Assessment of the Hemocue-b for measuring hemoglobin in horse blood

Our purpose was to assess the accuracy and precision of a point of care hemoglobinometer (HemoCue‐B hemoglobin photometer) for measuring hemoglobin concentration in horse blood. Samples of jugular venous blood from 12 healthy adult horses were collected in EDTA. In order to test the device over a wide range of values, each sample was divided into nine aliquots, and autologous plasma was added or removed from the aliquots to produce blood with PCV values that approximated 5, 10, 20, 30, 40, 50, 60, 70, and 80%, respectively. The aliquots were rocked to ensure mixing of plasma and cells. Then hemoglobin by HemoCue‐B (Hb_HQ) and hemoglobin by the cyanmethemoglobin method (Hb_CY) were measured on each aliquot. The PCV of each aliquot was also measured and this value was used for subsequent analyses. To test repeatability, hemoglobin was measured twice by the HemoCue‐B on approximately 40% samples. Samples with Hb_HQ >25.4 g dL^?1 required dilution prior to analysis. Hb_CY ranged from 1.6 to 33.4 g dL^?1. After regression, Hb_CY = ?0.16 + 1.04 Hb_HQ (n = 101; r² = 99.6%). By inspection of a modified Bland‐Altman plot, Hb_HQ values <16 g dL^?1 closely approximated Hb_CY; however, at greater values, Hb_HQ underestimated Hb_CY by as much as 3.2 g dL^?1. The difference between repeated measurements with the HemoCue‐B was 0.02 ± 0.16 g dL^?1 (mean ± SD; n = 10) and nonsignificant. After regression, PCV = ?0.76 + 2.78 Hb_HQ (n = 101; r² = 99.4%). We conclude that HemoCue‐B can be used to measure hemoglobin concentration in horse blood, and that it is accurate when hemoglobin is <16 g dL^?1. PCV can be estimated by multiplying Hb_HQ by 2.8 and then subtracting 0.8.     

Bovine spongiform encephalopathy: epidemiological studies on the origin.

The results of further epidemiological studies of bovine spongiform encephalopathy (BSE) support the previous findings that the onset of exposure of the cattle population to a scrapie-like agent, sufficient to result in clinical disease, occurred in 1981/82. The onset of this exposure was related to the cessation, in all but two rendering plants, of the hydrocarbon solvent extraction of fat from meat and bone meal. A further possible explanation, related to the geographical variation in the reprocessing of greaves to produce meat and bone meal, was identified for the geographical variation in the incidence of BSE.     

Sensitivity of boreal forest carbon balance to soil thaw

We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 +/- 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 +/- 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 +/- 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool ( approximately 150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.     

Prevalence of the causes of fleece derangement among sheep flocks in New South Wales

SUMMARY An investigation of sheep flocks with unknown histories of fleece derangement, selected at random from the main sheep raising areas of New South Wales, showed that Psorergates ovis was present in 53 of the 177 flocks surveyed and In 162 of the 3495 sheep examined. Of the single causes of fleece derangement, the most prevalent was grass seed contamination (15.7%) followed by Infestation with sheep body lice, Bovicola ovis, (14.7%) and Infestation with Itch mite (7.8%). The prevalence of fleece derangement was significantly higher on sheep In which lice were the only ectoparasites found than on those In which Itch mites were the only ectoparasites present. The greatest prevalence of P ovis was In flocks In the Young, Yass, Mudgee and Tenterfield districts. In most affected flocks, more than one potential cause of fleece derangement was present. Itch mite Infestation was more prevalent in flocks that received no treatment for ectoparasites than in those that had been treated in the year preceding the survey. Our results did not support a commonly held belief among farmers that arsenical compounds control Infestations of Itch mites more effectively than other types of pesticides. There was no significant difference in prevalence of fleece derangement between flocks treated with different pesticide groups and those that received no treatment, but mean fleece derangement score was significantly lower in sheep treated with organophosphates than in untreated sheep. Infestations of lice were significantly more prevalent in sheep from flocks treated with synthetic pyrethroids than from those treated with organophosphates or those that received no treatment.     

Comparison of tiletamine-zolazepam-ketamine and tiletamine-zolazepam-ketamine-xylazine anaesthesia in sheep

Summary The anaesthetic effects of intravenous tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg (TK) and tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg-xylazine 0.11 mg/kg (TKX) were evaluated in six wethers. Heart rate, respiration rate, arterial blood pressure, and the electrocardiogram were monitored during anaesthesia. Analgesia was tested by electrical stimulation in the left flank. Atropine (0.03 mg/kg) was given intramuscularly before induction, but after recording of baseline heart rate and respiratory rate. The duration of analgesia was 28.7 ± 6.9 min with TK and 82.8 ± 26.6 min with TKX. Heart rate increased significantly within 5 min after TK or TKX administration. Respiratory rate remained unchanged after TK administration, but increased significantly from 5 to 45 min after TKX administration. Arterial blood pressure decreased significantly at 15 min with TK and 30 min with TKX. Sheep remained recumbent for 201 min with TK and 166 min with TKX. All recovered uneventfully. We conclude that either TK or TKX may be used for anaesthetising sheep.