Preliminary evaluation of an indwelling epidural catheter for repeat methylprednisolone administration in canine lumbosacral stenosis.

Objective: To determine the complications, outcomes, and patency of a permanent epidural catheter and subcutaneous access port system (ECAPS) as part of conservative management of degenerative lumbosacral stenosis in dogs. Animals and procedure: Medical records of 11 client-owned dogs that underwent an ECAPS insertion were evaluated retrospectively. Clinical signs, complications related to the procedure, and system patency are reported. Results: All dogs had lumbosacral pain at their initial neurological assessment, with comfort levels adequately controlled following epidural infiltrations. None suffered from complications related to the ECAPS procedure. In 10 dogs, there were no malfunctions for the duration of the study. However, in 1 dog, there was a suspected leak at Day 814. The longest duration of patency reported in this study was 870 d (at the time of writing). Conclusion: Placement of an ECAPS is a feasible technique and a viable option to permit repeated epidural injections of steroids in dogs with degenerative lumbosacral stenosis that is managed conservatively. Further studies are required to evaluate complication rates.

Évaluation préliminaire d'un cathéter épidural permanent (à demeure) pour l'administration répétée de méthylprednisolone lors de sténose lombosacrée dégénérative chez le chien. Objectif: Décrire la technique, les complications, les résultats et la perméabilité d'un système composé d'un cathéter épidural et d'un port d'injection sous-cutanée (ECAPS) pour le traitement médical de la sténose lombosacrée dégénérative chez le chien. Animaux et protocole: Les dossiers médicaux de 11 chiens appartenant à des clients ayant subi l'implantation d'un ECAPS ont été évalués de façon rétrospective. Cette étude décrit les signes cliniques, les complications reliées à la procédure et la perméabilité du système. Résultats: Tous les patients inclus présentaient de la douleur lombosacrée à l'examen initial. Le niveau de confort de tous les patients suite aux injections épidurales fut maitrisé de façon adéquate. Aucun des patients n'a subi de complications reliées à l'implantation du système. Le système n'a pas démontré de dysfonctionnement dans le cas de dix patients. Chez un des patients, une fuite fut suspectée au jour 814. La durée maximale de perméabilité enregistrée dans cette étude est de 870 jours (au moment de la rédaction). Conclusion: L'implantation d'un système ECAPS représente une option faisable et viable pour l'administration additionnelle de stéroïdes pour une gestion conservatrice de sténose lombosacrée dégénérative chez les chiens atteints. Des recherches supplémentaires sont requises pour l'évaluation des taux de complications.(Traduit par les auteurs).

Evaluation of the technique of localization of the epidural space with the aid of a peripheral nerve stimulator and epidurographic, comparing two techniques for determining the infused volume, in rabbits (Oryctolagus Cuniculus).

Veterinary care for rabbits has been growing, and, consequently, the anesthetic and analgesic management of this species must be improved. The aim of the present study was to evaluate the technique of localization of the epidural space with the aid of a peripheral nerve stimulator and epidurographic, comparing two techniques for determining the infused volume in rabbits (Oryctolagus Cuniculus). In a prospective, randomized blinded study, six healthy New Zealand rabbits, adults, and weighing from 2.2 kg to 3.8 kg received two treatments, at 1 week intervals: 0.33 mL/kg (treatment I) or 0.05 mL per centimeter of the spine (treatment II) of ioexol epidurally. In both treatments, a peripheral nerve stimulator (2 Hz, 0.25 mA and 0.1 milliseconds) was used to determine the location of the epidural space. Latero-lateral and ventro-dorsal radiographs were taken after five (T5) and twenty-five minutes (T25) of iohexol administration. The epidural space was correctly accessed in 92% of attempts. Treatment I received a smaller volume of contrast than treatment II, 1.0 ± 0.2 mL versus 2.1 ± 0.1 mL (mean ± standard deviation), respectively (p = 0.007). At T5, the cranial progression of the contrast varied between L4 and L5 in treatment I, and L5 and T10 in treatment II. At T25, no contrast was observed in any rabbit. In conclusion, peripheral nerve stimulator aided in accessing the lumbosacral epidural space, and the administration of 0.05 mL per centimeter of the spine resulted in greater cranial progression of contrast.

Comparison of rostral spread of lumbosacral epidural volume calculated by body weight or length of the vertebral column in small-sized anesthetized dogs.

