, suggesting that this technique would block transmission from T16 to L2, assuming that staining indicates potential nerve block. Dorsal spread occurred in three of eight hemiabdomens. Further studies developing techniques for the cranial abdomen and adjusting volume and concentration of injectate are warranted.

Comparison of ultrasound- and electrostimulation-guided nerve blocks of brachial plexus in dogs.

OBJECTIVE: To compare the effectiveness of ultrasound- and electrostimulation-guided nerve blocks of the brachial plexus and to determine whether ultrasound guidance is feasible in conscious dogs. STUDY DESIGN: Blinded, crossover, experimental study. ANIMALS: Six clinically healthy adult Beagle dogs. METHODS: The nerves of the brachial plexus of the right thoracic limb were blocked under ultrasound guidance (UNB) in conscious dogs and under electrostimulation guidance (ENB) in anesthetized dogs with bupivacaine (0.4 mL kg-1, 0.25%). Saline (0.4 mL kg-1) was injected in control animals. Sensory nerve blockade was evaluated by scoring cutaneous sensation in targeted nerves. Motor nerve blockade was evaluated based on weight bearing, conscious proprioception and withdrawal reflex scores. Times to execute the technique in UNB and ENB were compared using t tests (p < 0.05). Scores for sensory and motor nerve blockades in each treatment were compared with scores before treatment and with control treatment scores using nonparametric repeated-measures two-way analysis of variance. Time to onset and duration of sensory nerve block were assessed using scores for four sensory nerve functions. A successful sensory nerve block was defined by decreases in scores for these functions. Success rates of nerve blocks were compared among treatments using McNemar's test. RESULTS: In UNB and ENB, onset times of sensory nerve blocks were 1 hour and 1.5 hours, respectively. Onset times of motor nerve blocks were 0.5 hour in both treatments. In UNB and ENB, durations of sensory nerve block were 3 hours and 0.5 hour, respectively, and durations of motor nerve block were 7.5 hours and 6.5 hours, respectively. Success rates did not differ between the techniques. CONCLUSIONS AND CLINICAL RELEVANCE: The UNB brachial plexus block had a shorter onset time and longer duration than ENB. UNB can be performed in conscious dogs or those under mild sedation.

Ultrasound-Guided Nerve Block Anesthesia.

Superficial nerves can be visualized through ultrasonography in the cattle and facilitate local anesthetic disposition around nerve structures. Expected advantages include a higher successful rate of nerve block improving the degree and duration of the block. Among others, conduction nerves of clinical interest in cattle include the paravertebral nerves, nerves of the epidural space, the brachial plexus, and the sciatic and femoral nerves, and nerves of the head.

Ultrasound-guided anaesthetic blockade of the pelvic limb in calves.

This study aimed to describe a suitable acoustic window to facilitate access to the sciatic and femoral nerves in calves and to study the effects of their blockade with local anaesthetics. The neuroanatomical and ultrasound (US) study was performed on the cadavers of 10 calves, and the effects of 2% lidocaine with epinephrine (0.2 mL/kg) were determined in five healthy calves. The sciatic nerve in the cadavers was easily visualised as a hyperechoic band distal to the femoral greater trochanter and caudal to the femoral shaft. The femoral nerve in the cadavers was not easily identified, and was visualised as a hyperechoic oval structure situated immediately medial to the psoas major muscle and lateral to the femoral artery. The sciatic nerve was stained by methylene blue, injected under US guidance, in 9/10 cases, and the femoral nerve was stained in 6/10 cases. Sciatic nerve blockade under US guidance produced adduction of the limb with metatarsophalangeal joint flexion, while the femoral nerve blockade produced reduced weight bearing. The sciatic nerve blockade produced a reduced response to the noxious stimulus, mainly in the phalanges, proximal and distal metatarsus, tarsus and tibia and, following the femoral nerve blockade, in the medial subarea of the femur. However, femoral nerve blockade produced a more variable degree of blockade. In conclusion, US -guided anaesthetic blockade of the sciatic nerve in calves may be considered for surgery in the distal pelvic limb, although further studies are necessary to determine its clinical application.

Peripheral nerve stimulation under ultrasonographic control to determine the needle-to-nerve relationship.

OBJECTIVE: To determine the needle-to-nerve distances during electrical nerve location in dogs at different currents and pulse duration using a peripheral nerve stimulator (PNS) under ultrasound control (US), and the minimal electrical thresholds (MET) necessary to obtain a motor response (MR) after achieving needle-to-nerve contact. STUDY DESIGN: Prospective in vivo experimental trial in a clinical setting ANIMALS: Thirty dogs, scheduled for locoregional anaesthesia of the sciatic nerve. METHODS: Needle-to-nerve distance was measured ultrasonographically after obtaining the MR of sciatic nerve with 2, 1 and 0.5 mA and pulse duration 0.1 ms (NS0.1). Thereafter the needle was placed in contact with the nerve and MET was determined. The procedure was repeated with 0.3 ms (NS0.3). Finally the needle was reintroduced to contact the sciatic nerve guided only by US, thus MET-US was determined. Data were analysed using Kruskal-Wallis or Mann-Whitney tests. RESULTS: Needle-to-nerve distances were greater when MR was obtained with 2 mA than with 1 and 0.5 mA at 0.1 and 0.3 ms. No significant differences were observed between the needle-to-nerve distances using 0.1 or 0.3 ms. The MET [median (range)] was 0.4 (0.18-1.3) mA in NS0.1, 0.32 (0.12-0.8) mA in NS0.3; while MET-US was 0.7 (0.32-1.5) mA. When the needle contacted the nerve, the MR achieved with currents below 0.3 mA was obtained in 17.2, 40 and 0% of cases using NS0.1, NS0.3 and US respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The electrical current necessary to obtain a MR decreased as the needle moved towards the nerve. However when the needle tip contacted the nerve, an MR with low current intensity could not be obtained. Thus the absence of motor response at currents below 0.3 mA cannot rule out needle-epineurium contact. When ultrasound is combined with PNS, it is more important to assess the correct needle position than searching for an MR at low currents.

Ultrasound guidance for the performance of sciatic and saphenous nerve blocks in dogs.

The aim of this study was to investigate the use of ultrasound (US) guidance to perform sciatic and saphenous nerve blocks in dogs. Five dogs were sedated with medetomidine and butorphanol. A high-resolution US transducer was used to locate the nerves, guide placement of the needle and visualise the perineural injection of lidocaine 2%. Electrostimulation was used to confirm correct placement prior to the sciatic block. Nerve functions were evaluated over a 3 h period following administration of atipamezole. Successful identification of the nerves and the quality of the blocks were recorded. Location of the nerves, complete sensory block of the saphenous nerve, and partial to complete sensory and motor blocks of the sciatic nerve were achieved in all dogs. The resultant US guidance is potentially valuable for blocking the sciatic and saphenous nerves in dogs, although further work will be required to ensure a complete block of the sciatic nerve.