Feline immunodeficiency virus neurotropism: evidence that astrocytes and microglia are the primary target cells.

To investigate the neuropathogenesis of feline immunodeficiency virus (FIV) infection in vitro, we have utilized three populations of cultured feline neural cells (astrocytes, microglia, brain endothelium) to assess the relative susceptibility to FIV infection, ability to produce viral antigens, and effects of infection on cell survival. Astrocytes appeared to be the most susceptible to infection, followed by microglia, whereas brain endothelial cells were relatively resistant to infection. Astrocyte infection resulted in syncytium formation and cell death, while microglial cells remained persistently and productively infected, without obvious cytopathic effects. These results suggest that FIV entry into the central nervous system probably does not occur via infected endothelium and that both astrocytes and microglia are more likely target cells for the virus.     

Flow Cytometry Identification of X- and Y-Chromosome-Bearing Goat Spermatozoa

Flow cytometric sorting technology was used to measure the difference in DNA content between X- and Y-chromosome-bearing spermatozoa in bucks. Spermatozoa were analysed by flow cytometry to characterize X- and Y-chromosome-bearing sperm populations and to quantify the DNA difference between them. Two symmetrical, overlapping and clearly separated peaks, corresponding to X- and Y-bearing spermatozoa, were detected. The difference in fluorescence intensity between the peaks was 4.4 +/- 0.03% without any significant inter- or intra-animal variations. Therefore, the identification and selection of high-purity samples of sperm populations for sex sorting is easier in bucks compared with other domestic species.     

Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

To evaluate factors contributing to fertility of thoroughbred mares, data from 3743 oestrous periods of 2385 mares were collected on a large thoroughbred farm in Ireland. Fourteen stallions (mean age 8.3 years; range 4–15 years) had bred 2385 mares (mean age 9.4 years; range 3–24 years). Maiden mares accounted for 12%, mares with a foal at foot for 64%, and barren, slipped or rested mares for 24% of the total. The mean pregnancy rate per cycle was 67.8% (68.6% in year 1 and 66.9% in year 2). Backward stepwise multivariable logistic regression analysis was utilized to develop two models to evaluate mare factors, including mare age, reproductive status, month of foaling, dystocia, month of cover, foal heat, cycle number, treatments, walk‐in status and stallion factors including stallion identity, stallion age, shuttle status, time elapsed between covers and high stallion usage on the per cycle pregnancy rate and pregnancy loss. Old age (p < 0.001) and cover within 20 days post‐partum (p < 0.003) were associated with lowered pregnancy rates. High mare age (p < 0.05) and barren, slipped or rested reproductive status (p = 0.05) increased the likelihood of pregnancy loss. Uterine inflammation or infection, if appropriately treated, did not affect fertility. Only high usage of stallions (used more than 21 times in previous week) was associated with lowered (p = 0.009) pregnancy rates. However, shuttle stallions were more likely to have increased (p = 0.035) pregnancy survival, perhaps reflecting a bias in stallion selection. In conclusion, mare age exerted the greatest influence on fertility; nonetheless, thoroughbreds can be effectively managed to achieve high reproductive performance in a commercial setting.     

B-cell lymphoma in a dog with ehrlichiosis (Ehrlichia canis) and systemic histoplasmosis (Histoplasma capsulatum)

A mixed breed dog treated for ehrlichiosis and systemic histoplasmosis developed a refractory thrombocytopenia. When an abdominal mass was detected, exploratory laparotomy and biopsies confirmed lymphoma, which on immunohistochemical stains was determined to be of B-cell origin. Conceivably, the B-cell lymphoma in this dog was associated with chronic inflammation from ehrlichiosis, histoplasmosis, or both.     

Biohydrogenation of unsaturated fatty acids in continuous culture fermenters during digestion of orchardgrass or red clover with three levels of ground corn supplementation

