Evaluation of a novel, low-cost, 3D printed video laryngoscope with borescope in anesthetized Beagle dogs

OBJECTIVE

To develop and evaluate a low-cost three-dimensional (3D)-printed video laryngoscope (VLVET) for use with a commercial borescope.

STUDY DESIGN

Instrument development and pilot study.

ANIMALS

A total of six adult male Beagle dogs.

METHODS

The VLVET consisted of a laryngoscope handle and a Miller-type blade, and a detachable camera holder that attached to various locations along the blade. The laryngoscope and camera holder were 3D-printed using black polylactic acid filament. Dogs were premedicated with intravenous (IV) medetomidine (15 μg kg-1) and anesthesia induced with IV alfaxalone (1.5 mg kg-1). The VLVET, combined with a borescope, was used for laryngeal visualization and intubation. Performance was evaluated by comparing direct and video-assisted views in sternal recumbency. The borescope camera was sequentially positioned at 2, 4, 6, 8 and 10 cm from the blade tip (distanceLARYNX-CAM), which was placed on the epiglottis during intubation or laryngoscopy. At the 10 cm distanceLARYNX-CAM, laryngeal visualization was sequentially scored at inter-incisor gaps of 10, 8, 6, 4 and 2 cm. Laryngeal visualization scores (0-3 range, with 0 = obstructed and 3 = unobstructed views) were statistically analyzed using the Friedman's test.

RESULTS

Under direct visualization, the 2 cm distanceLARYNX-CAM had a significantly lower score compared with all other distanceLARYNX-CAM (all p = 0.014) because the view was obstructed by the camera holder and borescope camera. With both direct and camera-assisted views, visualization scores were higher at inter-incisor gaps ≥ 4 cm compared with 2 cm (all p < 0.05).

CONCLUSIONS AND CLINICAL RELEVANCE

During laryngoscopy and intubation, the VLVET and borescope facilitated both direct and video laryngoscopy at distanceLARYNX-CAM in Beagle dogs when inter-incisor gaps were ≥ 4 cm.

Perianesthetic metabolic acidosis is associated with 2% dorzolamide eye drops in dogs that underwent ophthalmic surgery: a retrospective study (2019-2022)

OBJECTIVE

To evaluate whether the administration of 2% dorzolamide ophthalmic solution in dogs undergoing ophthalmic surgery is associated with perianesthetic metabolic acidosis.

ANIMALS

60 dogs, with or without dorzolamide administration, underwent arterial blood gas analysis immediately after anesthesia for ophthalmic surgery between 2019 and 2022; a total of 60 surgeries were evaluated.

METHODS

This was a retrospective cross-sectional study. Logistic regression analysis was performed to investigate the association between the administration of 2% dorzolamide ophthalmic solution in dogs and the development of metabolic acidosis. Additionally, the influence of various potential risk factors, including age, body weight, sex, use of topical or systemic NSAIDs, and preoperative medications on the occurrence of metabolic acidosis, was evaluated.

RESULTS

A significant association was found between the use of 2% dorzolamide ophthalmic solution and perianesthetic metabolic acidosis (OR, 6.79; 95% CI, 2.00 to 23.02; P = .002). Furthermore, topical dorzolamide administration was significantly associated with both perianesthetic hypokalemia (OR, 3.52; 95% CI, 1.11 to 11.20; P = .033) and perianesthetic hyperchloremia (OR, 9.25; 95% CI, 1.71 to 50.01; P = .010).

CLINICAL RELEVANCE

The use of 2% dorzolamide ophthalmic solution is associated with perianesthetic metabolic acidosis, hypokalemia, and hyperchloremia in dogs. It is prudent to be aware of these risks, especially before anesthesia.

Transillumination facilitates coccygeal arterial cannulation in anaesthetised small-breed dogs

BACKGROUND

Arterial access in small-breed dogs is challenging, but arterial visualisation may facilitate the procedure, as evidenced in human medicine. This prospective, randomised study investigated the result of using transillumination to guide coccygeal artery cannulation in small-breed dogs.

