Topic:Anesthesia
Anesthesia in horses involves the administration of drugs to induce a temporary loss of sensation or consciousness, facilitating surgical procedures and other medical interventions. This complex process requires a deep understanding of equine physiology and pharmacology to ensure the safety and well-being of the animal. Anesthesia in horses can be challenging due to their size, temperament, and unique anatomical and physiological characteristics. Common anesthetic agents used in equine practice include inhalants like isoflurane and sevoflurane, as well as injectable drugs such as ketamine and xylazine. The management of anesthesia in horses also involves careful monitoring of vital signs and the use of supportive measures to prevent complications such as hypotension, hypoventilation, and post-anesthetic myopathy. This page compiles peer-reviewed research studies and scholarly articles that explore the techniques, advancements, and clinical outcomes associated with anesthesia in equine medicine.
Retrospective study of the changes in dynamic compliance and ventilation/perfusion mismatch following salbutamol inhalation in hypoxaemic mechanically ventilated anaesthetized horses. To study the changes in dynamic compliance (C), ventilation/perfusion (V˙/ Q˙) mismatch and haemodynamic variables in hypoxaemic anaesthetized horses whose PaO increased following salbutamol inhalation. Methods: Retrospective, clinical, cohort study. Methods: A group of 73 client-owned horses treated with salbutamol when PaO <100 mmHg (13.3 kPa) during anaesthesia. Methods: Horses were divided into two groups: responders (R), where PaO after salbutamol ≥1.2 PaO before treatment (i.e. ≥20% increase), and non-responders (NR), where PaO after salbutamol <1.2 PaO before treatment. Demographi...
Clinical and echocardiographic evaluations of sedative and cardiovascular effects of combination of xylazine-acepromazine versus xylazine-pregabalin in horses. The aim of this study was to compare the sedative and cardiovascular effects of the combination of xylazine-acepromazine versus xylazine-pregabalin - in horses. Four healthy crossbred horses were included in the study and assigned to two treatments. In treatment I (T1), the animals received xylazine hydrochloride (1.00 mg kg) in combination with acepromazine maleate (0.05 mg kg) intravenously. In treatment II (T2), the animals received intragastric administration of pregabalin (4.00 mg kg) followed by xylazine hydrochloride (1.00 mg kg) intravenously after 60 min. Head height above ground (HHA...
A Review of Equine Anesthetic Induction: Are all equine anesthetic inductions “crash” inductions? Horses are the most challenging of the common companion animals to anesthetize. Induction of anesthesia in the horse is complicated by the fact that it is accompanied by a transition from a standing position to recumbency. The purpose of this article is to review the literature on induction of anesthesia with a focus on the behavioral and physiologic/pharmacodynamic responses and the actions and interactions of the drugs administered to induce anesthesia in the healthy adult horse with the goal of increasing consistency and predictability.
Fasting horses perioperatively decreases manure production and increases time to manure output postoperatively: a controlled randomized trial. To compare 3 perioperative feeding regimens and their effect on anesthetic complications, manure output, and colic proportion in healthy horses. Methods: 45 horses presenting for elective orthopedic procedures were randomly assigned to 1 of 3 groups: not fasted (NF; continuous access to hay perioperatively), fasted muzzled (FM; 10-hour preoperative fast with slow refeeding postoperatively and muzzle placement), or fasted not muzzled (FNM; same as FM without muzzle placement). Anesthetic protocol was standardized. Outcomes compared between groups included anesthesia time, arterial oxygenation, ...
Piezoelectric device use in sinus osteotomy for equines is feasible but may extend time to accomplish frontonasal bone flap. Sinus osteotomy is currently performed in equine surgery with conventional surgical methods, such as trephines and oscillating bone saw, leading to subsequent trauma to the bone during cutting. Piezoelectric devices are now used in maxillofacial surgery in humans as a standard tool as it is less traumatic than the oscillating bone saw and shortens the healing period. The aim of this study was to show that the piezoelectric device can be used for equine sinus surgery, compare its use with the oscillating bone saw, and describe the outcome of cases involving osteotomy performed with a piezoelect...