Diet digestibility and outputs of biohydrogenation intermediates were assessed in a continuous culture of ruminal microorganisms. Orchardgrass or red clover harvested and frozen during spring or fall served as the primary substrates for fermentation. During 10-d incubations, fermenters were fed thawed forage (50 g of DM/d), forage (42 g/d) plus 8 g/d of corn, or forage (34 g/d) plus 16 g/d of corn. Effluents from the last 3 d of incubation were composited for analyses. Starch input increased from 5 to 27% of DM as corn input increased from 0 to 16 g/d. Corn input reduced (P < 0.01) pH, increased (P < 0.01) microbial DM yield, and increased (P = 0.01) digestibility of DM, NDF, CP, and nonstructural carbohydrates. Overall, apparent hydrogenation (percentage) of cis9-18:1, 18:2n-6, and 18:3n-3 was greater (P < 0.05) with orchardgrass than clover. Hydrogenation of cis9-18:1 and 18:2n-6 increased (P = 0.01), but hydrogenation of 18:3n-3 decreased (P = 0.01) linearly due to corn input, regardless of forage. As a result, output of trans11, cis15-18:2 also decreased (P = 0.01). Average output of cis9,trans11-18:2 was greater (P = 0.01) for clover (1.3 mg/d) compared with orchardgrass (0.6 mg/d), but corn input with either forage increased (P = 0.01) cis9,trans11-18:2 output by 205%. Output of trans11-18:1 was greater (P = 0.01) from orchardgrass compared with clover (174 vs. 90 mg/d), but corn increased (P = 0.01) trans11-18:1 output only from clover fermentations. Output of trans10-18:1 was greater (P = 0.01) in response to orchardgrass compared with clover (10 vs. 4 mg/d), but corn addition doubled the output regardless of forage type. Output of trans10,cis12-18:2, which did not differ due to forage type, increased (P = 0.01) twofold in response to corn. Cis9,cis11-18:2 was a primary conjugated isomer produced from forage fermentations, but its output decreased (P = 0.03) in response to corn input. When inputs of 18:2n-6 plus 18:3n-3 were less than 0.9% of total DM (clover), hydrogenation was low (87%). When 18:2n-6 plus 18:3n-3 inputs were from 1.2 to 1.5% of total DM (orchardgrass), hydrogenation averaged 96%. Despite greater hydrogenation, incremental additions of cis9-18:1 and 18:2n-6 from corn grain increased (P < 0.05) outputs of trans10-18:1, trans11-18:1, trans10,cis12-18:2, cis9,trans11-18:2, and trans,trans-18:2 in effluent. Results suggest that forage species alone or in combination with corn grain can alter hydrogenation and profiles of intermediates to varying degrees.     

Plasma pharmacokinetics of selamectin after a single topical administration in the American bullfrog (Rana catesbeiana).

Parasitism is common in wild and captive amphibians; however, pharmacologic data are lacking for anthelmintic drugs. This study was developed to determine the plasma pharmacokinetics of selamectin after topical administration in bullfrogs. Thirty-two adult American bullfrogs (Rana catesbeiana) were randomly assigned into eight groups of four with each group representing a different collection time point. Seven groups received selamectin (6 mg/ kg) topically and the remaining group served as the untreated control group. One group of frogs was euthanized and blood samples immediately collected on days 0 (control), 1, 5, 10, 15, 20, 25, and 30. Plasma was analyzed for selamectin using high performance liquid chromatography with fluorescence detection. Individual samples were analyzed, then data were reported as the mean of the four frogs at each time point. A histologic evaluation of the lung, liver, kidney, and skin tissues was performed and none of the frogs showed histologic evidence of toxicity due to selamectin administration. The mean peak plasma concentration was 162.5 +/- 42.3 ng/ml, area under the curve was 2,856 ng day/ml, mean residence time was 12.2 days, and disappearance half-life was 1.87 days. Based on the plasma pharmacokinetics, bullfrogs appear to absorb selamectin very efficiently, concentrations reach high levels in the plasma, and there were no apparent histologic effects from single dose administration.     

Effects of delmadinone acetate on pituitary-adrenal function, glucose tolerance and growth hormone in male dogs

Objective To characterise the effects of delmadinone acetate on the pituitary-adrenal axis, glucose tolerance and growth hormone concentration in normal male dogs and dogs with benign prostatic hyperplasia.
Design A prospective study involving nine normal male dogs and seven with prostatic hyperplasia.
Procedure Delmadinone acetate was administered to six normal male dogs and seven dogs with benign prostatic hyperplasia at recommended dose rates (1.5 mg/kg subcuta-neously at 0, 1 and 4 weeks). Three normal controls received saline at the same intervals. Blood concentrations of ACTH, cortisol, glucose, insulin and growth hormone were measured over 50 days. Intravenous glucose tolerance and ACTH response tests were performed before and after treatment in the nine normal animals.
Results A substantial suppression of basal and 2 h post-ACTH plasma cortisol secretion was demonstrated after one dose in all dogs given delmadinone acetate. Individual responses after the second and third administration varied between recovery in adrenal responsiveness to continued suppression. Plasma ACTH concentration was also diminished after one treatment. No effects were evident on glucose tolerance or serum growth hormone concentrations.
Conclusion Delmadinone acetate causes adrenal suppression from inhibition of release of ACTH from the pituitary gland. Treated dogs may be at risk of developing signs of glucocorticoid insufficiency if subjected to stressful events during or after therapy. Neither glucose intolerance nor hyper-somatotropism seems likely in male dogs given delmadinone acetate at the recommended dose rate, but the potential for excessive growth hormone secretion in treated bitches remains undetermined.