山羊源海藻糖比伯斯坦杆菌(Bibersteinia trehalosi)转铁结合蛋白B的克隆与功能鉴定

山羊海藻糖比伯斯坦杆菌(Bibersteinia trehalosi)是造成山羊肺炎重要病原菌之一,其转铁结合蛋白B(transferrin binding protein B,TbpB)结构与功能的研究对于阐明其致病机理有重要作用。本研究在前期分离鉴定菌株基础上,通过生物信息学分析结果显示,海藻糖比伯斯坦杆菌TbpB包含氨基小叶(N-lobe)和羧基小叶(C-lobe)。分别对该菌TbpB~( 20-581 )(In-tact)、N-lobe、C-lobe进行克隆、表达与纯化,对纯化的蛋白与山羊转铁蛋白、绵羊转铁蛋白、猪转铁蛋白、牛转铁蛋白、鸡转铁蛋白进行特异性点阵杂交反应,发现山羊海藻糖比伯斯坦杆菌TbpB In-tact以及N-lobe与山羊转铁蛋白、绵羊转铁蛋白有特异结合反应,而与猪转铁蛋白、鸡转铁蛋白没有反应,山羊海藻糖比伯斯坦杆菌TbpB C-lobe与山羊转铁蛋白、绵羊转铁蛋白、猪转铁蛋白、牛转铁蛋白、鸡转铁蛋白均无反应。结果表明山羊海藻糖比伯斯坦杆菌TbpB与山羊转铁蛋白结合发生在N-lobe。     

一株羊源海藻糖比伯斯坦菌的分离鉴定及生物学分析

海藻糖比伯斯坦菌(Bibersteinia trehalosi)为人兽共患菌,但在我国的研究报道转少。本研究从病死羔羊肺脏组织中分离到一株革兰阴性短杆菌,对其进行了细菌分离、生化试验、16S rDNA和ropB基因的PCR扩增、小鼠致病性试验、药敏试验及四环素抗生素类与产超广谱β-内酰胺酶(ESBLs)等6种耐药基因的PCR检测。结果显示,该菌16S rDNA扩增序列与GenBank中B.trehalosi同源性达99%;其特异性rpoB基因PCR扩增条带与预期一致;对小鼠致病性强;对头孢哌酮、头孢呋辛、复方新诺明、氯霉素等多种抗生素均敏感,对青霉素、丁胺卡那、头孢拉啶耐药,仅扩增出约1 900 bp的BCT耐药基因片段,与公布的BCT基因序列同源性达99%,耐药表型与耐药基因检测结果一致,证明该分离菌株为B.trehalosi。本研究为该菌的有效防控与致病机理的研究奠定了基础,也为养殖临床用药提供参考。     

1株黄牛源多源曼氏杆菌的分离鉴定与转铁结合蛋白B结构预测

为确定引起肺炎病死黄牛的病原，从牛鼻拭子中分离纯化得到1株细菌，经生化试验和分子生物学方法鉴定为多源曼氏杆菌。利用生物信息学软件MEGA7.0对巴氏杆菌科细菌的16S rDNA和巴氏杆菌科、奈瑟菌科细菌的转铁结合蛋白B(TbpB)进行系统进化分析，并对TbpB进行了结构预测。结果显示，分离株16S rDNA基因序列与牛曼氏杆菌ZY190616株、肉芽肿曼氏杆菌ATCC49244株、多源曼氏杆菌10299株相似性最高，位于同一簇内，相似性超过97%;分离株TbpB序列与溶血曼氏杆菌、多源曼氏杆菌相似性较高，位于同一簇内，但与其他菌的TbpB序列相似性较低；TbpB结构模拟显示其序列与已经测定结构的溶血曼氏杆菌TbpB序列相似性较高。药敏试验显示该菌氨基糖苷类、β-内酰胺类抗生素有较强的耐药性，对头孢哌酮和氟喹诺酮类药物敏感小鼠致病性试验证实该分离菌株致死量约为2×10⁹CFU。结果表明，该分离株为多源曼氏杆菌，其TbpB序列与溶血曼氏杆菌和多源曼氏杆菌相似性较高。本研究为后续毒力基因相关研究和疫苗开发提供了理论基础。     

犊牛海藻糖比伯斯坦杆菌分离株鉴定与分析

新疆南疆某规模奶牛场犊牛发生呼吸道疾病,本研究无菌采集发病犊牛的血液、心脏、肝脏及肺脏等组织进行细菌分离培养、染色镜检、生化试验、PCR鉴定,药敏试验及致病性试验,并将分离株16S r RNA序列在NCBI的BLAST中进行了比对和核苷酸同源性比较分析。鉴定结果表明,该分离株为海藻糖比伯斯坦杆菌。     

牦牛源干燥棒状杆菌的分离与鉴定

一只牦牛屠宰后肝有干酪样结节,为了探究其形成原因,本研究对该牦牛肝进行细菌的分离培养,对所分离可疑致病菌的16SrRNA以及rpoB基因序列进行扩增和序列分析,并用Vitek 2全自动微生物鉴定仪进行生化表型的鉴定,用K-B法进行药敏试验。结果显示,经细菌分离培养得到一株革兰阳性、棒状、可疑致病菌;其16S rRNA扩增片段大小1 483bp,GenBank序列编号为MH000696,该菌的16SrRNA与干燥棒状杆菌GD34株(KF928790.1)等的相似性最高,序列一致性为99%,系统进化树显示,本菌与干燥棒状杆菌在同一进化分支上;rpoB基因扩增片段大小434bp,GenBank序列编号为MH006608;Vitek 2全自动微生物鉴定仪鉴定为变异库克菌,可信度为93%。该菌对妥布霉素、氨曲南、头孢哌酮、米诺环素等多种药物高度敏感。综上所述,分离的细菌为干燥棒状杆菌,但基因序列,如rpoB等以及生化表型均存在一定程度的变异,本研究为兽医临床上该菌的分离和鉴定提供了依据,且为该菌的致病性研究奠定了基础。     

鸭源鸡杆菌双重PCR检测方法的初步建立

为建立鸭源鸡杆菌(G.anatis)双重PCR检测方法,并对鸡杆菌分离株进行种类鉴定,本研究根据GenBank中G.anatis12656-12株的gtxA基因序列设计一对PCR引物,合成扩增rpoB基因的引物作为内参基因,建立了G.anatis双重PCR检测方法.检测结果显示:以G.anatis Yu-PDS-RZ-1-SLG株DNA为模板进行的双重PCR检测能够扩增出两条目的片段;其它16株细菌包括副鸡禽杆菌、多杀性巴氏杆菌、大肠杆菌、沙门氏菌、福氏志贺菌和奇异变形杆菌均只扩增出了一条目的片段;该方法可以检测到浓度为6.5×102 cfu/mL的G.anatis;34株鸡杆菌分离株均扩增出了两条预期大小的目的片段.此外,序列分析结果表明,10株鸡杆菌河南分离株的rpoB基因序列与鸭源鸡杆菌种参考株(CCUG15563)的同源性最高(97.5％～99.0％),属于鸭源鸡杆菌种.本研究建立的G.anatis双重PCR检测方法,可用于含gtxA基因鸡杆菌菌株的鉴定及临床病原学诊断.     

藏猪源肺炎克雷伯菌的分离鉴定及生物学特性研究

为了了解西藏地区藏猪源肺炎克雷伯菌荚膜血清型、耐药性、毒力基因及遗传进化现状,试验对从西藏地区林芝市、拉萨市采集的60份腹泻藏猪新鲜粪便进行细菌分离,对分离菌进行生化试验、16S rDNA基因和特异性基因检测并构建系统进化树,采用PCR方法对分离菌进行荚膜血清型、耐药基因和毒力基因检测,用17种常用抗菌药物进行药敏试验,并用分离菌对小鼠进行致病性试验。结果表明：从西藏地区林芝市样品中成功分离鉴定出3株藏猪源肺炎克雷伯菌,分离率为5%(3/60),分别命名为P1、P2、P3菌株。3株分离菌能够发酵多种糖类,且不产生硫化氢。PCR扩增得到大小约为1 400 bp和430 bp的目的条带。3株分离菌均与郑州红袋鼠源CP051490和广州鹦鹉源CP064129聚成一簇,其中P1菌株和P2菌株聚为一个小簇;P3菌株与广州鹦鹉源CP064129聚成一个小簇,亲缘关系最接近。3株分离菌均未鉴定出荚膜血清型。3株分离菌对青霉素、氨苄西林的耐药率最高,达100%;对派拉西林和红霉素的耐药率为66.7%;对头孢氨苄和头孢呋辛的耐药率为33.3%。3株分离菌只携带2种耐药基因,分别为sul2、 blaROB...     

