Transmission studies of Hendra virus (equine morbilli-virus) in fruit bats, horses and cats     

MM WILLIAMSON  PT HOOPER  PW SELLECK  LJ GLEESON  PW DANIELS  HA WESTBURY  PK MURRAY 《Australian veterinary journal》1998,76(12):813-818

Objective To determine the infectivity and transmissibility of Hendra virus (HeV). Design A disease transmission study using fruit bats, horses and cats. Procedure Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second exper iment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experi ment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody. Results Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated devel oped acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas. Conclusions Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus t o horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.  相似文献   

Luteolytic Effect of Prostaglandin F_2α on Bovine Corpus Luteum Depends on Cell Composition and Contact     

AJ Korzekwa  JJ Jaroszewski  I Woclawek-Potocka  MM Bah  DJ Skarzynski 《Reproduction in domestic animals》2008,43(4):464-472

Prostaglandin F_2α (PGF_2α) is a main luteolytic factor in vivo; however, its direct luteolytic influence on steroidogenic cells of bovine corpus luteum (CL) is controversial and not fully understood. The aim of the study was to clarify PGF_2α action on bovine CL in different in vivo and in vitro conditions and to examine whether the contact among all main types of CL cells is necessary for luteolytic PGF_2α action. In experiment 1, the bovine CL (day 15 of the oestrous cycle) was perfused using in vivo microdialysis system with dinoprost (an analogue of PGF_2α) for 0.5 h. Dinoprost caused a short‐time increase in progesterone (P4), whose concentration decreased thereafter (at 6‐, 10‐, 12‐ and 24‐h after treatment). In experiment 2, the direct effect of PGF_2α on P4 accumulation in CL steroidogenic cells cultured in monolayer (day 15 of the cycle) was determined. PGF_2α after 24 h of incubation increased P4 accumulation in steroidogenic CL cells. In experiment 3 steroidogenic, endothelial CL and immune cells (day 15 of the cycle) were incubated with PGF_2α in cocultures for 24 h in glass tubes and the levels of P4, stable metabolites of nitric oxide (NO) and leukotriene (LT) C₄ were determined. Although PGF_2α treatment increased P4 secretion in homogeneous steroidogenic CL cell culture, the decrease in P4 secretion in cocultures of all types of CL cells was observed. The secretion of NO and LTC₄ increased after the treatment of PGF_2α both in pure cultures of CL cells and in cocultures. The interactions between endothelial and immune cells with steroidogenic CL cells are needed for luteolytic PGF_2α action within the bovine CL. Our results indicate that the cell coculture model, including the main types of CL cells, is the most approximate to study PGF_2α role in vitro.  相似文献   

Effects of Methods Used For Blood Collection on Plasma Concentrations of Luteinising Hormone,Testosterone, And Cortisol In Male Dogs     

B. W. Knol  S. J. Dieleman  M. M. Bevers  W. E. van den Brom  J. A. Molt 《The Veterinary quarterly》2013,33(4):126-129

Summary

The effects of two putative stressors relative to the collection of blood, namely the environment of the treatment room and the pain associated with venepuncture, on plasma levels of luteinising hormone (LH), testosterone and cortisol were examined in six trained male experimental dogs. Blood samples were collected from the dogs in a treatment room as well as in the kennels (control), and by venepuncture as well as via an indwelling’ intravenous catheter (control). No significant influence of either stressor on plasma levels of LH, testosterone or cortisol was found Plasma concentrations of these hormones varied considerably both between and within dogs. Mean (± SEM; n = 6) plasma concentrations were 4.3 ± 1.0 μg/l for LH, 4.6 ± 1.9 nmol/l for testosterone and 68 ± 10 nmol/l for cortisol It was concluded that the putative stressors, the environment of the treatment room and the pain associated with venepuncture, did not significantly influence plasma levels of LH, testosterone or cortisol in trained male experimental dogs.  相似文献   

Effect of Acute Bull Exposure Around the Time of Artificial Insemination on Serum Oxytocin and Progesterone Concentrations and Pregnancy Rates in Dairy Cows     

MM Ababneh  IN Obeidat  MQ Husein  AQ Talafha 《Reproduction in domestic animals》2013,48(2):223-230

This study examined the effect of acute bull exposure around the time of artificial insemination (AI) on oxytocin and progesterone concentrations, and pregnancy rates in dairy cows. Ninety six dairy cows, stratified according to parity into primiparous and pluriparous, were divided into three groups; short bull exposure (SBE; 10 min, n = 32), long bull exposure (LBE; 4 h, n = 32) or no bull exposure (NBE; n = 32). On day 45 post‐partum, all cows were treated with PGF2α on three occasions 11–14 days apart to synchronize oestrus. They were submitted to fixed time AI 80 h after the third PGF2α injection. Cows in the SBE and LBE groups were artificially inseminated 5 min after the introduction of the bull. From a subset of cows (n = 6 per group; three primiparous and three pluriparous), blood samples were collected once every 5 min starting 15 min before AI until 15 min after AI and analysed for oxytocin concentrations. Additional blood samples were collected for measurements of progesterone (P4) concentrations once daily for 4 days starting on the day of AI and once every 3 days thereafter until day 22. The effects of bull exposure, time, parity, difficulty of AI, and pregnancy on oxytocin and P4 concentrations were analysed using the mixed linear model procedure. Mean oxytocin concentrations or change in oxytocin concentrations after bull exposure or AI were not different among groups. Pregnancy rates for the NBE, SBE and LBE groups were 55.5%, 33.3% and 44.4%, respectively, and were not different among groups. In conclusion, acute bull exposure around the time of AI did not affect oxytocin and progesterone concentrations and did not improve pregnancy rates in dairy cattle under these farms conditions.  相似文献   

