Investigation of a maxillary nerve block technique in guinea pigs (Cavia porcellus): A cadaveric study comparing two injectate volumes.

OBJECTIVE: To investigate and describe an extraoral approach to perform a maxillary nerve block in guinea pigs. STUDY DESIGN: Prospective, randomized, blinded, descriptive, cadaveric study. ANIMALS: A total of 14 adult guinea pig cadavers. METHODS: Two cadavers were used for anatomic dissection and determination of maxillary nerve block approach. A maxillary nerve block via infraorbital approach was then performed in 12 cadavers. A low volume (0.1 mL) or high volume (0.2 mL) of diluted methylene blue injectate was randomly assigned to the right or left side, with the other volume used for the contralateral side. The maxillary nerve was dissected after each injection by an investigator blinded to injectate volume. The region of dye distribution was identified, and the degree of staining assigned an accuracy score (0-2). Nerve coverage was considered adequate if ≥6 mm of circumferential staining was present. RESULTS: Accuracy evaluation indicated successful dye deposition in 10/12 [2 (0-2), median (range)] injections in the low volume group and 8/12 [2 (1-2)] injections in the high volume group. The majority (79.2%) of injections resulted in adequate nerve staining. There were no statistically significant differences between injectate volumes for accuracy (p = 0.64) or adequacy (p > 0.99) of staining. CONCLUSIONS: The infraorbital approach is a simple and practical method for maxillary nerve blockade in guinea pigs. An injectate volume of 0.1 mL results in adequate maxillary nerve coverage; however, additional studies are needed to assess the efficacy in clinical use.

Ultrasound-guided and 'blind' sciatic nerve injection techniques: Comparison in rat cadavers.

OBJECTIVE: To compare the success rate and extent of sciatic nerve staining with a bupivacaine-dye solution using two injection techniques: 'blind' or ultrasound-guided approach. STUDY DESIGN: Prospective, experimental, randomized, cadaveric study. ANIMALS: Adult female Wistar rat cadavers [n = 24, mass 352 g (323-374)]. METHODS: Each sciatic nerve was randomly allocated to one of two groups: 'blind' (group B) or ultrasound-guided approach (group US) to injection. Following injection of bupivacaine-dye solution (0.1 mL), gross anatomical dissection was performed to visualize nerve staining, categorizing it as either positive or negative. The length of nerve staining was then measured and visual inspection conducted to identify potential nerve damage. Fisher's exact test was used to compare positive or negative nerve staining, and the Wilcoxon signed rank test used to compare the length of nerve staining between groups. RESULTS: In group B, the bupivacaine-dye solution stained 16/24 sciatic nerves (67% success). In group US, staining was successfully observed in all 24 nerves (100% success, p < 0.004). The length of nerve staining [median (interquartile range)] was 2 (2-3) mm in group B and 5 (4-6) mm in group US (p < 0.001). One sciatic nerve in group B had injectate distributed over 16 mm, suggestive of an intraneural injection. No signs of laceration or nerve damage were visible under 6× magnification in either group. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrasound-guided approach for sciatic nerve injection demonstrated a higher success rate with superior injectate distribution when compared with the 'blind' approach. Ultrasound guidance is recommended over a 'blind' approach for sciatic nerve block in rats when possible.

In-Ovo injection of melittin into Alexandria chicken eggs: a way for early immune acceleration.

This study intended to assess the properties of in-ovo administration of Melittin (MLT) on hatchability, chick yield, hematology, immunological indices and relative organs weight of Alexandria chickens at hatch. A total of 600 eggs with an average weight of (45.12 g), were gathered and split into five groups: a non-injected group or negative control (NC), a saline injection group or positive control (PC), and three concentrations of MLT (5, 10 and 15 µg of MLT per egg, respectively). On day 18 of incubation, eggs from the injection groups were injected into the amniotic fluid from the large end with the in-ovo injection solutions (0.2 ml per egg). Results indicated that 10 µg MLT/egg positively affected the weight and yield of chicks. In addition, our findings indicated that the in-ovo administration with 10 or 15 µg MLT/egg was superior in most of the immunological indicators (spleen and bursa relative weights, immunoglobulins IgG and IgM, T cells and B cells). In conclusion, in order to improve the immune efficiency (early immune acceleration) of Alexandria chicks, which may contribute to offering a significant boost to their future performance, this study suggests injecting eggs with 5 or 10 µg MLT/egg.

