Comparison of three ultrasound guided approaches to the lumbar plexus in dogs: a cadaveric study

ObjectiveTo assess the accuracy of contrast material injection and the dispersion of injectate following ultrasound guided injections at the level of L6 and L7, in canine cadavers.Study designProspective, randomized, experimental study.AnimalsTwenty nine mixed breed canine cadavers (28.9 ± 6.0 kg).MethodsThree ultrasound-guided approaches to the lumbar plexus (LP) were compared: 1) a dorsal pre-iliac approach at the level of L6; 2) a lateral paravertebral approach at mid-L6; and 3) a lateral paravertebral approach at mid-L7. An isovolumic mixture of iodine-based contrast with new methylene blue (0.1 mL kg⁻¹) was injected bilaterally in the juxta-foraminal region along the L6 or L7 nerve root. Computed tomography was performed followed by segmentation and 3D reconstruction of the lumbar spine and contrast material volumes using dedicated software. Distances between contrast material and the fifth through seventh lumbar foraminae, and length of femoral (FN) and obturator (ON) nerve staining were measured and compared between approaches (p < 0.05).ResultsInjectate moved cranial and caudal to the site of injection, and dispersed into an ovoid shape between the quadratus lumborum, iliopsoas and psoas minor muscles. Injections at L7 resulted in significantly closer contrast proximity to the L6 and L7 foraminae (p < 0.001). Femoral nerve staining was similar for all approaches, ON staining was more consistent after L7 injections (p < 0.001).Conclusion and clinical relevanceAn ultrasound-guided lateral paravertebral approach to the LP proved very practical and accurate, with easy visualization of the plexus and associated nerves. To ensure that the ON is covered by injectate, an approach at the level of L7 is recommended. Further studies are necessary to determine if this correlates with clinically effective local anesthesia.     

Effect of benzodiazepines on the dose of alfaxalone needed for endotracheal intubation in healthy dogs

Objective

To evaluate the dose-sparing effect of midazolam or diazepam on the dose of alfaxalone required to achieve endotracheal intubation in premedicated dogs.

The time required to achieve endotracheal intubation in dogs: a comparison of veterinary students and qualified veterinary surgeons

ObjectiveTo determine whether final year veterinary students take longer to perform endotracheal intubation than qualified veterinary surgeons.Study designObservational cohort study.AnimalsA total of 38 healthy mesocephalic dogs undergoing general anaesthesia for a clinical purpose unrelated to this study.MethodsTime to successful endotracheal intubation, measured from termination of intravenous induction drug administration to confirmation of endotracheal intubation, was recorded for two groups: final year veterinary students (group S) and qualified veterinary surgeons (group V). Animal age, breed and anaesthetic induction agent were also recorded. Following normality testing the groups were compared for each variable using the Student’s t test or Mann–Whitney U test where appropriate. The level of significance was defined as p < 0.05. Timed data are presented as median and interquartile range.ResultsTime to successful intubation was 54.2 (31.3) seconds in group S and 11.7 (8.5) seconds in group V, the difference being significant (p < 0.001). There was also a significant difference between groups for animal age (p = 0.036) but not for breed (p = 0.573) or induction agent (p = 0.239).Conclusionsand clinical relevance Veterinary students take longer to achieve successful endotracheal intubation of anaesthetized healthy dogs compared with qualified veterinary surgeons. To mitigate any additional risk of dogs developing hypoxaemia, it is recommended that a 55 second time limit is set after which the supervisor intervenes and takes over the intubation procedure. Preoxygenation may be used as an additional mitigation strategy.     

