Principles for the use of macrocyclic lactones to minimise selection for resistance     

RJ DOBSON  RB BESIER  EH BARNES  SCJ LOVE  A VIZARD  K BELL  LF Le  JAMBRE 《Australian veterinary journal》2001,79(11):756-761

OBJECTIVE: To provide principles for the appropriate use of avermectin/milbemycin or macrocyclic lactone (ML) anthelmintics in sheep, to ensure effective worm control and to minimise selection for ML resistance. STRATEGY: The principles were based on an assessment of the information currently available. The MLs were categorised into three groups (ivermectin [IVM], abamectin [ABA] and moxidectin [MOX]) based on structural differences, persistence and efficacy against ML resistant strains. The reported order of activity or efficacy against ML resistant worm strains was IVM相似文献   

Reactions to Gudair® vaccination identified in sheep used for biomedical research     

GC Musk  H Kershaw  K Tano  A Niklasson  M von Unge  RJ Dilley 《Australian veterinary journal》2019,97(3):56-60

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The effects of ventilation on intercranial and cerebral perfusion pressures in isoflurane-anaesthetized horses     

RJ Brosnan  EP Steffey  RA LeCouteur  A Imai  GD Kortz 《Veterinary anaesthesia and analgesia》2002,29(2):91-92

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Salmonella Dublin infection in Queensland dairy cattle     

KF TRUEMAN  RJ THOMAS  AR MACKENZIE  LE EAVES  PF DUFFY 《Australian veterinary journal》1996,74(5):367-369

Objective: To investigate the presence of Salmonella Dublin in Queensland cattle.
Design: An epidemiological study using diagnostic laboratory information and farm records.
Procedure: Outbreaks of gastroenteritis or pneumonia in calves, and abortions and enteritis in cows were routinely investigated for the presence of salmonellae. Where S Dublin was isolated, attempts were made to gather further epidemiological information.
Results: Prior to 1983 only two outbreaks of S Dublin have been recorded in Queensland dairy cattle. In 1983 S Dublin abortions were diagnosed in dairy heifers introduced from southern Australia to south-east Queensland. Sampling indicated that at least 10% of the 500 introduced heifers were faecal excretors of S Dublin. On 3 of the 7 farms from which S Dublin was recorded, infection spread to other cattle that were in contact. From February 1985 to February 1996, 29 outbreaks of S Dublin in cattle occurred on 29 farms (28 in south east Queensland and 1 in north Queensland). Calves were primarily affected. Continuing outbreaks were confirmed on only 4 of these 29 farms. On 15 farms S Dublin infections were associated with the purchase of infected calves or cows, while another farm adjoined 2 previously infected farms. No source of S Dublin was evident for the other 13 farms, where histories were often inadequate.
Conclusion: There has been a marked increase in S Dublin outbreaks in Queensland dairy cattle since 1983. Introduction of S Dublin carrier and aborting dairy heifers from southern Australia, where S Dublin is not uncommon, was associated with the initial outbreaks.  相似文献   

Monitoring and surveillance in abattoirs of residues of antibacterial substances – a description of programs in Australia and the USA     

JL CUPIT  NL BLACKMAN†  TJ NICHOLLS†  IB STEPHENS†  RJ WILD 《Australian veterinary journal》1994,71(12):400-403

SUMMARY Australia and the USA are major international meat exporting countries. Both countries conduct programs to monitor and survey for antibacterial residues. Australian programs use a urine screening test, whereas the US programs use tissue fluids as the test medium. The development of surveillance programs to provide rapid feedback to producers is a feature of the Australian programs. The programs in each country compare favourably with regard to numbers of animals tested, results and action taken to prevent residues. The results of the Australian programs justify the promotion of a ‘clean food’ image for Australian meat products with respect to antibacterial drugs.  相似文献   

Anthelmintic resistance in the field: Changes in resistance status of parasitic populations in response to anthelmintic treatment     

PJ WALLER  RJ DOBSON  A. AXELSEN 《Australian veterinary journal》1988,65(12):376-378