Efficacy of in ovo delivered resveratrol (Trans 3, 4, 5-trihydroxystilbene) on growth, carcass weights, and blood metabolites of broiler chicks.

This research aimed to determine the impact of in ovo resveratrol (RV) (Trans.3, 4, 5-trihydroxystilbene) injection on performance, carcass weights, and blood constituents in Cobb chicks. A total of 300 fertile broiler breeder eggs were divided into five treatments as 60 eggs in each group, with 6 replicates (10 eggs each). The groups were as follows: (1) negative control (without additive), (2) positive control (saline injection), (3) 1.5 mg RV, 4) 3.0 mg RV, and (5) 4.5 mg in ovo RV injections. Significant changes were found in the amount of forage consumed per day, and the feed conversion ratio between treatment groups. RV injection significantly altered the parameters of the complete lipid profile, including total cholesterol, triglycerides, low-density lipoproteins, and very low-density lipoproteins, in plasma. RV injection significantly affected blood biochemical parameters, including total protein, albumin, and globulin in broiler chicken plasma. Liver and kidney functions were influenced by the injection of RV eggs into broiler chickens. The antioxidant enzymes also changed significantly after RV injection. Moreover, in egg injection from RV the immunogenicity (IgG and IgM) in broiler chickens were significantly altered. In conclusion, in ovo injection with RV significantly improved liver and kidney functions, antioxidant activity, and immune function in Cobb broilers.

Accuracy of drawing up liquid medications by veterinary anaesthetists and nurses.

OBJECTIVE: To evaluate the accuracy with which veterinary anaesthetists and nurses of different experience draw up small volumes of liquid. STUDY DESIGN: Prospective blinded randomized study. METHODS: A group of seven European College of Veterinary Anaesthesia and Analgesia (ECVAA) diplomates, six ECVAA residents and six anaesthesia nurses participated in the study. For each participant, five target volumes between 0.01 and 1.0 mL were randomly allocated. They were drawn up 20 times in random order using a 1 mL syringe attached to a 23 gauge needle. A total of 1900 measurements were analysed. An investigator filled the syringe and needle dead space with water for injection before each experiment. The change in mass of the syringe once filled to the target volume was used to calculate the actual volume of liquid drawn up. RESULTS: Large errors were made with measurements < 0.04 mL, so they were excluded from the statistical analysis. There was a significant effect of the target volume (p < 0.001) and of the order (p < 0.01). For each mL increase in the target volume, the absolute error decreased by 4% and from the first to the hundredth withdrawal each participant's absolute error decreased by 1%. The target volume was underestimated in 52.3% of measurements, 42% were overestimated and 5.7% were on target. None of the between-subject predictor variables approached significance. CONCLUSIONS AND CLINICAL RELEVANCE: Accuracy of veterinary anaesthetists and nurses in drawing up medications decreases as the target volume becomes smaller. Small veterinary patients receive small volumes of anaesthetic drugs with higher risks of overdosing compared with larger dogs. Years of experience and staff grade are not associated with greater accuracy. Large percentage errors may be seen with target volumes less than 0.04 mL. Dilutions are recommended for volumes > 0.19 mL in 1 mL syringe.

The investigation of the effects of vitamin A, vitamin E, and ß-carotene plus vitamin E on some fertility parameters in ewes.

This study was aimed at investigating the effects of vitamin A (VITA), vitamin E (VITE), and combined ß-carotene plus vitamin E (ßCAR+VITE) injections on some fertility parameters in ewes. Estrus synchronization was performed by treating the ewes with intravaginal FGA sponges impregnated with 30 mg of fluorogestone acetate. On the days of the insertion and withdrawal of the intravaginal sponges, groups VITA, VITE, and ßCAR+VITE were administered with 500 000 IU of vitamin A, 50 mg of vitamin E, and a combination of ß-carotene plus vitamin E, respectively. The ewes in the control group (C) were maintained for control purposes. Statistically significant differences were determined between groups VITA and ßCAR+VITE, groups VITE and ßCAR+VITE, and groups C and ßCAR+VITE, as well as groups VITE and C, groups VITA and C for the multiple birth rates. While significant differences were determined between groups VITA and C, groups VITE and C, and groups ßCAR+VITE and C for the lambing rates, it was ascertained that the ratio of newborn lambs to delivered ewes (litter size) significantly differed between groups VITA and ßCAR+VITE, groups VITA and C, groups VITE and ßCAR+VITE, groups VITE and C, and groups ßCAR+VITE and C. The highest MDA level and lowest GSH level were determined on day 20 after mating in the control group. In conclusion, it is suggested that both multiple birth rates and litter size can be increased by the combined administration of ß-carotene and vitamin E.