METHODS

Coccygeal artery cannulation was attempted in dogs anaesthetised with butorphanol, midazolam, propofol and sevoflurane. In 70 dogs (standard technique group [STECHNIQUE group]), arterial cannulation was performed using pulse palpation. In 71 dogs (transilluminating-standard technique group [TSTECHNIQUE group]), a transilluminating device was utilised. The device was placed on the dorsal tail, and the cannula was advanced towards the dark line visible against the bright background. If the artery was not well visualised due to pigmentation, pulse palpation was used. The success rate of arterial cannulation was compared between the groups using the chi-squared test.

RESULTS

Arterial cannulation was significantly more successful (p < 0.001) in the TSTECHNIQUE group (63/71 [88.7%]) than in the STECHNIQUE group (43/70 [61.4%]).

LIMITATIONS

The number of punctures attempted and the time to cannulation were not assessed, and the procedure was only performed by veterinarians experienced in arterial cannulation.

CONCLUSIONS

The transillumination allows for a more accurate approach to the coccygeal artery, improving the success of arterial cannulation when combined with pulse palpation.

Evaluation of an automatic approach device to the epidural space of Beagle dogs

OBJECTIVE

To compare the epidural anesthesia device (EPIA), which facilitates an automatic approach to location of the epidural space, with the performance of clinicians using tactile sensation and differences in pressure when inserting an epidural needle into the epidural space of a dog.

STUDY DESIGN

Prospective, crossover experiment.

ANIMALS

A total of 14 Beagle dogs weighing 7.5 ± 2.4 kg (mean ± standard deviation).

METHODS

Each dog was anesthetized three times at 2 week intervals for three anesthesiologists (two experienced, one novice) to perform 14 epidural injections (seven manual and EPIA device each). The sequence of methods was assigned randomly for each anesthesiologist. The dogs were anesthetized with medetomidine (10 μg kg^-1), alfaxalone (2 mg kg^-1) and isoflurane and positioned in sternal recumbency with the pelvic limbs extended cranially. Epidural puncture in the manual method was determined by pop sensation, hanging drop technique and reduced injection pressure, whereas using the device a sudden decrease in reaction force on the device was detected. A C-arm identified needle placement in the epidural space, and after administration of iohexol (0.3 mL), the needle length in the epidural space was defined as the mean value measured by three radiologists. Normality was tested using the Kolmogorov-Smirnov test, and significant differences between the two methods were analyzed using an independent sample t test.

RESULTS

In both methods, the success rates of epidural insertion were the same at 95.2%. The length of the needle in the epidural space using the device and manual methods was 1.59 ± 0.50 and 1.68 ± 0.88 mm, respectively, with no significant difference (p = 0.718).

CONCLUSIONS AND CLINICAL RELEVANCE

EPIA device was comparable to human tactile sense for an epidural needle insertion in Beagle dogs. Further research should be conducted for application of the device in clinical environments.

Agreement Between Tongue-Based Oscillometric and Invasive Blood Pressure in Anesthetized Dogs of Various Weights

This study aimed to evaluate the agreement between oscillometric blood pressure (OBP) measured from the tongue and invasive blood pressure (IBP) measured from the dorsal pedal artery in anesthetized dogs of various body weights. Forty-five client-owned dogs undergoing general anesthesia for surgery or imaging scan were included; weights ranged from 2.5 to 42.6 kg. Agreement between paired IBP and OBP during normotension was verified with reference standards used in small animals and humans. The data were stratified by body weight (≤5 kg versus >5 kg). In the >5 kg group (n = 29), the bias ± standard deviation for mean (2.1 ± 7.9 mm Hg) and diastolic pressure (-2.7 ± 7.9 mm Hg) exhibited reliability that met human standards (<5 ± 8 mm Hg). However, in the ≤5 kg group (n = 16), the bias ± standard deviation met only veterinary standards (≤10 ± 15 mm Hg) for mean (3.1 ± 10.2 mm Hg) and diastolic pressure (-2.5 ± 12.6 mm Hg). Agreement for systolic pressure did not meet either standard for both groups. This study demonstrates that tongue-based OBP is a close estimate of mean/diastolic blood pressure in anesthetized dogs (>5 kg) during normotension by small-animal and human criteria.

