Trimethoprim-sulfadiazine in the horse: serum, synovial, peritoneal, and urine concentrations after single-dose intravenous administration

Six healthy adult mares were given a single IV injection of trimethoprim (TMP)-sulfadiazine (SDZ) at a dosage rate of 2.5 mg of TMP/kg of body weight and 12.5 mg of SDZ/kg. Serum, synovial, peritoneal, and urine TMP-SDZ concentrations were measured serially over a 48-hour period. The highest measured mean concentrations of TMP and SDZ were found in the first (0.5 hour) sample of serum, synovial fluid, and peritoneal fluid. The mean peak concentrations of TMP and SDZ averaged 4.37 micrograms/ml and 21.81 micrograms/ml for serum, 2.95 micrograms/ml and 15.31 micrograms/ml for synovial fluid, and 3.88 micrograms/ml and 19.52 micrograms/ml for peritoneal fluid, respectively. Urine concentrations of the drugs were relatively high and peaked early. The elimination rate for TMP and SDZ averaged 0.41 and 0.26 hour-1, while the elimination half-life was 1.91 and 2.71 hours, respectively, and the volume of distribution averaged 0.59 and 0.52 L/kg, respectively.     

Catecholamines in ovarian follicles during the ovulatory cycle of White Leghorn hens

Dopamine (DA) concentrations in the largest ovarian follicle (F1) showed significant decrease at 12 and 8 h prior to ovulation. Nor-epinephrine (NE) and epinephrine (E) concentrations in the F1, sampled at different times of the ovulatory cycle, were found to increase with the approach of ovulation time. However, the concentration of epinephrine in the F1 was low just after oviposition compared with the immediate two previous stages investigated. The concentrations of DA, NE and E in the second largest follicles (F2) did not vary significantly during the ovulatory cycle. Average concentration of DA was low and that of NE and E high in the F1 compared with the respective concentrations in the F2.     

Investigation into intraoral approach for nerve block injection at the mental foramen in the horse

Invasive dental procedures performed in the standing, sedated horse are facilitated by local and regional anaesthesia. The traditional transcutaneous approach to the mental foramen is used to desensitise the incisive region including the mandibular incisors, but is not well tolerated by many sedated patients. In this study, a new, intraoral needle insertion technique for nerve block at the mental foramen was investigated. In 15 equine cadaver heads and two live horses, computed tomography (CT) was used to verify Tuohy needle placement into each mental foramen using an intraoral technique. Varying volumes of contrast medium (3, 6, 10 mL) were injected into the mandibular canal with and without digital occlusion of the mental foramen. The distance of retrograde flow was measured. Additionally, measurements were taken to determine the position of the mental foramen within the interdental space. Correct placement of Tuohy needles and injection of contrast medium into the mandibular canal using an intraoral approach at the mental foramen was achieved in all injections. Retrograde flow of contrast medium was accomplished with all volumes, regardless of occlusion. Although not statistically significant, the 10 mL group appeared to have a greater distance of flow. The needle insertion technique described here appears to be a potential alternative to traditional transcutaneous approaches to mental nerve block for procedures involving the incisive region. In addition, it was found that 79% of the mandibular canals injected with 10 mL of contrast medium had retrograde flow to the position of PM4, suggesting this method may be a useful alternative technique for nerve block for the more rostrally located cheek teeth. The location of the mental foramen was consistently found in the distal third of the interdental space (approximately 60–80% of the distance between the distal aspect of the lateral corner incisor and the mesial aspect of the second premolar).     

Chronic metabolic acid load induced by changes in dietary electrolyte balance increased chloride retention but did not compromise bone in growing swine