The first objective of this prospective, randomized, crossover experimental trial was to compare the rostral spread of lumbosacral epidural volume calculated by body weight (BW) or vertebral column length (LE) in 6 small, isoflurane-anesthetized female beagle dogs (BW: 7.5 to 10.2 kg; LE measured from the occipital crest to the sacrococcygeal space: 46 to 56 cm). The second objective was to assess the response to a noxious stimulus once the dogs recovered from anesthesia and to determine the effects of the injection on cardiopulmonary variables. While in sternal position, dogs were injected through an epidural catheter with a volume mixture of bupivacaine 0.25% and iopamidol 15% based on BW: 0.2 mL/kg or LE: 0.05 mL/cm (< 50 cm) or 0.07 mL/cm (50 to < 70 cm). Rostral spread was determined by counting the number of vertebrae reached by iopamidol using computed tomography. After anesthesia, cardiopulmonary variables, motor function, and responses to nociceptive stimuli were evaluated. Comparisons were completed with mixed linear models and 2-way analysis of variance (ANOVA) (P < 0.05). The volume of injectate (3.29 ± 0.74 versus 1.81 ± 0.21 mL; mean ± SD) and the number of vertebrae (22 ± 2 versus 19 ± 2 vertebrae) reached by iopamidol were significantly greater for LE than for BW. Response to nociception, time to return of pain sensation, motor function, and cardiopulmonary variables were similar between groups. In conclusion, dosing based on LE resulted in larger rostral spread than when based on BW in dogs of small size.

Le premier objectif de cet essai expérimental croisé prospectif randomisé était de comparer la propagation rostrale du volume épidural lombo-sacré calculé en fonction du poids corporel (PC) ou de la longueur de la colonne vertébrale (LE) chez 6 petites chiennes beagle anesthésiées à l'isoflurane (PC : 7,5 à 10,2 kg; LE mesuré de la crête occipitale à l'espace sacro-coccygien : 46 à 56 cm). Le deuxième objectif était d'évaluer la réponse à un stimulus nocif une fois que les chiens se sont remis de l'anesthésie et de déterminer les effets de l'injection sur les variables cardiopulmonaires. En position sternale, les chiens ont reçu une injection via un cathéter péridural d'un mélange volumique de bupivacaïne à 0,25 % et d'iopamidol à 15 % basé sur le poids corporel : 0,2 mL/kg ou LE : 0,05 mL/cm (< 50 cm) ou 0,07 mL/cm (50 à < 70 cm). La propagation rostrale a été déterminée en comptant le nombre de vertèbres atteintes par l'iopamidol en utilisant la tomodensitométrie. Après l'anesthésie, les variables cardiopulmonaires, la fonction motrice et les réponses aux stimuli nociceptifs ont été évaluées. Les comparaisons ont été complétées avec des modèles linéaires mixtes et une analyse de variance à 2 facteurs (ANOVA) (P < 0,05). Le volume d'injectat (3,29 ± 0,74 versus 1,81 ± 0,21 mL; moyenne ± SD) et le nombre de vertèbres (22 ± 2 versus 19 ± 2 vertèbres) atteints par l'iopamidol étaient significativement plus élevés pour LE que pour BW. La réponse à la nociception, le temps de retour de la sensation de douleur, la fonction motrice et les variables cardiopulmonaires étaient similaires entre les groupes. En conclusion, le dosage basé sur LE a entraîné une plus grande propagation rostrale que lorsqu'il était basé sur BW chez les chiens de petite taille.(Traduit par Docteur Serge Messier).

Evaluation of an automatic approach device to the epidural space of Beagle dogs.