Cardiovascular Responses to Nasal Stimulation Under Ethmoidal-Maxillary Nerve Block and Lidocaine Gel in Anesthetized Beagles

This study aimed to compare the effect of ethmoidal-maxillary nerve block (EMBLOCK) and topical application of 2% lidocaine gel (LGEL) on cardiovascular variables (heart rate and arterial blood pressure) during mechanical stimulation of the nasal cavity. The working hypothesis was that both techniques (EMBLOCK and LGEL) similarly blunt the cardiovascular responses to the stimulation. Six beagles were anesthetized using alfaxalone and isoflurane on three occasions with each treatment (EMBLOCK, LGEL, and control) in random order. The nasal cavity from the nose tip to the medial canthus was stimulated with a standard-tip cotton swab, and cardiovascular variables were recorded before and after stimulation. The maximum increases in heart rate and blood pressure were significantly smaller in EMBLOCK and LGEL than in the control. There was no significant difference between EMBLOCK and LGEL. Therefore, although further clinical studies are required, EMBLOCK and LGEL can be used because both EMBLOCK and LGEL attenuated the cardiovascular response to mechanical stimulation of the nasal cavity in dogs.

Effect of the respiratory rate on the pulse pressure variation induced by hemorrhage in anesthetized dogs

BACKGROUND

Studies on anesthetized dogs regarding pulse pressure variation (PPV) are increasing. The influence of respiratory rate (RR) on PPV, in mechanically ventilated dogs, has not been clearly identified.

OBJECTIVES

This study evaluated the influence of RR on PPV in mechanically ventilated healthy dogs after hemorrhage.

METHODS

Five healthy adult Beagle dogs were premedicated with intravenous (IV) acepromazine (0.01 mg/kg). Anesthesia was induced with alfaxalone (3 mg/kg IV) and maintained with isoflurane in 100% oxygen. The right dorsal pedal artery was cannulated with a 22-gauge catheter for blood removal, and the left dorsal pedal artery was cannulated and connected to a transducer system for arterial blood pressure monitoring. The PPV was automatically calculated using a multi-parameter monitor and recorded. Hemorrhage was induced by withdrawing 30% of blood (24 mL/kg) over 30 min. Mechanical ventilation was provided with a tidal volume of 10 mL/kg and a 1:2 inspiration-to-expiration ratio at an initial RR of 15 breaths/min (baseline). Thereafter, RR was changed to 20, 30, and 40 breaths/min according to the casting lots, and the PPV was recorded at each RR. After data collection, the blood was transfused at a rate of 10 mL/kg/h, and the PPV was recorded at the baseline ventilator setting.

RESULTS

The data of PPV were analyzed using the Friedman test followed by the Wilcoxon signed-rank test (p < 0.05). Hemorrhage significantly increased PPV from 11% to 25% at 15 breaths/min. An increase in RR significantly decreased PPV from 25 (baseline) to 17%, 10%, and 10% at 20, 30, and 40 breaths/min, respectively (all p < 0.05).

CONCLUSIONS

The PPV is a dynamic parameter that can predict a dog's hemorrhagic condition, but PPV can be decreased in dogs under high RR. Therefore, careful interpretation may be required when using the PPV parameter particularly in the dogs with hyperventilation.

Ethmoidal and maxillary nerve block versus systemic opioid administration during rhinoscopy in dogs: a non-randomised clinical trial

OBJECTIVES

This study aimed to evaluate the clinical effects of ethmoidal and maxillary nerve blocks during rhinoscopy in dogs.

