A comparison of 0.375% ropivacaine psoas compartment block and 2% prilocaine spinal anaesthesia in dogs undergoing tibial plateau levelling osteotomy.

BACKGROUND: In dogs undergoing routine elective orthopaedic surgeries carried out as same-day surgeries regional anaesthetic techniques (RATs) should aim to produce analgesia but minimising the postoperative motor dysfunction. Our objective was to compare the perioperative analgesic effects and the time to motor recovery between spinal anaesthesia (SA) with hyperbaric solution of prilocaine 2% (mg = 4 x [0.3 × BW (kg) + 0.05 × SCL (cm)]) and morphine (0.03 mg/kg) and combined ultrasound (US) and electro stimulator-guided psoas compartment and ischiatic nerve block (PB) with ropivacaine 0.375% (0.45 mL/kg). Dogs undergoing tibial plateau levelling osteotomy (TPLO) were randomly assigned to receive either SA or PB. Procedural failure, perioperative rescue analgesia, motor block recovery and complications were recorded. RESULTS: Procedural failure rate (PFR) was 19% (7 out of 36) for SA and 9% (3 out of 32) for PB (p = 0.31). Intraoperative rescue analgesia was administered to 6/29 (21%) SA group dogs and in 15/29 (52%) PB group dogs, respectively (p = 0.03). At 3 h after RAT, percentage of dogs with complete block recovery was 25/29 (86%) and 25/29 (86%) in group SA and PB, respectively (p = 1). Two cases of pruritus and one case of urinary retention were recorded in the SA group. Residual ischiatic nerve block was noted at 12 h after RAT in 2/15 (13%) of dogs in group PB; it completely resolved 24 h after RAT. CONCLUSIONS: SA with prilocaine 2% and PB with ropivacaine 0.37% were found suitable for dogs undergoing same-day TPLO surgery. Pruritus and urinary retention in SA and residual block in both groups might occasionally delay the time of discharge.

Incidence of dural sac puncture during neuraxial anesthesia in cats: an observational, retrospective study.

OBJECTIVES: The aim of this study was to determine the occurrence of dural puncture, indicated by cerebrospinal fluid (CSF) outflow, in cats receiving neuraxial anesthesia through a lumbosacral injection guided by a pop sensation method. METHODS: This was an observational, retrospective study. Cats that were scheduled for lumbosacral neuraxial anesthesia were included. Medical records were analyzed to investigate: (1) demographic data; (2) neuraxial anesthesia performed (epidural/spinal); (3) type of needle used, including gauge and length; (4) presence of CSF (yes/no) and/or blood (yes/no) in the hub of the needle; and (5) flicking of the tail during needle advancement (yes/no). RESULTS: A total of 94 medical records were analyzed. A 22 G 50 mm Tuohy needle was used in all cats scheduled for an epidural injection (n = 60), whereas a 22 G 40 mm Quincke needle was used in all cats scheduled for an intrathecal injection (n = 34). CSF outflow was detected in 55/60 (91.7%) cats in which a Tuohy needle was used, and 34/34 (100%) of the cats in which a Quincke needle was used (P = 0.15). Flicking of the tail was detected in 41/60 (68.3%) and in 24/34 (70.6%) injections with Tuohy and Quincke needles, respectively (P >0.99). Traces of blood, but not active blood outflow, were detected via staining of the first drops of CSF in 2/34 cats in which Quincke needles were used and in none of the cats in which Tuohy needles were used (P = 0.12). CONCLUSIONS AND RELEVANCE: This study shows that the lumbosacral approach for neuraxial anesthesia in cats may result in a dural sac puncture when 22 G Quincke or Tuohy needles are used. The pop sensation method should be deemed effective in predicting intrathecal but not epidural needle placement.

Comparison of Anesthetic Efficacy of Lidocaine and Bupivacaine in Spinal Anesthesia in Chickens.