一株肉牛源干燥棒状杆菌的分离鉴定

为了确定河北省昌黎县某肉牛场肉牛发病原因,本研究从呼吸道症状明显的病牛鼻粘液中分离纯化到1株优势菌,采用细菌培养、革兰氏染色、细菌生化鉴定、rpoB基因检测、16S rRNA序列分析方法鉴定,经K-B试纸法检测该分离菌对泰乐菌素、头孢拉定等18种抗生素的药物敏感性。结果显示,分离菌革兰氏染色呈阳性短杆状球菌,在血琼脂培养基上可生长为干燥且粗糙的淡黄色菌落,在LB液体培养基中呈沉淀生长,菌液上层轻微浑浊,下层有颗粒状、片状沉淀;rpoB基因PCR扩增检测结果为阳性;该分离菌具有脂酶、赖氨酸脱羧酶、β-葡萄糖苷酶、α-葡萄糖苷酶活性,能够发酵海藻糖、麦芽糖、蔗糖,结果符合干燥棒状杆菌生化特性;16S rRNA序列比对分析表明,该分离菌与干燥棒状杆菌同源性为99%,一致性为91.6%;对泰乐菌素、头孢拉定等7种药物耐药,对环丙沙星、恩诺沙星等9种药物敏感。试验结果表明该分离菌为干燥棒状杆菌。     

山羊源伪结核棒状杆菌的分离鉴定及其毒力评价

为了确定齐齐哈尔市某山羊养殖场疑似患有伪结核病病羊的病原及其毒力,试验从不同病羊的皮下脓包中采集脓汁病料3份,通过细菌的分离与纯化、生化鉴定、16S rDNA基因的PCR扩增与序列分析确定病原,并通过致病性试验对分离株的毒力进行评价。结果表明：共得到3株分离株,其菌落形态和生化特性菌与伪结核棒状杆菌相符,分别命名为CP045、CP073、CP969;分离株CP045、CP073、CP969的16S rDNA基因序列与伪结核棒状杆菌参考株的相似性分别高达98.8%、100%、99.8%,进一步确定3株分离株均为伪结核棒状杆菌。注射分离株CP073的3只小鼠中有2只于注射后36～48 h陆续死亡,1只精神极度沉郁、食欲不振;注射分离株CP045、CP969的3只小鼠于注射后5 d内均未见死亡,但状态不佳。注射分离株CP045、CP073、CP969的小鼠肝脏均不同程度出血、肿大,脾脏轻微出血;注射分离株CP073的小鼠皮肤表面有黄色脓汁渗出,皮下有黄白色玉米粒大小的结核样脓肿;注射分离株CP045和CP969的小鼠皮下未见明显脓肿。说明该山羊养殖场疑似患有伪结核病的病羊感染了伪结核棒状杆菌...     

豫陕两省14株鸡杆菌的gyrB、16S rRNA和rpoB基因序列比较分析

分析河南、陕西分离的14株鸡杆菌(Gallibacterium)之间的进化关系,及gyrB基因序列比较在该菌进化分析中的作用。PCR扩增鸡杆菌分离株的gyrB、16SrRNA和rpoB3个看家基因,PCR产物纯化后直接测序。将鸡杆菌分离株、国外参考株的3个看家基因序列进行比较分析,用Phylip 3.67软件构建进化树。结果表明,14株鸡杆菌与鸭源鸡杆菌(Gallibacterium anatis)模式株间的相似性为96.3%～98.0%(gyrB)、97.7%～99.6%(16SrRNA)和97.7%～99.0%(rpoB);14株鸡杆菌与鸡杆菌复合群1(Gallibacterium genomosp.1)参考株间的相似性为88.8%～89.9%(gyrB)、96.2%～97.5%(16SrRNA)和92.6%～93.6%(rpoB)。基于3个看家基因序列的进化分析,均显示14株鸡杆菌和鸭源鸡杆菌模式株形成单独的一个群。14株鸡杆菌分离株均属于鸭源鸡杆菌种;在3个看家基因位点,鸡杆菌河南株与陕西株之间、鸡杆菌输卵管炎病鸡分离株与健康鸡分离株之间均无明显遗传上的差异;gyrB基因序列分析可用于鸡杆菌分离株的种类鉴定,且对14株鸡杆菌与复合群1参考株的区别能力优于另外2个看家基因。     

