Toxicosis in sheep following ingestion of natural gas condensate.

Thirty of 200 ewes died or were euthanatized during a 21-day period following a 1-day accidental exposure to natural gas condensate, a complex mixture of hydrocarbons obtained during collection of natural gas from wells. Despite access to potable well water, the poisoned ewes willingly consumed toxic doses of condensate that contaminated surface water. Eight animals died without premonitory signs; the remainder became ill over the course of a few days to 3 weeks. The principal cause of mortality was aspiration pneumonia, but myocardial degeneration and necrosis, renal tubular damage, gastritis, enteritis, and meningeal edema and hyperemia were also observed. Gas chromatographic analysis identified chemical traces of the hydrocarbons in the tissues, and "fingerprinting," the process of matching chromatographic tracings, provided forensic proof of the contamination source. Atomic absorption spectroscopy and cholinesterase analyses were performed to eliminate the possibility of toxicosis by heavy metal contaminants or other constituents. This appears to be the first reported incidence of natural gas condensate toxicity involving sheep or other ruminants. Although the available literature presents a suggestive pattern of clinical signs and pathologic lesions of petroleum product poisoning, diagnostic investigations should employ detailed analytic examination because each source of petroleum hydrocarbons contains unique sets of components that may produce different toxic effects.     

Prevalence of feline leukemia virus and antibodies to feline immunodeficiency virus in cats in Norway.

Serum samples from 224 Norwegian cats were analyzed for the presence of feline leukemia virus (FeLV) p27 common core antigen, and for antibodies to feline immunodeficiency virus (FIV). Ninety specimens originated from the serum bank at the central referral clinic at the Norwegian College of Veterinary Medicine, which had been collected during the years 1983-1989; 67 sera were submitted from veterinarian practitioners; while 67 sera originated from cats presented for euthanasia. The cats were classified into one "healthy" and one "sick" group. Only 2.2% of sick cats and 1.2% of healthy cats showed FeLV antigenemia, a finding which is lower than which has been reported from many other countries. The prevalence of FIV antibodies was 10.1% in sick cats and 5.9% in healthy cats. Antibodies to FIV was most prevalent in male cats (14.7%) than in female cats (2.1%), and more prevalent among domestic cats (12.0%) compared to pedigree cats (2.4%). Antibodies to FIV in the cats demonstrated increasing prevalence with increasing age. It may be concluded that FeLV causes minor problems in Norwegian cats, while FIV is present in a similar prevalence to what is reported from other countries.     

An evaluation of two cypermethrin-based pour-on formulations on sheep infested with the biting louse, Bovicola ovis

Two synthetic pyrethroid (cypermethrin) based pour-on insecticide formulations, with high cis/trans isomer ratios (80:20) but differing in their respective active ingredient concentrations and solvent component(s), were applied to sheep infested with the biting-louse, Bovicola ovis. All treated sheep were penned with louse-infested sheep 9,12 and 15 weeks after the insecticide was applied. The 2% cypermethrin formulation achieved a higher level of control than the 1.25% cypermethrin formulation at each challenge interval when applied 12 weeks after shearing. The 2% cypermethrin formulation provided 97-100% control of lice from 4 to 16 weeks after application on sheep shorn 6 or 12 weeks prior to treatment. The 1.25% cypermethrin formulation provided 85% control of lice 4 weeks after application on sheep shorn 12 weeks prior to treatment, the level of control increasing to a maximum of 100% by week 9, and declining thereafter. The 2% cypermethrin formulation may provide a better level of control in long-woolled sheep than 1.25% cypermethrin, by compensating for the diluent effect of lipid.     

The biochemical basis of resistance of potato to soft rot bacteria

Evidence is presented that a number of mechanisms are involved in the resistance of commercial cultivars of potato to soft rottingErwinia spp. These include phytoalexins, phenolics, cell wall modification, and possibly proteins. The role of elicitor-active oligogalacturonides, which are released from plant cell walls by pectic enzymes, is discussed.     

Response of five temperate deciduous tree species to water stress

Gas exchange, tissue water relations, and leaf/root dry weight ratios were compared among young, container-grown plants of five temperate-zone, deciduous tree species (Acer negundo L., Betula papyrifera Marsh, Malus baccata Borkh, Robinia pseudoacacia L., and Ulmus parvifolia Jacq.) under well-watered and water-stressed conditions. There was a small decrease (mean reduction of 0.22 MPa across species) in the water potential at which turgor was lost (Psi(tlp)) in response to water stress. The Psi(tlp) for water-stressed plants was -1.18, -1.34, -1.61, -1.70, and -2.12 MPa for B. papyrifera, A. negundo, U. parvifolia, R. pseudoacacia, and M. baccata, respectively. Variation in Psi(tlp) resulted primarily from differences in tissue osmotic potential and not tissue elasticity. Rates of net photosynthesis declined in response to water stress. However, despite differences in Psi(tlp), there were no differences in net photosynthesis among water-stressed plants under the conditions of water stress imposed. In A. negundo and M. baccata, water use efficiency (net photosynthesis/transpiration) increased significantly in response to water stress. Comparisons among water-stressed plants showed that water use efficiency for M. baccata was greater than for B. papyrifera or U. parvifolia. There were no significant differences in water use efficiency among B. papyrifera, U. parvifolia, A. negundo, and R. pseudoacacia. Under water-stressed conditions, leaf/root dry weight ratios (an index of transpiration to absorptive capacity) ranged from 0.77 in R. pseudoacacia to 1.05 in B. papyrifera.