Lidocaine is used for epidural and spinal anesthesia in various animal species. The ideal drug for epidural and spinal anesthesia should have a long effective duration in addition to a fast onset of action, and adequate analgesia and muscle relaxation. Despite the delayed onset of action, bupivacaine provides a longer duration of anesthesia than lidocaine. The purpose of this study was to compare the onset to effect and duration of action between lidocaine and bupivacaine for spinal anesthesia in broiler chickens. Thirty-two, 8-week-old, female Ross broiler chickens were randomly divided into 4 groups of 8: 1) 2 mg/kg lidocaine (L); 2) 0.1 mg/kg bupivacaine (B0.1); 3) 0.25 mg/kg bupivacaine (B0.25); and 4) 0.5 mg/kg bupivacaine (B0.5). After aseptic preparation, a 23-gauge spinal needle was inserted into the synsacrococcygeal space of the chickens with correct needle placement confirmed by a sudden loss of resistance. Spinal anesthesia was performed with the aforementioned doses of lidocaine and bupivacaine. The respiratory rate and cloacal temperature were measured every 10 minutes in each chicken until the anesthetic effect was no longer present. The onset to effect and the duration of action were calculated for each bird based on the pinch test at predetermined time intervals. The results are demonstrated as mean ± SD. The onset of action for bupivacaine (9 ± 1.41, 4.33 ± 1.15, and 3.33 ± 1.23 minutes in B0.1, B0.25, and B0.5 groups, respectively) was significantly delayed compared with that of lidocaine (1.37 ± 0.52 minutes). The duration of action of B0.5 (54 ± 6.08 minutes) was significantly longer than that of any other group (17.87 ± 3.18, 11 ± 1.41, and 18 ± 4.36 min in L, B0.1, and B0.25 groups, respectively). The results showed that a spinal injection of 0.5 mg/kg bupivacaine produces approximately 55 minutes of spinal anesthesia in these broiler chickens, which is much longer than the 18 minutes of anesthesia provided by 2 mg/kg lidocaine. Considering the various disease conditions that affect the cloacal area of birds, one can use each of these anesthetic drugs for either short-term or long-term spinal anesthesia in chickens and possibly other avian species.

SPINAL ANESTHESIA IN GREEN SEA TURTLES (CHELONIA MYDAS) UNDERGOING SURGICAL REMOVAL OF CUTANEOUS FIBROPAPILLOMAS.

Techniques for anesthesia of green sea turtles (Chelonia mydas) are required for medical treatment. The use of spinal anesthesia has been reported in a few species of turtles for different purposes. The objective of this study was to evaluate the use of 2% lidocaine for spinal anesthesia of green sea turtles undergoing surgical removal of cutaneous fibropapillomas. Ten free-ranging green turtles presenting with cutaneous fibropapillomas were included in the study. Animals were accidentally captured or rescued by local fishermen and brought to the Ubatuba Research Base (Sao Paulo, Brazil) of the Brazilian Sea Turtle Conservation Program for rehabilitation. Animals were administered 2% lidocaine (0.2 ml/10 cm of carapace) in the epidural/subarachnoid space of the tail and monitored throughout surgery. The technique was effective for all animals, with fast onset of motor and sensory blockade (3 ± 1.76 min) and relatively fast recovery time (83.9 ± 16.2 min). Fibropapillomas were removed from all animals with no signs of pain (i.e., no behavioral response during surgical procedure, such as head and forelimb movement, showing discomfort) and they were all rehabilitated and successfully returned to their natural habitat. The technique was considered effective, safe, and affordable for use on green turtles undergoing surgical removal of cutaneous fibropapillomas.

Epidural and Spinal Anesthesia.

Epidural and spinal anesthesia with a combination of local anesthetics and opioids (when available) is a commonly used technique in veterinary medicine and a safe one when practiced under strict guidelines. It is a valuable tool in the analgesic armamentarium and can greatly extend the ability to provide analgesia and reduce postoperative opioid requirements. As with all regional anesthetic techniques, clinical experience should be gained in order to practice it efficiently, and care should be taken to minimize the risks and complications associated with its use.

Development and evaluation of a technique for spinal anaesthesia in broiler chickens.