24-Hour Secretion Patterns of Plasma Oestradiol 17β in Pony Mares in Late Gestation     

LJ O'Donnell  BR Sheerin  JM Hendry  MJ Thatcher  WW Thatcher  MM LeBlanc 《Reproduction in domestic animals》2003,38(3):233-235

The mare exhibits nocturnal uterine contractions in the last 6 days of gestation. It is hypothesized that estradiol 17β (O17β) may be associated with the nightly increase in uterine contractions. The 24‐h secretion pattern of plasma O17β was measured in 3 pony mares in late gestation to identify changes in release as the mare neared parturition. Blood was collected weekly at 08:00 hours beginning on day 240 and every third day from day 330 until delivery. Serial blood samples were collected from each mare every 30‐min for 24‐h beginning on gestation day 310 and every sixth day thereafter until parturition. Concentrations of O17β were elevated at night with lowest concentrations occurring directly before sunset (p < 0.01). The natural log of the variance was increased at sunset (p < 0.01) and was decreased during the 6‐h period immediately after sunrise. This pattern was especially evident in the 6 days that preceded parturition. The contrast between nocturnal and daytime concentrations of O17β in the last 6 days of gestation may contribute to night‐time delivery in the mare.  相似文献   

Alzheimer type II astrocytes in the brains of pigs with salt poisoning (water deprivation/intoxication)     

JW Finnie  PC Blumbergs  MM Williamson 《Australian veterinary journal》2010,88(10):405-407

The finding of Alzheimer type II astrocytes, in addition to the pathognomonic combination of laminar cerebrocortical necrosis and eosinophil infiltration, in the brains of pigs is reported for the first time in cases of indirect salt poisoning following water deprivation.  相似文献   

Diagnostic ultrasound in veterinary practice: How safe is it?     

MM HORDER  SB BARNETT†  MJ EDWARDS 《Australian veterinary journal》1996,73(1):10-15

This paper provides information on the safety of ultrasonic diagnostic procedures as currently used in veterinary practice. The known mechanisms of action are described and selected literature on biological effects of ultrasound is reviewed. Current international consensus is presented on the safety of medical ultrasound with respect to thermal effects. To date, there is no independently verified clinical evidence that the level of exposure delivered to the tissues during scanned grey-scale (‘B-mode’) imaging has any adverse effects. Lung haemorrhage has been observed in animal experiments using diagnostic exposures, but the effects have not been reported in the foetus. Equipment that uses pulsed Doppler transmits higher acoustic outputs in a stationary beam, and can produce temperature increases that may have significant biological consequences. When considering sonographic and pulsed Doppler examinations of the prenatal animal, the safety margins are small and the operator should be aware of the acoustic output of the equipment, the exposure time, and the sensitivity of target tissues.  相似文献   

Evidence for prolactin as the main luteotrophic factor in the cyclic dog     

A C Okkens  M M Bevers  S J Dieleman  A H Willemse 《The Veterinary quarterly》1990,12(4):193-201

The role of prolactin and LH in the control of the function of the corpus luteum in the dog was studied. Experiments were performed to interfere with the secretion of a) prolactin by administering a dopamine agonist and b) LH by desensitisation with a long-acting LHRH and by stimulation. Treatments with prolactin-lowering dosages of bromocriptine, (20 micrograms/kg body weight twice a day, orally; n = 8) which started between day 1-5 (n = 4) and day 20-24 (n = 4) of the luteal period resulted in a similar pattern of progesterone, concentration in peripheral blood in both groups. The progesterone release in the second half of the luteal period (13.1 +/- 1.8% (sem) of the progesterone release of the total luteal period) was significantly lower than in control dogs (24.7 +/- 2.2%). Treatment at about day 30 of the luteal period with LHRH CR (1.34 mg, intramuscularly; n = 3), which significantly suppressed the LH level, did not reduce the progesterone release in the second half of the luteal period, 21.3 +/- 4.7% compared to 24.7 +/- 2.2% in the control dogs. The endogenous LH peak resulting from treatment with LHRH had no effect on the progesterone concentration in the blood. It is concluded that prolactin is the main luteotrophic factor in the cyclic dog during the second half of the luteal period.  相似文献   

Endocarditis caused by Pasteurella caballi in a horse     

S. CHURCH  KE HARRIGAN  AE IRVING  MM PEEL 《Australian veterinary journal》1998,76(8):528-530

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Serum antibody response to Mycoplasma hyopneumoniae measured by enzyme-linked immunosorbent assay after experimental and natural infection of pigs   总被引：1，自引：0，他引：1  

RF SHELDRAKE  IA GARDNER  MM SAUNDERS  LF ROMALIS 《Australian veterinary journal》1990,67(2):39-42

Studies were conducted under experimental and field conditions to determine the effect of infection with M. hyopneumoniae on the immune response in serum as measured by ELISA. Following intratracheal challenge or contact exposure, serologically negative pigs derived from mycoplasma-free piggeries developed an immune response within 10 days. This response continued to rise for a further 50 days. In a field study in a commercial piggery, no animals (0/44) were observed to have M. hyopneumoniae antibodies at day 86 of life. However between day 86 and day 144, 97.7% (42/43) animals sero-converted. These results are discussed in terms of infection spread, particularly in the grower/finisher shed.  相似文献