No abstract

1. A cross-sectional observational study was carried out to investigate spatial, temporal and management aspects of foot-pad dermatitis in Swedish broilers. The efficacy of a control programme was evaluated. 2. Flock information on producer, breed, foodstuff manufacturer, region, abattoir, date of slaughter, age at slaughter, planned and actual stocking density was recorded. A total of 6988 flocks, representing approximately 110 million broilers was examined. A total of 175 broiler producers from 15 geographical regions is represented. 3. The total foot-pad score per flock ranged from 0 to 200, with a mean of 34.7 and a standard deviation of 40.9. 4. Simple linear regression analysis showed that the mean total score on a weekly basis decreased (P < 0.001) over time, mainly because of a decrease in the prevalence of severe foot-pad lesions. 5. There was an association (P < 0.05) between slaughterhouse, foodstuff supplier and geographic region respectively and the mean total foot pad score of the flocks slaughtered.

1. An experiment was conducted to determine whether different moisture levels of litter and perches with different hygienic conditions are involved in the manifestation of foot pad dermatitis in White Leghorn layers. 2. Four different treatments were compared: dry litter and dry perches; dry litter and wet perches; wet litter and dry perches; and wet litter and wet perches. Temperature, pH, air humidity and ammonia changes in the pens were monitored. 3. The mean prevalence of foot pad lesions in groups 1, 2, 3 and 4 was 17%, 13%, 49% and 48% respectively. The overall incidence of foot pad lesions in birds reared on dry litter was 38%, and in birds reared on wet litter 92%. 4. When the air temperature was above 20 degrees C, an increasing moisture content in the litter was associated with an increasing incidence of foot pad dermatitis. However, when the air temperature was below 20 degrees C there were no new cases of dermatitis in any of the 4 treatments. There were no significant differences in litter pH or ammonia between the 4 treatments when compared over the whole experiment. 5. Although the incidence of lesions was not significantly affected by the presence of wet perches, the area of the lesions tended to be in groups with wet patches than in groups with dry perches. 6. It is suggested that moisture and temperature are important contributing factors for the occurrence of foot pad dermatitis in laying hens. Wet perches may contribute to the severity of such lesions.

Detection times and screening limits (SL) are methods used to ensure that the performance of horses in equestrian sports is not altered by drugs. Drug concentration-response relationship and knowledge of concentration-time profiles in both plasma and urine are required. In this study, dexamethasone plasma and urine concentration-time profiles were investigated. Endogenous hydrocortisone plasma concentrations and their relationship to dexamethasone plasma concentrations were also explored. A single dose of dexamethasone-21-isonicotinate suspension (0.03 mg/kg) was administered intramuscularly to six horses. Plasma was analysed for dexamethasone and hydrocortisone and urine for dexamethasone, using UPLC-MS/MS. Dexamethasone was quantifiable in plasma for 8.3 ± 2.9 days (LLOQ: 0.025 μg/L) and in urine for 9.8 ± 3.1 days (LLOQ: 0.15 μg/L). Maximum observed dexamethasone concentration in plasma was 0.61 ± 0.12 μg/L and in urine 4.2 ± 0.9 μg/L. Terminal plasma half-life was 38.7 ± 19 h. Hydrocortisone was significantly suppressed for 140 h. The plasma half-life of hydrocortisone was 2.7 ± 1.3 h. Dexamethasone potency, efficacy and sigmoidicity factor for hydrocortisone suppression were 0.06 ± 0.04 μg/L, 0.95 ± 0.04 and 6.2 ± 4.6, respectively. Hydrocortisone suppression relates to the plasma concentration of dexamethasone. Thus, determination of irrelevant plasma concentrations and SL is possible. Future research will determine whether hydrocortisone suppression can be used as a biomarker of the clinical effect of dexamethasone.

The cortisol response to glucocorticoid intervention has, in spite of several studies in horses, not been fully characterized with regard to the determinants of onset, intensity and duration of response. Therefore, dexamethasone and cortisol response data were collected in a study applying a constant rate infusion regimen of dexamethasone (0.17, 1.7 and 17 μg/kg) to six Standardbreds. Plasma was analysed for dexamethasone and cortisol concentrations using UHPLC-MS/MS. Dexamethasone displayed linear kinetics within the concentration range studied. A turnover model of oscillatory behaviour accurately mimicked cortisol data. The mean baseline concentration range was 34-57 μg/L, the fractional turnover rate 0.47-1.5 1/h, the amplitude parameter 6.8-24 μg/L, the maximum inhibitory capacity 0.77-0.97, the drug potency 6-65 ng/L and the sigmoidicity factor 0.7-30. This analysis provided a better understanding of the time course of the cortisol response in horses. This includes baseline variability within and between horses and determinants of the equilibrium concentration-response relationship. The analysis also challenged a protocol for a dexamethasone suppression test design and indicated future improvement to increase the predictability of the test.