Efficacy and safety of suprachoroidal triamcinolone injection in horses with poorly responsive equine recurrent uveitis.

OBJECTIVE: Equine recurrent uveitis (ERU), a chronic, immune-mediated intraocular inflammatory disease, is a common cause of blindness in horses. The severity and recurrent nature of ERU makes it difficult to treat with current therapeutics leading to a poor visual prognosis. The suprachoroidal space (SCS), a potential space between the choroid and sclera surrounding the ocular posterior segment, offers a promising alternative site for drug application to the eye. Corticosteroid administration within this space is hypothesized to be safe and effective at controlling intraocular inflammation, especially in horses with poorly responsive ERU. ANIMAL STUDIED: Horses with active, poorly responsive ERU. PROCEDURE(S): A retrospective study was performed with 29 horses (36 total eyes) that received SCS injection of triamcinolone acetonide (TA) with ERU not well controlled with standard uveitis treatment. A standardized ocular inflammation score (OIS) was used to assess inflammation at the time of injection and at follow-ups. RESULTS: Standardized OIS revealed a significant decrease in ocular inflammation over time after SCS TA administration (p < .004). Adverse effects after injections occurred in <20% of the horses at follow-up, but some of these effects were attributed to chronic inflammation prior to effective treatment, long-term topical corticosteroid use, or complications from hospitalization rather than the SCS injections. Most horses (86.7%) in this study remained visual greater than 3 months after SCS injection. CONCLUSIONS: Based on these results, SCS TA injections appear to be a safe and possible effective treatment modality for managing poorly responsive ERU; further clinical study is warranted.

A pilot study comparing the pharmacokinetics of injectable cyanocobalamin and hydroxocobalamin associated with a trace mineral injection in cattle.

Injectable vitamin B12 (cobalamin) is traditionally used to prevent or treat vitamin B12 deficiencies in ruminants. Sheep and human studies have demonstrated the superiority of a single dose of hydroxocobalamin (OHB12) over cyanocobalamin (CNB12) in maintaining high levels of cobalamin in plasma and liver. However, limited data are available for cattle. The purpose of this study was to compare the pharmacokinetics of two forms of cobalamin-OHB12 and CNB12-as a single subcutaneous injection of 28 µg/kg BW at the same time of a trace mineral injection in six non-cobalt/B12 -deficient Holstein-Friesian steers. Plasma and liver samples were obtained to determine cobalamin concentration after treatment. Cyanocobalamin had lower retention in plasma and liver than OHB12 (p < .05). Cobalamin levels peaked in plasma by 8 h after treatment in both groups. However, OHB12 reached a higher peak compared to CNB12. Levels of cobalamin in plasma dropped closer to baseline levels 24 h after CNB12 treatment while OHB12 maintained higher concentrations. Hydroxocobalamin increased significantly hepatic concentration of cobalamin 28 days after treatment, while CNB12 did not increase liver levels relative to pre-treatment (p < .05). These results confirm that a single subcutaneous OHB12 injection increases the level of cobalamin in the blood in the first 24 hours, and this increase is maintained in the liver for at least 28 days.

Variation in syringes and needles dead space compared to the International Organization for Standardization standard 7886-1:2018.

OBJECTIVE: To measure the dead space of various syringe volumes and brands and a range of needles gauges commonly used in clinical practice, and to compare the results to the International Organization for Standardization (ISO) standard 7886-1:2018. STUDY DESIGN: Prospective observational study. METHODS: Syringes of five brands and seven volumes: 1, 2.5, 5, 10, 20, 30, and 60 mL, 10 of each, 10 1 mL low dead space syringes and 10 23, 21 and 18 gauge needles were analysed. Syringe dead space was estimated by weighing each syringe, drawing up and expelling its rated volume of water for injection and re-weighing the syringe. The difference in mass between the two measurements was calculated and converted to a volume based on the density of water. The dead space of the needles was estimated using a similar technique: each needle was attached to a 1 mL syringe of known dead space. A Mettler electronic balance was used for the measurements. Mean dead space was calculated for each syringe volume and needle gauge. Data were compared to the ISO standard. RESULTS: Syringe dead space for 1 and 2.5 mL was less than 0.07 mL. For 5 mL syringes four of five brands, and for 10 mL syringes one of five brands failed to comply with the ISO; the dead space was greater than 0.075 and 0.1 mL, respectively. For the 20, 30, 60 mL syringes the dead space was less than 0.2 mL. Needle dead space was 0.05 mL for 23 and 21 gauge, and 0.07 mL for 18 gauge, similar in order of magnitude to syringe dead space. CONCLUSIONS: The dead space of syringes differs between brands, and some do not meet the ISO standard. When calculating the amount of drug lost due to dead space, both that of the syringe and needle used should be considered.

Ultrasound-guided parasternal injection in dogs: a cadaver study.

OBJECTIVES: To describe the technique of performing an ultrasound-guided distal parasternal intercostal block and to determine the distribution of two volumes of methylene blue dye solution injected in canine cadavers. STUDY DESIGN: Prospective cadaver study. ANIMALS: A group of seven canine cadavers weighing 12-34 kg. METHODS: The space between the transversus thoracic and the internal intercostal muscles is a virtual cavity. Ultrasound-guided injections in the distal (parasternal) intercostal space were performed using dye solution at 0.05 mL kg-1 in each intercostal space from the second to seventh (LV, low volume, six injections per dog) in one hemithorax, and 0.1 mL kg-1 in the third, fifth and seventh intercostal spaces (HV, high volume, three injections in each dog) on the contralateral side. Anatomical dissection was carried out to describe dye spread characteristics and staining of intercostal nerves. RESULTS: The ultrasonographic landmarks for injection were identified in each cadaver. In the LV group the solution was found in every intercostal space (36/36), whereas the HV injection stained six intercostal spaces in two dogs, five in two, and in two dogs the solution was found in four and three spaces, respectively, demonstrating multisegmental distribution. Intrapleural staining was observed after two injections. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided injection of 0.05 mL kg-1 at the distal intercostal space resulted in staining of the intercostal nerve in all dogs when performed in every space and may be an appropriate alternative to previously reported techniques. A single injection of 0.1 mL kg-1 may anaesthetize more than one intercostal nerve, but not consistently. Clinical investigations are warranted to better characterize and to refine this locoregional technique.

The effects of maxillary nerve block, ethmoidal nerve block and their combination on cardiopulmonary responses to nasal stimulation in anesthetized Beagle dogs.

OBJECTIVE: To describe an approach for ethmoidal nerve block (EBLOCK) and to compare the effects of a maxillary nerve block (MBLOCK), EBLOCK and their combination (M-EBLOCK) on heart rate (HR), systolic (SAP), mean (MAP), diastolic (DAP) arterial pressures and respiratory rate (fR) during nasal stimulation in dogs. STUDY DESIGN: Prospective, blinded, randomized, crossover placebo-controlled study. ANIMALS: Beagle dogs (five cadavers, nine live dogs), with a median (interquartile range) weight of 10.5 (10.3-11.0) kg. METHODS: The accuracy of iohexol injections (each 1 mL) at the maxillary and ethmoidal foramina in cadavers was evaluated using computed tomography. Then, anesthetized dogs were administered four bilateral treatments separated by 1 week, saline or 2% lidocaine 1 mL per injection: injections of saline at the maxillary and ethmoidal foramina (Control), injections of lidocaine at the maxillary foramina and saline at the ethmoidal foramina (MBLOCK), injections of saline at the maxillary foramina and lidocaine at the ethmoidal foramina (EBLOCK) and injections of lidocaine at all foramina (M-EBLOCK). The ventral nasal meatus was bilaterally stimulated using cotton swabs, and HR, SAP, MAP, DAP and fR were continuously recorded. Values for each variable were compared before and after stimulation using Wilcoxon signed-rank test. Changes in variables among treatments were analyzed using Mann-Whitney U and Kruskal-Wallis tests (p ≤ 0.05). RESULTS: Computed tomography revealed iohexol distribution around the openings of the target foramina in all cadavers. In living dogs, HR, SAP, MAP, DAP and fR significantly increased after stimulation within each treatment (p < 0.03). Physiologic responses were significantly attenuated, but not absent, in the M-EBLOCK [HR (p = 0.019), SAP, MAP, DAP and fR (all p ≤ 0.001)] compared with those in the Control. CONCLUSIONS AND CLINICAL RELEVANCE: Concurrent injections of lidocaine at the maxillary and ethmoidal foramina attenuated HR, arterial pressure and fR responses to nasal stimulation in Beagle dogs.

Comparison of four peribulbar anaesthetic techniques: a preliminary study in equine cadavers.

OBJECTIVE: To compare the peribulbar injectate distribution and probability of regional anaesthesia of four peribulbar anaesthetic techniques in equine cadavers. STUDY DESIGN: Prospective experimental cadaver study. ANIMALS: A total of 12 isolated equine cadaver heads and 24 eyes. METHODS: The 24 orbits underwent one of four injection techniques (six orbits each) with a mixture (1:4) of contrast medium and saline (CM): 20 mL ventrolateral peribulbar injection (V-20), 20 mL dorsolateral peribulbar injection (D-20), combined ventrolateral and dorsolateral peribulbar injections 10 mL each (VD-20) or 20 mL each (VD-40). To evaluate and score CM distribution at the base of, within the extraocular muscle cone (EOMC), and around the optic nerve (before and after pressure application to the periorbital area), computed tomography was performed. To assess the probability of achieving locoregional anaesthesia, two criteria were applied and both scored as 'likely', 'possible' or 'unlikely'. To compare CM distribution scores between injection techniques, Kruskal-Wallis analysis of variance was used. Mann-Whitney U test was used for post hoc comparisons between groups when needed. A p value < 0.05 was considered significant. RESULTS: The CM distribution within the EOMC and around the optic nerve circumference was detected as 'possible' only after pressure application in seven out of 24 orbits (V-20, 3; D-20, 1; VD-40, 3). It was never considered 'likely' either before or after pressure application. The CM distribution at the EOMC base was considered 'likely' to provide regional anaesthesia in 50% (V-20), 0% (D-20), 33% (VD-20), 100% (VD-40) and in 66% (V-20), 16% (D-20), 50% (VD-20), 100% (VD-40) before and after applying pressure, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Complete regional anaesthesia seems more likely using the VD-40 technique, although the authors advise caution due to the risk of potential complications. Future studies are necessary to evaluate the efficacy of the technique in vivo.

Ultrasound detection of cosmic filler injection of lips in camel beauty pageants: first report in veterinary medicine.

This study was carried out in Saudi Arabia during the events of the 4th King Abdulaziz Camel Festival, Saudi Arabia. It was designed to describe the most frequent locations of injected cosmetic fillers in the head region as well as the ultrasound features of the injected material. Apparently healthy camels (Camelus dromedarius) (n = 11,626) were thoroughly examined for injection of cosmetic fillers in the head region. In parallel, 30 non-injected camels were used as controls. The lips of camels suspected of having been injected with fillers were subjected to high-resolution ultrasound examination. Of the 11,626 camels, 58 were found to have been injected with cosmetic fillers, 45 in the upper lip and 13 in both the upper and lower lip. None of the injected camels had a history of recent illness. In addition, in all the injected camels, no dermal lip lesions were seen by the naked eye. Swelling of the upper and/or lower lips was visually inspected and palpated by hand in 52 of the camels. Drooping and swinging of the injected lips were observed in all injected camels. Hardness was detected in the tip of the upper lips of 26 of the injected camels and multiple hard nodules were palpated in the injected lips of 44 camels. Swelling of the edges of the upper and lower lips was detected in 41 of the injected camels. Ultrasonographic features of the injected lips are described in detail. Blood samples were collected from both groups. In none of the injected camels did the hemato-biochemical profiles differ significantly than the control group. In conclusion, results clearly indicate the usefulness and convenience of ultrasound as a diagnostic tool to locate the presence of injected fillers and to help monitor the extension and complications of the deposits.