Flow-controlled expiration ventilation using a piston ventilator: effects of expiration time and speed on respiratory and pulmonary mechanics with focus on hysteresis and compliance in healthy horses. To investigate the effects of FLow-controlled EXpiration (FLEX) ventilation expiration time and speed on respiratory and pulmonary mechanics in anesthetized horses in dorsal recumbency. Methods: 6 healthy adult research horses. Methods: In this randomized crossover experimental study, horses were anesthetized 3 times and were ventilated each time for 60 minutes using conventional volume-controlled ventilation (VCV), linear emptying of the lung over 50% of the expiratory time (FLEX50), or linear emptying of the lung over 100% of the expiratory time (FLEX100) in a randomized order. The primary o...
A novel approach to ear pain in the horse: A case report. During electrochemotherapy (ECT), a chemotherapeutic drug is injected into the tumor and then an electroporation is provided. In horses, ear manipulation may be very painful, and combining a loco-regional technique with sedation might be a good option to avoid anesthesia-related risks. A two-injection-point block of the internal and external pinna and acoustic meatus was described in horse cadavers, and it permitted complete stain of all three branches of the great auricular nerve (GAN), internal auricular nerve branch (IAB), lateral auricular branch (LAB), and caudal auricular nerve (CAN), su...
Operational Radiation Safety Considerations During Equine Superficial Radiation Treatment Using Portable X-Ray Devices. Veterinary personnel exposure due to scattered x rays, when present during superficial radiation treatment (SRT), was evaluated. Veterinary personnel presence is needed during SRT to minimize the degree of required aesthesia to horses. Animal treatment was simulated, and exposure rates determined for 50, 70, and 100 kV x rays using eight different SRT applicators. Exposure rates at the surface of a solid water phantom (SWP) phantom ranged from 3.9 mR h-1 to 396 mR h-1 for 50 kV, from 41 mR h-1 to 2,880 mR h-1 for 70 kV, and from 235 mR h-1 to 7,500 mR h-1, for 100 kV, respectively. A horse pha...
Risk assessment in equine anesthesia: a first evaluation of the usability, utility and predictivity of the two-part CHARIOT. An accurate risk score that can predict peri-anesthetic morbidity and mortality in equine patients could improve peri-operative management, outcome and client communication. Unassigned: Three hunded horses underwent pre-anesthetic risk assessment using the American Society of Anesthesiologists-Physical Status augmented with equine-specific diseases (ASA-PS-Equine), a multifactorial 10-part rubric risk scale (10-RS), and a combination of both, the Combined horse anesthetic risk identification and optimization tool (CHARIOT). Intra-and post-anesthetic complications, the recovery phase and mortal...
Sensory nerve conduction stimulus threshold measurements of the infraorbital nerve and its applicability as a diagnostic tool in horses with trigeminal-mediated headshaking. To determine whether sensory nerve conduction stimulus threshold measurements of the infraorbital nerve are able to differentiate horses with idiopathic trigeminal-mediated headshaking (i-TMHS) from healthy horses and from horses with secondary trigeminal-mediated headshaking (s-TMHS). In a prospective trial, headshaking horses were examined using a standardized diagnostic protocol, including advanced diagnostics such as computed tomography and 3-Tesla-magnetic resonance imaging (MRI), to differentiate s-TMHS from i-TMHS. Clinically healthy horses served as controls. Within this process, patie...
Dexmedetomidine preconditioning reduces ischaemia-reperfusion injury in equine model of large colon volvulus. Large colon volvulus is a cause of colic in horses with high morbidity and mortality when not promptly treated. More treatment options are needed to improve the outcome of these cases by protecting against the damage caused by ischaemia and reperfusion injury. Objective: To determine the effect of preconditioning with dexmedetomidine prior to induction of ischaemia-reperfusion (IR) injury in a large colon volvulus model in the horse. Methods: Randomised blinded in vivo experiments. Methods: Horses received either a dexmedetomidine (DEX) or saline (CON) constant rate infusion (CRI) immediately ...