Effect of intravenous lidocaine on heart rate, systolic arterial blood pressure and cough responses to endotracheal intubation in propofol-anaesthetized dogs

OBJECTIVE: To evaluate the effect of intravenous lidocaine on coughing and variations in heart rate (HR) and systolic arterial pressure (SAP) at endotracheal intubation in propofol-anaesthetized dogs. STUDY DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: Eighty dogs, ASA grades I/II. METHODS: Dogs were randomly assigned to one of two treatments, with dogs in the lidocaine group receiving 1 mg kg(-1) lidocaine intravenously and those in the saline group receiving 0.05 mL kg(-1) saline intravenously before induction of anaesthesia with up to 6.5 mg kg(-1) propofol intravenously. An electrocardiogram was recorded continuously. Heart rate was calculated and SAP (using Doppler ultrasonic flow detection) was recorded at the following time points: pre-treatment, following lidocaine or saline administration, before and after intubation. The occurrence, number and strength of coughs were recorded. Systolic arterial pressure and HR were compared using one-sample t-tests to examine whether SAP and HR changed with test drug administration or following intubation. The number of coughs was compared between groups using t-tests. A cross tabulation and chi-square or Fisher's exact test was used to compare proportions of dogs that coughed and intensity of coughing in each group. The level of significance was set at p < 0.05. RESULTS: Heart rate did not change in either group. Systolic arterial blood pressure increased following intubation in both the lidocaine (p = 0.003) and saline groups (p = 0.001). There was no difference in the increase in SAP or in the number or intensity of coughs at intubation between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous lidocaine had no effect on the occurrence or intensity of coughing or on changes in SAP at endotracheal intubation in dogs anaesthetized with propofol. The use of 1 mg kg(-1) lidocaine intravenously before intubation in dogs to attenuate cough and the pressor response was not supported.     

Relationship of the iridocorneal angle, as measured using ultrasound biomicroscopy, with post-operative increases in intraocular pressure post-phacoemulsification in dogs

Objective  To investigate the relationship of the iridocorneal angle as it appears on ultrasound biomicroscopy (UBM) to increases in IOP post-phacoemulsification in the canine eye.
Animals studied  47 eyes of 28 dogs of various age, sex, and breed.
Methods  The ciliary process and limbus were used as a reference points to measure the angle opening distance (AOD), which was set by multiplying 0.45 by the distance between the ciliary process and limbus (when measured from the ciliary process). Pressure measurements were taken at five set points: Before, immediately post-, one day post-, 1 week post-, and 1 month post-phacoemulsification.
Results  A weak relationship between the AOD and the IOP one day post-phacoemulsification (Intercept: 2.83, Slope: –1.24, P -value: 0.0155) was observed. No relationship immediately post-operative (Intercept: 3.45, Slope: –1.34, P -value: 0.0651), 1 week post-phacoemulsification (Intercept: 2.31, Slope: –0.01, P -value: 0.9829), 1 month post-phacoemulsification (Intercept: 1.85, Slope: –0.49, P -value: 0.1533) was observed. The pre-operative measurements made with UBM were: Distance from limbus to ciliary process (DLCP): (Minimum: 1.152, Maximum: 2.992, Mean: 1.91, SD: 0.468); AOD (Minimum: 0.104, Maximum: 0.764, Mean: 0.40, SD: 0.172).
Conclusions  The relationship between AOD as measured by UBM pre-operatively is weakly associated with IOP pressure elevations at day one post-phacoemulsification. Further study is required prospectively to establish the importance of this relationship. Initial measurements of the canine iridocorneal angle were created, suggesting a method to be used in the future to establish true canine normal measurements.     

A prospective,randomized, double-blind,placebo-controlled multisite,parallel-group field study in dogs with osteoarthritis conducted in the United States of America evaluating bedinvetmab,a canine anti-nerve growth factor monoclonal antibody

