Leptospira interrogans serovar hardjo is not a major cause of bovine abortion in Victoria

The aim of this study was to determine whether evidence could be obtained of foetal infection with Leptospira interrogans serovar hardjo in aborted foetuses collected from dairy farms. Material from 197 abortions occurring over a wide area of Victoria was collected over 3 years. None of 195 foetal kidney cultures or 7 cultures from membranes was positive for leptospiral organisms. Immunogold silver staining for leptospires was performed on sections of kidneys, lungs or heart from 156 foetuses, with negative results. Evidence of transient leptospiral infection in 11 of 123 foetuses was obtained by foetal heart blood serology. Two isolates of L. interrogans serovar hardjo were obtained from the urine of milking cows. These strains were examined by restriction endonuclease analysis and both were shown to be of the genotype Hardjobovis, as have been all Australian isolates studied so far. It appears that foetal infection with serovar hardjo is not associated with any substantial proportion of bovine abortions in Victoria, in contrast to the situation in Northern Ireland. The apparent absence from Victoria of the pathogenic genotype Hardjoprajitno is a possible explanation.     

The survival of platypuses in captivity

Data are presented on the duration of survival of 228 platypuses at six Australian zoos between 1934 and 1988. Only 22.4% of all platypuses survived more than 1 year in captivity. Of 15 living platypuses, 3 had been held in captivity for less than 1 year, 5 for between 1 and 5 years, 6 for between 5 and 10 years and 1 for 21 years. Of 213 platypuses that died in captivity, 81.7% had died within 1 year; most within the first month. The duration of survival was unrelated to the age of animals at acquisition or to sex. The survival rate of animals donated to zoos, including "refugees", was similar to that of purpose-caught animals. Clearly, only a small proportion of platypuses adapted to captive husbandry. The cause of death of most platypuses was not established. However, infectious disease did not appear to be significant. Approximately 28% of deaths were related to inadequate husbandry. Recommendations are made to improve the survival of platypuses in captivity. Research has commenced in zoos to facilitate this goal.     

Comparative effects of abamectin and two formulations of ivermectin on the survival of larvae of a dung-breeding fly

Objectives To compare the survival of larvae of a dung-breeding fly in the faeces of cattle treated either with an injectable formulation of abamectin, or with oral or injectable formulations of ivermectin.
Design Replicated bioassays were conducted on larvae of the bush fly, Musca vetustissima, using faeces collected before and at intervals after drug treatment.
Animals Two cows and their calves were allocated to each of three drug treatments and dosed according to individual weights.
Procedures Differences in the proportions of larvae pupariating were used as measures of the toxicity of drug residues.
Results Development of fly larvae was inhibited in all faeces collected 1 to 4 days after treatment. In cattle treated with oral ivermectin, there was reduced larval survival in faeces collected 8 and 16 days after treatment, but by day 32, survival was equivalent to that recorded in the faeces of untreated cattle. With injectable ivermectin, there was no survival at day 8, limited survival at day 16 and, at day 32, survival was not significantly affected. With injectable abamectin, survival was completely suppressed until day 32, at which time the number of pupariating larvae did not differ significantly from that recorded in faeces from untreated animals.
Conclusion The oral formulation of ivermectin is eliminated more rapidly than the injectable formulation and, as a consequence, is likely to be less harmful to dung-feeding insects. Abamectin and ivermectin appear to equally toxic larvae of M vetustissima.     

Comparison of effects of uncomplicated canine babesiosis and canine normovolaemic anaemia on abdominal splanchnic Doppler characteristics--a preliminary investigation

A preliminary study was conducted to compare uncomplicated canine babesiosis (CB) and experimentally induced normovolaemic anaemia (EA) using Doppler ultrasonography of abdominal splanchnic vessels. Fourteen dogs with uncomplicated CB were investigated together with 11 healthy Beagles during severe EA, moderate EA and the physiological state as a control group. Canine babesiosis was compared with severe EA, moderate EA and the physiological state using Doppler variables of the abdominal aorta, cranial mesenteric artery (CMA), coeliac, left renal and interlobar, and hilar splenic arteries, and the main portal vein. Patterns of haemodynamic changes during CB and EA were broadly similar and were characterised by elevations in velocities and reductions in resistance indices in all vessels except the renal arteries when compared with the physiological state. Aortic and CMA peak systolic velocities and CMA end diastolic and time-averaged mean velocities in CB were significantly lower (P < 0.023) than those in severe EA. Patterns of renal haemodynamic changes during CB and EA were similar. However, the renal patterns differed from those of aortic and gastrointestinal arteries, having elevations in vascular resistance indices, a reduction in end diastolic velocity and unchanged time-averaged mean velocity. The left renal artery resistive index in CB was significantly higher (P < 0.025) than those in EA and the physiological state. Renal interlobar artery resistive and pulsatility indices in CB were significantly higher (P < 0.016) than those of moderate EA and the physiological state. The similar haemodynamic patterns in CB and EA are attributable to anaemia, while significant differences may additionally be attributed to pathophysiological factors peculiar to CB.     