Comparative efficacy of low-volume retrobulbar anesthesia using three commercial local anesthetics in adult horses. To compare the efficacy of low-volume (5-mL) locoregional retrobulbar anesthesia ("retrobulbar block") by use of 3 commercial local anesthetic formulations. Methods: 8 healthy adult mares. Methods: A block-randomized, masked, controlled design was used. A single ultrasound-guided retrobulbar block was performed with 2% lidocaine, 2% mepivacaine, or 0.5% bupivacaine (n = 5 eyes/group). Contralateral eyes served as untreated controls. End points performed at baseline and time intervals up to 24 hours postblock included the following: assessment of neurophthalmic reflexes/responses, intraocular p...
Comparison of Xylazine and Lidocaine Infusion versus Medetomidine Continuous Rate Infusion during General Anesthesia with Isoflurane in Horses Undergoing Emergency Laparotomy. (1) The main goals of general anesthesia include pain management and a safe anesthetic protocol for smooth recovery. In this retrospective study, we compared two anesthetic protocols for general anesthesia with isoflurane during emergency laparotomy: sedation with xylazine and the intraoperative infusion of lidocaine (X group) versus medetomidine as a preoperative sedation and intraoperative infusion (M group). (2) The medical records of horses who underwent emergency laparotomies between 2016 and 2023 were reviewed. According to the anesthetic protocol, patients were allocated to the X or M g...
Evaluation of Gastric pH and Gastrin Concentrations in Horses Subjected to General Inhalation Anesthesia in Dorsal Recumbency. The prevalence of gastric disorders in high-performance horses, especially gastric ulceration, ranges from 50 to 90%. These pathological conditions have negative impacts on athletic performance and health. This study was designed to evaluate changes in gastric pH during a 24 h period and to compare gastrin concentrations at different time points in horses undergoing general inhalation anesthesia and dorsal recumbency. Twenty-two mixed-breed mares weighing 400 ± 50 kg and aged 8 ± 2 years were used. Of these, eight were fasted for 8 h and submitted to 90 min of general inhalation anesthesia i...
Severe orbital hematoma with third eyelid swelling and prolapse following a blind maxillary nerve block in a horse. A 20-year-old quarter horse gelding was presented for routine dental examination. Periodontal disease and luxation of tooth 108 was diagnosed and oral extraction was planned. After an unsuccessful blind maxillary nerve block, it was elected to perform the procedure under total intravenous anesthesia. Following recovery, a focal superficial corneal ulcer, severe retrobulbar swelling, mild exophthalmos, and marked swelling and prolapse of the third eyelid (nictitating membrane) were observed. Clinical signs persisted beyond 48 h despite the use of systemic anti-inflammatories and topical ocular ...
A newly developed recovery-enhancing device improves recovery scores during emergence from general anesthesia in horses: a randomized trial. To compare the quality of recovery in horses emerging from general anesthesia with or without the assistance of a novel device (recovery-enhancing device [RED]) designed to minimize high-energy falls. Methods: 20 mixed-breed horses, between July 1, 2023, and January 24, 2024. Methods: A computer-controlled belay system designed to slow the acceleration of a horse during a fall was evaluated in this study. Horses were randomly assigned to 1 of 2 treatment groups: RED (belay, assisted) or FREE (unassisted). An inertia-measuring unit was fitted to all horses and data were live streamed and record...
A transmandibular lateral transsphenoidal navigated surgical approach to access a pituitary macroadenoma in a warmblood mare. A 16-year-old warmblood mare was referred with a progressive history of behavioral changes and left-sided blindness. Following neuroanatomical localization to the forebrain, magnetic resonance imaging of the head revealed a well-delineated, 4.5 cm in diameter, round pituitary mass causing marked compression of the midbrain and optic chiasm. Euthanasia was recommended but declined by the owners. Veterinary specialists and a human neurosurgeon collaboratively prepared for surgical case management. A novel navigated transmandibular lateral transsphenoidal approach was developed to access the re...