Dose-related antinociceptive effects of intravenous buprenorphine in cats

The dose-related antinociceptive effects of intravenous (IV) buprenorphine were evaluated in cats. Thermal (TT) and mechanical threshold (MT) devices were used for nociceptive stimulation. After baseline threshold recordings, buprenorphine was administered IV (0.01, 0.02 or 0.04 mg/kg; B1, B2 and B4, respectively) in a randomised, blinded and cross-over study. Data were analysed by ANOVA (P < 0.05) using 95% confidence intervals (CI). TT increased 15, 30, 45 min and 1 (5.2 ± 2.7 °C), 2, 3 and 4 h after B1; 15, 30, 45 min and 1 (5.1 ± 3.9 °C) and 2 h after B2, and 15, 30, 45 min and 1 (5.4 ± 3.3 °C), 2, 3, 6 and 8 h after B4. MT increased 15 and 45 min after B2 (260 ± 171 mmHg), and 30 (209 ± 116 mmHg) and 45 min and 1 and 2 h after B4. At 45 min, MT values were significantly higher after B2 compared to B1 (P < 0.05). With MT, B2 and B4 produced more antinociception and longer duration of action than B1, respectively. No dose response to thermal stimulation was detected.     

Effect of storage duration on egg quality,embryo mortality and hatchability in FUNAAB-ɑ chickens

Effect of extended storage on egg quality, embryo mortality and hatchability in FUNAAB-ɑ chickens was determined. Hatchable eggs (n = 288; weighing 53.2 ± 4.67 g) collected from a flock of FUNAAB-ɑ layer breeder hens aged 32 weeks were stored in egg tray with broad end up under 16 ± 1.5°C for either 0, 4, 8, 12, 16 or 20 d. Before incubation, eight eggs from each group were evaluated for internal and external quality traits. Remaining eggs were set in an incubator and transferred into hatcher on embryonic day 18. Data collected were subjected to one-way analysis of variance. Egg weight loss (EWL; p < .001), surface area (p < .001), yolk diameter (p < .001), inner and outer blastoderm diameters (p < .05) and dead in germ (DIG; p < .001) increased with storage duration while yolk height (p < .001), yolk index (p < .001), albumen weight (p < .05), albumen height (p < .05), albumen index (p < .01), Haugh's unit (HU; p < .05), fertility (p < .001), hatchability of set (HATCHS; p < .001) and fertile eggs (p < .05) decreased. Weight losses of 0, 1.2, 2.2, 3.4, 4.6 and 6.1% were recorded in egg stored for 0, 4, 8, 12, 16 and 20 days respectively. Eggs stored beyond 8 days exhibited higher DIG and lower HATCHS. Shell percentage in 4 days storage (11.4%) was lower (p < .05) than in 16 days storage (13.4%). Shell thickness was similar in eggs stored for 0 to 12 days, but 8 days storage (0.60 mm) had thinner (p < .01) shell than day 16 (0.71 mm) and day 20 (0.73 mm) storage. Internal quality unit (IQU) was higher (p < .05) in fresh eggs (180.4) than in 12 days (167.8) and 20 days (167.8) stored eggs. Extended storage of FUNAAB-ɑ eggs caused EWL, surface area shrinkage, lowered HU and IQU, loss of yolk and albumen quality, increased blastoderm diameters and DIG, and decreased egg fertility and HATCHS from day 8 forward. Storing FUNAAB-ɑ eggs beyond 8 days reduced quality parameters; therefore, other mitigating factors are recommended when storing beyond 8 days.     