MATERIALS AND METHODS

Fourteen dogs underwent rhinoscopy. Under general anaesthesia with isoflurane, ethmoidal and maxillary nerve blocks were applied bilaterally using 2% lidocaine before rhinoscopy in eight dogs (EM group). Six dogs were premedicated with hydromorphone (0.05 mg/kg) as a substitute for local nerve block (H group). During rhinoscopy, the heart rate, arterial blood pressure and end-tidal isoflurane concentration were recorded. The vaporizer setting was adjusted to increase the end-tidal isoflurane concentration when reflex movement was caused by nasal stimulation.

RESULTS

The H group, compared to the EM group, had an increase in HR that was 18 beats/minute (95% CI: 11 to 26) higher, an increase in SAP that was 22 mmHg (12 to 31) higher, an increase in MAP that was 15 mmHg (7 to 23) higher, an increase in DAP that was 12 mmHg (5 to 19) higher, and an increase in end-tidal isoflurane concentration that was 0.4% (0.3 to 0.5) higher. Head movement due to endoscope insertion was observed in 5/6 dogs (83.3%) in the H group and 1/8 dogs (12.5%) in the EM group (odds ratio, 0.029; ra95% CI, 0.001-0.574).

CLINICAL SIGNIFICANCE

Compared with administration of 0.05 mg/kg hydromorphone, concurrent block of the ethmoidal and maxillary nerves can reduce the cardiovascular response, reflex movement and anaesthetic requirement during rhinoscopy in dogs.

Effect of extension tube length on the damping coefficient and natural frequency in normotensive dogs

OBJECTIVE

To establish an acceptable extension tube length (ETL) to measure direct blood pressure (BP) in dogs.

DESIGN

Prospective, experimental study.

SETTING

University-based small animal research facility.

ANIMALS

Eight healthy Beagle dogs: 6 males and 2 females.

INTERVENTIONS

Each extension tube with lengths of 25, 50, 75, 115, 145, 205, and 275 cm were connected after the catheterization with a 22-Ga catheter in the dorsal pedal artery in sternal recumbency. A square wave from the fast-flush test was consecutively recorded 5 times to analyze the system's dynamic response characteristics according to the ETL. After recording the square wave, the ETL was converted to a Latin square. The dynamic response was analyzed using natural frequency (NF) and the damping coefficient (DC), both of which affect the damping factor. The average values of NF and DC were plotted against a graph showing the damping factor. Linear regression was used to evaluate the between-group changes in NF and DC.

MEASUREMENTS AND MAIN RESULTS

The DC gradually increased from 0.21 to 0.29 ξ, and the NF gradually decreased from 38 to 14 Hz according to the increase in ETL (P < 0.05). The dynamic response showed adequate damping with all ETLs.

CONCLUSION

With an increase in ETL, the NF decreased significantly, while the DC demonstrated a less significant change. Therefore, NF had a greater influence on the damping factor of arterial BP measurement. There was no difference between ETLs from 25 to 275 cm lines for measuring BP. An ETL of less than 275 cm is recommended as the damping amount is adequate. Moreover, an ETL less than 275 cm does not meaningfully affect BP measurement in dogs.

Modified retrograde intubation through the cricothyroid membrane in a cat with temporomandibular joint ankylosis

