Maternal dexamethasone treatment in late gestation induces precocious fetal maturation and delivery in healthy Thoroughbred mares

Reasons for performing study: The foal requires an active hypothalamo‐pituitary‐adrenal (HPA) axis for organ maturation and post natal survival. Prenatal administration of synthetic glucocorticoids may provide an effective method for inducing fetal maturation safely in the mare. Objectives: To determine whether dexamethasone administered to late pregnant mares: 1) will induce fetal maturation and precocious delivery; 2) is safe to use and 3) to identify endocrine responses in the mare and foal. Methods: Pregnant Thoroughbred mares received either 100 mg dexamethasone i.m. (treated n = 5) or 50 ml saline i.m. (control n = 5) at 315, 316 and 317 days of gestation. Plasma progestagens, cortisol and prostaglandin F_2α metabolite (PGFM) concentrations were measured before and after treatment. The foals were weighed, the crown‐rump length (CRL) measured and an adrenal stimulation test performed on Day 1. Results: Dexamethasone significantly (P<0.01) reduced gestation length in treated mares without apparent adverse effects. Plasma progestagens increased (P<0.05), and cortisol and PGFM (P<0.05) decreased, following dexamethasone treatment compared with control mares. Foals were clinically mature but those from dexamethasone treated mares had reduced (P<0.05) CRL, but not bodyweights, compared with controls. Their cortisol concentrations increased following exogenous adrenocorticotrophic hormone stimulation but 2 foals from dexamethasone treated mares showed evidence of adrenal suppression. Conclusions: Dexamethasone stimulates precocious fetal maturation and delivery in healthy late pregnant mares. However, fetal HPA activity may be suppressed. Potential relevance: Dexamethasone treatment could be used to improve foal viability in mares at risk of preterm delivery. The endocrine effects of such a therapy must be evaluated before clinical intervention with glucocorticoids can be recommended.     

Identification of the most common cutaneous neoplasms in dogs and evaluation of breed and age distributions for selected neoplasms

OBJECTIVE-To identify the most common cutaneous neoplasms in dogs and evaluate breed and age distributions for selected neoplasms. DESIGN-Retrospective epidemiological study. SAMPLE-Records available through the Veterinary Medical Database of dogs examined at veterinary teaching hospitals in North America between 1964 and 2002. PROCEDURES-Information on tumor type and patient breed and age was collected. Incidence and odds ratios with 95% confidence intervals were calculated. RESULTS-Records of 1,139,616 dogs were reviewed. Cutaneous neoplasms were diagnosed in 25,996 of these dogs; records for the remaining 1,113,620 dogs did not indicate that cutaneous neoplasms had been diagnosed, and these dogs were considered controls. The most frequent age range for dogs with cutaneous neoplasms was 10 to 15 years. Lipoma, adenoma, and mast cell tumor were the most common skin tumor types. CONCLUSIONS AND CLINICAL RELEVANCE-Results supported previously reported data regarding cutaneous neoplasia in dogs but provided updated information on the most common skin tumors and on age and breed distributions.     

Zilpaterol hydrochloride supplementation has no effect on the shelf life of ground beef

The objective of this study was to determine the effect of feeding zilpaterol hydrochloride (ZH) on the shelf life and stability of ground beef. Beef knuckles and plates were obtained from USDA Select beef heifer carcasses from control (CON) animals or those supplemented with ZH (8.33 mg/kg of dietary DM basis) for the last 20 d of the finishing period. Subprimals were coarsely ground and blended to produce an 80% lean product. The mixture was vacuum-stuffed into chubs and placed in dark storage at 2 to 4°C for 7, 14, or 21 d before fine grinding. Each week, the finely ground samples were packaged on expanded polystyrene trays overwrapped with polyvinyl chloride film and placed in refrigerated retail cases (0 to 2°C) under continuous fluorescent lighting to simulate retail display. Samples were subjected to a variety of analyses at different time intervals (h) during simulated display, including composition analysis, thiobarbituric acid-reacting substance analysis (TBA), sensory color, instrumental color, and aerobic plate count. Data analysis revealed trained sensory color and discoloration scores were similar between CON and ZH-treated samples. Instrumental L* and b* values for CON and ZH-treated samples did not differ (P = 0.13 and 0.19, respectively). Instrumental a* values declined (P < 0.05) over the display period for CON and ZH ground beef. However, a* values for ZH ground beef stored for 7 d were greater (P < 0.05) than CON values at 18 through 72 h of display. There was a treatment × storage day interaction (P < 0.001) for TBA values with ZH having smaller TBA values than CON after 7 d of dark storage. There was no difference (P = 0.21) in aerobic plate count between ZH and CON ground beef samples. Overall, ground beef from cattle supplemented with ZH was equal to or better than CON for sensory color and discoloration, instrumental color, and stability variables, including TBA reactive substances and aerobic plate counts.     

