Adenohypophyseal function in bitches treated with medroxyprogesterone acetate

The aim of this study was to investigate the effects of treatment with medroxyprogesterone acetate (MPA) on canine adenohypophyseal function. Five Beagle bitches were treated with MPA (10mg/kg, every 4 weeks) and their adenohypophyseal function was assessed in a combined adenohypophyseal function test. Four hypophysiotropic hormones (CRH, GHRH, GnRH, and TRH) were administered before and 2, 5, 8, and 11 months after the start of MPA treatment, and blood samples for determination of the plasma concentrations of ACTH, cortisol, GH, IGF-1, LH, FSH, prolactin, alpha-MSH, and TSH were collected at -15, 0, 5, 10, 20, 30, and 45 min after suprapituitary stimulation. MPA successfully prevented the occurrence of estrus, ovulation, and a subsequent luteal phase. MPA treatment did not affect basal and GnRH-induced plasma LH concentrations. The basal plasma FSH concentration was significantly higher at 2 months after the start of MPA treatment than before or at 5, 8, and 11 months after the start of treatment. The maximal FSH increment and the AUC for FSH after suprapituitary stimulation were significantly higher before treatment than at 5, 8, and 11 months of MPA treatment. Differences in mean basal plasma GH concentrations before and during treatment were not significant, but MPA treatment resulted in significantly elevated basal plasma IGF-1 concentrations at 8 and 11 months. MPA treatment did not affect basal and stimulated plasma ACTH concentrations, with the exception of a decreased AUC for ACTH at 11 months. In contrast, the maximal cortisol increment and the AUC for cortisol after suprapituitary stimulation were significantly lower during MPA treatment than prior to treatment. MPA treatment did not affect basal plasma concentrations of prolactin, TSH, and alpha-MSH, with the exception of slightly increased basal plasma TSH concentrations at 8 months of treatment. MPA treatment did not affect TRH-induced plasma concentrations of prolactin and TSH. In conclusion, the effects of chronic MPA treatment on adenohypophyseal function included increased FSH secretion, unaffected LH secretion, activation of the mammary GH-induced IGF-I secretion, slightly activated TSH secretion, suppression of the hypothalamic-pituitary-adrenocortical axis, and unaffected secretion of prolactin and alpha-MSH.     

Multiplication of attenuated and virulent porcine parvoviruses in colostrum-deprived, neonatal pigs

Colostrum-deprived, neonatal, 2 days old pigs were inoculated with the attenuated HT-/SK or the virulent 90HS strain of porcine parvovirus (PPV) by the oral or subcutaneous route and sacrificed 2, 4 or 6 days after inoculation. Then, comparison was made on viral multiplication in pigs between the two strains. Pigs inoculated with the HT-/SK strain showed no detectable viremia or HI antibody responses against PPV within 6 days after inoculation. Only in pigs inoculated by the subcutaneous route, a small amount of virus was recovered from the spleen, liver, or mesenteric lymph nodes. These viruses were distinguished from the parental virulent 90HS strain, as examined for rct maker in vitro. When pigs were inoculated with the virulent 90HS strain, viremia appeared in all of them 1 day after inoculation and continued for up to the sacrificed day. Moreover, a considerable amount of virus was also detected from all tissues, including brain, lung, liver, spleen, pancreas, small intestine, and lymph node tissues, in all pigs tested. HI antibodies were first detected 6 days after inoculation.     

Estimating stand transpiration in a Eucalyptus populnea woodland with the heat pulse method: measurement errors and sampling strategies

Sap flow measurement techniques, such as the heat pulse (compensation) method, are practical means for estimating the water use of individual trees and are often the only reasonable alternative for measuring forest and woodland transpiration in complex heterogeneous terrain. The need to scale estimates of water use from a sample of individual stems to a stand (population) of known area may be satisfied by applying scalars of flux based on tree size or domain. We estimated the aggregate errors in applying the heat pulse technique to the estimation of stand transpiration in a poplar box (Eucalyptus populnea F.J. Muell.) woodland in southeastern Queensland, Australia, by a combination of precision analyses, experimental validation and Monte Carlo simulations of sampling errors. Errors in sap flux density measurements were approximately 13%. The potential error in the flux estimates for individual stems with stratified sampling of sap flux density with depth and bole quadrant based on four sensors was an additional 25%. Conducting wood area, diameter at 1.3 m, leaf area and domain based on Ecological Field Theory all proved excellent scalars of flux at the stand level. With a sample size of six trees stratified by diameter, coefficients of variation in scaling to the stand level were approximately 5% for any of these scalars. The greatest potential source of error in estimating stand transpiration by the heat pulse method was in the measurement of the fluxes of individual stems; scaling these measurements to a homogeneous stand of trees involved less uncertainty.     

