Supplementation of Slow‐Release Melatonin Improves Recovery of Ovarian Cyclicity and Conception in Summer Anoestrous Buffaloes (Bubalus bubalis)

The role of melatonin as a protective neurohormone against restoring cyclicity in summer anoestrous animals in photoperiod species has gained wider acceptance. This study was designed to uncover the evidence the slow‐release melatonin (MLT) has on initiation of ovarian cyclicity and conception rate (CR) in summer anoestrous buffaloes. Thus, buffaloes diagnosed as summer anoestrous (absence of overt signs of oestrus, concurrent rectal examination and radioimmunoassay for serum progesterone at 10 days interval) were grouped as untreated (Group I, sterilized corn oil, n = 8) and treated (Group II, single subcutaneous injection of MLT @18 mg/50 kg bwt in sterilized corn oil, n = 20). Animals treated and detected in oestrus were artificially inseminated (AI) followed by division into Group III (second dose of MLT on 5th day post‐AI, n = 8) and Group IV (no melatonin administration, n = 10). Blood samples were collected at 4 days interval for estimation of serum MLT, progesterone and oestrogen using radioimmunoassay kit. Mean oestrous induction rate (OIR), oestrous induction interval (OII), interoestrous interval (IOI) and CR were estimated. Compared to control, concentration of melatonin was significantly (p < 0.05) higher in treated group ranging from 14.34 ± 1.72 to 412.31 ± 14.47 pg/ml whereas other two hormones did not show any concentration difference. Melatonin‐administered buffaloes showed significantly (p < 0.05) higher (90%) OIR with OII of 18.06 ± 1.57 days. Results showed improvement in conception rate in buffaloes administered with post‐insemination melatonin. It can be concluded from the study that slow‐release melatonin supplementation restored cyclicity in summer anoestrous animals resulting in improvement in conception rate in buffaloes.     

Evaluation of action thresholds for chronic rice insect pests in the Philippines. I. Less frequently occurring pests and overall assessment

Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga aenescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15?–?0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies >?90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides.     

Pharmacokinetics of single-dose oral pregabalin administration in normal dogs

ObjectiveTo describe the pharmacokinetics of pregabalin in normal dogs after a single oral dose.Study designProspective experiment.AnimalsSix adult Labrador/Greyhound dogs (four females and two males) aged 2.6 (2.6–5.6) years old (median and range) weighing 33.4 (26.8–42.1) kg.MethodsAfter jugular vein catheterization, the dogs received a single oral dose of pregabalin (～4 mg kg^?1). Blood samples were collected at: 0 (before drug administration), 15 and 30 minutes and at 1, 1.5, 2, 3, 4, 6, 8, 12, 24 and 36 hours after drug administration. Plasma pregabalin concentration was measured by HPLC. Noncompartmental analysis was used to estimate pharmacokinetic variables.ResultsNo adverse effects were observed. The median (range) pharmacokinetic parameters were: Area under the curve from time 0 to 36 hours = 81.8 (56.5–92.1) μg hour mL^?1; absorption half-life = 0.38 (0.25–1.11) hours; elimination half-life = 6.90 (6.21–7.40) hours; time over 2.8 μg mL^?1 (the presumed minimal effective concentration) = 11.11 (6.97–14.47) hours; maximal plasma concentration (C_max) = 7.15 (4.6–7.9) μg mL^?1; time for C_max to occur = 1.5 (1.0–4.0) hours. Assuming an 8-hour dosing interval, predicted minimal, average, and maximal steady state plasma concentrations were 6.5 (4.8–8.1), 8.8 (7.3–10.9), and 13.0 (8.8–15.2) μg mL^?1. The corresponding values assuming a 12-hour interval were 3.8 (2.4–4.8), 6.8 (4.9–7.9), and 10.1 (6.6–11.6) μg mL^?1.Conclusions and clinical relevancePregabalin 4 mg kg^?1 PO produces plasma concentrations within the extrapolated therapeutic range from humans for sufficient time to suggest that a twice daily dosing regime would be adequate. Further study of the drug's safety and efficacy for the treatment of neuropathic pain and seizures in dogs is warranted.     

Further investigation of equine fescue oedema induced by Mediterranean tall fescue (Lolium arundinaceum) infected with selected fungal endophytes (Epichloë coenophiala)

Abstract

AIMS

To determine if equine fescue oedema (EFO) induced by grazing Mediterranean-type tall fescue (Lolium arundinaceum) infected with selected endophytes (Epichloë coenophiala) could be prevented by treatment with the corticosteroid, methylprednisolone, and anti-histamine, cetirizine, and to determine concentrations of lolines, specifically N-acetyl norloline (NANL), in grasses grazed by horses that did and did not develop EFO.     

