Comparison of worm control strategies in grazing sheep in Denmark.

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.     

Identification of galegine, an isoprenyl guanidine, as the toxic principle of Schoenus asperocarpus (poison sedge)

SUMMARY An Isoprenyl guanldine, galegine, was isolated from the Western Australian sedge Schoenus asperocarpus (Cyperaceae). Synthetic galegine was shown to reproduce the clinical and pathological features of poisoning by this plant. Preliminary results suggest that the massive thoracic effusion observed in sedge poisoning is the result of a direct effect on pulmonary vascular permeability.     

Residues from long-acting antimicrobial preparations in injection sites in cattle

Objective To investigate tissue residues of two longacting oxytetracycline (OTC) preparations in cattle.
Design A randomised drug residue trial.  

Animals

Two hundred and forty beef cattle in 24 groups of ten.
Procedure Two blind-coded 200 mg/mL OTC preparations were used in five treatment regimens of various combinations of injection sites (from one to five) and administrations (one or two). Five cattle from each group were slaughtered at 21, 30 and 60 days after injection and the injection site, urine, kidney and diaphragm muscle analysed for residues.
Results The OTC concentration exceeded the maximum residue limit in kidney in animals slaughtered 21 days after treatment, which is the prescribed withholding period. Concentration at the injection site was much greater than the maximum residue limit 30 days post-treatment, but not 45 days post-treatment. The residue was smaller when OTC had been injected in multiple sites. There was no difference between the two OTC preparations.
Conclusion A review of the maximum injection volume, site of injection and the withholding period is needed for long-acting OTC formulations.     

Prostaglandin-induced abortion in swine: endocrine changes and influence on subsequent reproductive activity

Gilts were treated during midgestation with prostaglandin (PG) F to study the efficacy of different treatment regimens on induction of abortion and to determine the adverse consequences of PGF-induced abortion in swine. In study 1, pregnant purebred Duroc gilts (60 to 90 days of gestation) were given (IM) 500 micrograms of cloprostenol (n = 12), 20 mg of dinoprost tromethamine (n = 11), or 10 mg of dinoprost tromethamine repeated 12 hours later by an additional 10 mg of dinoprost tromethamine (n = 11). The percentage of gilts that aborted and percentage of aborted gilts that returned to estrus for each treatment group were as follows: cloprostenol, 91.7% and 100%, respectively; 20 mg of dinoprost tromethamine, 36.4% and 25.0%, respectively; and 10 + 10 mg of dinoprost tromethamine, 100% and 90.9%, respectively. Treatment with cloprostenol and with 10 + 10 mg of dinoprost tromethamine caused more gilts to abort (P less than 0.01) than did treatment with 20 mg of dinoprost tromethamine. Gilts that did not abort were given a second treatment with 10 + 10 mg of dinoprost tromethamine. When the abortions by gilts initially treated with 500 micrograms of cloprostenol or 10 + 10 mg of dinoprost tromethamine were combined with those re-treated with 10 + 10 mg of dinoprost tromethamine, 32 of 33 (97.0%) gilts aborted, and 30 of the 32 (93.8%) aborted gilts returned to estrus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence of coccidioides infection among dogs residing in a region in which the organism is endemic

OBJECTIVE: To determine the incidence of Coccidioides infection among dogs residing in a region in which the organism is endemic (Pima and Maricopa counties, Arizona) and estimate the rate of clinical illness. DESIGN: Community-based longitudinal and cross-sectional studies. ANIMALS: 124 healthy 4- to 6-month-old seronegative puppies (longitudinal study) and 381 4- to 18-month-old dogs with unknown serostatus (cross-sectional study). PROCEDURE: Dogs in the longitudinal study were tested at 6-month intervals for at least 1 year for anticoccidioidal antibodies. Dogs that became ill were evaluated for coccidioidomycosis. Dogs in the cross-sectional study were tested for anticoccidioidal antibodies once, and clinical abnormalities were recorded. RESULTS: 28 of the 104 (27%) dogs that completed the longitudinal study developed anticoccidioidal antibodies. Thirty-two of the 381 (8%) dogs in the cross-sectional study had anticoccidioidal antibodies. Five seropositive dogs in the longitudinal study and 13 seropositive dogs in the cross-sectional study had clinical signs of disease. The remaining seropositive dogs were otherwise healthy and were classified as subclinically infected. Survival analysis indicated that the cumulative probability of infection by 2 years of age was 28%, and the cumulative probability of clinical infection by 2 years of age was 6%. Titers for clinically and subclinically infected dogs overlapped. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that young dogs living in the study area had a high likelihood of becoming infected with Coccidioides spp, but few developed clinical illness. Serologic testing alone was insufficient for a diagnosis of clinical disease because of the overlap in titers between clinically and subclinically infected dogs.     

Endocrine Disruptors and Other Food-contaminating Environmental Pollutants as Risk Factors in Animal Reproduction

Pollutants of many chemical classes, derived primarily from anthropogenic activities, are ubiquitous in the environment, persistent, biologically available and can exert adverse effects on the reproductive and other, indirectly related, physiological systems. Food is generally considered to be the major route of animal exposure in vertebrate species but the relative contributions of other routes of exposure such as through lungs, gills or skin are not well studied and may be of importance for certain animal groups, depending on their immediate environment. Animals are particularly sensitive to exposure during developmental stages but the pattern of exposure to chemicals is likely to be different to that of adults. Quantification of the risk posed by the ingestion of pollutants in food is complex and depends on many factors including species, diet composition, duration of exposure to the food, efficiency of pollutant absorption, subsequent metabolism, sensitivity of target organs and stage of development. While the effects of high doses of single chemicals are proven, dietary exposure to pollutants generally involves prolonged, low-level exposure to a large number of compounds, each of which has different chemical characteristics, exerts different biological effects and is present at varying concentrations. Thus, while exposure to pollutants through feed is undoubtedly a significant risk factor for many species and may be the most important one for many terrestrial vertebrates, other routes of exposure may be more important in other groups.     

Determination of oryzalin in water, citrus fruits, and stone fruits by liquid chromatography with tandem mass spectrometry

A new methodology is described for rapidly determining the herbicide oryzalin in water, citrus fruits, and stone fruits by liquid chromatography with negative ion electrospray ionization tandem mass spectrometry (LC/MS/MS). Oryzalin is extracted from water using a polymeric sorbent solid phase extraction (SPE) column and from fruit using methanol. The water samples require no further purification, but an aliquot of the fruit sample extracts is diluted with water and purified using a polymeric 96 well SPE plate. Purified extracts are concentrated prior to determination by LC/MS/MS at m/z 345 (Q1) and m/z 281 (Q3) using an external standard for calibration. The validated limits of quantitation were 0.05 microg/L in water (drinking water, surface water, and groundwater) and 0.01 microg/g in citrus fruits (oranges and lemons) and stone fruits (peaches and cherries). Recoveries averaged 102% for water samples and 85-89% for the various types of fruit samples. For all fortification levels combined, the relative standard deviations ranged from 4 to 6% for water and from 2 to 4% for fruit.     

The influence of ovariectomy on luteinizing hormone concentrations in anestrous and cyclic sows

In an effort to determine whether anestrus in swine is due to aberrant ovarian feedback control of gonadotropin release, this study contrasted the influence of ovariectomy on LH concentrations in serum of anestrous sows and in sows that returned to estrus following weaning. Blood samples were collected at 6-h intervals from 7 d prior to until 4 d after ovariectomy of 22 anestrous and 24 cyclic sows. Blood samples also were collected at 15-min intervals for 8 h at 2 d prior to and 2 d after ovariectomy. Sampling at 6-h intervals continued until 12 d after ovariectomy and additional 8-h windows of 15-min samples were taken at 7 and 12 d after ovariectomy of seven anestrous and nine diestrous sows. Mean LH concentrations and LH pulse frequencies were greater (P less than .05) 2 d after ovariectomy than 2 d prior to ovariectomy in both anestrous and diestrous sows. Mean pulse amplitude had increased by 2 d after ovariectomy in anestrous sows but did not change in cyclic sows. Baselines as determined from the mean of all LH measurements excluding pulses, remained the same in both anestrous and diestrous sows at 2 d after ovariectomy. Pulse frequency, pulse amplitude, and mean LH concentration were greater (P less than .05) in both anestrous and diestrous sows at 7 and 12 d after ovariectomy than at 2 d prior to and 2 d after ovariectomy. Pulse amplitude on d 7 and 12 after ovariectomy decreased (P less than .05) in both anestrous and diestrous sows relative to those observed at earlier times.(ABSTRACT TRUNCATED AT 250 WORDS)     

T-lymphocyte predominance in lesions of canine coccidioidomycosis

Coccidioidomycosis is a systemic fungal infection endemic to the southwestern United States. Although cell-mediated immunity is considered critical in control of the infection, little is known of the cellular population in naturally occurring lesions. To characterize the lymphocytic infiltration, archived formalin-fixed, paraffin-embedded tissues (subcutis, pericardium/heart, lung, bone, and synovium) from 18 dogs with coccidioidomycosis were studied with immunohistochemistry for CD3 and CD79a. In nearly all lesions, T lymphocytes were more numerous than B lymphocytes and were distributed throughout the lesion with concentration in the periphery of granulomas, whereas B lymphocytes were mostly confined to the periphery of granulomas. The predominance of T lymphocytes in lesions of canine coccidioidomycosis was independent of the tissue evaluated, the number of intralesional organisms, and the nature or severity of the inflammatory response.