Foxtail-associated endocarditis in a cat

An adult female neutered domestic shorthair cat developed right heart failure 1 week after having surgical drainage of a neck abscess of unknown etiology established at our hospital. Echocardiography revealed a large vegetative mass adhered to the tricuspid valve. Post-mortem examination revealed fibrinous endocarditis and myocarditis associated with the presence of a grass awn (Hordeum species) foreign body. Foxtail migration with subsequent thrombus and endocarditis formation on the tricuspid valve is considered a very unusual sequel to foxtail migration.     

Impacts of Fire and Invasive Species on Desert Soil Ecology

A review of literature shows that both fire and invasive species may cause changes in biological, chemical, and physical properties of desert soils. Although soil may recover from the impacts of fire during succession, these changes are permanent under persistent invasive species. The most severe effects of fire occur under high temperatures with high fuel buildup and soil moisture that conducts heat downward. Deserts typically have low fuel mass and low soil moisture, both conditions that would contribute to lower impacts of fire than in mesic soils. Soil is a good insulator, so soil microorganisms will survive a few centimeters deep even in hot surface fires. Immediately postfire there is often an increase in mineral nitrogen (N) and a decrease in soil carbon (C) and organic N, but these changes are often minimal in desert soils, except under fertile shrub islands that have higher fuel loads and fire temperature. Both hot and cold deserts have experienced slow recovery of native shrubs and increased growth of invasive grasses following fire. Invasive species may either increase or decrease soil N and C depending on fire temperature and site and species characteristics. Mineralization and fixation of N are often high enough after fire that subsequent productivity balances N losses. The elimination of islands of fertility coupled with postfire erosion may be a major impact after fire in grass-invaded shrub lands. In the long term, the interaction of fire and invasive species may result in more frequent fires that eliminate fertile islands and reduce the productivity of deserts. Managers may use fire as a tool to control desert invasives without the concern that N will be irrevocably lost, but this must be done judiciously to avoid eliminating shrubs and further increasing invasive species.     

Skin layer evaporation to account for small precipitation events—An enhancement to the FAO-56 evaporation model

The FAO-56 soil water evaporation model is a simple ‘slab’ model that has been found to produce good estimates of evaporation from bare soil over a range of conditions due to its adherence to conservation of mass and energy. The simplicity of the model makes it straightforward to apply and to parameterize. An enhancement is made to the original formulation to accommodate light wetting events that wet the soil ‘skin’ near the surface and evaporate relatively quickly, even when the underlying soil is dry. In effect, the evaporation process, when the soil skin is wetted, reverts temporarily into stage 1 evaporation. The enhancement utilizes the ‘readily evaporable water’ (REW) term of the original model so that no new parameters are required. The extended model performs similar to the original model in the absence of small precipitation events, but increases the evaporation rate when small events occur. The FAO-56 method with the skin evaporation enhancement is shown to compare well against simulations made using the HYDRUS 1D model that bases evaporation on the Richards equation. The enhanced model also closely followed evaporation recorded by weighing lysimeter for a silt loam soil at Kimberly, Idaho, with root mean square difference of 0.39 and 0.69 mm d⁻¹ for two wetting/drying sequences. Total cumulative evaporation during the longest and wettest sequence was estimated at 92% of the measured value.     

Melanesian prehistory: some recent advances

Human occupation of New Guinea had begun 50,000 years ago, but islands further east were settled only in Recent times. In part of the New Guinea highlands, wet and dry horticultural systems began by 9000 years ago. Local intensification is evident until the present, but only the most recent major crop (sweet potato, which has been grown in the region for less than 300 years) is documented. On the south coast, exchange systems and economies locally diversify over the last two millennia. In the Melanesian islands, exotic materials were moved 3000 kilometers 3000 years ago, but whether traders or colonists were involved is not yet clear. The prehistory of the area is proving more complex than was believed even a decade ago.     

Ulysses solar wind plasma observations at high southerly latitudes

Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures.