Proximal RUMM block in dogs: preliminary results of cadaveric and clinical studies.

OBJECTIVE: To design and assess the perioperative analgesic efficacy of an ultrasound (US)-guided radial (R), ulnar (U), median (M) and musculocutaneous (Mc) nerve blocks, performed together in the axillary space by a single, in-plane approach. STUDY DESIGN: Anatomical research and prospective clinical study. ANIMALS: A group of three dog cadavers and 15 client-owned dogs undergoing orthopaedic thoracic limb surgery. METHODS: Phase 1: Anatomical dissection and US study of the axillary space were performed to design the US-guided proximal RUMM block. The technique was considered successful if a total volume of 0.15 mL kg-1 new methylene blue solution completely stained the four nerves in two cadavers for ≥2 cm. Phase 2: In 15 client-owned dogs undergoing orthopaedic thoracic limb surgery, the RUMM block designed in phase 1 was performed to provide analgesia using a total volume of 0.15 mL kg-1 of ropivacaine 0.5%. The block was considered effective if the intraoperative fentanyl requirement was <1.2 mcg kg-1 hour-1 and until the postoperative pain score was [short-form Glasgow Composite Measure Pain Scale (SF-GCMPS)] ≤5/20. RESULTS: Phase1: Detection of the four nerves was always feasible in a single US-window. The axillary artery and Mc nerve were used as landmarks. In-plane needling approach was feasible in both cadavers. All the nerves were completely stained for >2 cm. No intrathoracic dye spread was found. Phase 2: In 14/15 anaesthetized dogs, mean intraoperative fentanyl requirement was 0.25 ± 0.05 mcg kg-1 hour-1. Postoperatively, all dogs had SF-GCMPS ≤5/20 up to 8 hours. CONCLUSIONS AND CLINICAL RELEVANCE: The US-guided proximal RUMM block performed at the axillary level with a single, in-plane needling approach using 0.15 mL kg-1 of ropivacaine 0.5% minimized fentanyl requirement during thoracic limb surgery, contributing to postoperative analgesia up to 8 hours after execution of the peripheral nerve block.

Ultrasound-guided femoral and obturator nerves block in the psoas compartment in dogs: anatomical and randomized clinical study.

OBJECTIVE: To evaluate intraoperative and postoperative efficacy of ultrasound (US)-guided femoral (FN) and obturator (ON) nerves block, in the iliopsoas muscle compartment (IPM), using an in-plane technique. STUDY DESIGN: Anatomical research and randomized, prospective, 'blinded' clinical study. ANIMALS: Six dog cadavers and 20 client-owned dogs undergoing tibial plateau levelling osteotomy (TPLO) surgery. METHODS: In phase 1, anatomical dissections and US imaging of the IPM were performed to design an US-guided nerve block involving the FN and ON simultaneously. The technique was considered successful if new methylene blue solution injection (0.1 mL kg-1) stained FN-ON for ≥2 cm. In phase 2, the US-guided nerve block designed in phase 1, combined with US-guided sciatic nerve (ScN) block, was performed in 20 dogs undergoing TPLO surgery. Patients were assigned randomly to one of two treatment groups: ropivacaine 0.3% (R3, n=10) and ropivacaine 0.5% (R5, n=10) at a volume of 0.1 mL kg-1 for each nerve block. Intraoperative success rate (fentanyl requirement < 2.1 mcg kg-1 hour-1) and postoperative pain score [Short Form-Glasgow Composite Measure Pain Scale (SF-GCMPS) ≥ 5/20] were evaluated. RESULTS: In phase 1, the US image of FN-ON was detected between L6 and L7. In-plane needling technique produced a staining of >4 cm in six of six cases. No abdominal or epidural dye spread was found. In phase 2, median fentanyl infusion rates were 0.5 (0.0-0.9) µg kg-1 hour-1 for R3 and 0.6 (0.0-2.2) µg kg-1 hour-1 for R5. At 9 and 11 hours after the peripheral nerve blocks, an SF-GCMPS ≥ 5 was observed for R3 and R5, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The US-guided FN-ON block in the IPM, using an in-plane technique, combined with US-guided ScN block, provided sufficient analgesia to minimize the use of fentanyl during TPLO surgery. A longer postoperative analgesia was observed in group R5 compared with R3.

Stress-related biomarkers in dogs administered regional anaesthesia or fentanyl for analgesia during stifle surgery.

OBJECTIVES: To compare the effects of regional anaesthesia and opioid administration on adrenocortical and glycaemic responses, postoperative pain and recovery quality in dogs undergoing stifle surgery. STUDY DESIGN: Prospective, blinded clinical study. ANIMALS: Forty-five dogs anaesthetized for tibial tuberosity advancement or tibial plateau levelling osteotomy, and 15 healthy dogs undergoing non-invasive orthopaedic diagnostic procedures. METHODS: The baseline behaviour of each dog was classified on a descriptive scale before anaesthesia. Dogs were anaesthetized using a standard protocol. Those undergoing surgery were randomly assigned to one of three intraoperative analgesia protocols: 1) peripheral (femoral and sciatic) nerve block (bupivacaine 0.5%; 0.15 mL kg(-1) in each nerve; group PNB); 2) spinal anaesthesia (isobaric bupivacaine 0.5%; 0.05 mL kg(-1); group SPI); and 3) intravenous fentanyl variable rate infusion and postoperative methadone (0.2 mg kg(-1); group FEN). Blood samples were collected for measurement of cortisol and glucose concentrations on arrival (TAR), at induction (TIND), at tracheal extubation (TEXT), and 1 hour post-extubation (TPEX). After extubation, a researcher unaware of the dog's group assignment evaluated pain and recovery quality using the Glasgow Composite Measure Pain Scale (Short-Form) and a descriptive scale, respectively. RESULTS: Median recovery quality was significantly worse in group FEN (p < 0.0001) compared with all other groups. Postoperative pain scores were lower in group PNB compared with groups SPI and FEN. Cortisol and glucose concentrations increased significantly from TAR at TEXT and TPEX (p < 0.0001) in group FEN, and were unchanged from TAR in the other groups. CONCLUSIONS AND CLINICAL RELEVANCE: Analgesia with a peripheral nerve block or spinal anaesthesia prevented the glycaemic and cortisol responses to surgery, promoted better recovery quality, and decreased postoperative pain scores compared with FEN. In the present study, the regional anaesthesia techniques used were found to be excellent alternatives to fentanyl administration.

Effects of rocuronium bromide on globe position and respiratory function in isoflurane-anesthetized dogs: a comparison between three different dosages.

OBJECTIVE: To evaluate the effect on globe position and respiration of three dosages of intravenous rocuronium in isoflurane-anesthetized dogs. ANIMAL STUDIED: Thirty-two dogs anesthetized for ophthalmic procedures. PROCEDURES: The dogs were divided into four groups, each of eight animals (G1-G4). G1, G2, G3 received 0.075, 0.05, 0.03 mg/kg of IV rocuronium, respectively; G4 received 0.9% NaCl IV; all the treatments were administered when an end-tidal isoflurane of 1.1-1.2% was reached. Anesthesia was obtained with dexmedetomidine (2.5 mcg/kg IV), methadone (0.1 mg/kg IV), propofol (2 mg/kg IV), and isoflurane in oxygen. Neuromuscular function was assessed with acceleromyography by stimulation of the peroneal nerve using the train-of-four (ToF) and the ToF ratio (ToFR). Monitoring of cardiovascular and respiratory functions was performed. Changes in globe position were recorded. RESULTS: All three dosages of rocuronium produced centralization of the globe. Duration was 24.3 ± 4.2, 23.4 ± 3.6, and 8.7 ± 2.8 min, for G1, G2, and G3, respectively. The control group did not show globe centralization. No significant differences were found among the four groups in cardiovascular and respiratory parameters. Minute volume and ToFR were significantly lower in G1 compared with baseline values. CONCLUSIONS: All doses of rocuronium resulted in globe centralization. The higher dose provoked a transient respiratory depression and some degree of skeletal muscular blockade detectable with ToFR. No alterations in respiratory activity were present when 0.05 mg/kg was used. The 0.03 mg/kg dosage could be useful for very short ophthalmic procedures.

Peripheral nerve stimulation under ultrasonographic control to determine the needle-to-nerve relationship.

OBJECTIVE: To determine the needle-to-nerve distances during electrical nerve location in dogs at different currents and pulse duration using a peripheral nerve stimulator (PNS) under ultrasound control (US), and the minimal electrical thresholds (MET) necessary to obtain a motor response (MR) after achieving needle-to-nerve contact. STUDY DESIGN: Prospective in vivo experimental trial in a clinical setting ANIMALS: Thirty dogs, scheduled for locoregional anaesthesia of the sciatic nerve. METHODS: Needle-to-nerve distance was measured ultrasonographically after obtaining the MR of sciatic nerve with 2, 1 and 0.5 mA and pulse duration 0.1 ms (NS0.1). Thereafter the needle was placed in contact with the nerve and MET was determined. The procedure was repeated with 0.3 ms (NS0.3). Finally the needle was reintroduced to contact the sciatic nerve guided only by US, thus MET-US was determined. Data were analysed using Kruskal-Wallis or Mann-Whitney tests. RESULTS: Needle-to-nerve distances were greater when MR was obtained with 2 mA than with 1 and 0.5 mA at 0.1 and 0.3 ms. No significant differences were observed between the needle-to-nerve distances using 0.1 or 0.3 ms. The MET [median (range)] was 0.4 (0.18-1.3) mA in NS0.1, 0.32 (0.12-0.8) mA in NS0.3; while MET-US was 0.7 (0.32-1.5) mA. When the needle contacted the nerve, the MR achieved with currents below 0.3 mA was obtained in 17.2, 40 and 0% of cases using NS0.1, NS0.3 and US respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The electrical current necessary to obtain a MR decreased as the needle moved towards the nerve. However when the needle tip contacted the nerve, an MR with low current intensity could not be obtained. Thus the absence of motor response at currents below 0.3 mA cannot rule out needle-epineurium contact. When ultrasound is combined with PNS, it is more important to assess the correct needle position than searching for an MR at low currents.

Femoral nerve block: a novel psoas compartment lateral pre-iliac approach in dogs.

OBJECTIVE: To describe a new approach to block the femoral nerve and to evaluate the distribution of a dye injected into the psoas compartment using a new femoral nerve block approach; to assess its clinical application, when combined with a sciatic nerve block, for surgical anaesthesia/analgesia of the pelvic limb in dogs. STUDY DESIGN: Prospective anatomical, research and clinical study. ANIMALS: Two dog cadavers; two dogs that had to be euthanized for reasons unrelated to this study, and 15 dogs undergoing pelvic limb orthopaedic surgery. METHODS: Phase 1: anatomical dissections were performed to determine a simple method to approach the femoral nerve within the psoas compartment. Phase 2: 0.1 mL kg(-1) of a lidocaine-new methylene blue solution was injected bilaterally after successful electrolocation of the femoral nerve in two anaesthetized dogs. Colorant spread was evaluated through femoral nerve dissections after euthanasia. Phase 3: in 15 dogs undergoing pelvic limb orthopaedic surgery under light general anaesthesia with isoflurane, intra-operative analgesic effect (cardiovascular responses) and early post-operative pain score, of the novel femoral nerve block combined with a sciatic nerve block as the sole analgesic protocol, were evaluated. RESULTS: Phase 1: a needle inserted from the lateral aspect of the lumbar muscles, cranially to the iliac crest and with a 30-45° caudo-medial direction, reaches the femoral nerve in the caudal portion of the psoas compartment. Phase 2: Four femoral nerves were stained >2 cm. Phase 3: this novel lateral pre-iliac approach, combined with the sciatic nerve block, blunted the intra-operative cardiovascular response to surgical stimulation in 13 out of 15 anaesthetized dogs. In addition, rescue analgesia was not required in the early post-operative 2-hour period. CONCLUSION AND CLINICAL RELEVANCE: The lateral pre-iliac femoral nerve block technique may provide adequate intra- and early post-operative pain relief in dogs undergoing pelvic limb surgery.

Schirmer tear test type I readings and intraocular pressure values assessed by applanation tonometry (Tonopen® XL) in normal eyes of four European species of birds of prey.

OBJECTIVE: To determine normal values for Schirmer tear test I and intraocular pressure in four European species of birds of prey. ANIMALS STUDIED: Twenty birds from each of the following species: Eurasian Tawny owl (Strix aluco), Little owl (Athene noctua), Common buzzard (Buteo buteo), and European kestrel (Falco tinnunculus). PROCEDURES: Both eyes of all birds (80 eyes) underwent a complete ophthalmic examination, which included a Schirmer tear test type I (STT-I) performed with commercially available strips and the assessment of the intraocular pressure (IOP) by applanation tonometry, employing the Tonopen-XL(®) device. The animals, which had been taken to a rescue center, were examined for ocular lesions prior to their eventual release into the wild. STT-I readings and IOP values were expressed as means ± standard deviation. RESULTS: Schirmer tear test type I readings were as follows: Eurasian Tawny owls: 3.12 ± 1.92 mm/min; Little owls: 3.5 ± 1.96 mm/min; Common buzzards: 12.47 ± 2.66 mm/min; European kestrels: 6.20 ± 3.67 mm/min. IOP values were as follows: Eurasian Tawny owls: 11.21 ± 3.12 mmHg; Little owls: 9.83 ± 3.41 mmHg; Common buzzards: 17.2 ± 3.53 mmHg; European kestrels: 8.53 ± 1.59 mmHg. CONCLUSIONS: The results of this study give representative values for STT-I and IOP in four of the most common species of birds of prey in Europe.

Pharmacokinetics and pharmacodynamics of zolpidem after oral administration of a single dose in dogs.

OBJECTIVE: To evaluate the pharmacokinetics and pharmacodynamics of zolpidem after oral administration of a single dose (0.15 or 0.50 mg/kg) and assess any associated antianxiety and sedative effects in dogs. ANIMALS: 8 clinically normal sexually intact male dogs of various breeds. PROCEDURES: Dogs were assigned to 2 groups (4 dogs/group) and administered zolpidem orally once at a dose of 0.15 or 0.50 mg/kg in a crossover study; each dog received the other treatment once after an interval of 1 week. Blood samples were collected before and at intervals during the 24-hour period following dose administration. For each time point, plasma zolpidem concentration was evaluated via a validated method of high-performance liquid chromatography coupled with fluorescence detection, and pharmacodynamics were assessed via subjective assessments of sedation and level of agitation and selected clinical variables. RESULTS: The pharmacokinetic profile of zolpidem in dogs was dose dependent, and the plasma drug concentrations attained were lower than those for humans administered equivalent doses. The lower dose did not result in any clinical or adverse effects, but the higher dose generated paradoxical CNS stimulation of approximately 1 hour's duration and a subsequent short phase of mild sedation. This sedation phase was not considered to be of clinical relevance. The desired clinical effects were not evident at plasma zolpidem concentrations ≤ 30 ng/mL, and the minimal plasma concentration that induced adverse effects was 60 ng/mL. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that zolpidem is not a suitable drug for inducing sedation in dogs.

Safety and efficacy of bilateral topical application of rocuronium bromide for mydriasis in European kestrels (Falco tinnunculus).