A 6‐month‐old, 2.9‐kg, male, Korean short hair cat was referred for inadequate mouth opening (4 mm), and condylectomy was scheduled for ankylosis of the left temporomandibular joint. Retrograde intubation via the cricothyroid membrane was planned since direct visualisation of the larynx was not possible. In dorsal recumbency, the cricothyroid membrane was punctured with an 18‐gauge needle, and a J‐tip guidewire, inserted via the needle, was advanced and identified at the mouth. A 6‐Fr truncated feeding tube was inserted from the mouth to the cricothyroid membrane along the guidewire. The guidewire was removed, and the tip of the feeding tube was advanced as an anterograde guide to the inner trachea. Subsequently, an endotracheal tube was inserted along the feeding tube. Capnography was used to confirm correct intubation. Condylectomy was performed on the left temporomandibular joint, and the patient recovered from anaesthesia uneventfully. Retrograde intubation is less invasive than tracheostomy or cricothyroidotomy, and the cricothyroid membrane has been suggested as a suitable site for guidewire insertion in humans and dogs. However, when resistance is encountered during the advancement of endotracheal tube using the traditional technique without the anterograde guide, it may be difficult to distinguish where the resistance occurred leading to damage or oesophageal displacement in cats with relatively fragile airway. This report suggests that retrograde intubation via the cricothyroid membrane can be performed in cats with limited visualisation of the larynx, and an anterograde guide following the retrograde wire could reduce the potential damage or oesophageal displacement.

Evaluation of the tongue for oscillometric measurement of arterial pressure in anesthetized Beagle dogs

OBJECTIVE

To evaluate the agreement between oscillometric blood pressure (OBP) measured from the tongue and invasive blood pressure (IBP), and to compare OBPs measured from the tongue with OBPs measured from the pelvic limb and tail.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A total of eight adult Beagle dogs weighing 11.1 ± 1.2 kg.

METHODS

Animals were premedicated with intravenous (IV) acepromazine (0.005 mg kg^-1). Anesthesia was induced with alfaxalone (3 mg kg^-1) IV and maintained with isoflurane. The dorsal pedal artery was catheterized for IBP measurements. Systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressure were simultaneously measured from the tongue, pelvic limb and tail. Based on invasive SAP, hypertension (>140 mmHg), normotension (90-140 mmHg) and hypotension (<90 mmHg) were induced by controlling end-tidal isoflurane concentrations and/or dobutamine/dopamine administration. Agreement between paired IBP and OBP measurements was analyzed with reference standards for noninvasive blood pressure devices used in small animals and humans.

RESULTS

Regardless of cuff placement, the mean bias ± standard deviation between IBP and OBP met veterinary (≤10 ± 15 mmHg) and human (<5 ± 8 mmHg) standards for MAP and DAP. SAP measurements provided by the OBP device showed unacceptable agreement with IBP, and the bias between methods increased at higher blood pressures, regardless of cuff site. During hypotension, tongue OBP showed the largest percentage of absolute difference <10 mmHg in relation to IBP for SAP (90%), MAP (97%), and DAP (93%), compared with pelvic limb (60%, 97% and 82%, respectively) and tail OBP (54%, 92% and 77%, respectively).

CONCLUSIONS AND CLINICAL RELEVANCE

The tongue is a clinically useful site for measuring OBP in anesthetized Beagle dogs, providing reliable estimates of MAP and DAP. The tongue could replace other cuff placement sites and may be a relatively suitable site for assessing hypotension.

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 (E_BLOCK) and to compare the effects of a maxillary nerve block (M_BLOCK), E_BLOCK and their combination (M-E_BLOCK) on heart rate (HR), systolic (SAP), mean (MAP), diastolic (DAP) arterial pressures and respiratory rate (f_R) 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 (M_BLOCK), injections of saline at the maxillary foramina and lidocaine at the ethmoidal foramina (E_BLOCK) and injections of lidocaine at all foramina (M-E_BLOCK). The ventral nasal meatus was bilaterally stimulated using cotton swabs, and HR, SAP, MAP, DAP and f_R 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 f_R significantly increased after stimulation within each treatment (p < 0.03). Physiologic responses were significantly attenuated, but not absent, in the M-E_BLOCK [HR (p = 0.019), SAP, MAP, DAP and f_R (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 f_R responses to nasal stimulation in Beagle dogs.

