Introduction: Clinical doses of anaesthetic agents were administered to rabbits and effects on the brain, heart, and liver were investigated biochemically and histopathologically. Material and Methods: The rabbits were randomly divided into three main groups (16 rabbits each) and each group into study (n = 8) and control (n = 8) groups. All study group rabbits received 3 mg/kg of midazolam (M) intramuscularly. Group 1.1 (M) received nothing further, group 2.1 (MK) also received 25 mg/kg of ketamine, and group 3.1 (MKI) besides ketamine was also given 2% isoflurane to induce anaesthesia for 30 min. NaCl solution in the same volume as midazolam and ketamine was injected into the controls. Results: In clinical evaluation significant differences were detected in respiratory and heart rates. In blood gas analysis the PO2 and PCO2 values showed statistical differences in anaesthesia intervals. Significant biochemical value changes were recorded in creatine kinase-Mb, glucose, and total protein. Histopathological liver examinations revealed higher total apoptotic and normal cell numbers in the MK than in the M and MKI groups. Apoptotic cell numbers were statistically significant in M and MK groups. Conclusion: Anaesthetic agents may increase programmed apoptosis. The MKI anaesthetics combination was found to cause less cell destruction in general than the other study groups. It was indicated that MKI was the safer anaesthetic combination in rabbits.

OBJECTIVE To evaluate the cardiovascular effects of atipamezole administered at half the volume or the same volume as dexmedetomidine to isoflurane-anesthetized cats. ANIMALS 6 adult (1 to 2 years old) domestic shorthair cats (body weight, 3 to 6 kg). PROCEDURES Each cat was anesthetized with isoflurane and rocuronium 3 times; there was a 1-week washout period between successive anesthetic procedures. For each anesthetic procedure, dexmedetomidine (5 μg/kg) was administered IV. Five minutes after dexmedetomidine was administered, atipamezole (25 or 50 μg/kg) or saline (0.9% NaCl) solution was administered IM. Pulse rate, mean arterial blood pressure (MAP), cardiac output (CO), and systemic vascular resistance (SVR) were measured during anesthesia before dexmedetomidine administration (baseline), after dexmedetomidine administration, and 15, 30, 60, and 120 minutes after administration of atipamezole or saline solution. Pulse rate and MAP were also recorded when MAP was at its lowest value. Hemodynamic variables were compared among treatments at baseline, after dexmedetomidine administration, and after administration of atipamezole or saline solution. Effects of treatment and time on all variables were assessed with mixed-effects models. RESULTS Both doses of atipamezole resulted in a significantly lower MAP than did saline solution. Pulse rate, CO, and SVR were not significantly different among treatments after atipamezole or saline solution were administered. CONCLUSIONS AND CLINICAL RELEVANCE Atipamezole administered IM at half the volume or the same volume as dexmedetomidine was ineffective at increasing pulse rate or CO in anesthetized cats that received dexmedetomidine. However, atipamezole caused short-lasting but severe arterial hypotension.

OBJECTIVE To assess effects of catheter diameter and injection rate of flush solution (saline [0.9% NaCl] solution) on renal contrast-enhanced ultrasonography (CEUS) with perfluorobutane in dogs. ANIMALS 5 healthy Beagles. PROCEDURES CEUS of the kidneys was performed by IV injection of contrast medium (0.0125 mL/kg) followed by injection of 5 mL of saline solution at rates of 1, 3, and 5 mL/s through a 20-gauge or 24-gauge catheter; thus, CEUS was repeated 3 times for each catheter diameter. Time-intensity curves were created for regions of interest drawn in the renal cortex and medulla. Repeatability was determined by calculating the coefficient of variation (CV). Statistical analysis was used to assess whether perfusion variables or CV of the perfusion variables was associated with catheter diameter or injection rate. RESULTS Perfusion variables did not differ significantly between catheter diameters. Time to peak enhancement (TTP) in the renal cortex was affected by injection rate, and there were significantly lower values for TTP at higher injection rates. The CEUS variables with the lowest CVs among injection rates were TTP for the renal cortex; the CV for TTP of the renal cortex was the lowest at an injection rate of 5 mL/s. CONCLUSIONS AND CLINICAL RELEVANCE Use of a 24-gauge catheter did not alter CEUS with perfluorobutane; therefore, such catheters could be used for CEUS of the kidneys of small dogs. Moreover, a rate of 5 mL/s is recommended for injection of flush solution to obtain greater accuracy for renal CEUS in Beagles.

