Sedative and analgesic effects of medetomidine in beagle dogs infected and uninfected with heartworm

The sedative and analgesic effects of medetomidine were evaluated in heartworm-infected (HW+) and uninfected (HW–) beagle dogs by intravenous (IV) and intramuscular (IM) administration of 30 µg/kg and 40 µg/kg doses, respectively. Posture, response to noise and the pedal reflex were monitored. A procedure for mock radiographic positioning was performed to evaluate its overall clinical use. Observation times were 0, 15, 30, 60, 90, 120 and 180 min. In addition, the times from injection until the dog could not stand on its feet (down time), from lateral to sternal recumbency (sternal recumbency time), and from sternal recumbency to rising again (rising time) were also noted.Medetomidine produced rapid sedation and analgesia by both routes. Down times for the IM and IV routes were similar, which verified the manufacturer's recommended doses. The HW+ dogs had shorter down times, probably owing to increased blood flow to the brain caused by adrenergic alpha-2 activity. Sternal recumbency and rising times did not differ between the groups, suggesting a similar metabolism. Sedation and analgesia were adequate for performing the procedure in all dogs. HW– dogs showed less resistance to handling during the procedure than HW+ dogs. Overall, medetomidine seems to be a suitable agent for short-term chemical restraint in dogs, even with subclinical heartworm infestation.     

Comparison of arylalkylamine N-acetyltransferase and melatonin receptor type 1B immunoreactivity between young adult and aged canine spinal cord

Melatonin affects diverse physiological functions through its receptor and plays an important role in the central nervous system. In the present study, we compared immunoreactivity patterns of arylalkylamine N-acetyltransferase (AANAT), an enzyme essential for melatonin synthesis, and melatonin receptor type 1B (MT2) in the spinal cord of young adult (2~3 years) and aged (10~12 years) beagle dogs using immunohistochemistry and Western blotting. AANAT-specific immunoreactivity was observed in the nuclei of spinal neurons, and was significantly increased in aged dog spinal neurons compared to young adult spinal neurons. MT2-specific immunoreactivity was found in the cytoplasm of spinal neurons, and was predominantly increased in the margin of the neuron cytoplasm in aged spinal cord compared to that in the young adult dogs. These increased levels of AANAT and MT2 immunoreactivity in aged spinal cord might be a feature of normal aging and associated with a feedback mechanism that compensates for decreased production of melatonin during aging.     

Bacterial Pleuritis with Thickened Mesothelial Hyperplasia in a Young Beagle Dog

A five-month-old male beagle dog suddenly became moribund. Bloody fluid accumulated in the thoracic and abdominal cavities, and soft yellow flecks were floating in the thoracic fluid. The mediastinum and pericardium became dark reddish with villous thickening. Other parietal and pulmonary pleurae were rough, and the organs adhered to each other. Histologically, most mediastinal pleura formed papillary projections covered by a single layer of mesothelial cells. Many macrophages and neutrophils infiltrated the submesothelial connective tissue. At the mediastinum adjacent to the pericardium, cuboidal mesothelial cells proliferated solidly and formed a thick surface stratum. The flecks consisted of gram-negative filamentous or small bacillary (coccoid) bacteria. In the right posterior lobe of the lung, neutrophilic infiltration and a large encapsulated abscess including a bacterial colony were present. We diagnosed this case as “bacterial pleuritis with thickened mesothelial hyperplasia”. The cause of the pleuritis might be a chronic pleural infection spread via the lung abscess.     

比格犬皮肤病病原的分离与鉴定

对青岛某犬场一例比格犬皮肤病患犬进行了病原的分离培养以及鉴定。经过皮肤局部观察、寄生虫检查、真菌分离及18SrRNA基因测序、细菌分离及16SrRNA基因测序,结果显示本病例主要致病原因是寄生虫、细菌和真菌的混合感染,其中寄生虫感染以蠕形螨为主,细菌病原包括中间型葡萄球菌、链球菌和乳酸菌,真菌病原主要有隐球菌、青霉菌和念珠菌。调查结果为临床治疗提供了理论依据。     

比格犬埃立克体病实验模型研究Ⅲ病原观察

为了观察犬埃立克体病病犬血细胞中病原的感染情况,对6只人工感染埃立克体的比格犬血细胞进行了光镜和透射电镜观察.结果发现,单核细胞的细胞质和血小板中均存在埃立克体包涵体,其中单核细胞的包涵体内病原多达8个,血小板的包涵体内也发现数个病原.这一结果进一步证实我们成功地建立了比格犬埃立克体病实验模型,也为临床上诊断犬埃立克体病提供了形态学依据.     