Comparison of four drug combinations for total intravenous anesthesia of horses undergoing surgical removal of an abdominal testis

OBJECTIVE: To evaluate anesthetic effects of 4 drug combinations used for total intravenous anesthesia of horses undergoing surgical removal of an abdominal testis. DESIGN: Clinical trial. ANIMALS: 32 healthy cryptorchid horses. PROCEDURE: Horses were sedated with xylazine and butorphanol and were randomly assigned to 1 of 4 groups: induction of anesthesia with ketamine and diazepam and maintenance with bolus administration of ketamine and xylazine (KD/KX); induction and maintenance of anesthesia with bolus administration of tiletamine-zolazepam, ketamine, and detomidine (TKD); induction and maintenance of anesthesia with continuous infusion of xylazine, guaifenesin, and ketamine; and induction and maintenance of anesthesia with continuous infusion of guaifenesin and thiopental. Horses that moved 3 consecutive times in response to surgical stimulation or for which surgery time was > 60 minutes were administered an inhalant anesthetic, and data from these horses were excluded from analysis. RESULTS: Quality of induction was not significantly different among groups. Muscle relaxation and analgesia scores were lowest for horses given KD/KX, but significant differences among groups were not detected. Horses anesthetized with TKD had a significantly greater number of attempts to stand, compared with the other groups, and mean quality of recovery from anesthesia for horses in the TKD group was significantly worse than for the other groups. Anesthesia, surgery, and recovery times were not significantly different among groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that all 4 drug combinations can be used to induce short-term anesthesia for abdominal cryptorchidectomy in horses. However, horses receiving TKD had a poorer recovery from anesthesia, often requiring assistance to stand.     

Blood calcium,glucose and haematology profiles of parturient bitches diagnosed with uterine inertia or obstructive dystocia

Bitches with dystocia most often present with clinical signs of uterine inertia (UI). The aetiology of myometrial dysfunction in most of these cases is still not elucidated. We compared blood ionized calcium (iCa) and glucose concentrations in bitches diagnosed with primary UI (PUI, n = 14), secondary UI (SUI, n = 6) or obstructive dystocia (OD, n = 6), and we described their haematology profiles. Bitches diagnosed with UI had a patent birth canal and delivered no puppies yet (PUI) or only part of the whole litter (SUI). The OD group had no UI and showed strong abdominal contractions. Blood iCa did not differ between the PUI, SUI and OD groups and was not influenced by litter size. There was a significant positive relationship (R² = .241, p = .013) between iCa concentrations and the dam's body weight. Glucose concentrations were also not significantly different between dystocia groups or influenced by body weight and litter size. Hypocalcaemia was detected in 11 bitches, and hypoglycaemia in two bitches. Pregnancy‐associated anaemia was seen in about one‐third of the bitches. Eight of 12 dogs had increased platelet counts, and ten had leukocytosis with mature neutrophilia. Although iCa did not differ between dystocia groups, low concentrations may have contributed to the development of UI in some of the small size bitches. Hypoglycaemia was uncommon, and therefore, we consider low glucose concentrations not to have played an important role in the pathogenesis of UI in our study population. Pregnancy‐associated anaemia, thrombocytosis, leukocytosis and mature neutrophilia were common findings in otherwise healthy bitches diagnosed with different forms of dystocia.     

Pharmacokinetics of single-dose intravenous levetiracetam administration in normal dogs

Objective: To determine plasma pharmacokinetics of levetiracetam after a single intravenous dose (60 mg/kg) in normal dogs using a high‐performance liquid chromatography assay validated for canine plasma. Design: Pharmacokinetic study. Setting: A university‐based canine research facility. Animals: Six healthy adult dogs. Interventions: Intravenous drug administration, multiple blood sample procurement. Measurements and main results: There were no obvious adverse effects associated with the intravenous (IV) bolus administration of levetiracetam in any of the dogs. Plasma levetiracetam concentrations remained above or within the reported therapeutic range for humans (5–45 μg/mL) for all dogs, for all time periods evaluated. Mean and median (in parentheses) values for pharmacokinetic parameters included the following: maximum plasma concentration, 254 μg/mL (254 μg/mL); half‐life, 4.0 hours (4.0 hours); volume of distribution at steady state, 0.48 L/kg (0.48 L/kg); clearance, 1.4 mL/kg/min (1.5 mL/kg/min); and median residence time, 6.0 hours (6.0 hours). Conclusions: In normal dogs, a 60 mg/kg IV bolus dose of levetiracetam is well tolerated and achieves plasma drug concentrations within or above the therapeutic range reported for humans for at least 8 hours after administration. Based on the favorable pharmacokinetics and tolerability demonstrated for IV levetiracetam in this study, in addition to previously demonstrated efficacy of oral levetiracetam, IV levetiracetam may be a useful treatment option for emergency management of canine seizure activity.