Low‐density lipoproteins and milk serum proteins improve the quality of stallion sperm after vitrification in straws

Lipids and proteins can be used for sperm vitrification to preserve the integrity of sperm membranes or to increase the viscosity of the medium. This study evaluated the effect of low‐density lipoproteins (LDL) and milk serum proteins (Pronexcell) for stallion sperm vitrification. Hippex extender (Barex Biochemical Products, The Netherlands), plus 1% of bovine serum albumin and 100 mM of trehalose, was used as control for sperm vitrification. In experiment 1, different concentrations of LDL (L1 = 0.25, L2 = 0.5, L3 = 1%) and in experiment 2 of Pronexcell (P1 = 1, P2 = 5, P3 = 10%) were added to control extender. Vitrification was performed in 0.25‐ml straws directly plunged into liquid nitrogen. Total motility (TM, %) and progressive motility (PM, %) were analysed by CASA, and plasma membrane (IMS, %) and acrosome membrane integrity (AIS, %) were assessed under epifluorescence microscopy. Post‐warmed sperm parameters were compared between treatments by ANOVA. Results were expressed as mean ± SEM. In both experiments, the minimum concentration of LDL and Pronexcell obtained significantly higher values (p < 0.01) than the control extender for TM (L1 = 52.95 ± 4.4; P1 = 58.99 ± 4.6; C = 30.88 ± 3.0), PM (L1 = 36.79 ± 5.5; P1 = 47.25 ± 4.3; C = 19.20 ± 2.4), IMS (L1 = 68.88 ± 3.6; P1 = 47.25 ± 4.3; C = 52.81 ± 2.6) and AIS (L1 = 45.88 ± 3.6; P1 = 47.25 ± 4.3; C = 26.00 ± 2.1). No differences in sperm parameters were found among different concentrations of LDL or Pronexcell. In conclusion, the addition of 0.25% LDL and 1% Pronexcell to the vitrification extender is recommended to improve the quality of stallion sperm after vitrification.     

Comparison of the sedative effects of intranasal or intramuscular dexmedetomidine at low doses in healthy dogs: a randomized clinical trial

ObjectiveTo compare the sedative effects of dexmedetomidine administered either intranasally or intramuscularly to healthy dogs.Study designProspective, randomized, blinded, clinical trial.AnimalsA group of 16 client-owned healthy dogs.MethodsDogs were randomly allocated to one of two groups that were administered dexmedetomidine 5 μg kg^–1 via either the intranasal route (IN_Dex), through a mucosal atomization device in one nostril, or the intramuscular route (IM_Dex), into the epaxial muscles. Ease of intranasal administration, sedation score, onset of sedation, cardiopulmonary variables, mechanical nociceptive thresholds (MNTs) and response to venous catheterization were recorded at 0 (baseline), 5, 10, 15, 20, 25, 30, 35, 40 and 45 minutes, following drug administration. Data were compared with the one-way anova, Mann-Whitney U test, and chi-square test, where appropriate.ResultsGroups were not different for age, sex, weight, body condition score or temperament. Sedation scores, MNTs and response to intravenous catheter placement were not different when dexmedetomidine was administered by either route (p = 0.691; p = 0.630 and p = 0.435, respectively). Onset of sedation was not different between groups IN_Dex and IM_Dex reaching a score of 4.2 ± 0.9 and 5.5 ± 1.2 at 9 ± 5 and 8 ± 4 minutes, respectively (p = 0.467). The highest sedation score was achieved at 30 and 35 minutes and sedation scores were 9.7 ± 2.0 and 9.5 ± 2.3 in groups IN_Dex and IM_Dex, respectively (p = 0.799). Respiratory rate was higher in group IN_Dex (p = 0.014), while there were no differences between routes in heart rate (p = 0.275), systolic (p = 0.957), diastolic (p = 0.837) or mean arterial pressure (p = 0.921).Conclusions and clinical relevanceIntranasal administration of dexmedetomidine at 5 μg kg^–1 provides effective sedation in healthy dogs.     