AIMS: To develop a technique for the injection of local anaesthetic into the spinal canal of broiler chickens by first determining the ideal location for needle placement based on anatomy and histology, and then using the developed technique to assess the onset and duration of action of three doses of lidocaine. METHODS: Two-month-old Ross broiler chickens (n = 30) were used in this study. Computed tomography imaging followed by anatomical examination of fresh cadavers (n = 6) were used to identify a suitable intervertebral space for injection of local anaesthetic, and landmarks to locate this space. Histological evaluation of the microanatomy of the caudal vertebral column in another six birds was used to examine the position of the spinal cord within the canal. Spinal anaesthesia was attempted using injection of lidocaine at 0.5 mg/kg (n = 6), 1 mg/kg (n = 6), and 2 mg/kg (n = 6) via the selected intervertebral space. Analgesia was tested by pinching the skin of the pericloacal area with thumb forceps to determine the onset and duration of analgesia. Respiratory rate, and cloacal temperature were measured at 0 minutes and every 10 minutes after injection until sensation returned. RESULTS: The space between synsacrum and first free coccygeal vertebra (synsacrococcygeal space) was selected as the most suitable site for spinal injection. In this region, the dura mater adhered to the internal wall of the spinal canal, and the subarachnoid space was large indicating that injection would be into the subarachnoid rather than the epidural space. The interval to onset of analgesia was similar for all doses of lidocaine (1.5 (SD 0.7), 2 (SD 1) and 1.3 (SD 0.5) minutes for 0.5, 1 and 2 mg/kg, respectively; p = 0.604). Duration of analgesia was longer following injection with 2 than 0.5 or 1 mg/kg lidocaine (21.3 (SD 2.5) vs. 4.5 (SD 3.5) vs. 11.3 (SD 2) minutes, respectively; p = 0.002). Mean cloacal temperature decreased between 0 and 20 minutes after injection with all doses of lidocaine (p = 0.021). CONCLUSIONS AND CLINICAL RELEVANCE: Spinal anaesthesia in chickens is feasible and is a practical, inexpensive and simple technique for regional anaesthesia of the pericloacal area.

Effects of intravenous dexmedetomidine infusion on local anaesthetic block: A spinal anaesthesia clinical model in dogs undergoing hind limb surgery.

The aim of this randomised, prospective clinical trial was to determine how the administration of a low dose of dexmedetomidine (DEX) by IV constant rate infusion, modified the duration of the nerve block in dogs undergoing spinal anaesthesia (SA) in a clinical setting. Forty-four dogs undergoing hind limb orthopaedic surgery in a day-surgery regime, maintained under anaesthesia with isoflurane plus SA, were randomly assigned to receive 1 µg/kg/h (IV) of DEX (group D) or not (group C). Spinal anaesthesia was performed with a hyperbaric solution of bupivacaine and morphine at the L5-6 interspace. Every mean arterial pressure (MAP) increase by 30% above the pre-skin incision value was considered an intraoperative analgesic failure and treated with a bolus of fentanyl as intraoperative rescue analgesia (iRA). Time free from iRA was analysed with a Kaplan-Maier survival curve. The ability to walk at 5 h from SA and the event of bradycardia (HR lower 60 beat per min) and hypotension (MAP value lower 60 mmHg) were recorded. The mean times at which iRA was required were 77.4 (3.2) in group C and 112.2 (8.6) in group D (Logrank test P = 0.038). In groups C and D hypotension incidence was 11/17 (65%) and 2/22 (9%), (P = 0.0004) and bradycardia 3/17 (18%) and 6/22 (27%) (P = 0.704), respectively. The ability to walk 5 h after SA was 14/14 (100%) and 13/14 (93%) in groups C and D, respectively. DEX infusion significantly prolonged the duration of the nociceptive nervous block without prolonging the motor block or increasing the bradycardia events.

Combined spinal and general anaesthesia in 58 cats undergoing various surgical procedures: description of technique and retrospective perioperative evaluation.

