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An investigation into the possibility of bluetongue virus transmission by transfer of infected ovine embryos 全文
2011
Estelle H. Venter | Truuske Gerdes | Isabel Wright | Johan Terblanche
An investigation into the possibility of bluetongue virus transmission by transfer of infected ovine embryos 全文
2011
Estelle H. Venter | Truuske Gerdes | Isabel Wright | Johan Terblanche
Bluetongue (BT), a disease that affects mainly sheep, causes economic losses owing to not only its deleterious effects on animals but also its associated impact on the restriction of movement of livestock and livestock germplasm. The causative agent, bluetongue virus (BTV), can occur in the semen of rams and bulls at the time of peak viraemia and be transferred to a developing foetus. The risk of the transmission of BTV by bovine embryos is negligible if the embryos are washed according to the International Embryo Transfer Society (IETS) protocol. Two experiments were undertaken to determine whether this holds for ovine embryos that had been exposed to BTV. Firstly, the oestrus cycles of 12 ewes were synchronised and the 59 embryos that were obtained were exposed in vitro to BTV-2 and BTV-4 at a dilution of 1 x 102.88 and 1 x 103.5 respectively. In the second experiment, embryos were recovered from sheep at the peak of viraemia. A total of 96 embryos were collected from BTV-infected sheep 21 days after infection. In both experiments half the embryos were washed and treated with trypsin according to the IETS protocol while the remaining embryos were neither washed nor treated. All were tested for the presence of BTV using cell culture techniques. The virus was detected after three passages in BHK-21 cells only in one wash bath in the first experiment and two unwashed embryos exposed to BTV-4 at a titre of 1 x 103.5. No embryos or uterine flush fluids obtained from viraemic donors used in the second experiment were positive for BTV after the standard washing procedure had been followed. The washing procedure of the IETS protocol can thus clear sheep embryos infected with BTV either in vitro or in vivo.
显示更多 [+] 显示较少 [-]An investigation into the possibility of bluetongue virus transmission by transfer of infected ovine embryos
The dynamics of questing ticks collected for 164 consecutive months off the vegetation of two landscape zones in the Kruger National Park (1988-2002). Part I. Total ticks, Amblyomma hebraeum and Rhipicephalus decoloratus 全文
2011
Horak, Ivan G(University of Pretoria Department of Veterinary Tropical Diseases) | Gallivan, Gordon J(Ottawa) | Spickett, Arthur M(Onderstepoort Veterinary Institute Parasites, Vectors & Vector-borne Diseases Programme)
The dynamics of questing ticks collected for 164 consecutive months off the vegetation of two landscape zones in the Kruger National Park (1988-2002). Part III. The less commonly collected species 全文
2011
Gallivan, Gordon J(Ottawa) | Spickett, Andrea(Onderstepoort Veterinary Institute Parasites, Vectors & Vector-borne Diseases Programme) | Heyne, Heloise(Onderstepoort Veterinary Institute Parasites, Vectors & Vector-borne Diseases Programme) | Spickett, Arthur M(Onderstepoort Veterinary Institute Parasites, Vectors & Vector-borne Diseases Programme) | Horak, Ivan G(University of Pretoria Department of Veterinary Tropical Diseases)
