Abstract: Retrobulbar anaesthesia (RBA) is relevant for ocular surgery in standing sedated horses. Objective: Gathering insights on experiences with RBA techniques. Methods: Cross-sectional survey. Methods: An online survey collected information on the respondents' professional background, indications, injection methods, use of ultrasound assistance, medication, and complications associated with RBA in horses. Results: Two-hundred and thirty-eight veterinarians from 25 countries contributed. 86.1% were members of veterinary specialty colleges. RBA indications were enucleation (97.8%), corneal surgery (29.5%), eyelid surgery, paracentesis of the vitreous and anterior chamber, cataract surgery and vitrectomy (<10.0% each). The dorsal approach was most commonly used (88.8%), followed by the 4-point (34.8%), lateral (8.9%), and modified Peterson blocks (2.2%). Ultrasound-assisted needle positioning was used by 16.1%. Most commonly administered drugs were mepivacaine (67.4%), lidocaine (56.3%), and bupivacaine (37.9%). Complications included lack of anaesthesia (40.6%), exophthalmos (33.5%), chemosis (32.1%), and retrobulbar haemorrhage (22.8%). The choice of injection method and reported complications were significantly influenced by participants' professional backgrounds: as horse caseload percentage increased, dorsal injection use decreased (p = 0.011, OR 0.981, 95% CI 0.967-0.996), injection-related complications increased (p < 0.001, OR 1.015, 95% CI 1.006-1.024), and postoperative complications decreased (p < 0.001, OR 0.983, 95% CI 0.976-0.991). As ophthalmic case percentage increased, dorsal injection use increased (p = 0.009, OR 1.022, 95% CI 1.006-1.039), 4-point injection method decreased (p = 0.044, OR 0.993, 95% CI: 0.986-1.000), injection-related complications decreased (p < 0.001, OR 0.985, 95% CI 0.978-0.993), and postoperative complications increased (p < 0.001, OR 1.019, 95% CI 1.012-1.027). Conclusions: Results may reflect selection and recall bias; complication prevalence was not assessed. Conclusions: Dorsal and 4-point blocks are the most used, varying by participants' professional background. RBA causes mostly mild complications; severe ones are rare. Unassigned: La anestesia retrobulbar (RBA), es relevante en las cirugías oculares en el caballos sedado de pie. Objective: Acumular información de las experiencias con técnicas de RBA. DISEÑO DEL ESTUDIO: Encuesta transversal. MÉTODOS: Una encuesta en línea recolecto información sobre la formación profesional de los entrevistados, las indicaciones, métodos de inyección, uso de asistencia con ultrasonido, drogas y complicaciones asociadas con RBA en caballos. Results: 238 veterinarios de 25 países contribuyeron. 86.1% pertenecían de un colegio veterinario de especialización. Las indicaciones para RBA eran enucleaciones (97.8%), cirugía corneal (29.5%), cirugía de parpado, paracentesis del vitreo y cámara anterior, cirugía de catarata y vitrectomía (<10.0% cada una). El abordaje dorsal fue el más comúnmente usado (88.8%), seguido por el de 4 puntos (34.8%), lateral (8.9%), y bloqueo de Peterson modificado (2.2%). Posicionamiento de la aguja asistido por ultrasonido fue usado por 16.1%. Los fármacos usados más comúnmente fueron mepivacaina (67.4%), lidocaina (56.3%), bupivacaina (37.9%). Las complicaciones incluyeron falta de anestesia (40.6%), exoftalmos (33.5%), quemosis (32.1%), y hemorragia retrobulbar (22.8%). La elección del método de inyección y las complicaciones fueron significativamente influenciadas por la formación profesional de los participantes: a medida que el porcentaje de casos equinos aumento, las inyecciones dorsales disminuyeron (p = 0.011, OR 0.981, 95% CI 0.967–0.996), las complicaciones relacionadas a las inyecciones aumentaron (p < 0.001, OR 1.015, 95% CI 1.006–1.024), y las complicaciones post operativas disminuyeron (p < 0.001, OR 0.983, 95% CI 0.976–0.991). A medida que el porcentaje de casos oftalmológicos aumento, el uso de inyección dorsal aumento (p = 0.009, OR 1.022, 95% CI 1.006–1.039), el método de inyección en 4 puntos disminuyo (p = 0.044, OR 0.993, 95% CI: 0.986–1.000), las complicaciones relacionada a inyecciones disminuyeron (p < 0.001, OR 0.985, 95% CI 0.978–0.993), y las complicaciones post operativas aumentaron (p < 0.001, OR 1.019, 95% CI 1.012–1.027). Unassigned: Los resultados pueden reflejar la selección y el sesgo de memoria: la prevalencia de las complicaciones no fue evaluada. Conclusions: Los bloqueos dorsal y en 4‐puntos fueron los más utilizados, dependiendo de la formación profesional de cada participante. RBA causa en su mayoría complicaciones leves: las severas son raras.