OBJECTIVES: The aim of this retrospective study was to describe the spinal anaesthesia (SA) technique and evaluate the incidence of perioperative complications in cats. METHODS: The anaesthetic records of cats of American Society of Anaesthesiologists physical status I, II and III, which received general and SA for different surgeries between 2012 and 2016, were examined. SA was administered through a 25 G Quincke needle, using an isobaric solution of bupivacaine and morphine at the level of either the L7-S1 interspaces (sternal recumbency) or the L5-6/L6-7 interspaces (lateral recumbency). Procedural failure rate (PFR), drugs and dose used, heart rate (HR), arterial blood pressure, incidence of bradycardia (HR <100 bpm) and hypotension (mean arterial pressure [MAP] <60 mmHg for at least 5 mins), intraoperative rescue analgesia (iRA) and any other detrimental events and their treatment until discharge were recorded. Abdominal surgery cases were excluded from the intraoperative evaluation. RESULTS: A total of 58 anaesthetic records met the inclusion criteria and were analysed. PFR related to the space of injection (L7-S1 vs L5-6/L6-7) was 3/11 (27%) and 1/47 (2%), respectively (P = 0.017). The total median dose of intrathecal bupivacaine and morphine was 0.8 (range 0.5-1.6 mg/kg) and 0.10 (0.05-0.18 mg/kg), respectively. Nine of 46 (20%) cats received iRA, and no iRA cases were reported with a dose of bupivacaine higher than 0.8 mg/kg. Median HR and MAP before intrathecal injection (T0) and 10 mins after (T1) were, respectively, 118 bpm (range 74-190 bpm) and 106 bpm (67-160 bpm) (P = 0.005), and 65 mmHg (range 50-94 mmHg) and 52 mmHg (range 35-85 mmHg) (P = 0.003). Bradycardia was reported in 18/46 (39%) cats and hypotension in 23/46 (50%) cats. No complications were recorded during the observation period. CONCLUSIONS AND RELEVANCE: SA was characterised by a low PFR when performed at the L5-6/L6-7 interspaces and low postoperative complications. Hypotension and bradycardia were the most common side effects.

Ultrasound guided spinal catheter insertion in piglet: preliminary results.

OBJECTIVE: To describe the ultrasound (US) evaluation of the cervical, thoracic and lumbar spinal tracts in piglets and to evaluate the feasibility of the ultrasound guided spinal catheter placement in newborn and paediatric piglets. STUDY DESIGN: Prospective experimental study. ANIMALS: A total of two piglet cadavers (age, 7 and 14 days) and eight commercial crossbreed piglets divided into four groups according to age: 7 (P7), 14 (P14), 21 (P21) and 28 (P28) days. METHODS: In the first part of the study an ultrasound examination of the spinal tract was performed in piglet cadavers applying the transverse and the longitudinal approaches in sternal and lateral recumbencies. In the second phase, the piglets were anaesthetized with sevoflurane. A US examination with a 10 MHz linear probe was performed and a spinal catheter was introduced between the spinous processes of L2 and L3 lumbar vertebrae using an in-plane technique and its advancement was monitored with the probe. At the end of procedure, the catheter was removed. The piglets recovered from anaesthesia and were monitored for one week. RESULTS: In phase I the authors identified the paramedian longitudinal approach as the most feasible for spinal structure evaluation in piglets. In phase II, the paramedian longitudinal views enabled a good visualization of the spinal cord and of the catheter advancement up to the cisterna magna in groups P7 and P14. In groups P21 and P28 it was not possible to visualize the neuroaxial structures and the spinal catheter using the same approach. No clinical alterations were recorded during the procedure or the following days. CONCLUSIONS AND CLINICAL RELEVANCE: US-guided spinal catheter placement appeared a feasible technique in piglets younger than 14 days but it is not useful in older piglets.

Local, Regional, and Spinal Anesthesia in Ruminants.

Local, regional, and spinal anesthesias are safe, effective, often more desirable procedures for ruminants than general anesthesia. Many procedures can be performed safely and humanely in ruminants using a combination of physical restraint, mild sedation, and local, regional, or spinal anesthesia. This article focuses on the use of local anesthetics for providing anesthesia for dehorning, procedures of the nose and eye, laparotomy, reproductive procedures, teat repair, and procedures on the distal limb. Local, regional, and spinal anesthesia techniques are safe effective methods for providing anesthesia for common surgical procedures and analgesia for painful conditions in cattle and small ruminants.

Sonographic evaluation of epidural and intrathecal injections in cats.

