环丙沙星(ciprofloxacin)在鸡蛋中残留的研究

应用高效液相色谱法(HPLC)检测了鸡蛋中环丙沙星的残留。鸡蛋经乙腈溶液提取,提取液真空干燥后用流动相溶解。以0.015mol/L四丁基溴化铵/乙腈(94/6,V/V)作流动相,用SymmetryC18柱(5μm,3.9mm×150mm),在激发波长280nm、发射波长455nm处,用荧光检测器检测。将环丙沙星以0.05、0.50、1.00mg/kg分别添加到空白鸡蛋样品中,测得鸡蛋样品中环丙沙星的回收率分别为(82.2±6.8)%、(84.5±5.9)%、(87.9±4.7)%,相对标准差均低于8.3%。用该方法测定鸡蛋中环丙沙星的最低检测限为0.01mg/kg。各试验组产蛋鸡给药剂量分别按10.0、20.0mg/kg(体质量)内服环丙沙星水溶液,每天给药1次,连续5d。停药后鸡蛋中环丙沙星残留消除缓慢;休药8~9d时,鸡蛋中环丙沙星残留量低于0.03mg/kg;休药9~10d时,鸡蛋中环丙沙星残留量均低于最低检测限(0.01mg/kg);且随着环丙沙星给药剂量的增大,环丙沙星在鸡蛋中的残留量也相应增大。     

脱氢醋酸钠在猪组织中的残留研究

旨在研究脱氢醋酸钠作为饲料防霉剂应用后在猪组织中的残留消除。选用33只健康杜长大三元杂交猪,200 mg/kg脱氢醋酸钠拌料饲喂1个月。分别于停药1～21 d的不同时间取肌肉、肝脏、肾脏和脂肪组织, HPLC法测定脱氢醋酸钠含量。结果表明,脱氢醋酸钠在猪肾脏和肝脏组织中的残留水平较高,肌肉次之,脂肪中最少。休药1 d时,猪肾脏、肝脏、肌肉和脂肪中的平均残留量分别为1.12 mg/kg、1.06 mg/kg、0.59 mg/kg和0.21 mg/kg;脱氢乙酸钠在组织中的含量低于定量限0.2 mg/kg水平所需要的休药时间分别为:肌肉6 d、肝脏11 d、肾脏13 d、脂肪1 d后。脱氢乙酸钠在猪不同组织中的残留消除半衰期分别为:肌肉6.7 d、肝脏7.2 d、肾脏9.1 d、脂肪5.4 d。上述结果显示,脱氢乙酸钠在猪组织中的残留消除相对较快,组织残留量均低于1.2 mg/kg。     

恩诺沙星混悬液的研制及其在鸡组织中的残留研究

以恩诺沙星为主药,采用正交试验筛选配方,研制恩诺沙星混悬液,并对该制剂的药剂学特征及其在鸡组织中的残留进行研究。药剂学研究表明,混悬液的性状、pH及药物含量均符合混悬剂质量要求,且稳定性良好、易于再分散。健康鸡在饮水中添加75 mg/L(以恩诺沙星计)混悬液,自由饮水,连续用药5 d后休药;休药第5天,肌肉、肝脏及"皮肤+脂肪"组织中药物总残留量(恩诺沙星+环丙沙星)分别为11.12±10.53、79.29±28.86、50.08μg/kg±22.09μg/kg,而肾脏组织未检出;休药第8天,肌肉、肾脏、肝脏组织中均未检出恩诺沙星及环丙沙星,"皮肤+脂肪"的总残留量为13.84μg/kg±10.82μg/kg。采用WT1.4软件处理数据,计算出该混悬液在鸡体内的休药期为6 d。     

高效液相色谱法检测多种动物组织中氟喹诺酮类药物残留量的研究

建立了猪、牛、羊、鸡、兔的肌肉、脂肪、肝脏和肾脏四种组织中环丙沙星、达氟沙星、恩诺沙星、沙拉沙星和二氟沙星残留量检测的高效液相色谱法。试样经磷酸盐溶液提取,C18固相萃取柱浓缩净化后,用高效液相色谱分析,荧光检测器检测,外标法定量。5种药物在0.1～100μg/L浓度范围内线性关系良好。环丙沙星、恩诺沙星、沙拉沙星和二氟沙星在五种动物肌肉、脂肪组织中的定量限为5μg/kg,在肝脏、肾脏组织中的定量限为10μg/kg;达氟沙星在肌肉、脂肪组织中的定量限为1μg/kg,在肝脏、肾脏组织中的定量限为2μg/kg。在指定的三个浓度添加水平下,5种药物在各组织中的平均回收率为62%～103%;批内变异系数为0.30%～18%,批间变异系数为1.0%～17%。该方法操作简单,准确度和精密度好,动物品种及动物组织覆盖范围广,可以很好地满足实际检测工作的需要。     

