Antimicrobial use in the Australian pig industry: results of a national survey

Objective   To describe how various antimicrobials are used in commercial pig herds in Australia and for what disease conditions.
Procedure   Managers of large pig herds (> 200 sows) across Australia and their veterinarians participated in an internet-based survey in 2006. Questions were asked about herd management, the occurrence of bacterial diseases and the type and frequency of antimicrobial use. An antimicrobial usage index for each herd was derived as a summary of the risk of selection for antimicrobial resistance. Relationships between responses were explored with univariate and multivariate analysis.
Results   Responses were received for 197 herds estimated to represent at least 51% of all large pig herds in Australia. Most piggeries relied on drugs of low importance in human medicine (e.g. tetracyclines, penicillins and sulfonamides). For the two drugs of high importance in human medicine that can be legally prescribed to pigs in Australia, ceftiofur use was reported in 25% of herds and virginiamycin in none. Infections attributed to Lawsonia , Mycoplasma and Escherichia coli motivated the most use of antimicrobials. No useful association was found between management factors and the antimicrobial use index.
Conclusion   Most antimicrobial use in the Australian pig industry is based on drugs of low importance to public health. Enhanced control of E. coli infections without reliance on antimicrobials would further reduce the risk of selecting for antimicrobial resistance relevant to public health. The amount of variation in the usage index between herds suggests that antimicrobial use should be constantly reviewed on a herd by herd basis.     

In vitro antimicrobial and antioxidant activities of the essential oils and various extracts of Thymus eigii M. Zohary et P.H. Davis

This study was designed to examine the in vitro antimicrobial and antioxidant activities of the essential oil and various extracts obtained from aerial parts of Thymus eigii. The essential oil was particularly found to possess stronger antimicrobial activity, whereas other nonpolar extracts and subfractions showed moderate activity and polar extracts remained almost inactive. GC-MS analysis of the oil resulted in the identification of 39 compounds, representing 93.7% of the oil; thymol (30.6%), carvacrol (26.1%), and p-cymene (13.0%) were the main components. The samples were also subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and beta-carotene-linoleic acid assays. In the former case, the polar subfraction of the methanol extract was found to be superior to all extracts tested, only 16.8 microg/mL of which provided 50% inhibition, whereas all extracts, particularly the polar ones, seem to inhibit the oxidation of linoleic acid in the latter case. These data were further supported by total phenolics analysis, indicating that the antioxidative potential of the extracts was closely related to their phenolic constituents.     

Qualitative determination of volatile compounds and quantitative evaluation of safranal and 4-hydroxy-2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde (HTCC) in Greek saffron

Safranal (2,6,6-trimethyl-1,3-cyclohexadiene-1-carboxaldehyde) is the main component of saffron's essential oil. It was obtained using microsimultaneous hydro distillation-extraction (MSDE) and by ultrasound-assisted extraction (USE), which is a mild method. 4-Hydroxy-2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde (HTCC) is a precursor of safranal and was obtained in considerable amounts only by USE. Five C(13)-norisoprenoids were found in saffron for the first time. Using a gas chromatography technique, safranal and HTCC were quantified from Greek saffron samples. The quantity of safranal isolated by MSDE ranged between 288.1 and 687.9 mg/100 g of saffron, whereas in the case of USE safranal and HTCC ranged between 40.7 and 647.7 mg/100 g of saffron and between 41.7 and 397.7 mg/100 g of saffron, respectively. Freeze-drying was also tested as an alternative drying method. Over years of storage at 4 degrees C the quantity of safranal remained mostly constant while the quantity of HTCC decreased over the same periods.     

Pharmocokinetic and pharmacodynamic evaluation of intravenous morphine in dogs

Morphine is considered the prototypical opiate analgesic. Despite the common use of morphine in dogs, ideal dosing strategies have not been formulated due to the difficulty in assessing its analgesic effects. The purpose of this study was to: 1) evaluate a noninvasive mechanical threshold device (von Frey device) to measure antinociceptive responses (pharmacodynamics) of opiates in dogs and 2) evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of intravenous (IV) morphine in dogs. Six healthy Beagle dogs were used. The von Frey threshold (vFT) response was evaluated hourly for 8 hours in each dog to examine the effect of repeated testing (controls). PK and PD (vFT) measurements were then made following a 1 mg kg^–1 IV bolus of morphine sulfate. A two way blinded crossover consisted of an 8 hour IV constant rate infusion of saline or morphine with hourly PD measurements. The individual CRI was based on individual PK data and adjusted every 2 hours to attain targeted plasma concentrations of morphine of 10, 20, 30, and 40 ng mL^–1. Blood samples were taken hourly in all phases, except the controls. No significant (p > 0.05) intraindividual changes in vFT occurred in the controls over 8 hours. The morphine bolus produced increased vFT at 1, 2, 3, and 4 hours post injection (p < 0.05). The E_MAX and EC₅₀ following the IV bolus were 213 ± 104% (increase from baseline) and 13.9 ± 5.8 ng mL^–1, respectively. The CRI produced increased vFT at plasma concentrations >30 ng mL^–1, when compared to saline controls (p < 0.05). Targeted plasma concentrations were inconsistent at higher infusion rates, suggesting the PK of morphine may change during CRI. The actual mean ± SD CRI plasma concentrations (ng ml^–1) were 10.8 ± 3.0, 22.7 ± 7.4, 32.4 ± 13.9, 35.7 ± 16.9. Morphine dosing protocols should be re‐evaluated, as sufficient analgesia may not be obtained from published dosages. Intravenous boluses may be more predictable than CRI.     