OBJECTIVE To determine whether an enrofloxacin–silver sulfadiazine emulsion (ESS) labeled for treatment of otitis externa in dogs has ototoxic effects in rabbits following myringotomy. ANIMALS 6 healthy adult New Zealand White rabbits. PROCEDURES Rabbits were anesthetized for brainstem auditory-evoked response (BAER) tests on day 0. Myringotomy was performed, and BAER testing was repeated. Saline (0.9% NaCl) solution and ESS were then instilled in the left and right middle ears, respectively, and BAER testing was repeated prior to recovery of rabbits from anesthesia. Application of assigned treatments was continued every 12 hours for 7 days, and rabbits were anesthetized for BAER testing on day 8. Rabbits were euthanized, and samples were collected for histologic (6 ears/treatment) and scanning electron microscopic (1 ear/treatment) examination. RESULTS Most hearing thresholds (11/12 ears) were subjectively increased after myringotomy, with BAER measurements ranging from 30 to 85 dB in both ears. All day 8 hearing thresholds exceeded baseline (premyringotomy) values; results ranged from 30 to 85 dB and 80 to > 95 dB (the upper test limit) in saline solution–treated and ESS-treated ears, respectively. All ESS-treated ears had heterophilic otitis externa, epithelial hyperplasia of the external ear canal, various degrees of mucoperiosteal edema, and periosteal new bone formation on histologic examination. Scanning electron microscopy revealed that most outer hair cells in the ESS-treated ear lacked stereocilia or were absent. CONCLUSIONS AND CLINICAL RELEVANCE Results supported that ESS has ototoxic effects in the middle ear of rabbits. Further research is needed to confirm these findings. Myringotomized laboratory rabbits may be useful to study ototoxicity of drugs used in human medicine.

OBJECTIVE To describe a technique for endoscopic evaluation of the coelomic viscera of koi (Cyprinus carpio) and to evaluate the ability to visually examine coelomic structures by use of an approach cranial or caudal to the pelvic girdle. ANIMALS 16 subadult koi. PROCEDURES Koi were anesthetized with buffered tricaine methanesulfonate. Coelioscopic examination was performed via a ventral midline incisional approach cranial or caudal to the pelvic girdle. A 2.7-mm × 18-cm 30° oblique endoscope within a 4.8-mm operating sheath and infusion of saline (0.9% NaCl) solution was used. Ease of entry into the coelomic cavity and visual examination of structures were scored for each fish. Fish were euthanized 2 or 8 weeks after the procedure, and necropsy was performed. RESULTS The coelioscopic procedure was tolerated well, and all koi recovered uneventfully. For all fish, ease of entry and visual examination scores of the liver, intestines, gonads, heart, and anterior kidney were satisfactory to excellent. Visual examination of the posterior kidney and swim bladder was satisfactory to difficult, whereas the spleen and gallbladder were not visually identified. No significant differences were noted in entry or visual examination scores between the cranial and caudal approaches or between sexes. Minor complications included mild hemorrhage, rupture of the gonadal capsule, formation of adhesions between the viscera and incision site, and delayed healing of the incision. CONCLUSIONS AND CLINICAL RELEVANCE Diagnostic coelioscopy of koi appeared to be safe and effective. This procedure could have potential for use in examination of coelomic structures and disease diagnosis.