Treatment of lidocaine-refractory ventricular tachycardia using procainamide in an anesthetized horse. To highlight the use of procainamide as a potential alternative treatment modality in cases of ventricular tachycardia that are refractory to lidocaine and magnesium sulfate. Methods: 1 adult horse weighing 380 kg. Unassigned: A 25-year-old Arabian gelding presented with severe colic signs. Due to persistent pain, it was elected to carry out an exploratory laparotomy. During the procedure a diagnosis of severe, unstable ventricular tachycardia was made based on the ECG findings, with an initial heart rate of 195 beats per minute and severe hypotension. Results: Initial treatment consisted of d...
Investigation of integrated time nanosecond pulse irreversible electroporation against spontaneous equine melanoma. Integrated time nanosecond pulse irreversible electroporation (INSPIRE) is a novel tumor ablation modality that employs high voltage, alternating polarity waveforms to induce cell death in a well-defined volume while sparing the underlying tissue. This study aimed to demonstrate the in vivo efficacy of INSPIRE against spontaneous melanoma in standing, awake horses. Unassigned: A custom applicator and a pulse generation system were utilized in a pilot study to treat horses presenting with spontaneous melanoma. INSPIRE treatments were administered to 32 tumors across 6 horses and an additional 1...
One-stage surgical case management of a two-year-old Arabian horse affected by male-pseudo hermaphroditism. A two-year-old Arabian horse presented for abnormal external genitalia and dangerous stallion-like behavior was diagnosed with disorder of sexual development (DSD), also known as intersex/hermaphroditism. Standing 1-stage surgical procedure performed under sedation, and local anesthesia to concurrently eliminate stallion-like behavior, risk of neoplastic transformation of intraabdominal gonads, and to replace ambiguous external genital with a functional, and cosmetically more acceptable anatomy. Step-1) Laparoscopic abdominal exploration and gonadectomy; Step-2) Rudimentary penis resection and...
Standing hand-assisted laparoscopic ovariohysterectomy to treat chronic pyometra in a mare. To describe a standing hand-assisted laparoscopic ovariohysterectomy in a mare. Methods: A 15-year-old maiden Oldenburg mare. Unassigned: The mare was presented for evaluation of bucking under saddle and uncharacteristic aggressive behavior. Evaluation of a 24-hour video of the mare in a stall showed behavior consistent with caudal visceral abdominal discomfort. Reproductive evaluation revealed a pyometra secondary to complete transluminal cervical adhesions. The mare was initially managed medically with disruption of the adhesions and uterine lavage, but the adhesions reformed within 6 weeks ...
Dural and deep cervical musculature anesthetic blockade for atlantoaxial collection of cerebrospinal fluid in horses. The analysis of cerebrospinal fluid has diagnostic, prognostic, and therapeutic value in neurological illnesses in horses. There are different methods for obtaining cerebrospinal fluid, with the collection between the C1 and C2 vertebrae being a more recent methodology, which allows the procedure to be performed in standing patients, without the limitations of general anesthesia and with a low contamination of the sample with blood, presenting itself as a practical alternative. This study evaluated the efficacy and safety of a local dural blockade in healthy horses submitted to cerebrospinal f...
Lower airway ultrasonographic, endoscopic, and cytological changes in horses undergoing inhalation anesthesia with controlled ventilation for minor elective surgeries. Effects of general anesthesia with controlled ventilation on the respiratory system have had limited evaluation in horses. A prospective observational study was performed with eleven client-owned horses undergoing elective surgery. Physical examination, auscultation with a rebreathing bag, complete blood cell count, lung ultrasound imaging, tracheal endoscopy imaging and transendoscopic tracheal wash were conducted before and 24 hours after anesthesia. Lung ultrasound imaging was also repeated just after recovery. A significant increase in blood neutrophil count between pre- and post-anesthesi...
