Anesthetic procedures in animals are widely used in hospital for routine surgery. For induction of anesthesia in dogs, propofol has been shown to be the drug of choice. The objectives of this study were the assessment of induction of anesthesia using propofol or propofol-ketamine. Twenty client-owned dogs were randomly assigned to treatment and control groups. All patients were administered acepromazine (0.05 mg kg-1) and fentanyl (5 µg kg-1) for premedication by intramuscular (IM) injection. Dogs in the treatment group were administered ketamine (1 mg kg-1), while dogs in the control group were administered 0.9% saline solution, by intravenous (IV) injection. Induction of anesthesia was done using IV propofol at a rate of 1 mL minute-1. Cardiopulmonary patterns were assessed before application of premedication, 15 minutes after application of premedication and after induction of anesthesia with propofol. Additionally, data regarding tracheal intubation score, presence of adverse effects and dose of propofol necessary for induction of anesthesia were collected. The control group showed significantly more adverse effects and changes in cardiopulmonary patterns when compared to the treatment group. There was a clinically significant reduction in the dose of propofol necessary for induction of anesthesia when associated with ketamine. The association of ketamine for induction of anesthesia in healthy dogs using propofol was able to reduce the dose of the induction agent necessary for tracheal intubation. Moreover, there was a reduction in the occurrence of adverse effects and cardiopulmonary depression, which allowed for a safer procedure for the patients.

Introduction: The aim of this study was to investigate fluorescein use in the diagnosis of bladder ruptures in rabbits as an experimental model.Material and Methods: The study was conducted on male New Zealand rabbits divided into a retrograde fluorescein group (n = 8) and an intravenous (IV) fluorescein group (n = 8). Following general anaesthesia, 10 mL of 10% fluorescein dye (sodium fluoresceine powder) was administered via ureterorenoscope to the bladder of the first group, and 0.5 mL of 10% fluorescein was administered intravenously to the second group. Then, the bladder was viewed through the cystoscope by urethral aspect. After experimental bladder perforation, groups were comparatively evaluated by paracentesis and laparotomy.Results: Following IV injection of fluorescein dye, the bladder veins were stained green within 10 s and then fluorescein mixed with urine flowed into bladder lumen. The green fluid flow was observed in the abdominal cavity after the perforation of the bladder in both groups.Conclusion: Fluorescein can be used as a marker in diagnosis of bladder ruptures. If there is no bleeding or intestinal content in the abdominal cavity, although a smoky yellow-green image is observed, bladder rupture can be suspected.

OBJECTIVE To evaluate the correlation coefficient of the ratio between diameter of the caudal vena cava (CVC) and diameter of the aorta (Ao) in dogs as determined ultrasonographically with systolic pressure variation (SPV). ANIMALS 14 client-owned dogs (9 females and 5 males; mean ± SD age, 73 ± 40 months; mean body weight, 22 ± 7 kg) that underwent anesthesia for repair of skin wounds. PROCEDURES Anesthesia was induced. Controlled mechanical ventilation with a peak inspiratory pressure of 8 cm H2O was immediately started, and SPV was measured. During a brief period of suspension of ventilation, CVC-to-Ao ratio was measured on a transverse right-lateral intercostal ultrasonographic image obtained at the level of the porta hepatis. When the SPV was ≥ 4 mm Hg, at least 1 bolus (3 to 4 mL/kg) of Hartmann solution was administered IV during a 1-minute period. Bolus administration was stopped and the CVC-to-Ao ratio measured when SPV was < 4 mm Hg. Correlation coefficient analysis was performed. RESULTS 28 measurements were obtained. The correlation coefficient was 0.86 (95% confidence interval, 0.72 to 0.93). Mean ± SD SPV and CVC-to-Ao ratio before bolus administration were 7 ± 2 mm Hg and 0.52 ± 0.16, respectively. Mean ± SD SPV and CVC-to-Ao ratio after bolus administration were 2 ± 0.6 mm Hg and 0.91 ± 0.13, respectively. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the CVC-to-Ao ratio was a feasible, noninvasive ultrasonographically determined value that correlated well with SPV.

OBJECTIVE To determine the minimum alveolar concentration that blunts adrenergic responses (MAC(BAR)) for isoflurane and evaluate effects of fentanyl on isoflurane MAC(BAR) in sheep. ANIMALS 13 healthy adult Dorset-cross adult ewes. PROCEDURES In a crossover design, each ewe was anesthetized 2 times for determination of isoflurane MAC(BAR). Anesthesia was induced with propofol administered IV. Sheep initially received fentanyl (5 μg/kg, IV, followed by a constant rate infusion of 5 μg/kg/h) or an equivalent volume of saline (0.9% NaCl) solution (control treatment). After a washout period of at least 8 days, the other treatment was administered. For MAC(BAR) determination, a mechanical nociceptive stimulus (ie, sponge forceps) was applied at the coronary band for 1 minute. The MAC(BAR) values of the 2 treatments were compared by means of a paired t test. During MAC(BAR) determination, blood samples were collected for measurement of plasma fentanyl concentration. RESULTS Mean ± SD isoflurane MAC(BAR) of the fentanyl and control treatments was 1.70 ± 0.28% and 1.79 ± 0.35%, respectively; no significant difference was found between the 2 treatments. Plasma concentration of fentanyl reached a median steady-state concentration of 1.69 ng/mL (interquartile range [25th to 75th percentile], 1.47 to 1.79 ng/mL), which was maintained throughout the study. CONCLUSIONS AND CLINICAL RELEVANCE Administration of fentanyl at 5 μg/kg, IV, followed by a constant rate infusion of the drug at 5 μg/kg/h did not decrease isoflurane MAC(BAR). Further studies to determine the effect of higher doses of fentanyl on inhalation anesthetic agents and their potential adverse effects are warranted.

OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses. ANIMALS 6 clinically normal adult horses. PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and anesthesia was induced with propofol mixed with ketamine hydrochloride. Horses were positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen and a continuous rate infusion of butorphanol tartrate. One hour after anesthesia was induced, the blood sample protocol was repeated. Plasma ACTH concentrations were quantified by use of a commercially available sandwich assay. Generalized estimating equations that controlled for horse and an expressly automated deconvolution algorithm were used to determine effects of anesthesia on plasma ACTH concentrations and pulsatility, respectively. RESULTS Anesthesia significantly reduced the plasma ACTH concentration in blood samples collected from the cavernous sinus. CONCLUSIONS AND CLINICAL RELEVANCE Mean plasma ACTH concentrations in samples collected from the cavernous sinus of anesthetized horses were reduced. Determining the success of partial ablation of the pituitary gland in situ for treatment of pituitary pars intermedia dysfunction may require that effects of anesthesia be included in interpretation of plasma ACTH concentrations in cavernous sinus blood.

OBJECTIVE To determine the onset, duration, and extent of regional nerve blocks performed by administration of lidocaine or lidocaine-bupivacaine into the infraorbital canal in dogs. ANIMALS 6 healthy hound-type dogs. PROCEDURES Under general anesthesia, stimulating needles were inserted into the gingiva dorsolateral to both maxillary canine (MC) teeth and the maxillary fourth premolar (MPM4) and second molar (MM2) teeth on the treatment side. A reflex-evoked muscle potential (REMP) was recorded from the digastricus muscle after noxious electrical stimulation at each site. After baseline measurements, 1 mL of 2% lidocaine solution or a 2% lidocaine-0.5% bupivacaine mixture (0.5 mL each) was injected into the infraorbital canal (at approx two-thirds of the canal length measured rostrocaudally). The REMPs were recorded for up to 7 hours. The REMP data for the contralateral (untreated control) canine tooth were used to normalize results for all stimulation sites. RESULTS With both treatments, nerve block for MC teeth on the treated side was achieved by 5 (n = 5 dogs) or 10 (1) minutes after injection, but nerve block for ipsilateral MPM4 and MM2 teeth was successful for only 3 dogs and 1 dog, respectively. Mean duration of nerve blocks for MC teeth was 120 and 277 minutes following injection of lidocaine and lidocaine-bupivacaine, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Local anesthesia, as performed in this study, successfully blocked innervation of MC teeth, but results for MPM4 and MM2 teeth were inconsistent. This specific technique should not be used during tooth extractions caudal to the MC teeth.

OBJECTIVE To evaluate the effects of a medetomidine-ketamine combination on tear production of clinically normal cats by use of the Schirmer tear test (STT) 1 before and during anesthesia and after reversal of medetomidine with atipamezole. ANIMALS 40 client-owned crossbred domestic shorthair cats (23 males and 17 females; age range, 6 to 24 months). PROCEDURES A complete physical examination, CBC, and ophthalmic examination were performed on each cat. Cats with no abnormalities on physical and ophthalmic examinations were included in the study. Cats were allocated into 2 groups: a control group (n = 10 cats) anesthetized by administration of a combination of medetomidine hydrochloride (80 μg/kg) and ketamine hydrochloride (5 mg/kg), and an experimental group (30) anesthetized with the medetomidine-ketamine combination and reversal by administration of atipamezole. Tear production of both eyes of each cat was measured by use of the STT I before anesthesia, 15 minutes after the beginning of anesthesia, and 15 minutes after administration of atipamezole. RESULTS Anesthesia with a medetomidine-ketamine combination of cats with no ophthalmic disease caused a significant decrease in tear production. The STT I values returned nearly to preanesthetic values within 15 minutes after reversal with atipamezole, whereas the STT I values for the control group were still low at that point. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a tear substitute should be administered to eyes of cats anesthetized with a medetomidine-ketamine combination from the time of anesthetic administration until at least 15 minutes after administration of atipamezole.