The avian iris is mainly composed of striated muscle fibers, and the topical parasympatholytic drugs used in mammals to induce pupil dilation are ineffective in birds. The achievement of mydriasis in conscious birds is only possible by using neuromuscular blocking agents such as curariform drugs. To determine the efficacy of the neuromuscular blocking agent rocuronium bromide as a mydriatic agent in European kestrels (Falco tinnunculus) and to assess possible adverse effects due to its use, 10 kestrels received a single topical instillation with a pipette of 0.12 mg of rocuronium in each eye (total dose, 0.24 mg/bird). Pupil diameter was measured with a pupillary gauge, and pupillary light reflex was assessed by using a standard light source from time zero (Tbase) to 250 minutes after application (T250). Baseline pupil size (Tbase) was 3.30 (0.71) mm in both eyes. Maximal mydriasis was achieved at T90 minutes with a mean (SD) pupillary diameter of 6.30 (0.42) mm and 6.35 (0.41) mm in the right eye and left eye, respectively. At the dose used, rocuronium bromide induced a consistent bilateral simultaneous mydriasis without noticeable adverse effects, and it can be considered a reliable and safe topical mydriatic agent in kestrels.

Evaluation of the endotracheal tube cuff pressure resulting from four different methods of inflation in dogs.

OBJECTIVE: To evaluate the endotracheal tube cuff pressure achieved by four different inflation methods. STUDY DESIGN: Prospective clinical study. ANIMALS: Eighty client owned dogs. METHODS: After anaesthesia induction, endotracheal intubation was performed using plastic or silicone tubes. A clinician unaware of tube type inflated the cuff by simple digital palpation (method A), thereafter the cuff was deflated and inflated again by a second clinician who tried to reproduce a previously learned cuff pressure of between 19 and 24 mmHg (method B). During method C the cuff was inflated to the minimum occlusive volume at an airway pressure of 20 cm H(2) O, and in method D the cuff was incrementally deflated until an audible air leak could be heard from the oral cavity at an airway pressure of 25 cm H(2) O. For all the methods, an operator recorded the actual cuff pressure obtained using a manometer. Heart rate, respiratory rate and mean arterial pressure were monitored throughout the procedure. RESULTS: The mean inflation pressure for plastic tubes was 56 ± 28 mmHg for method A, 20 ± 9 mmHg for method B, 35 ± 32 mmHg for method C and 46 ± 39 mmHg for method D. Pressures using silicone tubes were significantly higher than for plastic tubes, the mean registered pressures being 79 ± 39, 33 ± 16, 77 ± 50 and 92 ± 56 mmHg for methods A, B, C and D. CONCLUSIONS AND CLINICAL RELEVANCE: None of the methods evaluated in this study can be considered effective for inflating the endotracheal tube cuff to within the optimal range when using silicone tubes. Direct measurement of the cuff pressure with a manometer is therefore recommended.

Anatomical and radiological study of the thoracic paravertebral space in dogs: iohexol distribution pattern and use of the nerve stimulator.