Despite many studies regarding tick ecology, limited information on long-term changes in tick populations exist. This study assessed the long-term population dynamics of the less frequently collected questing ixodid ticks in the Kruger National Park (KNP). From 1988 to 2002, monthly dragging of the vegetation was performed in three habitats (grassland, woodland and gully) at two sites in the KNP (Nhlowa Road, Landscape Zone 17, and Skukuza, Landscape Zone 4). Amblyomma marmoreum and Rhipicephalus evertsi evertsi were collected as larvae most commonly. Most A. marmoreum larvae were collected at Skukuza and numbers peaked from March to July. More R. evertsi evertsi larvae were collected at Nhlowa Road and numbers peaked in summer and in winter, while at Skukuza there was a single peak in spring. Haemaphysalis elliptica, Rhipicephalus simus and Rhipicephalus turanicus were collected as adults most commonly. More Ha. elliptica and R. turanicus were collected at Nhlowa Road than at Skukuza, while R. simus numbers from the two sites were approximately equal. Ha. elliptica were collected most often between February and June, and R. simus and R. turanicus during February and March. All three species were collected more frequently in gullies than in grassland or woodland. Their numbers increased in 1994/1995 following an eruption of rodents, the preferred hosts of the immature stages. The different host-seeking strategies of ticks largely determine the development stage at which they are likely to be collected during vegetation dragging and reflect a complex interaction between ticks, their hosts and the environment
显示更多 [+] 显示较少 [-]Rumen protozoa in South African sheep with a summary of the worldwide distribution of sheep protozoa 全文
2011
Booyse, Dirk(University of Pretoria Department of Anatomy and Physiology) | Dehority, Burk A.(Ohio State University Department of Animal Sciences)
Protozoa species were identified in rumen contents of four domestic sheep (Ovis aries) from South Africa. All animals were fed a forage diet which consisted of 50% lucerne and 50% teff hay. Ten new host records were identified, bringing the total number of species and forms observed in sheep in South Africa to 30. The occurrence and geographic distribution of ciliate protozoa in both domestic and wild sheep from around the world are summarised. It was found that 15 genera and 131 species occur in domestic sheep globally.
显示更多 [+] 显示较少 [-]Ixodid ticks, fleas and lice infesting dogs and cats in Hawassa, southern Ethiopia 全文
2011
Kumsa, Bersissa E.(Addis Ababa University Department of Parasitology ,University of Padova Department of Experimental Sciences) | Mekonnen, Shewit(Addis Ababa University Department of Parasitology)
This study investigated the prevalence, risk factors and species composition of ticks, fleas and lice infesting dogs and cats in and around Hawassa in southern Ethiopia. In total, 200 dogs and 100 cats were examined from November 2008 to April 2009. Of the dogs and cats examined, 99.5%and 91.5%, respectively, were infested with one or more species of ticks, fleas or lice. The overall prevalence was higher in dogs than in cats. A total of six different species of ectoparasites were collected and identified from dogs, but only three species from cats. Ctenocephalides felis was the predominant species amongst the animals, with a prevalence of 82.9% on dogs and 67% on cats. Other prevalent species on dogs included Ctenocephalides canis (73.8%), Heterodoxus spiniger (4%), nymphs of Amblyomma spp. (3.5%), Pulex irritans (2.5%) and Haemaphysalis leachi (0.5%). C. canis (18%) and P. irritans (6%) were also found on cats. More female than male fleas and lice were observed. The study revealed that the prevalence of fleas, ticks and lice on dogs was not significantly different between male and female animals or between young and adult dogs. However, the prevalence of these ectoparasites was significantly higher in female than in male and in adult than in young cats. The study showed that the prevalence of ectoparasites on both dogs and cats was significantly higher on animals with flea allergy dermatitis (FAD) than those without FAD, and on animals with lesions on their skin compared with those without lesions.