盐酸沃尼妙林预混剂在猪组织中残留消除规律研究

建立了猪肝脏、肾脏、肌肉和脂肪中盐酸沃尼妙林的高效液相色谱检测方法并研究盐酸沃尼妙林预混剂在猪体内各组织中的残留消除规律。对24头健康猪以200mg/kg的剂量混饲给药21d。在停药后0、6、12、18、24、36h分别宰杀4头猪,采集各组织进行药物残留测定。方法的检测限为0.025～0.062 5μg/g,定量限为0.05～0.1μg/g,肝脏的平均回收率为75.5%～76.4%,变异系数为2.3%～3.8%;肾脏的平均回收率为75.8%～78.5%,变异系数为4.1%～6.0%;肌肉的平均回收率为79.3%～80.0%,变异系数为3.0%～4.7%;脂肪的平均回收率为76.7%～77.3%,变异系数为3.3%～5.4%。结果表明,盐酸沃尼妙林在肝脏中残留量最高,肾脏其次;肌肉和脂肪中的残留量显著低于肝脏和肾脏,停药24h时,残留量低于定量限;停药36h时残留量均低至检测限以下。盐酸沃尼妙林预混剂在猪组织中消除迅速,建议休药期为2d。     

猪肾脏等组织中盐酸莱克多巴胺的HPLC检测方法及其残留消除

本研究建立了猪肝脏、肾脏、肌肉和脂肪中盐酸莱克多巴胺的高效液相色谱检测方法。方法的检测限为1ng/g,定量限为2 ng/g,肝脏的平均回收率在73.4%～83.2%,变异系数在2.1%～6.6%;肾脏的平均回收率在73.1%～95.5%,变异系数在3.8%～4.0%;肌肉的平均回收率在80.7%～82.5%,变异系数在4.9%～9.1%;脂肪的平均回收率在73.3%～78.8%,变异系数在2.9%～6.7%。对60头健康猪以18 mg/kg的剂量混饲给药28d,停药饲喂14 d。在给药7、142、8 d和停药1、2、3、7、9、14 d分别屠宰6头猪,取各组织进行残留量测定。结果显示：肾脏中残留量最高,肝脏其次,残留量在停药期间较给药期间显著降低。其中肾脏和肝脏中的残留量分别在停药14 d、停药9 d后降至定量限以下;肌肉和脂肪中的残留量显著低于肾脏和肝脏,给药28 d时,残留基本低于定量限;停药1 d时均低至检测限以下。     

脱氢乙酸钠在肉鸡组织中的残留消除

研究脱氢乙酸钠作为饲料防霉剂在鸡组织中的残留消除,为其在鸡组织中的残留监控及休药期的制定提供理论依据。黄羽肉鸡连续饲喂200 mg/kg脱氢乙酸钠30 d后,于不同时间分别取肌肉、肝脏、肾脏和皮脂样品,采用反相高效液相色谱(HPLC)方法测定样品中脱氢乙酸钠含量。休药1 d时,鸡肾脏、肝脏、肌肉和皮脂中脱氢乙酸钠残留量分别为0.68、0.59、0.34和0.20 mg/kg。随着休药时间延长,各组织中脱氢乙酯钠的残留量逐渐降低,脱氢乙酸钠在肉鸡各组织中的残留水平依次为肾脏、肝脏、肌肉和皮脂。在组织中的残留消除半衰期分别为肾脏5.86 d、肝脏6.02 d、肌肉8.88 d及皮脂为10.38 d。若以0.2 mg/kg为临时最大残留限量(MRLs),则脱氢乙酸钠在鸡不同组织中的休药期分别为肾脏12.37d、肌肉9.37 d、肝脏9.18 d、皮脂4.16 d。得出结论:200 mg/kg脱氢乙酸钠拌料饲喂肉鸡30 d,在肉鸡各组织中的残留水平较低,均低于0.7 mg/kg;残留消除相对较快。     