OBJECTIVE: To describe the landmarks and methodology to approach the thoracic paravertebral space in dogs; to evaluate if intercostal muscular response could be evoked by a nerve-stimulator; to radiographically assess the distribution pattern of a radio-opaque contrast medium after thoracic paravertebral injections. STUDY DESIGN: Randomized, controlled, experimental trial. ANIMALS: Two mongrel dog cadavers (anatomical study) and 24 mongrel dogs (experimental study). METHODS: For the anatomic study 0.2 mL kg(-1) of new methylene blue (NMB) was injected at the 5th thoracic paravertebral space; for the experimental study dogs were divided into three groups and received 1 (T(5)), 2 (T(4) and T(6)) or 4 (T(4), T(5), T(6) and T(7)) paravertebral injections of iohexol. The paravertebral approach was performed with insulated needles using landmarks and a blind technique. When the needle tip reached the respective thoracic paravertebral space, the nerve-stimulator was switched-on and the presence/absence of intercostal muscular twitch was registered, thus a total volume of 0.2 mL kg(-1) of iohexol, divided into equal parts for each injection point, was administered. Radiological studies were performed with two orthogonal projections at different times. Positive injection was confirmed when the paravertebral space was occupied by iohexol in both projections. RESULTS: NMB was distributed in the T(5) paraverterbal space. In the experimental study, when the needle tip reached the respective paravertebral space, intercostal twitching was obtained in 80% of the total injections with a stimulating current of 0.5 mA. The incidence of positive cases when the intercostal twitch was obtained with 0.5 mA was 83.3%. The main distribution pattern observed was cloud like without longitudinal diffusion. CONCLUSION AND CLINICAL RELEVANCE: Intercostal muscular responses obtained with a stimulating current of 0.5 mA could be useful to locate thoracic spinal nerves in dogs and in our study the injected solution was confined to one thoracic paravertebral space.

Combined paravertebral plexus block and parasacral sciatic block in healthy dogs.

OBJECTIVE: To evaluate the effectiveness of paravertebral lumbar plexus block combined with parasacral sciatic block to anesthetize one hind limb in awake dogs. STUDY DESIGN: Randomized, controlled, blinded experimental study. ANIMALS: Eight healthy mongrel dogs weighing 12.4 ± 4.5 kg and aged 7 ± 2.33 years. METHODS: After sedation with medetomidine, dogs received B1: bupivacaine 0.25%, 0.2 mL kg(-1), B2: bupivacaine 0.5%, 0.2 mL kg(-1) , B3: bupivacaine 0.25% 0.4 mL kg(-1), P1: NaCl 0.2 mL kg(-1), P2: NaCl 0.4 mL kg(-1) . The lumbosacral plexus was blocked through a paravertebral block of the fourth, fifth and sixth lumbar nerves combined with a parasacral block. The relevant nerves were located using a nerve stimulator and injections of each treatment were administered. Degree and durations of sensory blockade were determined through the response to a Halsted clamp pressure on the skin innervated by the saphenous/femoral and lateral cutaneous femoral nerves (lumbar dermatomes) and by the peroneal and tibial nerves. The degree and duration of motor blockade was assessed evaluating the ability to walk normally and proprioception. RESULTS: P1 and P2 treatments did not show any grade of sensory or motor blockade. The B2 treatment produced a higher degree of sensory blockade compared to B1 and B3 for both lumbar and sciatic dermatomes. There was no significant difference in the degree of sensory blockade comparing B1 to B3. The B2 treatment had greater motor blockade compared to B1 and B3. The duration of sensory and motor blockade was longer in B2 compared to B1 and B3. CONCLUSION AND CLINICAL RELEVANCE: When the nerve stimulator is used to perform the lumbosacral plexus block, the concentration of the bupivacaine has a more important role than the volume to produce a more solid and longer block.

Continuous positive airway pressure administered via face mask in tranquilized dogs.

OBJECTIVE: To evaluate the tolerance of a continuous positive airway pressure (CPAP) mask in tranquilized dogs and compare PaO2 in arterial blood in dogs receiving oxygen with a regular face mask or CPAP mask set to maintain a pressure of 2.5 or 5 cm H2O. DESIGN: Prospective, randomized clinical study. SETTING: University teaching hospital. ANIMALS: Sixteen client-owned dogs without evidence of cardiopulmonary disease were studied. INTERVENTIONS: Eight animals were randomly assigned to each of 2 treatment groups: group A received 2.5 cm H2O CPAP and group B received 5 cm H2O CPAP after first receiving oxygen (5 L/min) by a regular face mask. Animals were tranquilized with acepromazine 0.05 mg/kg, i.v. and morphine 0.2 mg/kg, i.m.. An arterial catheter was then placed to facilitate blood sampling for pHa, PaO2, and PaCO2 determinations before and after treatments. Direct mean arterial pressure, heart rate, respiratory rate, and temperature were also recorded after each treatment. MEASUREMENTS AND MAIN RESULTS: CPAP administration was well tolerated by all animals. The mean arterial pressure, heart rate, respiratory rate, temperature, PaCO2, and pHa, did not differ at any time point between groups. Differences were seen in oxygenation; in group A, PaO2 significantly increased from a mean of 288.3 ± 47.5 mm Hg with a standard mask to a mean of 390.3 ± 65.5 mm Hg with the CPAP mask and in group B, PaO2 increased similarly from 325.0 ± 70.5 to 425.2 ± 63.4 mm Hg (P<0.05); no differences were detected between the 2 CPAP treatments. CONCLUSIONS: In healthy tranquilized dogs noninvasive CPAP is well tolerated and increases PaO2 above values obtained when using a regular face mask.