OBJECTIVES: To describe the ultrasonographic anatomy of the caudal lumbar spine in cats and to detect ultrasound (US) signs associated with epidural or intrathecal injection. STUDY DESIGN: Prospective, clinical study. ANIMALS: Twenty-six client-owned cats. METHODS: Transverse (position 1) and parasagittal (position 2) two-dimensional US scanning was performed over the caudal lumbar spine in all cats. Midline distances between the identified structures were measured. Cats assigned to epidural injection (group E, n = 16) were administered a bupivacaine-morphine combination confirmed by electrical stimulation. Cats assigned to intrathecal injection (group I, n = 10) were administered a morphine-iohexol combination injected at the lumbosacral level and confirmed by lateral radiography. The total volume injected (0.3 mL kg-1 ) was divided into two equal aliquots that were injected without needle repositioning, with the US probe in positions 1 and 2, respectively. The presence or absence of a burst of color [color flow Doppler test (CFDT)], dural sac collapse and epidural space enlargement were registered during and after both injections. RESULTS: US scanning allowed measurement of the distances between the highly visible structures inside the spinal canal. CFDT was positive for all animals in group E. In group I, intrathecal injection was confirmed in only two animals, for which the CFDT was negative; seven cats inadvertently and simultaneously were administered an epidural injection and showed a positive CFDT during the second aliquot injection, and the remaining animal was administered epidural anesthesia and was excluded from the CFDT data analysis. Dural sac collapse and epidural space enlargement were present in all animals in which an epidural injection was confirmed. CONCLUSIONS AND CLINICAL RELEVANCE: US examination allowed an anatomical description of the caudal lumbar spine and real-time confirmation of epidural injection by observation of a positive CFDT, dural sac collapse and epidural space enlargement.

Retrospective clinical evaluation of hypobaric spinal anaesthesia in dogs undergoing pelvic limb orthopaedic surgery.

OBJECTIVE: To evaluate intraoperative effects, complications, postoperative rescue analgesia requirement and presence of postoperative unilateral blockade after hypobaric spinal anaesthesia in dogs. METHODS: Retrospective review of case records of dogs that underwent pelvic limb orthopaedic surgery and received hypobaric spinal anaesthesia. Cases that contained complete information on perioperative analgesia, end tidal anaesthetic agent, arterial blood pressure, postoperative urination, motor function and assessment at the sixth week re-examination were selected. RESULTS: Twenty-four of forty-eight records were sufficiently complete to meet the selection criteria. Local anaesthetic dose and volume of the solution administered were 0 · 22 (±0 · 06) mg/kg and 0 · 16 (±0 · 05) mL/kg, respectively. Fentanyl was administered intraoperatively in seven dogs (29%); mean ± sd end-expired isoflurane was 1 · 09 ± 0 · 17%; hypotension was observed in nine dogs (37 · 5%). Unilateral blockade was documented in 18 dogs (75%); 6 dogs (25%) required methadone postoperatively; urinary retention was not observed. One dog developed steroid responsive meningitis arteritis. CLINICAL SIGNIFICANCE: Hypobaric spinal anaesthesia achieved unilateral postoperative pelvic limb motor blockade in dogs, although bilateral block occurred in a proportion of animals; intraoperative hypotension was not infrequent. Fentanyl and postoperative methadone might be required to control nociception and pain, despite technical success in performing spinal anaesthesia.

Comparison of lidocaine, lidocaine/epinephrine or bupivacaine for thoracolumbar paravertebral anaesthesia in fat-tailed sheep.