OBJECTIVE: To compare the epidural anesthesia device (EPIA), which facilitates an automatic approach to location of the epidural space, with the performance of clinicians using tactile sensation and differences in pressure when inserting an epidural needle into the epidural space of a dog. STUDY DESIGN: Prospective, crossover experiment. ANIMALS: A total of 14 Beagle dogs weighing 7.5 ± 2.4 kg (mean ± standard deviation). METHODS: Each dog was anesthetized three times at 2 week intervals for three anesthesiologists (two experienced, one novice) to perform 14 epidural injections (seven manual and EPIA device each). The sequence of methods was assigned randomly for each anesthesiologist. The dogs were anesthetized with medetomidine (10 µg kg-1), alfaxalone (2 mg kg-1) and isoflurane and positioned in sternal recumbency with the pelvic limbs extended cranially. Epidural puncture in the manual method was determined by pop sensation, hanging drop technique and reduced injection pressure, whereas using the device a sudden decrease in reaction force on the device was detected. A C-arm identified needle placement in the epidural space, and after administration of iohexol (0.3 mL), the needle length in the epidural space was defined as the mean value measured by three radiologists. Normality was tested using the Kolmogorov-Smirnov test, and significant differences between the two methods were analyzed using an independent sample t test. RESULTS: In both methods, the success rates of epidural insertion were the same at 95.2%. The length of the needle in the epidural space using the device and manual methods was 1.59 ± 0.50 and 1.68 ± 0.88 mm, respectively, with no significant difference (p = 0.718). CONCLUSIONS AND CLINICAL RELEVANCE: EPIA device was comparable to human tactile sense for an epidural needle insertion in Beagle dogs. Further research should be conducted for application of the device in clinical environments.

Evaluation of electrical nerve stimulation to confirm sacrococcygeal epidural needle placement in dogs.

OBJECTIVES: To evaluate the use of 0.7 mA as a fixed electrical current to indicate epidural needle placement and to confirm that 0.7 mA is greater than the upper limit of the minimal electrical threshold (MET) for sacrococcygeal epidural needle placement in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: A group of 20 client-owned dogs. METHODS: During general anesthesia and with standard monitoring, the presence of the patellar reflex was confirmed in all dogs. An insulated needle was inserted through the sacrococcygeal intervertebral junction, and absence of tail movement was confirmed when a fixed electrical current of 0.7 mA was applied. Then, the needle was further advanced toward the epidural space until the expected motor response was obtained - the nerve stimulation test (NST). The NST was considered positive when a motor response of the muscles of the tail was elicited but not the perineal muscles, whereas it was considered negative when no movement of the tail was evoked. The electrical current was turned to 0 mA and then increased by 0.01 mA increments until tail movement was evoked; this was recorded as the MET. In the positive NST cases, 0.05 mL cm-1 occipitococcygeal length of 2% lidocaine or 0.25-0.5% bupivacaine was administered. Epidural blockade was confirmed by the loss of patellar reflex. Descriptive statistics were used to present data. RESULTS: Sacrococcygeal epidural needle placement, corroborated by loss of the patellar reflex, was correctly predicted in 89.5% (95% confidence interval, 68.6-97.1%) of the cases. The MET was 0.22 mA (0.11-0.36). CONCLUSIONS AND CLINICAL RELEVANCE: A current of 0.7 mA is approximately twice the upper limit of the MET for epidural placement. Therefore, this study demonstrates, with a success rate of 89.5%, the adequacy of using 0.7 mA as the fixed electrical current to detect sacrococcygeal epidural needle placement in dogs.

Dural sac localization using myelography and its application to the lumbosacral epidural in dogs.

Background: The techniques described for the identification of the lumbosacral (LS) epidural space in dogs do not guarantee the needle position or an accidental subarachnoid puncture, especially in small size dogs. Aim: To determine the relationship between body weight and the location of the dural sac (DS) using myelography in dogs, and to determine the possibility of subarachnoid puncture during LS epidural based on the position of the DS. Methods: Four masked observers evaluated 70 myelographic studies of dogs, annotating the vertebrae where the DS ended, if it was localized before or after the LS space, and if accidental subarachnoid puncture during LS epidural injection was possible (yes/no). Body weight (kg) was categorized into: less than 10 kg, between 10 and 20 kg, and more than 20 kg and was also converted to body surface area (BSA) as a continuous variable. Results: The DS ended at the LS space or caudally in 50% of dogs. There was a statistically significant difference between the position of the DS and the dog's BSA (p = 0.001). The DS ended caudal to the LS space in 72.7% of dogs weighing <10 kg, in 25% of dogs between 10 and 20 kg and in 15% of dogs in the >20 kg category. The observers considered a possible subarachnoid puncture during LS epidural in 69.7% of patients <10 kg, 16.6% on those between 10 and 20 kg, and in 11.7% of the dogs >20 kg. Conclusion: The DS ended caudal to the LS space in almost 3/4 dogs in the <10 kg category, so accidental subarachnoid puncture during LS epidural is highly possible in this weight range.

The influence of the choice of preemptive analgesia on long-term postsurgical pain after tibial plateau leveling osteotomy in dogs.

