托芬那酸注射液在犬体内的生物等效性研究

为研究国产和进口托芬那酸注射液在犬体内的药代动力学和生物等效性,采用双处理、双周期随机交叉试验设计,将20头健康比格犬随机分成2组,按0.1 m L/kg体重肌肉分别单剂量注射受试制剂和参比制剂,采用高效液相色谱法测定血浆中托芬那酸的浓度,利用WinNonlin6.3软件计算主要药动学参数,并评价两种制剂的生物等效性。结果显示,受试制剂和参比制剂的Tmax分别为(0.2±0.1)h和(0.3±0.2)h;Cmax分别为(5.12±1.55)μg/m L和(5.38±2.04)μg/m L;AUC0-t分别为(12.1±2.97)μg·h·m L~(-1)和(12.28±3.24)μg·h·m L~(-1);AUC_(0-∞)分别为(13.38±3.10)μg·h·m L~(-1)和(13.85±3.40)μg·h·m L~(-1)。托芬那酸注射液受试制剂和参比制剂的AUC_(0-t)、AUC_(0-∞)、C_(max)、T_(max)均无显著性差异(P0.05)。双单侧t检验结果显示两种制剂生物等效,临床上可相互替代。该试验为兽医临床给药方案的制定以及合理用药提供参考。     

阿莫西林混悬注射液在猪体内的生物等效性研究

为了研究阿莫西林混悬注射液在猪体内的药代动力学和生物等效性,采用双处理、双周期随机交叉试验设计,将24头健康猪随机分成2组,按15 mg/kg体重肌肉分别单剂量注射受试制剂和参比制剂,采用高效液相色谱法测定血浆中阿莫西林的浓度,利用Win Nonlin6.4软件计算主要药动学参数,并评价两种制剂的生物等效性。结果显示,受试制剂和参比制剂的Tmax分别为(3.45±2.49)h,(1.34±1.74)h;Cmax分别为(6.94±4.73)mg/L,(4.39±2.87)mg/L;AUC0-t分别为(37.00±11.48)mg·h·L-1,(30.02±8.93)mg·h·L-1;AUC0-∞分别为(40.26±13.36)mg·h·L-1,(38.46±15.38)mg·h·L-1。阿莫西林混悬注射液受试制剂和参比制剂的AUC0-t、AUC0-∞、Cmax、Tmax均有显著性差异,双单侧t检验结果显示两种制剂生物不等效,试验为兽医临床给药方案的制定以及合理用药提供参考。     

硫酸头孢喹肟注射液在猪体内的生物等效性研究

为研究国产和进口硫酸头孢喹肟注射液(7.5%)在猪体内的药代动力学特征和生物等效性,采用双处理、双周期随机交叉试验设计,将20头健康三元杂交猪随机分成2组,按3mg/kg体重分别单剂量肌内注射受试制剂和参比制剂。采用超高效液相色谱-串联质谱法测定血浆中头孢喹肟的浓度,利用Win Nonlin6.3软件计算主要药动学参数,并评价两种制剂的生物等效性。结果显示,受试制剂和参比制剂的Tmax分别为2.30±0.73h和2.25±0.55h;Cmax分别为2.37±0.34μg/mL和2.45±0.36μg/mL;AUC0-t分别为26.38±2.30μg·h·mL^-1和24.86±2.19μg·h·mL^-1;AUC0-∞分别为26.74±2.34μg·h·mL^-1和25.07±2.20μg·h·mL^-1。硫酸头孢喹肟注射液受试制剂和参比制剂的AUC0-t、AUC0-∞、Cmax、Tmax均无显著性差异(P>0.05)。双单侧t检验结果显示两种制剂生物等效,临床上可相互替代。该试验可为兽医临床合理用药提供参考。     

盐酸贝那普利咀嚼片在犬体内的生物等效性研究

为研究国产和进口盐酸贝那普利片在犬体内的药代动力学和生物等效性,将20只健康比格犬随机分成2组,采用双周期交叉试验设计,按0.5 mg/kg体重分别单剂量口服受试产品和参比产品。采用UPLC-MS/MS法测定血浆中盐酸贝那普利及贝那普利拉的浓度,利用WinNonlin5.2.1软件计算主要药动学参数,并评价两种产品的生物等效性。结果显示,受试产品和参比产品中盐酸贝那普利Tmax分别为（0.85±0.36）h和（0.98±0.40）h;Cmax分别为（65.85±31.14）ng?mL-1和（52.02±25.79）ng?mL-1;AUC0-t分别为（46.98±29.77）h?ng?mL-1和（40.54±20.76）h?ng?mL-1;AUC0-∞分别为（48.28±30.05）h?ng?mL-1和（41.54±20.85）h?ng?mL-1;受试产品和参比产品的贝那普利拉Tmax分别为（1.78±0.55）h和（1.90±0.72）h;Cmax分别为（63.05±28.44）ng?mL-1和（55.29±36.01）ng?mL-1;AUC0-t分别为（249.09±87.90）h?ng?mL-1和（212.50±90.03）h?ng?mL-1;AUC0-∞分别为（274.15±93.86）h?ng?mL-1和（264.42±161.86）h?ng?mL-1。受试产品和参比产品的Tmax、Cmax、AUC0-t和AUC0-∞均无显著性差异（P>0.05）。双单侧t检验及90%置信区间结果均提示两种制剂生物等效,临床上可相互替代。该试验为兽医临床安全使用该药提供科学的依据。     