Fluoroscopy-guided approach to the lumbar dorsal root ganglion in dogs: cadaver study in Beagles

OBJECTIVE

To evaluate an approach to the canine lumbar dorsal root ganglion (DRG), a significant contributor to the pain pathway, using new methylene blue staining.

STUDY DESIGN

Prospective randomized study.

ANIMALS

A total of three Beagle dog cadavers weighing 10.4 ± 0.7 kg (mean ± standard deviation).

METHODS

Bilateral third to fifth lumbar DRG approaches were performed in three dog cadavers positioned in sternal recumbency. The mammillary process was palpated, and a 22 gauge spinal needle was inserted through the skin 1 cm lateral to the process and directed towards the median plane at a 45° angle to the dorsal plane. The needle was advanced along the transverse plane until touching bone, or a popping sensation was detected. Under fluoroscopic guidance, the position of the needle tip was adjusted to be in the cranioventral part of the intervertebral foramen. The location of the needle was confirmed by demarcation of the nerve roots after iohexol (0.1 mL) injection. For evaluation of the DRG approach, new methylene blue (0.1 mL) was injected. Subsequently, anatomical dissection of the area was performed. The DRG staining was scored as follows: 0, no staining; 1, partial (<50%); 2, partial (≥50%); and 3, complete staining. Comparisons among the staining scores of the third to fifth DRG were assessed with the Friedman test.

RESULTS

Staining score 3 was achieved in 14 of 18 (77.8%) sites. Staining scores 2, 1 and 0 were identified at two, one and one of the 18 sites, respectively. No significant difference was noted in the staining scores among the third to fifth DRGs (p = 0.78).

CONCLUSIONS AND CLINICAL RELEVANCE

The technique used for DRG injections achieved adequate DRG staining, supporting use of the fluoroscopy-guided approach to the canine lumbar DRG.

Effect of intra-abdominal hypertension on plasma exogenous creatinine clearance in conscious and anesthetized dogs

OBJECTIVE

To evaluate the effect of intra-abdominal pressure (IAP) on plasma exogenous creatinine clearance in both conscious and anesthetized dog models using a balloon technique to generate intra-abdominal hypertension.

DESIGN

Prospective, cross-over, experimental study.

SETTING

University-based small animal research facility.

ANIMALS

Six healthy male Beagle dogs.

INTERVENTIONS

A balloon device comprising a Foley urinary catheter and latex balloon was placed in the intra-abdominal cavity. Plasma exogenous creatinine clearance was compared after intravenous administration of exogenous creatinine solution at 80 mg/kg under 4 different treatment conditions as follows: control and IAP levels of 25 mm Hg in conscious dogs and control and IAP levels of 25 mm Hg in anesthetized dogs (CC, C25, AC, and A25, respectively). Samples were obtained before (T0) and 10, 20, 30, 60, 90, 120, 240, 360, 480, and 600 min after administration of creatinine in all treatment groups.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in plasma creatinine concentration for CC, AC, and C25 during the treatment period. However, in the A25 treatment condition, the plasma creatinine concentration increased significantly at 10, 20, 30, 60, 90, and 120 min after administration of creatinine (P < 0.05). Plasma creatinine clearances were 5.0 ± 0.5, 4.7 ± 1.2, 5.5 ± 0.9, and 2.5 ± 0.5 mL/kg/min for 600 min (CC, AC, C25, and A25, respectively). In the A25 treatment condition, the plasma exogenous creatinine clearance decreased significantly to 50%, 47%, and 55% of that under control conditions (CC, AC, and C25, respectively). After decompression of the abdomen, plasma creatinine concentrations declined rapidly and returned to basal concentrations.

CONCLUSIONS

Intra-abdominal hypertension under general anesthesia could cause renal hypoperfusion. Timely decompression may improve the outcome of acutely increased IAP when surgery and/or general anesthesia is required in canine patients.

Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs

OBJECTIVE

To evaluate endotracheal tube intracuff pressure (P_cuff) changes over time and the effect of these changes on air leak pressure (P_leak).