OBJECTIVE: To evaluate the prevalence of chronic postsurgical pain (CPSP) after tibial plateau leveling osteotomy (TPLO) in dogs and to determine the influence of preemptive locoregional analgesia on CPSP. STUDY DESIGN: Retrospective study. ANIMALS: One hundred twenty client-owned dogs. METHODS: Medical records of dogs that underwent TPLO between 2012 and 2016 were reviewed for demographic information and type of preemptive analgesia. Owners were contacted to retrospectively assess the quality of life of their dogs by using the Helsinki Chronic Pain Index (HCPI) before and 6 months after surgery and at the time of questioning. An HCPI score > 12 was considered indicative of CPSP. Medical records were reviewed for demographic information and type of preemptive analgesia. A cumulative logit model was used to assess correlation of type of perioperative analgesia, HCPI, and demographic data. RESULTS: The HCPI score was consistent with CPSP in 41 of 101 dogs with long-term follow-up (2.9 ± 1.5 years after surgery). Chronic postsurgical pain was documented in 11 of 32 and 13 of 28 dogs that received a spinal or epidural injection, respectively, or in 28 of 80 and 25 of 67 dogs with sciatic-femoral block at 6 months or with long-term follow-up after TPLO, respectively (P > .05). A negative correlation was found between HCPI and both weight and age 6 months after surgery. Only weight remained negatively correlated 2.9 years after surgery. CONCLUSION: Forty-one percent of dogs that were evaluated exhibited HCPI values compatible with CPSP long-term after TPLO, regardless of the type of preemptive analgesia. Increased body weight was a negative prognostic factor for CPSP development. CLINICAL SIGNIFICANCE: Additional studies are required to evaluate CPSP development after TPLO.

Dispersão da lidocaína administrada por via epidural em cães posicionados em decúbito lateral ou esternal / [Dispersion of lidocaine epidurally administered to dogs positioned on lateral or external decubitus]

O objetivo do estudo foi verificar clinicamente a dispersão da lidocaína no espaço epidural de cães posicionados em diferentes decúbitos. Foram utilizados 16 cães, com peso médio de 17,5 quilogramas. Esses foram tranquilizados com acepromazina, anestesiados com propofol e alocados em dois grupos, conforme o decúbito de posicionamento: decúbito esternal (GE) e decúbito lateral direito (GLD). Ambos os grupos receberam lidocaína a 2%, no volume de 0,25mL/kg, e permaneceram no mesmo decúbito por 20 minutos. Em seguida, avaliou-se o bloqueio dos membros pélvicos e a extensão do bloqueio, a partir da sétima vértebra lombar, por meio de pinçamento interdigital e do panículo paravertebral. Foi, então, realizada cirurgia de orquiectomia. Após tal procedimento, avaliou-se o tempo total de bloqueio dos membros pélvicos. Todos os cães apresentaram bloqueio bilateral, sem diferenças quanto à extensão cranial entre os grupos, sendo a mediana de 7,5 (1-14) vértebras para GE e de 4 (1-14) para GLD. O tempo de bloqueio dos membros direito e esquerdo foi de 123 ± 26 e 130 ± 20 minutos, para GE, e de 120 ± 21 e 121 ± 20 minutos, para GLD, sem diferenças entre os grupos ou entre os membros. Conclui-se que o decúbito não interfere na distribuição da lidocaína administrada por via epidural.(AU)

The aim of this study was to clinically verify the dispersion of lidocaine in the epidural space of dogs placed in different positions. Sixteen dogs with an average weight of 17.5 kilograms were used. These were tranquilized with acepromazine, anesthetized with propofol and allocated to two groups: sternal decubitus (GE) and right lateral decubitus (GLD). Both groups received 2% of lidocaine in the volume of 0.25mL/kg and remained in the same position for 20 minutes. The blocking of the pelvic limbs and the extension of it from the seventh lumbar vertebra were evaluated by means of interdigital and paravertebral panniculus clamping. Orchiectomy surgery was then performed. Afterwards, the total blocking time of the pelvic limbs was evaluated. All dogs presented bilateral blocking, with no differences in cranial extension between groups, with a median of 7.5 (1-14) vertebrae for GE and 4 (1-14) for GLD. The blocking time of the right and left limbs were 123 ± 26 and 130 ± 20 minutes for GE, and 120 ± 21 and 121 ± 20 minutes for GLD with no difference between groups or between limbs. It is concluded that the decubitus does not interfere with the epidural lidocaine distribution.(AU)

Dexmedetomidine and Bupivacaine Association in Caudal Epidural Injection in Mares.