两种磷虾油在家兔体内的药动学及生物利用度研究

为了研究两种磷虾油在家兔体内的药动学及生物利用度评价,将18只家兔随机分成3组,分别单剂量灌服南极磷虾油(受试制剂T1),太平洋磷虾油(受试制剂T2),鱼油(参比制剂R)。用GC-MS检测血浆中EPA,DHA的浓度,采用3p97程序计算药动学参数。结果对EPA而言,参比制剂R与受试制剂T1,T2的峰浓度(Cmax)分别为(190.03±4.21μg/m L),(192.79±3.64μg/m L),(218.35±5.47μg/m L);达峰时间(Tmax)分别为(8.02±0.65)、(12.04±0.31)、(12.10±0.24)h;药时曲线下面积(AUC)分别为(23.32±6.72),(20.43±4.58),(19.23±6.24 mg)h/m L。对DHA而言,参比制剂R与受试制剂T1,T2的峰浓度(Cmax)分别为(243.50±3.47μg/m L)、(219.52±2.04μg/m L)、(233.27±2.87μg/m L);达峰时间(Tmax)分别为(7.04±0.52)、(10.06±0.60)、(7.10±0.29)h;药时曲线下面积(AUC)分别为(16.08±4.98)、(23.49±4.84)、(9.70±0.67 mg)h/m L。以鱼油做为对照物,南极磷虾油中EPA和DHA的相对生物利用度(F)分别为(83.27±10.21)%、(134.56±20.51)%。太平洋磷虾油中EPA和DHA的相对生物利用度(F)分别为(84.73±12.03)%,(49.26±8.79)%。结论表明与鱼油相比,南极磷虾油显著提高了DHA的相对生物利用度。     

两种复方磺胺嘧啶混悬液在肉鸡体内药动学及生物等效性研究

为了解多益与相同成份进口产品的生物等效性,在建立血浆中磺胺嘧啶(SD)和甲氧苄啶(TMP)的HPLC检测方法基础上,比较两种制剂在肉鸡体内的药代动力学特征.选用30只健康白羽肉鸡,进行单剂量口服给药,给药剂量均为20mg/kg(以SD计),用反相高效液相色谱法测定血浆中SD和TMP浓度,计算其药动学参数并评价两种制剂的生物等效性.用Kinetic药动学软件处理血药浓度-时间数据,得出受试制剂和参比制剂中SD的主要药动学参数分别为:Cmax分别为:(10.60±6.68)、(11.45± 5.96) mg/L,Tmax分别为:(4.93±4.25)、(3.87±4.06) h,AUC分别为:(89.31±48.50)、(86.81±45.78) mg/L·h,Clearance 分别为:(7.94±14.06)、(6.54±7.70) L/kg·h,Vz分别为:(3.57±6.12)、(10.43±31.75) L/kg.受试制剂多益相对参比制剂的相对生物利用度为102.88％,表明受试制剂与参比试剂具有生物等效性.     

恩诺沙星灌注液在健康母猪体内的药代动力学研究

旨在考察恩诺沙星灌注液与恩诺沙星普通注射液在母猪体内的药代动力学特征。作者选用16头健康长白×大白二元杂交成年母猪,随机分成2组,每组8头,分别进行单剂量耳缘静脉注射恩诺沙星普通注射液(2.5mg·kg~(-1))和子宫灌注恩诺沙星灌注液(50mL·头~(-1)),反相高效液相色谱法(RP-HPLC)测定母猪血浆中恩诺沙星及其代谢产物环丙沙星含量,运用药动学软件Winnonlin 5.2.1非房室模型分析并计算出相关药动学参数。结果显示,静脉注射恩诺沙星普通注射液后,其主要药动学参数如下:t_(1/2)(21.71±1.66)h,Vd(1.89±0.33)L·kg~(-1),Cl(60.18±8.92)mL·h~(-1)·kg~(-1),AUC_(0-t)(39.94±5.75)mg·h·L~(-1),AUC_(0-∞)(42.32±6.03)mg·h·L~(-1)。母猪子宫灌注恩诺沙星灌注液后,其主要药动学参数分别如下:t_(1/2)(28.55±2.31)h,T_(max)(3.19±1.46)h,C_(max)(1.61±0.20)mg·L~(-1),AUC_(0-t)(49.06±5.18)mg·h·L~(-1),AUC_(0-∞)(53.55±5.84)mg·h·L~(-1),F为63.15%。所有样品中均未检测出环丙沙星。结果表明,恩诺沙星灌注液可经子宫灌注吸收进入母猪体内,并且在母猪体内分布广泛,消除缓慢,生物利用度较高,临床用药时应考虑局部给药对机体的全身性影响。     