OBJECTIVE: To evaluate the speed of onset and duration of loss of sensation in the flank following paravertebral administration of lidocaine (with or without epinephrine) or bupivacaine. STUDY DESIGN: Blinded, randomized experimental study. ANIMALS: Nine healthy fat-tailed male lambs (mean weight ± SD, 22.9 ± 3 kg). Each animal was used twice. METHODS: Animals were allocated randomly to receive two of three treatments: lidocaine 2% (LID, n = 6), lidocaine with epinephrine 5 µg mL(-1) (LIDEP, n = 6) or bupivacaine 0.5% (BUP, n = 6). The sheep received a total volume of 9 mL (3 mL for each paravertebral nerve) of anaesthetic. Onset and duration of loss of sensation on the flank were evaluated using nociceptive stimuli (superficial and deep pin-prick and clamping with a haemostat). Values for heart (HR) and respiratory (f(R) ) rates, rectal and skin temperatures were recorded before and at predetermined intervals after paravertebral injection. Parameters were compared using anova followed by Duncan's test where relevant. RESULTS: Mean ± SD times to onset of loss of flank sensation following paravertebral administration of LID, LIDEP or BUP were 1.8 ± 1.2, 2.0 ± 0.9 and 3.6 ± 1.3 minutes, respectively. Durations of action in minutes were 65 ± 18, 95 ± 46 and 303 ± 98, respectively. Onset and duration of effects after BUP treatment were significantly longer than after LID or LIDEP (p < 0.05), but did not differ significantly between LID and LIDEP. No clinical signs of local anaesthetic toxicity were noticed and HR and f(R) remained stable with all protocols. CONCLUSIONS AND CLINICAL RELEVANCE: Paravertebral administration of bupivacaine produces a longer duration of anaesthesia when compared to lidocaine with or without epinephrine and is indicated when prolonged flank surgery is to be performed.

Efficacy and side effects of intraoperative analgesia with intrathecal bupivacaine and levobupivacaine: a retrospective study in 82 dogs.

OBJECTIVE: To evaluate spinal (intrathecal) anaesthesia (SA) in addition to general anaesthesia in dogs, and report the incidence of side effects and cardiovascular response (CR) to surgery. STUDY DESIGN: Retrospective clinical study. ANIMALS: One hundred and fifteen dogs undergoing general anaesthesia for surgery caudal to the diaphragm between 2005 and 2008. METHODS: Records of anaesthetized dogs that had received SA with bupivacaine or levobupivacaine 0.5%, together with morphine or fentanyl were reviewed. Success rate of SA, complication rate and incidence of CR were recorded and examined in relation to the dose of local anaesthetic administered and the type of surgery. Univariate and Cusum analysis were performed to identify independent predictors of response to surgical stimulation and characterize the learning curve for the technique, respectively. RESULTS: Eighty-two dogs received successful SA. The Cusum plot suggested that a failure rate of 10% is achieved when the procedure is performed more than 66 times. Median local anaesthetic dose related to weight was 0.40 mg kg(-1) (0.3-0.5), and to spinal cord length 0.1 mg cm(-1) (0.07-0.12). Morphine was added to the local anaesthetic in 56 and fentanyl in 22 dogs. CR post-stimulus occurred in 29 cases: 11 of 22 ovariohysterectomies, 14 of 33 hindlimb-surgeries, 2 of 10 caudal-abdominal-surgeries and 2 of 17 Caesarean sections. Anaesthetic dose related to weight was not a predictor of CR. Bradycardia occurred in seven, hypotension in 24, urinary retention in four and hypersalivation in 6 of 82 dogs. CONCLUSIONS: SA was practicable to apply, but in this study did not totally block CR, Side effects were minimal, with an incidence similar to that in humans. CLINICAL RELEVANCE: SA can be used in clinical cases with few side effects although monitoring of and ensuing treatment of hypotension is required. Comparative prospective studies are required to establish efficacy and a reliable dose.

Spinal anesthetics and analgesics in the horse.

In the past 10 years, there have been many recent advances in spinal techniques in horses, both epidural and subarachnoid, to identify drugs or drug combinations that have sensory effects without motor nerve paralysis, thus providing pain control without these horses becoming recumbent. Opioids, alpha-2 agonists, dissociative drugs, and others have been investigated. Many of these drugs, which have serious side effects when injected systemically in horses, have been shown to have useful analgesic effects when injected spinally. Morphine-like opioids have the greatest potential for spinal use as they produce long-lasting analgesia without motor effects. Often the doses used spinally are significantly lower than those needed for systemic effects.

Hypobaric intrathecal anaesthesia for partial hemipelvectomy in a dog.