ObjectiveBedinvetmab, a fully canine anti-nerve growth factor monoclonal antibody, was evaluated in dogs for control of osteoarthritis-related pain in a study conducted to support registration in the USA.Study designRandomized, double-blind, placebo-controlled, multicenter, parallel-group study.AnimalsGeneral practice client-owned dogs with osteoarthritis (n = 272).MethodsDogs were block randomized 1:1 to placebo (saline, n = 137) or bedinvetmab (n = 135; 0.5–1.0 mg kg^–1) administered subcutaneously, once monthly. The primary end point, day 28 Canine Brief Pain Inventory (CBPI) treatment success (TS), required pain severity score (PSS; 0–10) decrease ≥1 and pain interference score (PIS; 0–10) decrease ≥ 2. CBPI TS rates [and number needed to treat (NNT)], change in scores [and standardized effect size (ES)], change in quality of life (QoL) and bedinvetmab half-life were calculated.ResultsSignificant (p < 0.05) improvement with bedinvetmab over placebo occurred (days 28, 42, 56, 84) for CBPI TS. Of cases evaluable for day 28 CBPI TS (placebo, n = 131; bedinvetmab, n = 128), success rates were 36.6% and 47.4%, respectively (p = 0.0410) (NNT, 9.3; PSS and PIS ES, 0.3). CBPI TS increased after the second dose in both groups, plateaued for bedinvetmab at day 42 and decreased for placebo beginning day 84. Day 84 NNT (4.3), PSS (0.4) and PIS (0.5) showed continued improvement with monthly dosing. After the first dose, mean (± standard deviation) bedinvetmab half-life was 19.1 (8.3) days. Adverse events were similar between groups and not considered treatment-related. There was a significant effect of bedinvetmab versus placebo on all CBPI components (PIS, PSS, QoL).Conclusions and clinical relevanceThese results corroborated those previously reported and provide further support of safety and effectiveness of bedinvetmab (0.5–1.0 mg kg^–1) administered subcutaneously at monthly intervals to dogs for control of osteoarthritis-related pain.     

A complication probability planning study to predict the safety of a new protocol for intracranial tumour radiotherapy in dogs

Technical advances make it possible to deliver radiation therapy for canine intracranial tumours in fewer fractions, under the assumption of equivalent tumour control. With the aim of estimating the late toxicity risk profile for various tumour sizes and locations, the present paper evaluates the normal tissue complication probability (NTCP) values for the intracranial organs at risk. By making isoeffect calculations, a new 10‐fraction radiation protocol was developed with the same tumour control probability (TCP) as a currently used 20‐fraction standard protocol, and complication risk profiles for brain, brainstem and optic chiasm were modelled using a representative population of 64 dogs with brain tumours. For >59% of cases, the new 10‐fraction protocol yielded an acceptable, low risk estimate of late toxicity (<10%). Our calculations suggest that it may be safe to treat small to intermediate‐sized tumours that are neither located near the optic chiasm nor at the brainstem with 10 daily fractions of 4.35 Gy.     

MRI features can help to confirm a diagnosis of progressive myelomalacia,but may not be accurate in dogs lacking characteristic clinical signs at the time of imaging

Progressive myelomalacia (PMM) is a fatal sequela of acute thoracolumbar intervertebral disc extrusion in dogs, with unpredictable onset in the days after the inciting injury. No single reliable diagnostic test is currently available. Magnetic resonance imaging (MRI) features such as T2-weighted spinal cord hyperintensity and loss of subarachnoid signal in a half-Fourier single-shot turbo spin echo (HASTE) sequence have been associated with PMM, but are sometimes present in other dogs with severe deficits. Magnetic resonance imaging findings in 22 dogs with a clinical or histopathologic diagnosis of PMM and 38 deep pain-negative paraplegic dogs were compared in a retrospective case-control study. Length of T2-weighted hyperintense spinal cord change and HASTE signal loss were significantly associated with clinically evident PMM (P = .0019 and P = .0085), however, there were no significant differences between groups when analysis was restricted to dogs not yet showing clinical signs of PMM. The PMM group also had significantly shorter compressive lesions than the control group (P = 0.026), suggesting a possible role of more severe focal pressure at the extrusion site. A segment of total loss of contrast enhancement in the venous sinuses and meninges, a feature not previously described, was more common in the PMM group and the difference approached significance (P = 0.054). Findings show that MRI features can support the diagnosis in dogs with clinical evidence of PMM, and absence of these features supports absence of PMM at time of imaging. However, their absence does not reliably differentiate dogs with imminent progressive myelomalacia from other dogs with severe deficits following intervertebral disc extrusion.     