A meta-analysis on effects of supplementing low-quality roughages with foliages from browses and tree fodders on intake and growth in sheep

A meta-analysis of data obtained from previous studies was conducted to understand the responses of foliage supplementation on intakes of basal DM (BDMI) and total DM (TDMI), and daily gain (ADG). Thirty-four published studies containing 223 treatments and 1127 sheep met criteria for inclusion in the meta-analysis. Major predictive variables considered were percentages of foliages in diet (SD), CP in foliages (PS), NDF in foliages (FS), NDF in forages (FB), CP in basal roughages (PB), CP in diet (PD) and foliage CP intake (SPI). TDMI (g/d) increased quadratically (P < 0.001) with increasing PS, FS, SPI (R² = 0.66), PB, SD (R² = 0.58) and PD (R² = 0.73). The maximal response of TDMI were 778 g/d at 42% of SD, 894 g/d at 19.8% PD, 893 g/d at 148 g/d SPI and 749 g/d at 26.4% PS (P < 0.001; R² = 0.58, 0.73, 0.66, and 0.37, respectively). BDMI increased quadratically with increasing SD, PD and PB, but decreased quadratically (P < 0.001) with increasing PS (P < 0.001; R² = 0.07). The breakpoint of BDMI was 570 g/d at 6.58% of PD in the diet (P < 0.001, R² = 0.28). Overall, BDMI responded at very low level of SD in the diet, peaking at 7.6% SD with BDMI of 572 g/d (P < 0.001, R² = 0.72). However, when PB was less than 3%, the maximal BDMI was 489 g/d at foliage levels of 25.7%. When PB was between 3 and 6%, maximal BDMI was at 13% of foliage in the diet and the basal forage intake of 597 g/d; whereas, BDMI decreased linearly with SD when PB was greater than 6%. BDMI (g/d) decreased quadratically when foliage CP percentages were lesser than 10%, but increased quadratically with PS when foliage CP percentages were greater than 10%. ADG responded positively and quadratically to PS, SPI, SD, PD and TDMI (g/d) and the relationships were moderate to high. However, ADG (g/d) decreased linearly with increasing FS (P < 0.001, R² = 0.35). The maximal ADG was 42 g/d at 43% of SD, 41 g/d at 9.4% PD, 42 g/d at 53 g/d SPI, 35 g/d at 25% PS and 46 g/d at TDMI of 889 g/d (P < 0.001; R² = 0.74, 0.84, 0.74, 0.29 and 0.74, respectively). It is concluded that the interactions of quality and quantity of foliage supplements and quality of basal forages affect intakes of basal and total DM, and growth in sheep.     

Influence of dietary lysine level on whole-body protein turnover, plasma IGF-I, GH and insulin concentration in growing pigs

Four growing pigs (initial liveweight 25.9 ± 0.54 kg, final liveweight 43.0 ± 1.06 kg) were used to study the effect of dietary lysine level on nutrient digestibility, whole-body protein turnover, plasma insulin-like growth factor-I (IGF-I), growth hormone (GH), insulin, glucose, and urea nitrogen (PUN). Four diets, containing 7.0 g (L1), 9.5 g (L2), 12.0 g (L3) and 14.5 g (L4) lysine per kg diet respectively, were formulated as experimental treatments. The animals and diets were allocated in a 4 × 4 Latin square design. Nitrogen (N) metabolism and whole-body protein turnover were measured by classical method and single-dose ¹⁵N end-product method, respectively. The blood samples were taken at the end of each experimental period. Results showed that N retention (NR) and N biological value (NBV) were significantly increased from L1 to L4 (P < 0.05). However, differences in NR and NBV between L2, L3 and L4 were not significant (P > 0.05). There was no significant difference on dry matter (DM) digestibility, organic matter (OM) digestibility and N digestibility between different treatments (P > 0.05). Whole-body protein synthesis, protein degradation and protein accretion increased markedly from L1 to L2 (P < 0.05), but did not increase further from L2 to L4. Whole-body protein accretion (y, g/kg W^0.75/d) increased with dietary lysine (x, g/kg) in a quadratic manner: y = − 0.09x² + 2.12x − 5.14 (r² = 0.96, n = 4, P < 0.05).The results also showed that differences in plasma IGF-I, GH, glucose and PUN concentration between different treatments were not significant (P > 0.05). Plasma insulin concentration (y, μIU/ml) was increased with dietary lysine (x, g/kg) in a quadratic manner: y = 0.23x² − 4.10x + 32.25 (r² = 0.99, n = 4, P < 0.05), but it was not found that plasma insulin concentration was related to NR. A significant correlation was found between NR (y, g/d) and plasma IGF-I (x, ng/ml): y = − 3.1 × 10^− 3x² + 1.31x − 122.28 (r² = 0.99, n = 4, P < 0.05).It was concluded that dietary lysine level had a significant influence on NR and whole-body protein turnover but not on plasma IGF-I and GH concentration. Plasma IGF-I may be an important factor controlling N metabolism of growing pigs. Further research was needed to study the mechanism.     