Sustained-release voriconazole-thermogel for subconjunctival injection in horses: ocular toxicity and in-vivo studies.

BACKGROUND: Keratomycosis is a relatively common, sight threatening condition in horses, where treatment is often prolonged and costly. Subconjunctival (SCo) injections offer less resistance to drug diffusion than the topical route, resulting in better penetration to the ocular anterior segment. Voriconazole, a second generation triazole antifungal, is effective against common fungal organisms causing keratomycosis. If combined with a thermogel biomaterial, voriconazole can be easily injected in the SCo space to provide sustained drug release. The purpose of this study was to evaluate the drug concentrations in the anterior segment and clinical effects after SCo injections of voriconazole-containing thermogel: poly (DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) in healthy equine eyes. RESULTS: Voriconazole aqueous humor (AH) and tear concentrations were compared between 6 horses, receiving 1% voriconazole applied topically (0.2 mL, q4h) (Vori-Top) or 1.7% voriconazole-thermogel (0.3 mL) injected SCo (Vori-Gel). For the Vori-Gel group, voriconazole concentrations were measured in AH and tears at day 2 and then weekly for 23 days, and at day 2 only for the Vori-Top group. Ocular inflammation was assessed weekly (Vori-Gel) using the modified Hackett-McDonald scoring system. Ocular tissue concentrations of voriconazole following SCo 1.7% voriconazole-thermogel (0.3 mL) injections were evaluated post euthanasia in 6 additional horses at 3 different time points. Three horses received bilateral injections at 2 h (n = 3, right eye (OD)) and 48 h (n = 3, left eye (OS)) prior to euthanasia, and 3 horses were injected unilaterally (OS), 7 days prior to euthanasia. Voriconazole-thermogel was easily injected and well tolerated in all cases, with no major adverse effects. On day 2, drug concentrations in tears were higher in the Vori-Top, but not statistically different from Vori-Gel groups. For the Vori-Gel group, voriconazole was non-quantifiable in the AH at any time point. Total voriconazole concentrations in the cornea were above 0.5 µg/g (the target minimum inhibitory concentration (MIC) for Aspergillus sp.) for up to 48 h; however, concentrations were below this MIC at 7 days post treatment. CONCLUSIONS: Voriconazole-thermogel was easily and safely administered to horses, and provided 48 h of sustained release of voriconazole into the cornea. This drug delivery system warrants further clinical evaluation.

Optimizing corneal riboflavin administration in ex vivo horse, dog, rabbit, and pig samples for use in corneal collagen cross-linking.

PURPOSE: Determine optimal iontophoresis times for riboflavin delivery to the corneal stroma across different species and compare these to corneal injection. METHODS: Ex vivo horse, dog, rabbit, and pig globes were treated with riboflavin administered with either iontophoresis for 2.5-20 minutes with or without corneal epithelium; or with purpose-designed precise corneal injection (PCI) application with intact epithelium. Immediately following riboflavin administration, samples were harvested, frozen, and sectioned. Riboflavin penetration was imaged using fluorescence microscopy. RESULTS: Horse samples processed with iontophoresis without epithelium for 2.5, 5, and 7.5 minutes, and processed with intact epithelium for 20 minutes, had mean percent stromal penetration (%SPmean ) of 63.4%, 93.8%, 100.0%, and 0.0% (respectively). Dog samples processed with iontophoresis without epithelium for 2.5 and 5 minutes, had %SPmean of 60.7% and 82.1% (respectively). Pig samples processed with iontophoresis for 5 minutes without and with epithelium had %SPmean of 63.3% and 35.1% (respectively). Rabbit samples processed with iontophoresis without epithelium for 2.5 and 5 minutes, had %SPmean of 81.8% and 100.0% (respectively). For all injected volumes, riboflavin was observed spanning throughout the corneal stroma, and lamellar separation was noted surrounding all sites of injection. CONCLUSIONS: Both iontophoresis and injection via PCI needles provide efficient and effective means of riboflavin administration in ex vivo horse, dog, rabbit, and pig corneas. Epithelial debridement is required for stromal delivery of riboflavin using iontophoresis in horses. Following epithelial removal, riboflavin penetrated through the horse corneal stroma faster than all other species tested.