Using remote sensing to predict outbreaks of Oestrus ovis in Namibia

The Directorate of Veterinary Services of the Ministry of Agriculture, Water and Rural Development of Namibia issues warnings to farmers in the south of the country about the likelihood of infestation of small-stock by the nasal bot fly, Oestrus ovis. Farmers can then treat their stock at the most appropriate time. The O. ovis puparia develop at shallow depths in the soil and the timing of emergence is directly dependent on climatic conditions, specifically the number of degree-days above a particular threshold soil temperature. Based on temperature measurements from only a few stations scattered throughout the country, the veterinary department warnings lack precision in space and time. This paper presents an attempt to support the programme of warnings with accumulated temperature information from Meteosat satellite images, in order to strengthen predictions of the time of emergence in specific places, and to improve the precision and reliability of warnings given to farmers.     

The effects of body composition on the pharmacokinetics of subcutaneously injected ivermectin and moxidectin in pigs

Macrocyclic lactones are characterized by their long persistence in animals because of their extensive distribution into fat. This study examined the influence of body condition on the disposition of ivermectin (IVM) and moxidectin (MXD) in blood and fat following subcutaneous (s.c.) drug administration. 'Fat' and 'thin' lines of pigs were established using two different diets. All animals were then injected with either MXD or IVM at 300 microg/kg and blood samples were taken at regular intervals until slaughter. Two IVM-treated animals from each diet group were slaughtered at either 3 days or 3 weeks posttreatment. Two MXD-treated animals from each diet group were slaughtered at 3 days, 3, 6 or 9 weeks after treatment. Samples of backfat were taken from all animals at slaughter. Fluorescence HPLC was used to determine the concentrations of MXD or IVM in the plasma and fat samples. The plasma IVM concentration peaked more rapidly in the thin IVM treated pigs compared with the fat pigs. The concentration of IVM in backfat was significantly lower in the thin animals slaughtered 3 weeks after treatment. The MXD plasma concentration peaked within the first hour in both the thin and fat groups, but from 12 h posttreatment there was a higher MXD concentration in the plasma of the fat pigs resulting in MXD being detectable in these pigs for 28 days compared with only 17 days in the thin pigs. Despite this difference in plasma persistence no differences were seen in the MXD concentration of backfat between fat and thin animals. Body condition influenced the kinetic disposition of IVM and MXD following s.c. drug administration with both drugs being less persistent in thin compared with fat animals.     

The correlation between in-situ,real-time aerosol photoemission intensity and particulate polycyclic aromatic hydrocarbon concentration in combustion aerosols

Aerosol photoemission (APE) has been found to be an excellent surrogate measure of particulate PAH concentration in combustion aerosols under a variety of laboratory and field conditions. Samples of oil stove, automobile exhaust, and urban air particulate matter were concurrently analyzed for aerosol photoemission intensity and particulate PAH concentration. In-situ, real-time analysis of the particulate matter was performed by UV-induced electron photoemission. Two photon energies, 4.9 and 6.7 eV, were chosen for irradiation. The latter energy was more sensitive and less selective. Particulate PAH concentrations were determined by collecting the particulate matter on a filter, solvent extracting the filter, and analyses of the extracts by gas chromatography / mass spectroscopy. Linear correlations (0.84≤r²≤1.00) were observed between aerosol photoemission intensities and the sum of particulate PAH concentrations for laboratory and field studies under a wide variety of conditions. The studies performed to date cover a dynamic range of three orders of magnitude (1 to 1000 ng / m³). The time resolution is in the order of a few seconds.     

Analysis of genomic mutation and immunohistochemistry of platelet‐derived growth factor receptors in canine vascular tumours

We examined whether mutation of the platelet‐derived growth factor receptor protein tyrosine kinase (PDGFR)‐α and PDGFR‐β genes contributes to their overexpression in canine vascular tumours. Genomic sequences of trans‐ or juxtamembrane regions of PDGFR‐α and PDGFR‐β were analysed with immunohistochemical staining and polymerase chain reaction‐direct sequencing using DNA from paraffin‐embedded neoplastic tissues of 27 hemangiosarcomas (HSAs) and 20 hemangiomas (HAs). Immunohistochemically, 75% of the HA cases were positive for PDGFR‐α and almost most of the HA cases were negative for PDGFR‐β. Of the HSA cases, 55.6% were negative for PDGFR‐α and 63% were strongly positive for PDGFR‐β. Among the HA cases, 1 missense mutation was detected in PDGFR‐α exon 18 and 1 in PDGFR‐β exon 17. Two HSA cases had missense mutations in exon 14 and 1 in exon 17 of PDGFR‐β. Thus, genomic mutation of trans‐ or juxtamembrane regions of PDGFRs was not the main mechanism driving the activation of receptors in HSA and HA.