Spirometra erinacei / S. erinaceieuropaei in a feral cat in Manawatu with chronic intermittent diarrhoea

CASE HISTORY: A feral cat captured in the Manawatu region of New Zealand was treated for worms and fleas, and kept confined in a metabolic cage. It showed good appetite and weight gain but had intermittent watery, yellow diarrhoea.

CLINICAL FINDINGS: Clinical examination under sedation was unremarkable and routine blood tests showed no significant abnormalities. The cat was negative for feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV). Different canned cat foods did not alter the course of the diarrhoea, and the cat was euthanised 6 months after capture. At necropsy, two sections of adult Spirometra tapeworms were found in the jejunum and typical Spirometra eggs were found in colonic contents. Molecular identification of the parasite was undertaken, using the cytochrome- c oxidase subunit-1 gene (cox1) sequence.

DIAGNOSIS: Chronic intermittent diarrhoea associated with Spirometra erinacei / S. erinaceieuropaei infection.

CLINICAL RELEVANCE: Spirometra has not been reported in New Zealand before but has been associated with gastrointestinal disease in cats in other parts of the world. It requires speciestargeted treatment to be eliminated effectively, and is zoonotic. Diagnosis could be diffi cult for clinicians who are not familiar with the parasite and its life cycle.     

Distal aortic aneurysm presumed to be secondary to an infected umbilical artery in a foal

Abstract

CASE HISTORY:?A 3-month-old female Warmblood foal was presented after displaying signs of colic with pyrexia for 5 days.

CLINICAL AND PATHOLOGICAL FINDINGS:?The foal continued to show signs of colic, frequently passed urine, and was pyrexic with an elevated white blood cell count. The umbilical stalk was thickened but there was no evidence of purulent material. Exploratory laparotomy revealed an enlarged left umbilical artery remnant tightly adhered to the bladder wall. The left umbilical artery continued to an aneurysm involving the distal aorta. The foal was subject to euthanasia and post-mortem examination confirmed a spherical aortic aneurysm, in the dorsal midline caudal to the kidneys that contained a large thrombus. Histopathological examination revealed inflammation and necrosis of the tunica intima and tunica media of the left umbilical artery with suppuration and bacterial colonies evident in the periarterial tissues.

DIAGNOSIS:?Infected aortic aneurysm presumably caused by an umbilical artery infection.

CLINICAL RELEVANCE:?A previously undetected umbilical infection appears to have resulted in an unusual delayed complication causing signs of colic in a foal. Veterinarians should be aware of this condition, and the possibility that it may be a cause of signs of colic in foals. Diagnosis based on ultrasonography should be possible, but may require sedation, visceral analgesia and careful examination.     

Expression of Apoptosis Regulatory Genes and Incidence of Apoptosis in Different Morphological Quality Groups of In Vitro‐produced Bovine Pre‐implantation Embryos

Apoptosis occurs during early development in both in vivo‐ and in vitro‐produced embryos, and is considered as one of the causes of embryonic loss. The objectives of this study were, therefore, investigating stage‐specific expression profiles of apoptosis regulatory genes in three quality groups of in vitro‐produced bovine pre‐implantation embryos; and analysing the relationship between cell number and DNA fragmentation with expressions of those genes. The relative abundance of mRNA of 9 pro‐ (Bax, caspase‐9, Bcl‐xs, P53, Caspase‐3 and Fas) and anti‐ (Bcl‐w and Mcl‐1) apoptotic genes was analysed. Differential cell staining and terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end labelling were performed to analyse the variation in cell numbers and detect apoptotic nuclei respectively. Expression of Bax and Caspase‐3 genes was significantly (p < 0.05) higher in poor quality pre‐implantation embryos as compared with that of morphologically good quality embryos of the same developmental stages. Moreover, Mcl‐1 expression was significantly higher in good quality immature oocytes than that in the poor quality group. Moreover, higher DNA fragmentation was evidenced in morphologically poor quality blastocysts. In conclusion, our study demonstrates that Bax, caspase‐3 and Mcl‐1 can be used as potential markers of embryo quality to evaluate in vitro‐produced bovine embryos. Further studies are required to investigate specific molecular signatures that can be used in evaluating in vivo‐derived embryos.     

A three‐dimensional alginate system for in vitro culture of cumulus‐denuded feline oocytes

In the case of high valuable individuals with very precious genetic material, widening the genetic pool including gametes with poor morphological characteristics, as cumulus‐denuded oocytes (CDOs), could be an option. To improve the in vitro culture of low‐competence feline CDOs, an enriched three‐dimensional (3D) system in association with competent cumulus–oocyte complexes (COCs) was developed. For this purpose, domestic cat CDOs were cultured with or without companion COCs in the 3D barium alginate microcapsules. The overall viability and the meiotic progression of feline CDOs cocultured with COCs or cultured separately in 3D or in 2D (traditional microdrops) system were compared. The 3D system was able to support viability and meiotic resumption of the feline oocytes, as well as the 2D microdrops. In 3D microcapsules, the presence of COCs resulted in a higher viability of CDOs (91.1%, p < .05), than that obtained without COCs or in 2D microdrops (71.2% and 67.3%, respectively), but the percentages of meiotic resumption were similar of those of CDOs cultured separately (55.4% vs. 40.4%, p > .05). It is notable that the presence of CDOs seemed to enhance the meiotic progression of the associated COCs. In conclusion, the 3D barium alginate microcapsules are a suitable system for feline oocytes in vitro culture, but more specific enriched conditions should be developed to improve the CDOs full competence in vitro.