Changes in anthelmintic resistance in nematode parasites were monitored in sheep grazing on 2 separate farms, but with the same anthelmintic treatment program, over 16 years. High levels of benzimidazole resistance emerged in Ostertagia and Trichostrongylus spp populations on both farms following 9 years of continuous use of this class of drug. Subsequently, variations in the levels of resistance occurred for the same species between farms and between species on the same farm. A change to levamisole for 2 years resulted in a significant reversion towards benzimidazole susceptibility, but a concomitant rise in levamisole resistance, in Ostertagia on one farm. However, benzimidazole resistance increased rapidly following the re-introduction of oxfendazole into the anthelmintic treatment program. Results from both farms illustrate the pitfalls of using one anthelmintic class for an extended period and provide indirect support for the alternation of anthelmintic classes at approximately yearly intervals.  相似文献   

Feeding practices in Thoroughbred and Standardbred racehorse stables     

LLD SOUTHWOOD  DL EVANS  WL BRYDEN  RJ ROSE 《Australian veterinary journal》1993,70(5):184-185

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Pyrrolizidine alkaloidosis of cattle associated with Senecio lautu     

JW NOBLE  JdeB CROSSLEY  BD HILL†  RJ PIERCE†  RA McKENZIE‡  M. DEBRITZ§  AA MORLEY¶ 《Australian veterinary journal》1994,71(7):196-200

Summary Serious incidents of pyrrolizidine alkaloidosis of cattle in 10 herds exposed to the Australian native plant, Senecio lautus (Asteraceae), were seen in central Queensland during 1988–1992. The deaths of 226 cattle were recorded. A mean of 8% of cattle died in affected groups (range 2 to 58%). Sickness and deaths usually occurred some months after access to S lautus. Typically, affected cattle lost body condition to the point of emaciation before dying and had persistent diarrhoea. Some animals developed abnormal behaviour and died after a shorter illness. Liver specimens from affected cattle in all herds contained lesions consistent with pyrrolizidine alkaloidosis. Thin layer chromatography of extracts of blood and liver samples from cattle from 5 herds detected pyrrolic metabolites. The identity of these was confirmed by mass spectroscopy on samples from one herd. Unseasonal autumn and winter rain after a dry summer appeared to favour growth of S lautus at the expense of other pasture species. A subsequent dry period promoted consumption of S lautus and was followed by a cluster of poisoning incidents.  相似文献   

Relationships between vaccine and virulent strains of Babesia bovis during co-infection in calves     

WK JORGENSEN  PJ JESTON  PM BOWLES  J. CROFT  AE LEW  JB MOLLOY  RJ DALGLIESH 《Australian veterinary journal》1998,76(1):57-58

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The response of oilseed rape (Brassica napus ssp. oleifera) accessions with different glucosinolate and erucic acid contents to four isolates of Peronospora parasitica (downy mildew) and the identification of new sources of resistance     

N. I. NASHAAT  C. J. RAWLINSON 《Plant pathology》1994,43(2):278-285

A total of 101 Brassica napus ssp. oleifera accessions with seed differing in glucosinolate and erucic acid contents were screened for resistance to four isolates of Peronospora parasitica at the cotyledon stage. Two groups of accessions with different resistance factors were identified. Lines that were homogeneous for resistance were selected from seedling populations of accessions that exhibited a heterogeneous reaction to some isolates. The resistance of one group differs from that of cv, Cresor, the only oilseed rape cultivar reported to have an isolate-specific gene for resistance to P. parasitica. The isolate specificity of the second group was identical to that of cv, Cresor, A comparison of the response of host accessions which expressed moderate to full susceptibility at the cotyledon stage, with no clear differential response to any of the four P. parasitica isolates, indicated that those with high glucosinolate and high erucic acid contents (12 accessions) were slightly but significantly less susceptible than those with high glucosinolate and low erucic acid (19 accessions), or low glucosinolate and low erucic acid contents (28 accessions). The mean differences between accessions with low erucic acid but differing in glucosinolate content were inconsistent. The last result was further confirmed by investigating the expression of resistance to three isolates of P. parasitica at three different seedling growth stages among 11 accessions of oilseed rape with seeds low in erucic acid but differing in glucosinolate content.  相似文献