Effect of intracameral epinephrine on heart rate, post-operative ocular hypertension, and long-term outcome following canine phacoemulsification.

PURPOSE: To determine the effect of intrsacameral epinephrine on heart rate, blood pressure, post-operative ocular hypertension, and complications following canine phacoemulsification. PROCEDURES: A prospective, double-blinded, controlled trial was carried out using 30 client-owned dogs undergoing phacoemulsification. Eyes were randomly assigned to a treatment group receiving intracameral (IC) epinephrine (n = 31) or balanced salt solution (n = 25) at the beginning of surgery. Heart rate, post-operative intraocular pressures, and outcomes were compared between treatment groups. RESULTS: No adverse reactions to IC epinephrine or saline were observed. Post-operative ocular hypertension developed at the 2 and/or 4 hours pressure reading in 35% and 46% in the epinephrine and saline groups, respectively (P = .5072). There were 9.7% and 23.1% eyes that developed complications in the IC epinephrine and saline groups, respectively (P = .2373). CONCLUSIONS: Intracameral epinephrine is safe to use, and non-significant decreases in post-operative ocular hypertension and long-term complications were observed.

Development of a lateral ultrasound-guided approach for the proximal radial, ulnar, median and musculocutaneous (RUMM) nerve block in cats.

OBJECTIVE: To describe a lateral ultrasound (US)-guided approach to the radial, ulnar, median and musculocutaneous (RUMM) nerves through a single proximal in-plane insertion in cats and to determine whether one or two injection points are required to successfully stain all the target nerves. STUDY DESIGN: Prospective study. ANIMALS: A total of eight client-owned healthy cats and 12 cat cadavers. METHODS: In live cats, the US anatomy of the brachium, the landmarks and the site for needle accesses were determined. Then, 12 thawed feline cadavers were used to assess the spread of dye solution and nerve staining following the US-guided proximal-lateral-humeral RUMM injection using one and two injection points. Each cadaver was injected with 0.15 mL kg-1 of a 0.25% new methylene blue solution in either a single injection aimed for the radial nerve of one limb (G1) or via two sites delivering 0.1 mL kg-1 and 0.05 mL kg-1 aimed for the radial and musculocutaneous nerves of the opposite limb, respectively (G2). Upon dissection, staining of the target nerves around their circumference for length of >1 cm was considered successful. RESULTS: Sonoanatomy was consistent with anatomy upon dissection and target nerves were identified in all cadavers. Staining was 100% successful for the radial, median and ulnar nerves in both groups, and 41.7% and 100% for the musculocutaneous nerve in G1 and G2, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: This novel lateral US-guided approach for the proximal RUMM nerve block allowed a good identification of the nerves and related structures, and it provided a consistent muscular structure through which the needle could be easily guided. An injection performed in two aliquots (within the caudal and cranial compartments of the neurovascular sheath) appeared to be necessary to successfully stain all the target nerves.

Injection techniques for auricular nerve blocks in the rabbit cadaver.

OBJECTIVE: To describe the landmarks for localization and to determine the methodology and volume of methylene blue dye to adequately stain the auricular nerves in rabbit cadavers. STUDY DESIGN: Prospective, randomized, cadaveric study. ANIMALS: A total of 26 rabbit cadavers (Dutch-Belted and New Zealand White breeds). METHODS: Part I: anatomical dissections were performed to identify the sensory auricular nerves and to establish the ideal injection approach and volume of dye required for nerve staining. Part II: a single injection technique using 0.1 mL kg-1 dye was evaluated for staining the greater auricular nerve and two techniques (perpendicular and angled needle approaches) using 0.075 mL kg-1 dye were evaluated for the auriculotemporal nerve. Dye spread was evaluated through cadaveric dissections and nerve staining graded using a 0-2 point scale. Injections were considered successful if the nerve was stained circumferentially. Cadavers were assessed for staining of the mandibular nerve owing to the close proximity to the auriculotemporal nerve. Fisher's exact test and mixed effects logistic regression model were used for statistical analysis. RESULTS: The greater auricular nerve was stained in 24/27 (88.9%) injections. The auriculotemporal nerve was stained in 7/12 injections (58.3%) with the perpendicular needle approach; staining success increased to 80% (12/15 injections) with the angled needle approach; however, this difference was not statistically significant (p = 0.228). Mandibular nerve staining occurred on seven auriculotemporal injections with no statistically significant difference in the incidence of nerve staining between techniques. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the auricular nerves in rabbit cadavers can be successfully located and stained using anatomic landmarks and the described injection techniques.