Double-blind pilot study on the effects of ketoconazole on intradermal skin test and leukotriene C4 concentration in the skin of atopic dogs

Abstract The effects of ketoconazole on intradermal skin test results and on leukotriene C₄ (LTC₄) concentration in the skin of atopic dogs were evaluated in a pilot study. Twelve atopic dogs without a detectable Malassezia dermatitis were selected. All dogs had positive immedíate reaction to intradermal injection of house dust mite (HDM) at 25 PNU mL^-1. Six dogs received a control sugar tablet and six dogs received ketoconazole at 5 mg kg^-1 PO b.i.d. for 3 weeks. On days 0 and 21, intradermal injections of saline, lipopolysaccharide (LPS) and house dust mite (HDM) were performed and biopsies of the injection sites were taken at 90 min postinjection to measure the concentration of LTC₄ in the skin. Intradermal skin test results were not affected by ketoconazole therapy. Ketoconazole significantly decreased the concentration of LTC₄ that could be elicited by the intradermal injection of saline and LPS. Ketoconazole also decreased the HDM-induced LTC₄ but differences between the prevalues and postvalues were not statistically significant. The mean decrease of LTC₄ concentration in the ketoconazole group was 37% for the saline injection, 42% for the LPS injection and 26% for HDM injection. In the control group no significant changes in the LTC₄ concentrations were found over the 3-week time of the study. This pilot study showed that ketoconazole has anti-inflammatory properties and suggests that this drug may be effective in decreasing the skin concentrations of LTC₄ in atopic dogs. Résumé— Les effets de kétoconazole sur les résultats des tests intradermiques et la concentration en leucotriène C4 (LTC₄) dans la peau de chiens atopiques ont étéévalués dans une étude en double aveugle. Douze chiens atopiques sans dermite à Malassezia ont été selectionnés. Tous les chiens ont des tests intradermiques positifs aux acariens de la poussière de maison à 25 PNU mL^-1à 20 minutes. Six chiens ont reçu des comprimés de sucre, six autres ont reçu du kétoconazole à 5 mg kg^-1, 2 fois par jour par voie orale pendant 3 semaines. Aux jours 0 et 21, des injections intradermiques de liposaccharides (LPS), d'eau salée et d'aeariens de la poussière de maison sont réalisées et des biopsies des points d'injections sont effectuées 90 minutes après l'injection afin de mesurer la concentration en LTC₄ dans la peau. Les résultats des tests intradermiques ne sont pas modifies par la thérapeutique au kétoconazole. Par contre, le kétoconazole diminue significativement la concentration en LTC₄ induit par les injections intradermiques de LPS et d'eau salee. Le kétoconazole diminue également le LTC₄ induit par les acariens de la poussière de maison, mais il n'existe pas de différence significative entre les valeurs avant et après. La diminution moyenne de LTC₄ dans le groupe traité au kétoconazole est de 37% pour l'injection intradermique d'eau salée, de 42% pour l'injection intradermique de LPS et de 26% pour l'injection intradermique d'acariens de la poussière de maison. Dans le groupe de contrôle, aucune différence significative dans les concentrations en LTC₄ n'est observée durant les 3 semaines de l'étude. Cette étude démontre que le kétoconazole a des propriétés antiinflammatoires et suggèrent qu'il peut être efficace dans la diminution des concentrations en LTC₄ chez les chiens atopiques. [Marsella R, Kunkle, GA, Vaughn, DM, Macdonald, J. Double-blind pilot study in the effects of kétoconazole on intradermal skin test and leukotriene C₄ concentration in the skin of atopic dogs. (Etude en double aveugle sur les effets du kétoconazole sur les tests intradermiques et la concentration en leucotriène C₄ dans la peau de chiens atopiques.) Veterinary Dermatology 1997; 8 : 3–10.] Resumen Se evaluaron en un estudio piloto los efectos del ketoconazol sobre los resultados del test intradérmico cutáneo y sobre las concentraciones de leucotrieno C₄ (LTC₄) en la piel de perros