Bilateral mydriasis in common buzzards (Buteo buteo) and little owls (Athene noctua) induced by concurrent topical administration of rocuronium bromide.

OBJECTIVE: To evaluate the achievement of a bilateral mydriasis in raptors induced by a concurrent topical application of rocuronium bromide and to assess any side effects that might result from its use. Animals studied Ten healthy adult common buzzards (Buteo buteo) and 10 healthy adult little owls (Athene noctua). PROCEDURES: Common buzzards (Group 1) received a single dose of 0.40 mg of rocuronium bromide in each eye (total dose 0.80 mg/bird), whereas the little owls (Group 2) received a single dose of 0.20 mg in each eye (total dose 0.40 mg/bird). The drug was topically instilled in all the birds of both groups. The pupil diameter was measured with a pupillary gauge and the assessment of the pupillary light reflexes was performed using a standard light source. RESULTS: Maximal pupillary diameter was 8.10 ± 0.56 mm in the right eye and 8.05 ± 0.59 mm in the left eye for Group 1 and 10.0 ± 0.75 mm in both eyes for Group 2. No statistical differences were evidenced between the achieved pupillary diameters of both eyes in each group. The maximal pupillary diameter was achieved at T110 min and T40 min for Groups 1 and 2, respectively. The drug did not cause noticeable adverse effects in the examined birds. CONCLUSIONS: A single concurrent topical administration of rocuronium bromide to the eyes of the examined birds induced a complete bilateral mydriasis in both eyes without causing any adverse effect.

Mydriatic effect of topically applied rocuronium bromide in tawny owls (Strix aluco): comparison between two protocols.

OBJECTIVE: To evaluate the mydriatic efficacy of a neuromuscular blocking agent (rocuronium bromide) applied topically to only one eye of nocturnal birds of prey and to assess for any general and/or local adverse effects due to its use. Animal studied Twelve healthy adult tawny owls (Strix aluco) were randomly divided in two groups. PROCEDURES: Six birds (Group 1) received a single dose of 0.35 mg of rocuronium bromide. The second group of subjects (Group 2) received two doses of 0.35 mg of rocuronium bromide (total 0.70 mg/eye). In both groups, the curariform agent was instilled topically. Pupil diameter was measured with a pupillary gauge in 10 min intervals for a total of 100 min and then every 20 min for a total of 240 min. The assessment of the pupillary light reflex was performed using a standard light source during pupillary size recording. RESULTS: Maximal pupillary diameter was 11.5 ± 0.3 mm for Group 1 and 11.0 ± 0.6 mm for Group 2 and no statistically significant differences were detected among the two groups. The maximal pupillary diameter was achieved at T80 for Group 1, and at T60 for Group 2. A complete fundus examination was possible on all treated eyes of subjects of both groups. The drug did not cause any noticeable adverse effects in any of the examined birds. CONCLUSION: Results of the present study suggest that a single topical administration of 0.35 mg of rocuronium bromide to the eyes of healthy tawny owls results in sufficient mydriasis to allow for a complete examination of the fundus.