Evaluation of injectate distribution after ultrasound-guided peribulbar injections in canine cadavers.

OBJECTIVE: To describe a contrast medium distribution pattern after peribulbar injection in cadavers. STUDY DESIGN: A cadaveric study. ANIMALS: A group of eight male dogs and four canine cadaver heads. METHODS: In phase 1, ultrasound-guided peribulbar injections (1.0 mL dye) were performed in four orbits using a subzygomatic approach. After dissection, the procedure was considered successful if 1) no dye was found in the retrobulbar space, 2) the peribulbar compartment was stained and 3) the dye reached the orbital fissure. In phase 2, using 16 orbits, the same technique was used to inject 0.1 mL kg-1 contrast medium into (group A, n = 8) or outside (group B, n = 8) the peribulbar compartment. After freezing at -20°C, orbits were imaged using computed tomography, and the contrast medium distribution was analysed. RESULTS: In phase 1, the procedure was successful in all four eyes. In phase 2, two orbits (one in each group) were removed from the study: one was not injected and the other was injected twice. The contrast medium was found inside the peribulbar compartment in six of seven (85.7%) group A orbits and two of seven (28.6%) group B orbits. In all of these cases, distribution to the orbital fissure, rostral alar foramen, mandibular foramen and inside the skull was observed. The oval foramen was reached in three of seven (42.9%) group A orbits and one of seven (14.3%) group B orbits. In one/seven (14.3%) group A orbits and five/seven (71.4%) group B orbits, the contrast medium was found inside the masseter and temporal muscles, and no distribution towards the aforementioned structures was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided peribulbar injection of 0.1 mL kg-1 contrast medium in canine cadavers can lead to an extensive distribution of the injectate that reaches the orbital fissure, the rostral alar, oval, and mandibular foramina and can be found intra-cranially.

Mandibular nerve block in juvenile Nile crocodile: a cadaveric study.

OBJECTIVE: To develop a technique for performing the mandibular nerve block in Nile crocodiles. STUDY DESIGN: Experimental cadaveric study. ANIMALS: A total of 16 juvenile Nile crocodile heads. METHODS: To study the course of the mandibular nerve, one head was dissected. Computed tomography (CT) examination was performed in two heads to identify useful landmarks. Thereafter, a hypodermic needle was inserted through the external mandibular fenestra of 17 hemimandibles (13 heads), and a mixture of methylene blue and iohexol was injected. Injection volumes were 0.5 (n = 7) and 1.0 mL (n = 10) for hemimandibles < 15 and ≥ 15 cm long, respectively. Iohexol spread and nerve staining with methylene blue were assessed with CT and anatomical dissection, respectively. Data were analysed with one-sample t test or Mann-Whitney U test. Significance was set at p < 0.05. RESULTS: Both anatomical dissection and imaging confirmed the external mandibular fenestra as a useful anatomical landmark for needle insertion. The CT images acquired after needle positioning confirmed that its tip was located on the medial bony mandibular surface formed by the fusion of the angular and coronoid bones in 100% cases. In all the hemimandibles, the rostrocaudal spread of contrast was > 23 mm. The length of the stained mandibular nerve in the temporal region and of the stained medial branch of the mandibular nerve, as well as the dorsoventral and mediolateral spread of iohexol, was greater in group 1.0 than in group 0.5 (p < 0.001). The caudal spread of iohexol was greater in group 1.0 than in group 0.5 (p = 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: The technique developed in this study is feasible. Both injection volumes resulted in staining of the mandibular nerve. The spread of contrast in the anatomical region of interest may result in successful sensory block.