EARLY POSTOPERATIVE MAGNETIC RESONANCE IMAGING FINDINGS IN FIVE DOGS WITH CONFIRMED AND SUSPECTED BRAIN TUMORS

Early postoperative neuroimaging has been performed in people for over 20 years to detect residual brain tumor tissue and surgical complications. The purpose of this retrospective study was to describe characteristics observed using early postoperative magnetic resonance imaging in a group of dogs undergoing craniotomy for brain tumor removal. Two independent observers came to a consensus opinion for presence/absence of the following MRI characteristics: residual tumor tissue; hemorrhage and ischemic lesions; abnormal enhancement (including the margins of the resection cavity, choroid plexus, meninges) and signal intensity changes on diffusion‐weighted imaging. Five dogs were included in the study, having had preoperative and early postoperative MRI acquired within four days after surgery. The most commonly observed characteristics were abnormal meningeal enhancement, linear enhancement at margins of the resection cavity, hemorrhage, and a thin rim of hyperintensity surrounding the resection cavity on diffusion‐weighted imaging. Residual tumor tissue was detected in one case of an enhancing tumor and in one case of a tumor containing areas of hemorrhage preoperatively. Residual tumor tissue was suspected but could not be confirmed when tumors were nonenhancing. Findings supported the use of early postoperative MRI as a method for detecting residual brain tumor tissue in dogs.     

Utilization of nitrogen and energy by Holstein steers fed formaldehyde- and formic acid-treated alfalfa or orchardgrass silage at two intakes

Our objective was to measure the utilization of energy (E) and N by Holstein steers when fed alfalfa and orchardgrass silages offered at 65 and 90 g DM/kg live weight (LW).75 daily. Twelve steers adapted to the Beltsville respiration chambers were assigned to three Latin squares with 42-d periods. Steers in one square had permanent catheters in the portal and two mesenteric veins. Energy and N balance were measured during a 7-d collection of feces and urine that included a 3-d measurement of respiratory exchange. Energy and N variables were not different between catheterized and uncatheterized steers. Apparent digestibilities of DM, OM, CP, neutral detergent solubles and permanganate lignin were higher (P less than .01) and digestibilities of NDF and ADF, hemicellulose and cellulose were lower (P less than .01) for steers consuming alfalfa compared to orchardgrass silage. When fed alfalfa, steers' daily gross energy intake, DE, urine energy, ME, heat production and tissue energy retention were greater (P less than .01) and fecal energy losses were less (P less than .01) than when they were fed orchardgrass. Partial efficiency of ME use for tissue energy (TE) was greater (P less than .01) for steers when fed alfalfa (46.1%) than when fed orchardgrass (35.6%). Apparent ME (kcal/LW.75) required for maintenance of TE was similar for steers when fed alfalfa (133.9) and orchardgrass (131.2) silages. Nitrogen retention (g/d) was 48% greater (P less than .01) for steers when fed alfalfa (30.6) than when fed orchardgrass (20.7). This study demonstrates that steers used ME from alfalfa more efficiently for TE deposition than ME from orchardgrass.     

TERMINATION OF EARLY PREGNANCY IN EWES BY USE OF A PROSTAGLANDIN ANALOGUE AND SUBSEQUENT FERTILITY

SUMMARY Of 87 Dorset ewes injected at 20 to 60 days of pregnancy with either 125 μg or 250 μg of the prostaglandin F^2α analogue, cloprostenol, 72 (83%) were detected in oestrus by teaser rams within 7 days. A total of 60 ewes mated with fertile rams 14 to 28 days after treatment and 36 of these (60%) subsequently lambed. Thirty-eight ewes mated with fertile rams 29 to 56 days after treatment and 30 of these (79%) subsequently lambed. The difference in fertility between the 2 periods was not significant.
Six additional ewes which did not respond to the cloprostenol lambed normally within 6 weeks. They were more than 100 days pregnant when treated.
In ewes which first exhibited oestrus by 7 days of treatment, plasma progesterone concentrations fell from near 4 ng/ml to 0.6 ng/ml within 48 h of treatment. In ewes not detected in oestrus progesterone concentrations did not decrease to similar low levels (1.4 ng/ml; t-test p < 0.005). Concentrations in the 6 ewes treated near 100 days of pregnancy dropped from 7.4 to 4.4 ng/ml over 48 h. Overall, the progesterone concentrations indicated that 92% of ewes treated at 20 to 60 days of pregnancy experienced rapid luteolysis in response to the cloprostenol.
There were no differences between the 2 doses of cloprostenol in the responses or subsequent fertility of the ewes.     

Carbon kinetics of milk formation in Holstein cows in late lactation

Carbon transfer to milk in Holstein cows in late lactation was measured by introducing changes in the natural stable carbon isotope composition of the feed. Six Holstein cows in mid-lactation were placed on a diet naturally low in 13C (-25.0% vs Pee Dee belemnite [PDB] an international carbon isotope standard), based on alfalfa-barley, and six others were placed on a diet naturally enriched in 13C (-11.5% vs PDB), based on corn. After a 7-wk equilibration period on these diets, three cows were switched from alfalfa-barley to corn, and three were switched from corn to alfalfa-barley. The three other cows in each group served as controls. 13C/12C ratios were measured in daily morning milk samples during the week before and for 6 wk after the changes in diet. After the diets had been switched, milk isotope ratios rapidly approached the isotopic composition of the new diet, indicating rapid transfer of dietary carbon into milk. The data were consistent with a model whereby milk was synthesized from a single precursor pool that responded rapidly to dietary perturbation. The milk precursor pool had a half-life of approximately .9 d and had a mass of approximately 7 kg of carbon, which was renewed daily by the entry of 5 kg of digestible dietary carbon.