The effects of chronic dietary acid loads on shifts in bone mineral reserves and physiological concentrations of cations and anions in extracellular fluids were assessed in growing swine. Four trials were conducted with a total of 38 (8.16 +/- 0.30 kg, mean +/- SEM) Large White x Landrace x Duroc pigs randomly assigned to one of three dietary treatments. Semipurified diets, fed for 13 to 17 d, provided an analyzed dietary electrolyte balance (dEB, meq/kg diet = Na+ + K+ - Cl-) of -35, 112, and 212 for the acidogenic, control, and alkalinogenic diets, respectively. Growth performance, arterial blood gas, serum chemistry, urine pH, mineral balance, bone mineral content gain, bone-breaking strength, bone ash, and percentage of bone ash were determined. Dietary treatments created a range of metabolic acid loads without affecting (P > 0.10) growth or feed intake. Urine pH was 5.71, 6.02, and 7.65 +/- 0.48 (mean +/- SEM) and arterial blood pH was 7.478, 7.485, and 7.526 +/- 0.006 for pigs fed acidogenic, control, and alkalinogenic treatments, respectively. A lower dEB resulted in an increased (P < 0.001) apparent Cl- retention (106.6, 55.4, and 41.2 +/- 6.3 meq/d), of which only 1.6% was accounted for by expansion of the extracellular fluid Cl- pool as calculated from serum Cl- (105.5, 103.4, 101.6 +/- 0.94 meq/L (mean +/- SEM) for pigs fed acidogenic, control, and alkalinogenic treatments, respectively. A lower dEB did not decrease (P > 0.10) bone mineral content gain, bone-breaking strength, bone ash, percentage of bone ash, or calcium and phosphate balance. In conclusion, bone mineral (phosphate) was not depleted to buffer the dietary acid load in growing pigs over a 3-wk period.     

Describing the growth and molt of modern domestic turkey (Meleagris gallopavo) primary wing feathers

The use of feathers as noninvasive physiological measurements of biomarkers in poultry research is expanding. Feather molting patterns and growth rates, however, are not well described in domestic poultry. These parameters could influence the measurement of these biomarkers. Therefore, the objective of this study was to describe the juvenile primary feather molting patterns and feather growth rates for domestic turkeys. The 10 primary wing feathers of 48 female turkeys were measured weekly from week 1 (0 d of age) to week 20. Feathers were manually measured, and the presence or absence of each primary feather was recorded weekly. Generalized linear mixed models were used to investigate if feather growth differed between the primary feathers. The molting of the juvenile primary feathers followed a typical descending pattern starting with P1 (5 wk of age), while P9 and P10 had not molted by the end of the study (20 wk of age). The average feather growth rate was 2.4 cm/wk, although there was a significant difference between the 10 primary feathers (P < 0.0001, 2.1 to 2.8 cm/wk). Over time, feather growth followed a pattern where the growth rate reaches a peak and then declines until the feather is molted. The results of this study provide a critical update of patterns of molting and feather growth in primary wing feathers of modern turkeys. This can have implications for the interpretation of physiological biomarkers, such as the longitudinal deposition of corticosterone, in the feathers of domestic turkeys.     

Expression of MHC-I and -II in Uterine Tissue from Early Pregnant Bitches

The aim of the study was to investigate the expression of major histocompatibility complex (MHC)-I and -II in uterine tissues from pregnant and non-pregnant bitches, taken at different time periods after mating. The pregnant bitches were ovariohysterectomized during the pre-implantation (group 1, n = 4), implantation (group 2, n = 7) and placentation stage (group 3, n = 7). Non-pregnant animals in diestrus served as controls (group 4, n = 7). The expression of MHC- I and -II in salpinx, apex, middle horn, corpus uteri and at implantation sites was investigated by immunohistochemistry as well as qualitative and quantitative RT-PCR; MHC-I mRNA was detected in all tissues and with quantitative RT-PCR, and no significant changes were detected until placentation. Immunohistologically, at the apex and corpus site, the average number of MHC-II positive cells increased from the pre-implantation to the post-implantation stage (apex: 1.54 ± 1.21 to 3.82 ± 2.93; corpus: 1.62 ± 1.9 to 5.04 ± 4.95; p < 0.05). The greatest numbers of MHC-II positive cells were observed at placentation sites (6.64 ± 5.9). In parallel, a marked increase in the relative mRNA expression of MHC-II in uterine tissues was assessed from the pre-implantation to the placentation stage (relative to Glycerinaldehyd-3-phosphate-Dehydrogenase (GAPDH): 6.9 ± 9.5, 8.4 ± 5.8, p > 0.05). Immunohistologically, in the salpinx, significantly greater numbers of MHC-II positive cells were found in the tissues of pregnant animals than in the control group (p < 0.05). It is proposed that the increase in MHC-II is pregnancy-related, even though the impact on maintenance of canine pregnancy is still unclear.