The objective of the study was to compare the effects of caudal epidural bupivacaine and dexmedetomidine (DEX) combination, with bupivacaine or DEX plain for perineal analgesia in mares. Six healthy saddle mares weighing 330-370 kg and aged 10-15 years were used in this study. Each mare was assigned to receive three treatments: 0.04 mg/kg 0.25% bupivacaine (BP), 2 µg/kg DEX (DX), or 0.02 mg/kg bupivacaine and 1 µg/kg DEX (BPDX). The order of treatments was randomized. All drugs were injected into the caudal epidural space (Co1-Co2) through a 16-G Tuohy epidural needle. After the epidural injections, heart rate, respiratory rate, arterial blood pressures (systolic, diastolic, and mean), and rectal temperature were measured at 5, 10, 15, 30, 60, 90, and 120 minutes, and after this time, every 60 minutes until the end of the experiments. A subjective score system was used to assess analgesia, behavioral and motor blockade at the same time points. The BPDX treatment produced analgesic action with twice the duration (200 minutes) of the BP treatment (97 minutes), but with an analgesic duration shorter than the DX treatment (240 minutes) in the regions of the tail, perineum, and upper hind limbs in mares. All treatments showed mild motor blockade. No behavioral changes were observed in any of the animals. There was hemodynamic stability without significant changes in respiratory rate for all treatments. Epidural analgesia using DEX alone or the combination of DEX and bupivacaine may be an option for painful obstetric and gynecological procedures in mares.

Single dose epidural methylprednisolone as a treatment and predictor of outcome following subsequent decompressive surgery in degenerative lumbosacral stenosis with foraminal stenosis.

Alternative treatments to surgery in canine degenerative lumbosacral stenosis (DLSS) remain limited and reliable predictors of outcome are lacking. The aims of this clinical trial were threefold: to assess the usefulness of single epidural steroid injection (ESI) in DLSS, to compare the outcomes of ESI and decompressive surgery, and evaluate ESI as a predictor of outcome following decompressive surgery. Dogs diagnosed with DLSS were prospectively recruited and administered an ESI. If clinical signs persisted or relapsed, decompressive surgery was recommended. Follow-up was obtained. Thirty-two dogs underwent ESI with 17 having subsequent surgery. Improvement after ESI was seen in 27/32 dogs (84.4%), with 17/22 (77.2%) relapsing within 6 months (n = 15/17 relapsing within 2 months). Five dogs failed to respond to ESI and another five (15.6%) presented a persistent post-ESI favourable response (mean follow-up time, 9.4 months). Post-surgical improvement occurred in all dogs. Outcome appeared more favourable following surgical decompression, with a trend towards reduced pain, increased mobility, and greater quality of life score. This study was unable to demonstrate that ESI could predict surgical outcome. ESI was confirmed as an effective treatment in most but not all cases, leading to transient alleviation of clinical signs for longer than previously reported. ESI provided a complete and apparently long-term sustained resolution of clinical signs in a subset of dogs. Despite this, there was indication that surgical decompression can lead to a more favourable outcome. Epidural steroid injection has a role in the management of DLSS dogs, particularly when surgery is not an option.

Identification of the sacrococcygeal epidural space using the nerve stimulation test or the running-drip method in dogs.

OBJECTIVE: To compare the nerve stimulation test (group NS) with the running-drip method (group RUN) for successful identification of the sacrococcygeal (SCo) epidural space prior to drug administration in dogs. ANIMALS: A total of 62 dogs. STUDY DESIGN: A randomized clinical study. METHODS: Dogs requiring an epidural anaesthetic as part of the multimodal anaesthetic plan were randomly allocated to one of the two study groups. In group NS, the epidural space was located using an insulated needle connected to a nerve stimulator; in group RUN, the epidural space was identified using a Tuohy needle connected to a fluid bag elevated 60 cm above the spine via an administration set. The success of the technique was assessed 5 minutes after epidural injection by the disappearance of the patella reflex. Data were checked for normality, nonparametric data was analysed using a Mann-Whitney U test and success rate was analysed using a Fisher's exact test. The significance level was set at p < 0.05, and the results are presented in absolute values, percentage (95% confident interval) and median (range). RESULTS: The success in identification of the epidural space did not differ between groups NS and RUN [87.1% (70.2%-96.4%) versus 90.3% (74.2%-98%); p = 1.000]. The time required for identification of the epidural space was shorter in group RUN [26 (15-53) seconds] than in group NS [40 (19-137) seconds] (p = 0.0225). No other differences were found in any studied variables. CONCLUSION: and clinical relevance In this study, both RUN and NS techniques were successful in identifying the epidural space at the SCo intervertebral space. RUN requires no specialised equipment, can be performed rapidly and offers an alternative to the NS for use in general veterinary practice.