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Overview
This study surveyed veterinarians globally to understand their experiences and preferences with various retrobulbar anesthesia (RBA) techniques in horses undergoing ocular surgery.
The research identified commonly used RBA methods, medications, complications encountered, and how professional background influenced technique choice and complication rates.
Introduction to Retrobulbar Anaesthesia (RBA) in Horses
RBA is an important anesthetic technique used to provide ocular analgesia and akinesia in standing, sedated horses.
It is applied for various ocular surgeries such as enucleations, corneal surgeries, eyelid interventions, and cataract surgeries.
The study aimed to collect global practitioner insights to describe current practices, drugs used, complications, and procedural variations.
Study Design and Methods
The research was conducted as a cross-sectional survey delivered online to veterinary professionals worldwide.
Respondents provided information on:
Their professional background and specialization
Indications for using RBA
Preferred injection approaches and techniques
Use of ultrasound guidance
Types of anesthetic drugs administered
Complications observed from RBA procedures
238 veterinarians from 25 countries participated, with the majority (86.1%) being members of veterinary specialty colleges.
Findings: Indications and Techniques
Indications for RBA in horses primarily included:
Enucleation of the eye (97.8%)
Corneal surgery (29.5%)
Other procedures such as eyelid surgery, paracentesis, cataract surgery, and vitrectomy were less common (<10%)
The most common injection method was the dorsal approach (88.8%), followed by:
4-point injection technique (34.8%)
Lateral approach (8.9%)
Modified Peterson block (2.2%)
Ultrasound guidance for needle placement was used by only 16.1% of respondents.
Medications Used for RBA
The top anesthetic agents administered included:
Mepivacaine (67.4%)
Lidocaine (56.3%)
Bupivacaine (37.9%)
These drugs are local anesthetics differing in onset time and duration, selected based on case and clinician preference.
Retrobulbar hemorrhage (bleeding behind the eye) (22.8%)
The overall complications were mostly mild; severe complications were rare according to respondents.
Influence of Professional Background
Variation in injection methods and complication rates correlated with the veterinarians’ caseloads and specialization:
As the percentage of equine cases increased:
Use of the dorsal injection technique decreased.
Incidence of injection-related complications increased.
Postoperative complications decreased.
As the percentage of ophthalmic cases increased:
Use of the dorsal injection technique increased.
Use of the 4-point injection method decreased.
Injection-related complications decreased.
Postoperative complications increased.
These trends suggest that expertise and experience in eye-related cases influence technique choice and complication patterns.
Limitations and Study Considerations
The study relies on self-reported data from veterinarians and may be affected by selection bias and recall bias.
Prevalence rates of complications cannot be precisely determined because the survey did not assess total case numbers or all complications exhaustively.
Findings should be interpreted cautiously, recognizing these methodological constraints.
Overall Conclusions
Dorsal and 4-point retrobulbar blocks are the most commonly utilized anesthesia techniques in horses, with choice influenced by practitioner background and clinical caseload.
Most complications due to RBA are mild and manageable; severe adverse events are uncommon.
The study highlights the need for further research, possibly with prospective designs, to accurately quantify complication rates and compare efficacy of different RBA techniques.
Cite This Article
APA
Lieberth S, Thieme K, Dancker C, Merle R, Eule JC.
(2025).
Global survey on the utilisation and experiences with different retrobulbar anaesthesia techniques in horses.
Equine Vet J.
https://doi.org/10.1111/evj.70082
Unit for Ophthalmology, Centre for Veterinary Clinical Services, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Equine Clinic, Veterinary Hospital, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Thieme, Katharina
Unit for Ophthalmology, Centre for Veterinary Clinical Services, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Dancker, Christian
Valera Small Animal Clinic Berlin, Berlin, Germany.
Merle, Roswitha
Institute of Veterinary Epidemiology and Biostatistics, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Eule, Johanna Corinna
Unit for Ophthalmology, Centre for Veterinary Clinical Services, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
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