Comparison in gnotobiotic pigs of lesions caused by verotoxigenic and non-verotoxigenic Escherichia coli

To compare the pathogenesis of calf and rabbit strains of E. coli, gnotobiotic pigs were infected with 10(10) colony forming units (cfu) of verotoxigenic strain RDEC-1 or S102-9, or a non-verotoxigenic E. coli (X114/83). Pigs were killed 4 days later, and intestinal tissue was fixed and examined by light, scanning, and transmission electron microscopy. Strains S102-9 and RDEC-1 caused diarrhea, attached to enterocytes, and effaced microvilli, confirming that the calf and rabbit strains possessed similar mechanisms of pathogenicity. Non-verotoxigenic strain X114/83 did not cause diarrhea, but in 5/5 piglets it was detected in histological sections adherent to enterocyte surfaces. Exfoliated enterocytes were seen in 4/5. Bacteria attached to enterocytes by "cups" and "pedestals," with effacement of microvilli, were seen by electron microscopy in 1/5 piglets. It was concluded that strain S102-9 appears to be an animal equivalent of human enterohemorrhagic E. coli, that verotoxin is not essential in the pathogenesis of attaching and effacing lesions, and that the lesions induced by S102-9 are more severe in gnotobiotic pigs than in gnotobiotic or conventional calves.     

Vesicles Cytoplasmic Injection: An Efficient Technique to Produce Porcine Transgene‐Expressing Embryos

The use of vesicles co‐incubated with plasmids showed to improve the efficiency of cytoplasmic injection of transgenes in cattle. Here, this technique was tested as a simplified alternative for transgenes delivery in porcine zygotes. To this aim, cytoplasmic injection of the plasmid alone was compared to the injection with plasmids co‐incubated with vesicles both in diploid parthenogenic and IVF zygotes. The plasmid pcx‐egfp was injected circular (CP) at 3, 30 and 300 ng/μl and linear (LP) at 30 ng/μl. The experimental groups using parthenogenetic zygotes were as follows: CP naked at 3 ng/μl (N = 105), 30 ng/μl (N = 95) and 300 ng/μl (N = 65); Sham (N = 105); control not injected (N = 223); LP naked at 30 ng/μl (N = 78); LP vesicles (N = 115) and Sham vesicles (N = 59). For IVF zygotes: LP naked (N = 44) LP vesicles (N = 94), Sham (N = 59) and control (N = 79). Cleavage, blastocyst and GFP+ rates were analysed by Fisher's test (p < 0.05). The parthenogenic CP naked group showed lower cleavage respect to control (p < 0.05). The highest concentration of plasmids to allow development to blastocyst stage was 30 ng/μl. There were no differences in DNA fragmentation between groups. The parthenogenic LP naked group resulted in high GFP rates (46%) and also allowed the production of GFP blastocysts (33%). The cytoplasmic injection with LP vesicles into parthenogenic zygotes allowed 100% GFP blastocysts. Injected IVF showed higher cleavage rates than control (p < 0.05). In IVF zygotes, only the use of vesicles produced GFP blastocysts. The use of vesicles co‐incubated with plasmids improves the transgene expression efficiency for cytoplasmic injection in porcine zygotes and constitutes a simple technique for easy delivery of plasmids.     

Role of noradrenergic signaling by the nucleus tractus solitarius in mediating opiate reward

Norepinephrine (NE) is widely implicated in opiate withdrawal, but much less is known about its role in opiate-induced locomotion and reward. In mice lacking dopamine beta-hydroxylase (DBH), an enzyme critical for NE synthesis, we found that NE was necessary for morphine-induced conditioned place preference (CPP; a measure of reward) and locomotion. These deficits were rescued by systemic NE restoration. Viral restoration of DBH expression in the nucleus tractus solitarius, but not in the locus coeruleus, restored CPP for morphine. Morphine-induced locomotion was partially restored by DBH expression in either brain region. These data suggest that NE signaling by the nucleus tractus solitarius is necessary for morphine reward.