阿莫西林在鸡组织中的残留消除规律

本试验旨在研究阿莫西林在鸡组织中残留消除规律。鸡组织样品经磷酸二氢钠溶液提取,乙腈去蛋白,正己烷去脂肪,饱和二氯甲烷萃取,上清液经水杨醛在酸性条件下沸水浴衍生化后,在激发波长358nm、发射波长440nm处用高效液相色谱荧光检测器检测。该方法测定鸡组织中阿莫西林的检测限为5μg/kg、定量限为13μg/kg。阿莫西林在鸡组织样品中平均回收率为73.64%~88.82%,相对标准差为6.21%~9.63%。各试验组京海黄鸡分别按体质量以30、60mg/kg剂量内服阿莫西林,每天1次,连续给药7d,休药4h后(零休药期)各组织中阿莫西林残留量最高,休药第3天各组织中阿莫西林残留量均迅速降低;休药后第5天阿莫西林残留量低于最高残留限量(50μg/kg);休药第9天所有组织中阿莫西林残留量均低于检测限;休药后相同时间点鸡肌肉中药物残留量最低,肝脏中的药物残留量最高;阿莫西林在鸡肾脏中残留比鸡肌肉、肝脏消除缓慢且消除时间长;阿莫西林在鸡组织中的残留量与给药剂量呈正相关。根据WT1.4软件计算所得,建议黄羽肉鸡按体质量以30、60mg/kg剂量给药,每天1次,连续7d后,其休药期(WT)分别为3、4d。     

氟佐隆在牛组织中残留消除规律的研究

为研究氟佐隆在牛组织中的残留消除规律,1.5 mg/kg体重氟佐隆皮下注射干奶期荷斯坦奶牛,分别于用药后2周、6周、8周、10周、12周和16周用高效液相色谱法(HPLC)检测牛肌肉、肝脏、肾脏和不同部位脂肪中氟佐隆的残留量。HPLC方法的检测限(LOD)为0.02 mg/kg,定量限(LOQ)为0.08 mg/kg。结果表明,氟佐隆残留消除速度较慢,在脂肪组织中的残留量远高于其他组织。氟佐隆在组织中的残留量:脂肪>肝脏>肾脏>肌肉。肌肉中残留量在用药后8周达到峰值,12周后低于检测限;肝脏和肾脏中残留水平在用药后10周达到峰值,16周后接近或低于检测限;脂肪组织中10周后达到峰值,16周后仍高于检测限。皮下、腹部和肾脏脂肪中的残留量没有明显差异(P>0.05)。1.5 mg/kg体重皮下给药后氟佐隆在牛组织中的残留量均不超过JECFA规定的残留限量。     

高效液相色谱-串联质谱法检测鸡蛋和鸡组织中恩诺沙星、环丙沙星残留的研究

为建立一种高效液相色谱-串联质谱法检测鸡蛋和鸡组织(肝脏、肾脏、肌肉、脂肪)中恩诺沙星、环丙沙星的残留,鸡蛋和鸡组织(肝脏、肾脏、肌肉、脂肪)经酸化乙腈提取,正己烷除脂净化,以0.1%甲酸水溶液和乙腈为流动相进行梯度洗脱,同位素内标法定量。结果显示:恩诺沙星、环丙沙星均在线性范围内呈现良好线性关系,相关系数(R2)均大于0.99;恩诺沙星、环丙沙星在组织中的检测限为1μg/kg,定量限为5μg/kg;两种药物的平均回收率范围为75.5%～106%,批内、批间变异系数均小于11.2%。研究表明,该方法样品前处理简单,灵敏度高,适用同时检测鸡组织(肝脏、肾脏、肌肉、脂肪)和鸡蛋中恩诺沙星、环丙沙星残留。     

白术、微米白术和白术多糖对断奶仔猪生长性能和肠道形态及微生态区系的影响

试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Y‐chromosomal variation of local goat breeds of Turkey close to the domestication centre

Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Feline intracranial neoplasia: retrospective review of 160 cases (1985-2001)

The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

A brief history of the prevention of infectious diseases by immunisations

Infectious diseases have always been a terrible scourge for humans. The appearance of these plagues, as they were called without distinction, was generally connected to various conditions: asters, climatic changes or religious reasons. The concept of contagious, and then infectious, diseases came slowly. Variolation, i.e. transmission of ‘virulent’ matter to induce a natural disease and the immunity against it, was brought from Constantinople to England by Lady Montague, in 1721. This ‘variolation’ technique was also often performed in veterinary medicine against diseases like sheep-pox or pleuropneumonia. As ‘vaccination’ is the term generally accepted for ‘immunisation’, variolation can be the word designating such a technique. The second period of the history of immunisation began, in 1880, with the studies of Pasteur and his collaborators. A great number of bacterial vaccines were developed: dead, live but attenuated or only parts of pathogens. The viruses were produced in animals, then in eggs and at last, in tissue cultures. Second generation vaccines appeared with genetic engineering: recombinant vaccines, vector vaccines, nucleic acids vaccines, and markers vaccines, among others. These novel technologies can permit the development of new ones and improve the quality of the vaccines already existing.