OBJECTIVE To investigate the in vitro stability of atrial natriuretic peptide (ANP) in plasma samples under various storage conditions and the influence of anesthesia on plasma ANP concentration in cats. ANIMALS 1 cat with congestive heart failure and 5 healthy adult mixed-breed cats. PROCEDURES A plasma sample from the cat with heart failure was serially diluted, and dilutional parallelism of ANP concentration was evaluated. Plasma samples containing aprotinin or serum samples from the 5 healthy cats were kept at room temperature (27°C) for ≤ 12 hours. Plasma samples from the same healthy cats were stored at −70°, −20°, or 4°C for ≤ 14 days. Plasma samples were obtained from the healthy cats before and during isoflurane anesthesia. Plasma ANP concentrations were measured at a commercial laboratory by use of a human ANP chemiluminescence assay. RESULTS Intra- and interassay coefficients of variation were 1.5% and 2.5%, respectively, and dilutional parallelism was established. Although ANP concentration decreased by 82.4 ± 13.6% (mean ± SD) after sample storage for 12 hours at room temperature, this decrease was prevented by aprotinin. Plasma ANP concentrations were stable for 7 days at −20°C and for 14 days at −70°C. However, concentrations decreased markedly to 57.6 ± 6.9% at −20°C and to 18.0 ± 3.0% at 4°C after 14 days. Plasma ANP concentration decreased significantly in cats during anesthesia and was correlated with blood pressure. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that aprotinin should be added routinely in preparation of plasma samples from cats for measurement of ANP concentration, and those samples, if stored, should be frozen immediately at ≤ −20°C. General anesthesia or systemic blood pressure may affect plasma ANP concentration in cats.

OBJECTIVE To evaluate pharmacokinetics of bupivacaine after IP administration to cats undergoing ovariohysterectomy. ANIMALS 8 healthy cats. PROCEDURES Anesthesia was induced with propofol and maintained with isoflurane. Buprenorphine (0.02 mg/kg, IV) and meloxicam (0.2 mg/kg, SC) were administered. A 20-gauge catheter was inserted into a jugular vein for blood sample collection. A ventral midline incision was made, and a solution of 0.5% bupivacaine (2 mg/kg) diluted with an equal volume of saline (0.9% NaCl) solution (final concentration, 0.25% bupivacaine) was injected into the peritoneal space over the right and left ovarian pedicles and caudal aspect of the uterus before ovariohysterectomy. Cats were monitored for signs of bupivacaine toxicosis. Venous blood samples (2 mL) were collected before (time 0) and 2, 5, 10, 15, 20, 30, 60, 120, and 240 minutes after bupivacaine administration. Plasma bupivacaine concentrations were determined with a liquid chromatography–tandem mass spectrometry method. Pharmacokinetic parameters were determined by data plotting followed by analysis with a noncompartmental model. RESULTS No signs of bupivacaine toxicosis were observed. Maximum bupivacaine plasma concentration was 1,030 ± 497.5 ng/mL at a mean ± SD value of 30 ± 24 minutes after administration. Mean elimination half-life was 4.79 ± 2.7 hours. Mean clearance indexed by bioavailability and volume of distribution indexed by bioavailability were 0.35 ± 0.18 L•h/kg and 2.10 ± 0.84 L/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Intraperitoneal administration of bupivacaine resulted in concentrations that did not cause observable toxicosis. Studies to investigate analgesic effects for this technique in cats are warranted.

OBJECTIVE To determine the effects of acepromazine maleate premedication on cardiovascular function before and after infusion of dobutamine hydrochloride for 30 minutes in isoflurane-anesthetized horses. ANIMALS 6 healthy adult horses. PROCEDURES Each horse was anesthetized once following premedication with acepromazine (0.02 mg/kg, IV) administered 30 minutes prior to anesthetic induction (ACP+ treatment) and once without premedication (ACP– treatment). Anesthesia was induced with IV administration of xylazine hydrochloride (0.8 mg/kg), ketamine hydrochloride (2.2 mg/kg), and diazepam (0.08 mg/kg). Horses were positioned in right lateral recumbency, and anesthesia was maintained via inhalation of isoflurane delivered in oxygen. End-tidal isoflurane concentration was adjusted to achieve a target mean arterial blood pressure of 60 mm Hg (interquartile range [25th to 75th percentile], 57 to 63 mm Hg) for at least 15 minutes. Cardiac index, oxygen delivery index, and femoral arterial blood flow indices were determined 60 minutes after anesthetic induction (baseline). Dobutamine was then infused to achieve a target mean arterial blood pressure of 80 mm Hg (interquartile range, 76 to 80 mm Hg). Data collection was repeated 30 minutes after the start of dobutamine infusion for comparison with baseline values. RESULTS Complete data sets were available from 5 of the 6 horses. Dobutamine administration resulted in significant increases in oxygen delivery and femoral arterial blood flow indices but no significant change in cardiac index for each treatment. However, at baseline or 30 minutes after the start of dobutamine infusion, findings for the ACP+ and ACP– treatments did not differ. CONCLUSIONS AND CLINICAL RELEVANCE In isoflurane-anesthetized horses, dobutamine administration increased oxygen delivery and femoral arterial blood flow indices, but these changes were unaffected by premedication with acepromazine.