Transient Horner’s syndrome in horses following cervical plexus local anesthesia. To report the development of transient Horner's syndrome in horses following local anesthesia of the cervical plexus. Methods: A total of 37 horses. Methods: Observational retrospective short case series. Methods: Medical records of cases undergoing ultrasound-guided cervical plexus anesthesia for standing prosthetic laryngoplasty at a single referral institution were evaluated (2019-2020). Results: Five of 37 horses (14%) developed transient signs of Horner's syndrome postoperatively. Obvious clinical signs began 2 to 5 h following local anesthesia and persisted for two to 4 h. Profuse un...
Effect of isolation protocols and cryoprotectants on freezing of stallion epididymal spermatozoa. The recovery of spermatozoa from the cauda epididymis may be the only option to obtain genetic material from elite stallions that had undergone castration or sudden death due to colic or severe injury. Objective: To evaluate two different protocols for retrieval of stallion epididymal spermatozoa and to evaluate different cryoprotectants on the freezability of the epididymal spermatozoa. Methods: Six epididymides from three stallions were collected immediately after routine castration under general anesthesia. In the first experiment, each epididymis (of two testes) of the same stallion were p...
Standing gustatory papillae biopsy procedure for antemortem diagnosis of equine grass sickness. Diagnosing equine grass sickness (EGS) requires histopathological evidence of chromatolysis and/or neuronal loss in peripheral autonomic ganglia. Previous investigators performed postmortem biopsies of gustatory papillae located on the tongue and found chromatolytic subgemmal neurons in all 13 EGS horses. The present study aimed to design a standardized lingual biopsy sampling method through a transbuccal approach in healthy standing horses and assess the quality of the obtained samples, to allow antemortem diagnosis of EGS in clinical cases. Methods: 6 healthy horses. Methods: A transbuccal a...
Large animal ventilator-integrated volumetric capnography generates clinically acceptable values of physiologic dead space in anesthetized healthy adult horses. To evaluate the agreement between the Tafonius large animal ventilator-integrated volumetric capnography (vCap) software and the Respironics NICO noninvasive cardiac output monitor reference system. Methods: Data were collected from 56 healthy adult horses undergoing general anesthesia. Methods: Animals were placed under general anesthesia and connected to the Tafonius large animal ventilator circle system. A flow partitioning device with CO2 and flow sensors was utilized to couple the endotracheal tube to the NICO monitor. Tafonius CO2 and flow sensors are incorporated into the Y-piece of the...
Dose effect and duration of action of liposomal bupivacaine administered as a perineural analgesic in a reversible and adjustable frog-pressure model of equine lameness. To determine the dose effect of peri-neural liposomal bupivacaine (LB) in an induced forelimb lameness model. Methods: 12 clinically normal adult horses. Methods: A randomized cross-over design was performed with 1 limb receiving saline and the other LB: low dose (6), high dose (6). Lameness was induced in 1 forelimb using a frog-pressure model. In the lame limb, peri-neural injection of the palmar nerves at the proximal sesamoid bones was performed using saline, low dose LB (0.25 mg/kg) (LDLB), or high dose LB (0.5mg/kg) (HDLB) in random order with a 1-week washout period between treatments. ...
Sperm Quality Assessment in Stallions: How to Choose Relevant Assays to Answer Clinical Questions. Stallion sperm analysis is indicated for infertility diagnosis, pre-sale expertise, production of fresh or frozen doses, and frozen straw quality control. Various collection methods are described, and numerous assays can be performed on semen. Determining an approach for each of these cases is challenging. This review aims to discuss how to obtain relevant clinical results, answering stallion owners' concerns. Semen can be collected with an artificial vagina on a phantom or a mare, by electro-ejaculation under anesthesia, or after pharmacological induction. The collection method influences the...