OBJECTIVE: To report the intrathecal use of a hypobaric anaesthetic solution for partial hemipelvectomy in a nine-year-old, neutered female, Golden Retriever dog, weighing 34 kg. METHODS: Under inhalational anaesthesia, with the dog lying in lateral recumbency and the surgical side uppermost, 1.9 ml of a hypobaric solution containing 3.42 mg of bupivacaine and 0.66 mg of morphine were administered in the subarachnoid space at L5-6 level 30 minutes before surgery. Following the intrathecal injection the dog was maintained for five minutes in a 10 degrees head-down position, then for three minutes in a 10 degrees head-up position. RESULTS: Apart from a transient increase in heart and respiratory rates during resection of the sartorius muscle, which was treated with a plasma Target Controlled Infusion (TCI) of fentanyl, spinal anaesthesia provided cardiovascular stability and excellent relaxation of the surgical site. Neither motor blockade nor proprioceptive deficit were apparent in the contra-lateral hind limb at recovery, 200 minutes after injection. Postoperatively, rescue analgesia was not required in the 48 hours following surgery. CLINICAL SIGNIFICANCE: In dogs, the use of intrathecal hypobaric bupivacaine and morphine as a part of a balanced anaesthetic protocol should be considered during unilateral major orthopaedic surgeries of the pelvis and hind limb, as it allowed a reduction in the dose administered compared to isobaric solutions, providing selective spinal anaesthesia, excellent long-lasting analgesia, and rapid recovery of ambulation.

The effects of preoperative extradural bupivacaine and morphine on the stress response in dogs undergoing femoro-tibial joint surgery.

OBJECTIVE: To evaluate the efficacy of preoperative extradural bupivacaine and morphine in attenuating the stress response in dogs undergoing femoro-tibial joint surgery. STUDY DESIGN: Prospective clinical study. Animal population Twelve client-owned dogs undergoing surgery for either repair of cruciate ligament rupture (ten) or correction of luxating patella (two). Body masses ranged from 12 to 45 kg (mean: 28.58 +/- 18.38). Age ranged from 19 to 121 months (mean: 66.5 +/- 49.5). MATERIALS AND METHODS: Six of the dogs received extradural bupivacaine (up to 1.5 mg kg(-1)) combined with morphine (0.1 mg kg(-1); ED) while the other six received no extradural analgesia (C). The levels of cortisol, acute phase proteins (APPs), and red and white blood cell variables were measured in both groups of dogs before, and at various times after surgery. Pain was also assessed at various times after surgery. The number of postoperative morphine doses required, and their time of administration, was recorded for each animal. Method of statistical analysis Data were analysed using anova for repeated measures with p-values of <0.05 considered significant. RESULTS: Cortisol levels in the ED group were significantly (p < 0.05) lower than those of the control group at the end of surgery. No statistically significant differences were found in APPs or red and white cell variables between dogs receiving, and those not receiving extradural bupivacaine and morphine. Four dogs in the control group and one in the ED group required postoperative morphine. CONCLUSIONS AND CLINICAL RELEVANCE: Pre-emptive extradural bupivacaine and morphine was effective in lowering the neuroendocrine stress response (cortisol) in the ED group but had no effect on the inflammatory response (acute phase response).

Combined spinal-epidural anesthesia in a dog.

OBJECTIVE: To report use of combined spinal epidural anesthesia for tail resection and surgical exploration of the pelvic canal and the perineal-pararectal area in a dog. ANIMAL: A 4-month-old, 13 kg male Collie dog. METHODS: Under inhalant anesthesia, an epidural catheter was threaded through a Tuohy needle at L5-L6. Then using a Whitacre spinal needle bupivacaine and fentanyl were administered in the subarachnoid space at L6-L7 level. Fifteen minutes later, morphine was administered epidurally. Bupivacaine and morphine were administered epidurally 4 hours after the subarachnoid injection. RESULTS: No cardiorespiratory response to surgical stimulation was observed. Postoperative analgesia was satisfactory, and the catheter was removed 30 hours later. No complications or neurologic sequelae occurred before discharge or were noted 10 days later. CONCLUSION: Combined spinal-epidural anesthesia provided excellent intraoperative anesthesia and perioperative analgesia in a dog undergoing surgery involving the pelvic canal. CLINICAL RELEVANCE: Combined spinal-epidural anesthesia can be performed in dogs, and its use should be considered in major surgeries caudal to the diaphragm, as the epidural catheter allows cranial extension of the block, providing excellent intraoperative anesthesia and perioperative analgesia.