STUDY DESIGN

Prospective experimental study.

ANIMALS

A group of nine healthy adult Beagle dogs.

METHODS

In part I, in vitro measurements of P_cuff were recorded for 1 hour in eight endotracheal tubes subjected to four treatments: room temperature without lubricant (RT0L), room temperature with lubricant (RTWL), body temperature without lubricant (BT0L), and body temperature with lubricant (BTWL). In part II, nine dogs were endotracheally intubated and P_leak was evaluated at P_cuff of 25 mmHg. Subsequently, P_cuff was reset to 25 mmHg (baseline) and P_cuff measurements were recorded every 5 minutes for 1 hour. Subsequently, a second P_leak measurement was recorded at the current P_cuff. The data were analyzed using Wilcoxon signed-rank test, repeated measures anova and Mann-Whitney U test.

RESULTS

In part I, P_cuff differed significantly between the RT0L and RTWL treatments at 5-60 minutes, and between the BT0L and BTWL treatments at 5-35, 55 and 60 minutes (p < 0.05). In part II, compared with baseline pressures, mean P_cuff decreased to <18 mmHg at 10 minutes and significant decreases were recorded at 15-60 minutes (P_cuff range: 10.0 ± 4.9 to 13.4 ± 6.3 mmHg, mean ± standard deviation). Significant differences were observed between the first and second P_leak measurements (p = 0.034). P_leak decreased in six of nine dogs, was not changed in two dogs and increased in one dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Significant decreases in P_cuff over time were measured. P_leak may decrease during anesthesia and increase the risk for silent pulmonary aspiration. The results indicate the need for testing P_cuff more than once, especially at 10 minutes after the onset of anesthesia.

A novel balloon technique to induce intra-abdominal hypertension and its effects on cardiovascular parameters in a conscious dog model

OBJECTIVE

To evaluate a new balloon technique to induce intra-abdominal hypertension (IAH) and abdominal compartment syndrome in a conscious dog model, and to evaluate the effect of intra-abdominal pressure (IAP) on cardiovascular, respiratory, and arterial blood gas values in conscious dogs with IAH.

DESIGN

Prospective, experimental study.

SETTING

University-based small animal research facility.

ANIMALS

Six healthy Beagle dogs, 4 males, and 2 females.

INTERVENTIONS

A new balloon device designed for this study using a Foley urethral catheter and latex balloon was placed in the abdominal cavity. Consecutive measurements of IAP were made by measuring the intravesicular pressure. The abdomen was inflated with air to IAPs of 10, 15, 20, and 25 mm Hg. Heart rate, respiratory rate, systolic arterial blood pressure, and arterial blood gases were evaluated at baseline and at 15, 30, 45, 60, 120, 240, and 300 minutes after IAP increase.

MEASUREMENTS AND MAIN RESULTS

The air insufflated into the intra-abdominal balloon device significantly increased the IAP and led to sustained IAH. The respiratory rate increased significantly (P < 0.05) when IAP was increased to 15, 20, and 25 mm Hg. Although heart rate, systolic arterial blood pressure, PaO₂ , and PaCO₂ did not show statistically significant differences between baseline and posttreatment values over time, the dogs with increased IAP showed a distended abdomen and apparent discomfort, and 4/6 (67%) vomited. After measurement of IAP, air was removed. There were no adverse effects noted after removal of the balloon device.

CONCLUSION

The balloon device was successfully insufflated and led to sustained IAH in conscious dogs. This balloon technique does not require general anesthesia for instillation or removal of gas after installment. An acute IAP increase in normal conscious dogs induced discomfort, vomiting, and increased respiratory effort.

Effect of tiletamine-zolazepam on the intraocular pressure of the dog

OBJECTIVE

To determine the effect of tiletamine-zolazepam (TZ) on canine intraocular pressure (IOP).

ANIMALS STUDIED

Six healthy dogs without ocular abnormalities were used in this study.