Effect of food on the pharmacokinetics of oral cefuroxime axetil in dogs

Cefuroxime axetil pharmacokinetic profile was investigated in 12 Beagle dogs after single intravenous and oral administration of tablets or suspension at a dose of 20 mg/kg, under both fasting and fed conditions. A three-period, three-treatment crossover study (IV, PO under fasting and fed condition) was applied. Blood samples were withdrawn at predetermined times over a 12-hr period. Cefuroxime plasma concentrations were determined by HPLC. Data were analyzed by compartmental analysis. No statistically significant differences were observed between formulations and feeding conditions on PK parameters. Independently of the feeding condition, absorption of cefuroxime axetil after tablet administration was low and erratic. The drug has been quantified in plasma in 3 out of 6 and 5 out of 6 dogs in the fasted and fed groups. For this formulation, the bioavailability (F), peak plasma concentration (C_max), and area under the concentration–time curve (AUC) of cefuroxime axetil were significantly enhanced (p < .05) by the concomitant ingestion of food (32.97 ± 13.47–14.08 ± 7.79%, 6.30 ± 2.62–2.74 ± 0.66 µg/ml, and 15.75 ± 3.98–7.82 ± 2.76 µg.hr/ml for F, C_max, and AUC in fed and fasted dogs, respectively), while for cefuroxime axetil suspension, feeding conditions affected only the rate of absorption, as reflected by the significantly shorter absorption half-life (T_½(a)) and time to peak concentration (T_max) (0.55 ± 0.27–1.15 ± 0.19 hr and 1.21 ± 0.22–1.70 ± 0.30 for T_½(a) and T_max in fed and fasted dogs, respectively). For cefuroxime axetil tablets, T > MIC (≤1 µg/ml) was <2 hr in fasted and ≈4 hr in fed animals, and for cefuroxime axetil suspension, T > MIC (≤1 µg/ml) was ≈5 hr and for T >MIC (≤4 µg/ml) was ≈2.5 hr for fasted and fed dogs, respectively. Cefuroxime axetil as a suspension formulation seems to be a better option than tablets. However, its short permanence in plasma could reduce its clinical usefulness in dogs.     

Factors affecting dystocia and offspring vigour in different sheep genotypes

Birth difficulty and poor lamb vigour are significant causes of perinatal lamb mortality. In this study we investigated whether sheep breeds differing in appearance, muscularity and selection history also had differences in dystocia and lamb vigour, and considered some of the factors that may contribute to the variation in these traits. Data were collected at birth from a total of 3252 lambs of two terminal sire breeds selected for lean growth (Suffolk [S], n = 500 and Texel [T], n = 1207), from a Hill breed (Scottish Blackface [B], n = 610), which has been mainly selected for hardiness, and a crossbred (Mule × T [M], n = 935) representing a maternal line. For each lamb the degree of assistance at delivery, lamb presentation, amount of assistance to achieve successful sucking, sex, litter size and birth weight were recorded. T lambs required the most, and B and M lambs the least assistance at birth, S lambs were intermediate (% lambs assisted: T = 55.7, S = 30.7, B = 22.7, M = 24.9, P < 0.001). T and S lambs were equally likely to be malpresented at birth (29% of births) and more likely to be malpresented than B or M lambs (20%; P < 0.001). In T and S breeds lambs requiring veterinary assistance at delivery were mainly heavy and singleton lambs, whereas in B and M breeds these were exclusively low birth weight lambs in multiple litters. Although heavier lambs needed greater birth assistance, T lambs were lighter than S and M lambs, but heavier than B lambs (birth weight (kg): S = 4.66, M = 4.56, T = 4.32, B = 3.67, P < 0.001). S lambs were more likely to require assistance with sucking than other breeds, and T lambs also required more assistance than B or M lambs (% lambs assisted to suck: S = 56.0, T = 31.6, M = 19.8, B = 18.4, P < 0.001). Heavier lambs were more likely to suck unaided than lighter lambs (P < 0.001). The data suggest that the two terminal sire breeds, selected narrowly for greater productivity (muscle growth and conformation), are more likely to experience birth difficulty and poorer lamb vigour than the breed selected for hardiness, or the cross breed. Whether these effects arise as a consequence of genetic selection (e.g. for specific lamb conformation), or as a result of management practices to achieve selection goals (e.g. increased intervention at lambing) is unknown. Specific actions to improve birth difficulty and lamb vigour, such as including these traits in the selection index, would be beneficial in improving the welfare of ewes and lambs of the terminal sire breeds.     