Effect of phentolamine mesylate on regression of lidocaine-epinephrine epidural anaesthesia in sheep.

OBJECTIVE: To determine the impact of epidural phentolamine on the duration of anaesthesia following epidural injection of lidocaine-epinephrine. STUDY DESIGN: Blinded randomized experimental study. ANIMALS: A group of 12 adult ewes weighing 25.7 ± 2.3 kg and aged 8-9 months. METHODS: All sheep were administered epidural lidocaine (approximately 4 mg kg-1) and epinephrine (5 µg mL-1). Of these, six sheep were randomized into three epidural treatments, separated by 1 week, administered 30 minutes after lidocaine-epinephrine: SAL: normal saline, PHE1: phentolamine (1 mg) and PHE2: phentolamine (2 mg). The other six sheep were administered only epidural lidocaine-epinephrine: treatment LIDEP. Each injection was corrected to 5 mL using 0.9% saline. Noxious stimuli were pinpricks with a hypodermic needle and skin pinch with haemostatic forceps to determine the onset and duration of sensory and motor block. Heart rate, noninvasive mean arterial pressure (MAP), respiratory rate and rectal temperature were recorded. RESULTS: The onset times were not different among treatments. Duration of sensory block was significantly shorter in SAL (57.5 ± 6.2 minutes), PHE1 (60.7 ± 9.0 minutes) and PHE2 (62.0 ± 6.7 minutes) than in LIDEP (81.7 ± 13.4 minutes) (p < 0.05). Duration of motor blockade was significantly shorter in PHE1 (59.4 ± 5.4 minutes) and PHE2 (54.3 ± 4.0 minutes) than in SAL (84.8 ± 7.0 minutes) and LIDEP (91.5 ± 18.2 minutes) (p < 0.01). MAP in PHE2 was decreased at 10 minutes after administration of phentolamine (p < 0.05). CONCLUSION AND CLINICAL RELEVANCE: Epidural administration of 5 mL normal saline after epidural injection of lidocaine-epinephrine reduced the duration of sensory but not motor block in sheep. Epidural administration of phentolamine diluted to the final volume of 5 mL diminished both the duration of sensory and motor block in sheep administered epidural lidocaine-epinephrine.

Morphine plasmatic concentration in a pregnant mare and its foal after long term epidural administration.

BACKGROUND: Epidural administration of morphine has been shown to be an effective analgesic strategy in horses; however, the possible occurrence of side effects limits its usage. In order to decrease their frequency, it is important to target the minimal effective plasma concentration and avoid overdosing. As to date species-specific pharmacokinetics data are not available for epidural morphine, the dosing regimen is usually established on the basis of clinical reports and personal experience. In certain physiological conditions, like gestation, the outcome of an empirical dosing scheme can be unpredictable. The aim of this case report is to describe the pharmacological profile of morphine and its metabolites after prolonged epidural administration in a pregnant mare and her foal. CASE PRESENTATION: A 20 years old pregnant mare was presented to our hospital because of severe lameness, 2 months before delivery. Following an ineffective systemic pain treatment, an epidural catheter was inserted and morphine administered (initial dose 0.1 mg/kg every 8 h). Due to its efficacy in controlling pain, it was continued until end of gestation. Plasmatic concentration of morphine and its metabolites were assessed in the mare 6 weeks after starting the treatment, and in both the mare and foal during the first days after delivery. Plasmatic values similar to those previously reported in the literature following morphine short term administration through various routes and not accompanied by side effects were found in the mare, except during an excitatory period. Moreover, no evidence of dangerous drug accumulation or significant milk passage was noticed in the foal. Mild reduction of feces production with no signs of colic and two self-limiting episodes of excitement occurred during treatment in the mare. No side effects occurred during gestation and first phases of life in the foal. CONCLUSION: Prolonged epidural administration of morphine in a pregnant mare allowed good pain control in absence of clinically relevant side effects, in both the mare and her foal. Sudden increase in morphine plasmatic concentration can occur and side effects appear; careful treatment to the lowest effective dose and continuous monitoring of the clinical condition of the treated horse should be performed.