PROCEDURES

The study was carried out as a crossover experimental trial with a 7-day interval between treatments. TZ combination was administered intravenously (IV) at a dose of 5, 10, and 20 mg/kg (TZ5, TZ10, and TZ20, respectively). Following preanesthetic baseline readings of IOP, each dog received IV TZ and then the IOP values were measured every 10 min for 40 min in all treatments.

RESULTS

The baseline IOP values (mean ± standard deviation) for TZ5, TZ10, and TZ20 were 12.7 ± 0.8, 14.4 ± 1.2, and 15.3 ± 1.7 mmHg, and each IOP changed to 11.1 ± 1.1, 13.1 ± 1.4 and 13.5 ± 1.7 mmHg after intravenous administration of each TZ treatment, respectively. However, there were no statistical differences between baseline and post-treatment values.

CONCLUSIONS

The TZ combination had no clinically significant effect on IOP of the dog. This could be an option for induction or surgical procedures in dogs with ophthalmic problems when an increase in IOP is undesirable.

Evaluation of risk factors for development of corneal ulcer after nonocular surgery in dogs: 14 cases (2009-2011)

OBJECTIVE

To evaluate the prevalence of and risk factors for development of corneal ulcers after nonocular surgery performed with general anesthesia in dogs.

DESIGN

Retrospective case-control study.

ANIMALS

14 dogs with development of corneal ulcers after nonocular surgery and 718 control dogs.

PROCEDURES

Medical records of dogs evaluated at the Veterinary Medical Teaching Hospital of Seoul National University from January 2009 to June 2011 were reviewed for assessment of risk factors for development of corneal ulcers.

RESULTS

Among the 732 reviewed cases, 14 (1.9%) dogs of 6 breeds developed a corneal ulcer after nonocular surgery. Duration of anesthesia was significantly longer in dogs with ulcers than dogs without ulcers. The number of medications received and procedures performed were also significantly higher in dogs with ulcers than dogs without ulcers. Dogs with a small skull (OR, 8.59; 95% confidence interval [CI], 1.04 to 70.90) and dogs that received neurosurgery (OR, 21.12; 95% CI, 5.77 to 77.25) were more susceptible to development of corneal ulcers. Also, postoperative application of a fentanyl patch was a risk factor for development of corneal ulcers (OR, 4.53; 95% CI, 1.05 to 19.60).

CONCLUSIONS AND CLINICAL RELEVANCE

Several risk factors were identified for development of corneal ulcers after nonocular surgery was performed with general anesthesia in dogs. Perioperative eye protection strategies and postoperative ophthalmic examination are needed to reduce the occurrence of corneal ulcers and their progression, especially for high-risk dogs and procedures.

Sedative and analgesic effects of intravenous xylazine and tramadol on horses

This study was performed to evaluate the sedative and analgesic effects of xylazine (X) and tramadol (T) intravenously (IV) administered to horses. Six thoroughbred saddle horses each received X (1.0 mg/kg), T (2.0 mg/kg), and a combination of XT (1.0 and 2.0 mg/kg, respectively) IV. Heart rate (HR), respiratory rate (RR), rectal temperature (RT), indirect arterial pressure (IAP), capillary refill time (CRT), sedation, and analgesia (using electrical stimulation and pinprick) were measured before and after drug administration. HR and RR significantly decreased from basal values with X and XT treatments, and significantly increased with T treatment (p < 0.05). RT and IAP also significantly increased with T treatment (p < 0.05). CRT did not change significantly with any treatments. The onset of sedation and analgesia were approximately 5 min after both X and XT treatments; however, the XT combination produced a longer duration of sedation and analgesia than X alone. Two horses in the XT treatment group displayed excited transient behavior within 5 min of drug administration. The results suggest that the XT combination is useful for sedation and analgesia in horses. However, careful monitoring for excited behavior shortly after administration is recommended.