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Vet News

  • Effects of GnRH, a progesterone-releasing device, and energy balance on an oestrus synchronisation program in anoestrous dairy cows

    Thursday, Jul 27 '17 08:08

    Objective The aim of this research was to study the roles of the day 0 energy balance and gonadotrophin-releasing hormone (GnRH) and progesterone levels on dominant follicle (DF) and corpus luteum (CL) development during the first 7 days of a gonadotrophin–prostaglandin–gonadotrophin (GPG) + progesterone (P4) program in anoestrous dairy cows. Methods Cows (n = 81) were allocated to one of the three treatments: (1) GPG + P4 (days 0 and 9, 100 µg GnRH; day 0–7, intravaginal P4 device; day 7, 500 µg PGF2α); (2) GPG (as for treatment 1 but excluding the P4 device) and (3) prostaglandin + GnRH + P4 (as for treatment 1, but excluding day 0 GnRH). DF and CL size, plasma concentrations of insulin, insulin-like growth factor-I (IGF-I) and non-esterified fatty acid (NEFA) were measured on days 0 and 7. Results The proportion of cows with a CL on day 7 was significantly different between groups (GPG: 78%, GPG+P4: 69%, PGF2α + GnRH + P4: 42%, P = 0.02). The CL volume on day 7 was significantly associated with treatment, treatment by time postpartum and plasma concentrations of insulin, IGF-I and NEFA. Conclusion In cows without a CL present on day 0 of an oestrus synchronisation program, removal of the day 0 GnRH treatment led to reduced CL development; however, no effect of adding progesterone was found. In contrast, in cows with a CL present on day 0 inclusion of a progesterone device led to a higher CL volume, but removal of the first GnRH injection had no effect. Response to the treatment was affected by plasma concentrations of insulin, IGF-I and NEFA. Read more...

  • Chemical stability of morphine and methadone, and of methadone in combination with acepromazine, medetomidine or xylazine, during prolonged storage in syringes

    Thursday, Jul 27 '17 08:08

    Objective To assess the chemical and physical stability of morphine and methadone stored in syringes for 12 months and of methadone when mixed with acepromazine, medetomidine or xylazine. Methods A high-performance liquid chromatography (HPLC) technique was developed and validated for the analysis of morphine and methadone. Morphine and methadone were dispensed into syringes and stored at 25°C/60% relative humidity (RH) and 40°C/75% RH. Solutions containing mixtures of methadone combined with acepromazine, medetomidine or xylazine were stored in syringes at 25°C/60%RH. At initiation, after 1 week and then 1, 3, 6, 9 and 12 months, samples were analysed by HPLC for the quantification of the morphine or methadone. Measured concentrations were assessed as a function of storage time and temperature using linear regression statistics to calculate stability. Results When stored at 40°C/75%RH as pre-dispensed syringes, severe physical and chemical changes were observed after the third month for both morphine and methadone. In contrast, at 25°C/60%RH both drugs remained chemically stable for 12 months, with concentration variations not exceeding a 5% change from initiation as stipulated in VICH stability guidelines. When in combination with acepromazine or xylazine, methadone also remained chemically stable, but the combination with medetomidine failed stability criteria prior to 6 months. Precipitation compromised the physical stability of methadone in all unsealed syringes prior to 9 months’ storage. Conclusion Pre-dispensing morphine or methadone into unsealed syringes compromises the drugs’ physical stability. Mixing of methadone with other drugs can degrade its chemical stability. Read more...

  • Artificial infection of sheep with multiple strains of Dichelobacter nodosus to induce footrot

    Thursday, Jul 27 '17 08:08

    Objectives To establish multiple strains of Dichelobacter nodosus in two flocks of sheep and to assess the virulence of five of these strains. Methods In experiment 1, sheep were challenged with five D. nodosus strains, which varied in both virulence and serotype. In experiment 2, consisting of four replicates (paddock groups), sheep were challenged with seven different strains of D. nodosus. In experiment 3, sheep were challenged with one of five D. nodosus strains. Results In experiment 1, at 28 days post challenge, four of the five challenge strains were present. Multiple-strain infections were present in 27 feet, with isolates from three serogroups being recovered from 5 feet, and four serogroups from 1 foot. Challenged hind feet were more frequently affected (P < 0.001). In experiment 2, four of the seven strains were recovered from one replicate and three strains from the remaining three replicates. Significantly more hind feet were affected (262/471, 55.6%) than front feet (198/481, 42%) (P < 0.001). Clinically, in both experiments 1 and 2 the footrot resembled an intermediate form, despite the inclusion of a virulent strain of D. nodosus. In experiment 3, this virulent strain caused a higher prevalence of more severe footrot, a greater mean total foot score and, in Merino sheep, resulted in significantly lower weight gains (P < 0.05). Interaction between D. nodosus strain and breed occurred, with Polwarth sheep being significantly more severely affected by one strain than Merino sheep. Discussion The clinical expression of multiple-strain infections has implications for both research and control of footrot. A novel method of control is proposed. Read more...

  • In this issue – August 2017

    Thursday, Jul 27 '17 08:08


  • Erratum

    Thursday, Jul 27 '17 08:08


Vet News

  • Pictures of cute animals may boost marital satisfaction

    Sunday, Jun 25 '17 05:00

    Learning to associate spouses with unrelated positive stimuli - such as pictures of puppies - could help to improve marital satisfaction, study suggests. Read more...

  • Snake venom could lead to safer blood clot prevention

    Sunday, Jun 11 '17 05:00

    Researchers have found that a protein in the venom of the Tropidolaemus wagleri snake may lead to a safer antiplatelet medication. Read more...

  • Dogs: Personal trainers for older owners?

    Saturday, Jun 10 '17 05:00

    Older dog owners walk more than non-dog owners, according to a new study, adding further evidence that owning a dog is good for our health. Read more...

  • Six ways your pet can boost health and well-being

    Saturday, Jun 3 '17 01:00

    Our pets not only bring us joy and companionship, they offer benefits for health and well-being, too. We take a closer look at what these are. Read more...

  • Declawing linked to aggression and other abnormal behaviors in cats

    Thursday, May 25 '17 05:00

    Declaw surgery (onychectomy) is illegal in many countries but is still a surprisingly common practice in some. Read more...