atópicos. Se seleccionaron doce perros atópicos sin Dermatitis por Malassezia detectable. Todos los perros mostraban respuesta positiva inmedíata a la inyección del ácaro del polvo doméstico (HDM) a 25 PNU mL^-1. Seis perros recibieron una tableta control de azúcar y seis recibieron ketoconazol a dosis de 5 mg kg^-1 PO BID durante 3 semanas. En los días 0 y 21 se realizaron inyecciones intradérmicas de suero salino, lipopolisacárido (LPS) y ácaro del polvo doméstico, y se tomaron biopsias de las zonas inyectadas a los 90 minutos postinyección para cuantificar la concentración de LTC₄ en la piel. Los resultados de los tests intradérmicos no se afectaron por la terapia con ketoconazol. El ketoconazol disminuyó significativamente la concentración de LTC₄ que pudo haber provocado la inyección intradérmica de suero salino y LPS. El ketoconazol también disminuyó el LTC₄ inducido por el HDM pero las diferencias entre los valores previos y posteriores no fueron estadisticamente significativos. La disminución en la concentración medía de LTC₄ en el grupo de ketoconazol fue del 37% para la inyección de suero salino, 42% para la de LPS y 26% para la de HDM. En el grupo control no se encontraron alteraciones significativas en las concentraciones de LTC₄ durante las 3 semanas que duró el estudio. Este estudio piloto mostró que el ketoconazol posee propiedades antiinflamatorias y sugiere que este fármaco puede ser efectivo en disminuir las concentraciones cutáneas de LTC₄ en perros atópicos. [Marsella R, Kunkle, GA, Vaughn, DM, Macdonald, J. Double-blind pilot study in the effects of ketoconazole on intradermal skin test and leukotriene C₄ concentration in the skin of atopic dogs. (Estudio doble ciego sobre los efectos del ketoconazol en los tests intradérmicos cutaneos y en la concentración de leucotrieno C₄ en la piel de perros atópicos.) Veterinary Dermatology 1997; 8 : 3–10.] Zusammenfasung In einer Pilotstudie wurden die Wirkung von Ketoconazol auf Ergebnisse des intrakutanen Hauttests und der Leukotrien C₄ (LTC₄)-Konzentration in der Haut atopischer Hunde bewertet. Zwölf atopische Hunde ohne feststellbare Malassezia Dermatitis wurden ausgewählt. Alle Hunde hatten eine positive Sofortreaktion zu Hausstaubmilbenextrakt von 25 PNU mL^-1. Sechs Hunde erhielten eine Zuckertablette als Kontrolle und sechs Hunde erhielten Ketoconazol in einer Dosis von 5 mg kg^-1 oral zweimal täglich für drei Wochen. An den Tagen 0 und 21 wurden intrakutane Injektionen von physiologischer Kochsalzlösung, Lipopolysaccharid (LPS) und Hausstaubmilbenextrakt durchgeführt und 90 Minuten danach Biopsien an den Injektionsstellen entnommen, um die Konzentration von LTC₄ in der Haut zu messen. Ketoconazoltherapie hatte keinen Einfluss auf die Ergebnisse des Intrakutantests. Ketoconazol verminderte die LTC₄ Konzentration in den intrakutanen Injektionsstellen von physiologischer Kochsalzlösung und LPS. Die Konzentrationen des von Hausstaubmilbenextrakt-induzierten LTC₄ waren ebenfalls vermindert, die Unterschiede zwischen den Werten vor und nach der Injektion waren jedoch nicht statistisch significan. Die durchschnittliche Verminderung der LTC₄ Konzentration in der Ketoconazol-Gruppe betrug 37% für die Injektion mit Kochsalzlösung, 42% für die Injektion mit LPS und 26% für die Injektion mit Hausstaubmilbenextrakt. In der Kontrollgrupe wurden während der dreiwöchigen Studie keine signifikanten Veränderungen in der LTC₄ Konzentration festgestellt. Diese Pilotstudie zeigt die entzündungshemmende Wirkung von Ketoconazol und deutet darauf hin, daß dieses Medikament geeignet sein könnte, die Hautkonzentration von LTC₄ in atopischen Hunden zu verringern. [Marsella R, Kunkle, GA, Vaughn, DM, Macdonald, J. Double-blind pilot study in the effects of ketoconazole on intradermal skin test and leukotriene C₄ concentration in the skin of atopic dogs. (Doppelblind-Pilotstudie über die Wirkung von Ketoconazol auf den intrakutanen Hauttest und die Konzentration von Leukotrien C₄ in der Haut atopischer Hunde.) Veterinary Dermatology 1997; 8 : 3–10.]