显示更多 [+] 显示较少 [-]Ticks on pastures and on two breeds of cattle in the Eastern Cape province, South Africa 全文
2011
Nyangiwe, Nkululeko(Döhne Agricultural Development Institute) | Goni, Sindisile(Döhne Agricultural Development Institute) | Hervé-Claude, Louis P.(University of Veterinary Medicine of Hannover Institute of Biometry) | Ruddat, Inga(University of Veterinary Medicine of Hannover Institute of Biometry) | Horak, Ivan G.(University of Pretoria Department of Veterinary Tropical Diseases ,University of the Free State Department of Zoology and Entomology)
Many studies on the population dynamics of questing ticks on pastures and of parasitic ticks on cattle have been conducted. Few, however, have attempted to link the two in a single study. This study aimed to assess the population dynamics of questing ixodid ticks on pastures and of adult ticks on two breeds of cattle with different levels of susceptibility to tick infestation on the same pastures. Between January 2005 and December 2009 questing ixodid ticks were collected monthly from natural pastures at the Döhne Agricultural Development Institute and at the adjacent Campagna Production System in the Amahlathi District, Eastern Cape province, South Africa. Between February 2007 and January 2010 adult ticks were collected monthly from Bonsmara and Nguni cattle grazing these pastures. Ten tick species were collected from the pastures and 12 from the cattle. Significantly more questing larvae of Rhipicephalus appendiculatus, Rhipicephalus decoloratus, Rhipicephalus evertsi evertsi and Rhipicephalus microplus were recovered from the pastures grazed by Bonsmara cattle than from those grazed by Nguni cattle (p <0.05). Significantly more adult Hyalomma rufipes, Rhipicephalus follis, R. appendiculatus, R. decoloratus, R. evertsi evertsi and R. microplus were collected from the Bonsmara cattle than from the Nguni cattle (p < 0.05). The study showed that Nguni cattle are less susceptible to tick infestation than are Bonsmara cattle and fewer questing ticks are collected from pastures grazed by Nguni cattle than by Bonsmara cattle.
显示更多 [+] 显示较少 [-]Use of real-time quantitative reverse transcription polymerase chain reaction for the detection of African horse sickness virus replication in Culicoides imicola 全文
2011
Scheffer, Elisabeth G.(University of Pretoria Equine Research Centre ,Freie Universität Berlin Institut für Virologie) | Venter, Gert J.(ARC-Onderstepoort Veterinary Institute ,University of Pretoria Department of Veterinary Tropical Diseases) | Joone, Christopher(University of Pretoria Equine Research Centre) | Osterrieder, Nikolaus(Freie Universität Berlin Institut für Virologie) | Guthrie, Alan J.(University of Pretoria Equine Research Centre)
Despite its important role as vector for African horse sickness virus (AHSV), very little information is available on the dissemination of this virus in Culicoides (Avaritia) imicola Kieffer (Diptera: Ceratopogonidae). This study reports on the applicability of a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) to detect AHSV in dissected midges. A total of 96 midges were fed on AHSV-infected blood, after which one test group was dissected into head/thorax and abdomen segments immediately after feeding and the other only after 10 days of incubation. The majority of the midges (96%) ingested the virus successfully and there was no significant difference between the virus concentration in the heads/thoraxes and the abdomens immediately after feeding. After incubation, virus was detected in 51% of the midges and it was confined to the abdomen in the majority of these. The fact that virus was detected only in the heads/thoraxes of four Culicoides midges after incubation suggests the presence of a mesenteronal escape barrier. Replication in the salivary glands was not shown. An increase of the mean virus concentration in the abdomen after incubation indicates localised viral replication. The real-time RT-qPCR is recommended for further studies investigating the replication and dissemination of AHSV in Culicoides midges.
显示更多 [+] 显示较少 [-]Presence and characterization of Campylobacter jejuni in organically raised chickens in Quebec 全文
2011
Thibodeau, Alexandre | Fravalo, Philippe | Laurent-Lewandowski, Sylvette | Guévremont, Evelyne | Quessy, Sylvain | Letellier, Ann
The objective of this study was to estimate the presence of the important foodborne pathogen Campylobacter jejuni in organically raised chickens in the province of Quebec. The recovered isolates were further characterized for their antimicrobial resistance profile, autoagglutination property and chemotaxis. Antimicrobial resistance was evaluated using agar dilution for: tetracycline, erythromycin, chloramphenicol, ciprofloxacin, gentamicin, nalidixic acid, clindamycin, ampicillin, azithromycin, bacitracin, and ceftiofur. Autoagglutination was measured by monitoring optical density changes in a bacterial suspension after 3 h of incubation at room temperature. Chemotaxis was evaluated after a contact time of 3 h between isolates and mucin, using a quantitative protocol. A total of 10 lots of chickens was sampled in August and September 2009; half of them were positive for the presence of C. jejuni. Antimicrobial resistance was found only for tetracycline (44%), erythromycin (6%), azithromycin (6%) and clindamycin (2%). Variation was observed in the minimum inhibitory concentrations (MICs) for ceftiofur and bacitracin, for which C. jejuni possess intrinsic resistance. Autoagglutination and chemotaxis varied among isolates and lot-level differences in these were observed. Autoagglutination and chemotaxis levels appeared as independent isolate properties. Further monitoring and characterization of isolates originating from organic chickens is of interest since this type of production might represent another source of exposure of consumers to a variety of the foodborne pathogen C. jejuni.