长效土霉素注射液在猪体内的生物等效性研究

研究自制长效土霉素注射液与进口长效土霉素注射液(得米先注射液)在猪体内单剂量注射的药代动力学和生物等效性,为临床应用提供参考和依据.采用双处理、双周期随即交叉试验设计.12头健康猪分为两组,分别先后单剂量肌肉注射自制长效土霉素注射液与得米先注射液,用高效液相色谱法测定血浆中土霉素的浓度,3P97软件计算药代动力学参数.自制长效土霉素注射液与参比制剂的主要药动学参数如下:AUC分别为(145.41 ±3.59)、(159.28 ±4.47) μg·mL-1·h,T1/2β分别为(84.776±2.21)、(72.740±1.95)h,Cmax分别为(3.519±1.66)、(3.924±1.34)μg/mL,Tmax分别为(1.848±0.54)、(1.760±0.41)h.采用3P97药代动力学软件分析比较AUC和Cmx90％置信区间,自制长效土霉素注射液的AUC、Cmax的90％置信区间分别为94.7％～105.2％、85.0％ ～114.6％,分别落在参比制剂的80％～125％、70％ ～143％范围内,两组参数差异不显著(P＞0.05),结果表明二者具有生物等效性.     

两种烯丙孕素口服液在猪体内的比较药动学研究

比较国产和进口烯丙孕素口服液在健康母猪体内的药物代谢动力学。将16头健康苏姜商品母猪随机分为2组,分别单剂量灌服国产烯丙孕素口服液和进口烯丙孕素口服液,按体重给药量均为1.0 mg/kg,进行药动学比较研究。给药后按预定时间采集血样,采用液相色谱-串联四级杆质谱法测定血浆中烯丙孕素含量,实测血药浓度-时间数据采用WINNONLIN 6.3版药动学分析软件处理。国产制剂和进口制剂的达峰时间(Tmax)分别为(0.81±0.14)h、(1.59±0.80)h;达峰浓度(Cmax)分别为(175.19±58.12)ng/m L、(100.47±19.64)ng/m L;消除半哀期(t1/2)分别为(3.89±0.75)h、(3.14±0.24)h;平均滞留时间(MRT0~t)分别为(5.05±0.36)h、(5.06±0.71)h;药时曲线下面积(AUC0-t)分别为(729.82±179.76)ng·h·m L-1、(554.56±156.55)ng·h·m L-1。国产烯丙孕素口服液的相对生物利用度为131.60%。国产烯丙孕素口服液Cmax显著高于进口烯丙孕素口服液,而其它参数t1/2、Tmax、AUC0-t、MRT0~t无显著性差异。研究表明,国产烯丙孕素口服液在母猪体内具有吸收好、消除快、生物利用度高等优点。     

牛皮下注射卡洛芬注射液的药动学试验研究

为研究卡洛芬注射液在牛体内的药动学特征,将8头健康牛随机分为两组,每组4头,给药剂量为1.4 mg/kg BW,给药后按设计的采血点采集血样,采用超高液相色谱-串联质谱法(UPLC-MS/MS)测定血浆中卡洛芬的药物浓度,用WinNonlin8.1软件计算药动学参数。结果显示：牛单次皮下注射受试制剂卡洛芬注射液在牛体内主要药动学参数如下：平均最高血药浓度(Cmax)为(17473.30±2398.73)ng·mL^-1,平均药时曲线下面积(AUClast)为(1052647.93±143055.37)h·ng·mL^-1,平均达峰时间(Tmax)为8.00±2.62 h,平均消除半衰期(T_1/2)为55.69±3.25 h;牛单次皮下注射参比制剂卡洛芬注射液的主要药动学参数如下：平均最高血药浓度(Cmax)为(15695.98±4865.73)ng·mL^-1,平均药时曲线下面积(AUClast)为(1002858.15±297235.31)h·ng·mL^-1,平均达峰时间(Tmax...     

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.     

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.     

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.     

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.