SUPERPARAMAGNETIC IRON OXIDE-ENHANCED MAGNETIC RESONANCE IMAGING OF THE LIVER IN BEAGLE DOGS

The role of superparamagnetic iron oxide as a tissue-specific contrast medium has been established in humans, especially for hepatic imaging. Superparamagnetic iron oxide particles exhibit a tissue-specific biodistribution to the reticuloendothelial system, where they predominantly shorten transverse T2 relaxation time. Most hepatic tumors lack Kupffer cells; therefore, the T2 of tumors remains virtually unchanged after administration of superparamagnetic iron oxide. The resulting loss of signal intensity from the liver, with unchanged tumor signal intensity, increases lesion-to-liver contrast. In this study, MR images were acquired with fast gradient echo recalled at steady state (FGRE) in five Beagle dogs before and after injection of superparamagnetic iron oxide. The effect of superparamagnetic iron oxide on signal intensity of the liver with time was assessed. A signal intensity decrease of 65.7+/-10.0% was detected at 20 minutes, and it continued to decrease until the last time point of MR scanning (200 minutes). The liver intensity of all dogs dropped to half its value after 20 minutes. The effect of motion was minimized by breath holding. Superparamagnetic iron oxide did not have any adverse effects on the dogs.     

Pharmacokinetics of tildipirosin in beagle dogs

The objective of this study was to investigate the pharmacokinetic profile of tildipirosin (TD) in 24 beagle dogs following intravenous (i.v.) and intramuscular (i.m.) administration, respectively, at 2, 4, and 6 mg/kg. Plasma samples at certain time points (0–14 days) were collected, and the concentrations of drug were quantified by UPLC‐MS/MS. Plasma concentration–time data and relevant parameters were described by noncompartmental through WinNonlin 6.4 software. After single i.m. injection at 2, 4, and 6 mg/kg body weight, mean maximum concentration (C_max) was 412.73 ± 76.01, 1,051 ± 323, and 1,061 ± 352 ng/ml, respectively. Mean time to reach C_max was 0.36 ± 0.2, 0.08 ± 0.00, and 0.13 ± 0.07 hr after i.m. injection at 2, 4, and 6 mg/kg, respectively. The mean value of T_1/2λz for i.m. administration at doses of 2, 4, and 6 mg/kg was 71.39 ± 28.42, 91 .33 ± 50.02, and 96.43 ± 45.02 hr, respectively. The mean residence times were 63.81 ± 10.96, 35.83 ± 15.13, and 38.18 ± 16.77 hr for doses of 2, 4, and 6 mg/kg, respectively. These pharmacokinetic characteristics after i.m. administration indicated that TD could be rapidly distributed into tissues on account of the high lipid solubility and then released into plasma. In addition, the absolute bioavailability of 2 mg/kg after i.m. injection was 112%. No adverse effects were observed after i.v. and i.m. administration.     

美洛昔康片对比格犬的靶动物安全性评价

为研究美洛昔康片对靶动物比格犬的安全性,选取24只健康的比格犬随机分成4组,每组6只。各组试验犬分别以0、推荐剂量(0.2 mg/kg bw)、3倍推荐剂量(0.6 mg/kg bw)、5倍推荐剂量(1.0 mg/kg bw)口服美洛昔康片,每日1次,连续给药7 d。对一般临床状况、采食量、增重、饲料转化率、血液生理和生化指标、病理组织学等进行观察和检测。结果显示,除5倍推荐剂量对犬的肾脏和胃有一定的病理性影响外,其他各项指标与空白对照组相比差异均不显著。表明美洛昔康片毒性小,在犬体内耐受性高,以推荐剂量给药对靶动物犬是安全的。     

High performance liquid chromatography determination of low concentration metformin hydrochloride in beagle dogs plasma

Our objective is to develop a method to quantify low concentration metformin hydrochloride in beagle dog plasma using High Performance Liquid Chromatography(HPLC). HPLC is conducted on a Dikma Diamonsil C18 (150 mm×4.6 mm, 5μm) with acetonitrile-10.0 mmol/L sodium dihydrogen phosphate (7.5 mmol/L SDS, pH5.5)(32:68) as a mobile phase, column temperature 30℃, detection wavelength 235 nm, and flow rate 1.0 mL/min. The internal standard method is used. The results show that the identified characteristics of metformin hydrochloride and the internal standard are distinct. The regression equation is Y =0.686 8X +(-0022 2) r=0.999 5 and the linear range is 0.05~4.0 μg/L. The recovery rates are within 9978%~107.90%. The intra precision RSD is less than 3.85%, and the inter precision is less than 563%. The developed method is sensitive, accurate, rapid and simple, and can be adopted to determine low concentration metformin hydrochloride in beagle dog plasma and in pharmacokinetic study.