显示更多 [+] 显示较少 [-]Changes in hoof surface strain distribution in response to moderate exercise in Standardbreds 全文
2011
Faramarzi, Babak | Cruz, Antonio M. | Sears, William C.
Objective—To quantify changes in hoof wall strain distribution associated with exercise and time in Standardbreds. Animals—18 young adult Standardbreds. Procedures—9 horses were exercised 4 d/wk for 30 to 45 minutes at a medium trot for 4 months; 9 nonexercised horses served as the control group. Rosette strain gauges were used to measure the principal surface strains at the toe, lateral quarter of the hoof wall (LQ), and medial quarter of the hoof wall (MQ) of the right forefoot at the beginning and end of the experiment. Midstance maximal (msepsilon1) and minimal (msepsilon2) principal and peak minimal principal (pkepsilon2) surface strains were measured; SDs of each of those variables were also calculated. Results were compared through ANOVA of time and exercise effects between and within the groups. Results—Both the exercised and nonexercised groups had changes in strain distribution in their hooves over time. The msepsilon1 did not change significantly with exercise; however, it changed significantly in both groups at both hoof quarters over time. At the beginning of the study, mean msepsilon2 and pkepsilon2 values were significantly higher in the exercised group than in the control group at the MQ and LQ but not at the toe. At the end of the study, these values were significantly higher in the control group than in the exercised group at the toe but not at the MQ or LQ. Conclusions and Clinical Relevance—Detected changes in hoof wall surface strain may indicate the ability of hoof capsule material to respond to exercise. A better understanding of hoof adaptation to applied forces may allow implementation of proper trimming and shoeing techniques to promote adaptation to exercise loads in horses.
显示更多 [+] 显示较少 [-]Comparison of the efficacy and adverse effects of sustained-release buprenorphine hydrochloride following subcutaneous administration and buprenorphine hydrochloride following oral transmucosal administration in cats undergoing ovariohysterectomy 全文
2011
Catbagan, Davina L. | Quimby, Jessica M. | Mama, Khursheed R. | Rychel, Jessica K. | Mich, Patrice M.
Objective—To compare the efficacy and adverse effects of sustained-release (SR) buprenorphine following SC administration and buprenorphine following oral transmucosal (OTM) administration in cats undergoing ovariohysterectomy. Animals—21 young healthy female cats. Procedures—As part of anesthetic premedication (0 hours), 10 cats received buprenorphine (0.02 mg/kg) via OTM administration with additional doses at 12, 24, 36, 48, and 60 hours and 11 cats received an equivalent total dose as a single SC injection of SR buprenorphine (0.12 mg/kg). The SR product contained buprenorphine hydrochloride in a proprietary SR matrix. All other anesthetic drugs and a single postoperative dose of meloxicam were administered similarly to all cats. Behavioral and physiologic variables were recorded, and signs of pain were assessed by use of 2 pain assessment scales and von anesthesia (RFA), and at 12, 24, 36, 48, 60, and 72 hours. Results—Heart rate increased and temperature (determined via microchip transponder thermometry) decreased from baseline values during RFA in both groups. Compared with baseline values, pain scores were increased during RFA and at the 12- and 24-hour time points in both groups; von Frey scores were higher during RFA. Behavioral and physiologic variables did not differ significantly between groups at any time point. Conclusions and Clinical Relevance—In cats undergoing ovariohysterectomy, SC administration of a preoperative dose of SR buprenorphine appeared to have comparable efficacy and adverse effect profile as that of twice-daily OTM administration of buprenorphine before and after surgery.
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