Efficacy of a mephentermine‐based product as a vasopressor and a cardiac performance enhancer when given intramuscularly to cattle

The goal of this study was to confirm the vasopressor and cardiac effects of POTENAY^® INJETÁVEL (POT), a mephentermine‐based product, given to cattle with induced vascular/cardiac depression. Ten healthy Holstein cattle (206 ± 13 kg) followed a randomized‐complete‐block design (RCBD) utilizing crossover study design. Each animal randomly received (1 ml/25 kg, IM) of either POT (n = 10) or volume‐matched placebo control (0.9%NaCl, CP, n = 10). A subset of animals (n = 5) received POT first (day 0) while the remaining (n = 5) received CP; after a six‐day washout period, cattle received the opposite compound. Animals were anesthetized and catheterized for systemic/left ventricular hemodynamic monitoring. Myocardial dysfunction/hypotension was induced by increasing the end‐tidal isoflurane concentration until arterial blood pressure was 20% lower than at baseline and remained stable. Once the animal was determined to be hypotensive and hemodynamically stable, steady‐state hypotensive baseline data (BL2) were acquired, and treatment with either POT or CP was given. Data were acquired post‐treatment at every 15 min for 90 min. POT improved cardiac output (+68 L/min, ±14%, p < 0.05), MAP (+14 mmHg, ±4%, p < 0.05), HR (+22 bpm, ±8%, p < 0.05), and peak rates of ventricular pressure change during both systole (dP/dt_max: +37 mmHg/s ±13%, p < 0.05) and diastole (dP/dt_min: +31 mmHg/s, ±7%, p < 0.05). No improvements were noted following placebo‐control administration. Results indicate that POT improves cardiac performance and systemic hemodynamics in cattle with induced cardiovascular depression when given as single intramuscular injection.     

Cardiopulmonary and sedative effects of intravenous or epidural methadone in conscious dogs

Cardiopulmonary and sedative effects of intravenous or epidural methadone were compared. Six beagles were randomly assigned to group MIV (methadone 0.5 mg/kg IV + NaCl 0.9% epidurally) or MEP (methadone 0.5 mg/kg epidurally + NaCl 0.9% IV). Cardiopulmonary, blood gas and sedation were assessed at time (T) 0, 15, 30, 60, 120, 240 and 480 min after drug administration. Compared to T0, heart rate decreased at T15–T120 in MIV (p < .001) and T15–T240 in MEP (p < .05); mean arterial pressure was reduced at T15–T60 in MEP (p < .01); respiratory rate was higher at T15 and T30 in both groups (p < .05); pH was lower at T15–T120 in MIV (p < .01) and T15, T30 and T120 in MEP (p < .05); PaCO₂ was higher at T15–T60 in MIV (p < .01) and T15, T30 and T120 in MEP (p < .01); sedation scores were higher at T15 and T30 in MIV and T15–T60 in MEP (p < .05). At T120 and T240, sedation score was higher in group MEP compared with group MIV (p < .01) In conclusion, cardiopulmonary and sedative effects of identical methadone doses are similar when administered IV or epidurally to conscious healthy dogs.