Effects of a single-bolus bupivacaine injection into the coccygeal spinal canal of rabbits.

It has been reported that drugs intended for epidural administration through the lumbosacral junction are accidentally administered into the subarachnoid space frequently in rabbits. Therefore, we evaluated the epidural single-bolus injection technique for the administration of bupivacaine into the coccygeal spinal canal of rabbits. After epidural distribution was confirmed by the injection of iohexol into the coccygeal spinal canal, 0.3 ml/kg 0.5% bupivacaine or 0.3 ml/kg normal saline was injected via the same needle. After the first attempt of iohexol injection, although the contrast was found in the epidural space in all rabbits, the additional contrast was also found in blood vessel in 3 rabbits and in muscular layer in 1 rabbit. Subarachnoid distribution was not observed in any of the rabbits. The time taken to regain normal anal reflex, movement of the hind limbs during walking, conscious proprioception of the hind limbs, and pain sensation of the tail and left hind limb, following coccygeal spinal canal injection, were significantly longer in the bupivacaine group than in the normal saline group. These findings indicated that coccygeal epidural injection of bupivacaine in rabbits may provide anesthesia for the hind limbs, perineum, and tail, but inadvertent vascular entry of the epidural drug may occur.

The use of ultrasound to assist epidural injection in obese dogs.

OBJECTIVE: To evaluate the use of ultrasound for identifying the site for needle puncture and to determine the depth to the epidural space in obese dogs. STUDY DESIGN: Prospective study in dogs undergoing elective orthopedic surgery. ANIMALS: A group of seven obese Labrador male dogs aged 6.93 ± 2.56 years and weighing 46.5 ± 4.1 kg (mean ± standard deviation). METHODS: The anesthetic protocol for these dogs included epidural anesthesia. With the dogs anesthetized and positioned in sternal recumbency with the pelvic limbs flexed forward, ultrasound imaging was used to locate the lumbosacral intervertebral space. Intersection of dorsal and transverse lines about the probe identified the point of needle insertion. A 17 gauge, 8.9 cm Tuohy needle was inserted perpendicularly through the skin and advanced to the lumbosacral intervertebral space. The number of puncture attempts was recorded and needle depth was compared with skin to ligamentum flavum distance. RESULTS: Epidural injection was performed in all dogs at the first attempt of needle insertion. The distance from skin to epidural space was 5.95 ± 0.62 cm measured by ultrasound and 5.89 ± 0.64 cm measured with the Tuohy needle. These measurements were not different (p = 0.26). A highly significant correlation coefficient of 0.966 between measurement techniques was obtained (p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound imaging identified the point of needle insertion for lumbosacral epidural injection in seven obese dogs. The results indicate that ultrasound can be used to locate the lumbosacral intervertebral space and identify an appropriate point for needle insertion to perform epidural injection.

Clinical effects of epidurally administered dexmedetomidine with or without lidocaine in sheep.

BACKGROUND: The aims of this study were evaluate cardiopulmonary, sedative and antinociceptive effects of dexmedetomidine-lidocaine combination via lumbosacral epidural injection in sheep. METHODS: Six Santa Inês breed sheep, 16±6 months old and weighing 42.2 ± 5.7 kg were used. Sheep were subjected to epidural anaesthesia with three treatments: L, lidocaine (1.2 mg/kg), D, dexmedetomidine (2.5 µg/kg) or DL, dexmedetomidine plus lidocaine (2.5 µg/kg + 1.2 mg/kg). Drugs were injected via pre-placed lumbosacral epidural catheters. Cardiopulmonary, arterial blood gases, electrolytes, degree of sedation and antinociceptive aspects were measured before drug administration (T0) and then at 15, 30, 60 and 120 min after drug injection (T15-T120) in all treatments and at T0 to T240 in DL. RESULTS: There were significantly increases in PaCO2 at times T60 and T120 in D, and at T30-T120 in DL, compared to baseline. The antinociceptive effects were observed up to 240 min in DL and 60 min in L, and were more intense in DL. Treatment D provided analgesia only in the perineal region, and only at T15. CONCLUSION: The combination of DEX with lidocaine produced similar cardiopulmonary changes compared with either drug alone, but with greater and more prolonged antinociceptive effects.