Whereas the clinical efficacy of vaccination against pseudorabies has been studied extensively, methods to evaluate the influence of vaccination on pseudorabies virus (PRV) transmission have only recently become available. In this study, PRV transmission and growth performance in finishing pigs vaccinated either once or twice were compared. The incidence of PRV infections was significantly (P = 0.039) higher in the group vaccinated once (38%) than in the group vaccinated twice (10%). The reproduction ratio R, which is defined as the average number of new infections caused by 1 infectious individual, was estimated in both groups. This ratio was also significantly (P = 0.025) higher among single vaccinated pigs (R = 3.4) than among pigs that had received double vaccination (R = 1.5). In compartments where serologic evidence of PRV introduction was observed, the mean daily weight gain was significantly (P = 0.029) lower in pigs vaccinated once (698 g/d) than in pigs vaccinated twice (721 g/d). Results of this study document the possibility to objectively evaluate the effect of vaccination on PRV transmission under field conditions. From the results, we concluded that double vaccination is advantageous in populations of finishing pigs at risk for PRV introduction. However, even among pigs vaccinated twice, extensive spread of PRV can occur.

The effect that topical administration of cyclosporine would have on the number and type of microorganisms isolated from the corneal surface of dogs with keratoconjunctivitis sicca was studied. Schirmer tear tests were performed on and corneal swab specimens were collected from 61 eyes of 31 dogs with keratoconjunctivitis sicca prior to and after 3, 6, and 12 months of treatment with cyclosporine. In eyes that responded to cyclosporine treatment (Schirmer tear test value increased by greater than or equal to 5 mm/min, compared with pretreatment value), the percentage of eyes from which bacteria were isolated after 3, 6, and 12 months of treatment was significantly (P < 0.001) less than the percentage from which bacteria were isolated prior to treatment. However, among eyes that did not respond to treatment, we did not detect a significant change over time in prevalence of bacteria or type of bacteria isolated. The percentage of eyes from which fungi were isolated decreased during treatment; however, the small number of eyes in which fungal culture results were initially positive precluded demonstration of a significant change. For all eyes, we did not detect any significant differences over time in the frequency with which specific bacterial genera were isolated, with the exception of beta-hemolytic Streptococcus spp. Opportunistic corneal infections were not detected even though none of the dogs received antibiotics. An increase in production of tears, which contain anti-infection proteins, was believed to be the primary factor responsible for the decrease in the percentage of eyes from which microorganisms could be isolated.

The core protein and the transmembrane protein, encoded for the structural genes gag and env, respectively, of caprine arthritis-encephalitis virus were amplified by use of polymerase chain reaction, cloned into a pGEX-2T vector, and expressed in Escherichia coli as fusion proteins with the glutathione S-transferase at their C-terminus. The recombinant proteins were purified and evaluated by use of an ELISA. Sera from 269 goats were tested, and the results were compared with those obtained by use of immunoblot analysis. When results from both recombinant ELISA (r-ELISA) were compared, it appeared that the transmembrane glycoprotein was more immunoreactive than the core protein, because it was recognized by a higher percentage of sera from infected goats. When results of the 2 ELISA (p28 r-ELISA and p40 r-ELISA) were combined in parallel, they were comparable to those of the immunoblot test, with sensitivity of 100% and specificity of 98.3%. It was also found that use of both r-ELISA makes it possible to compare the variable immunoreactivity against gag and env viral antigens, which may be correlated with the disease state. The r-ELISA, using core and transmembrane proteins, appears to be highly sensitive and specific for detection of antibodies against caprine arthritis-encephalitis virus.

Sequential histologic, immunologic, and virologic features of herpesvirus-induced keratitis were studied in 18 experimentally infected cats. Histologic changes were assessed by use of light microscopy, and the presence of viral antigen, B lymphocytes, and T lymphocytes was verified immunohistochemically. Flow cytometry was used to monitor changes in blood T lymphocytes (CD4 and CD8 homologues) and B lymphocytes. Cellular immunity was assessed by use of the lymphocyte proliferation assay. Development of stromal keratitis was preceded by prolonged absence of corneal epithelium, decreased numbers of circulating lymphocyte subsets, decreased mitogen responses, and acquisition of viral antigen by the corneal stroma. Return to normal of circulating lymphocyte numbers and function was temporally associated with the arrival of neutrophils and B and T lymphocytes in the corneal stroma. Sequelae to stromal inflammation were fibrosis and scarring. Findings suggest that suppression of local immune responses allows virus access to the corneal stroma, and that subsequent keratitis is mediated by an immune response to viral antigen.

Paired blood samples were collected from the postoccipital venous plexus and jugular vein of desert tortoises (Gopherus agassizii) for hematologic and plasma biochemical analyses. Comparison of hematologic values revealed significantly (P less than or equal to 0.05) lower PCV, RBC count, WBC count, and hemoglobin values for samples obtained from the occipital site. When comparisons were made between plasma biochemical values for the 2 sites, significant (P less than or equal to 0.05) differences were measured for: glucose, potassium, chloride, uric acid, calcium, phosphorous, total protein, albumin, globulin, alkaline phosphatase, aspartate transaminase, alanine transaminase, and total cholesterol. Significant differences between hematologic and plasma biochemical values from the occipital region samples vs jugular vein samples were attributed to hemodilution of the occipital region samples with extravascular fluid or lymph or both.

Effects of selenium (Se) deficiency and supplementation on production of colostral immunoglobulins by beef cows and transfer of antigen-specific and nonspecific immunoglobulins to their calves were examined. Eighty beef cows, with marginal to deficient Se status (blood Se concentration, 50 micrograms/L), were allotted by breed and age to 1 of 4 Se treatment groups (n = 20/group): no supplemental Se; parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg of body weight; ad libitum consumption of 120 mg of Se/kg of salt-mineral mix (SMM); and parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg plus ad libitum consumption of 120 mg of Se/kg of SMM. All cows were inoculated IM with lysozyme. Cows consumed Se-deficient pastures or hay (21 to 62 micrograms/kg) during the study that began at mid-gestation and ended at postpartum hour 24. Although the concentration of specific lysozyme antibodies was not affected, cows given 120 mg of Se/kg of SMM (treatments 3 and 4) had higher colostral IgG concentration (P < 0.002) than did Se-deficient cows (treatments 1 and 2). Calves from cows in treatments 3 and 4 had higher postsuckle serum concentrations of IgG (P < 0.01) than did calves from cows in treatments 1 and 2. Colostral IgM and calf serum IgM concentrations did not differ among treatments.

Once-daily administration of aminoglycosides may be a safe and effective therapeutic regimen, on the basis of the microbiologic and pharmacokinetic characteristics of these antibiotics. This study was designed to determine serum and tissue concentrations following IV administration of gentamicin, at dosages of 6.6 mg/kg of body weight, every 24 hours, and 2.2 mg/kg, every 8 hours, for 10 days in adult horses. Nephrotoxicosis from these dosage regimens also was compared, and microbiologic effects, including postantibiotic effects, were determined with various concentrations of gentamicin against an equine clinical isolate of Pseudomonas aeruginosa. Treatment at the 6.6-mg/kg dosage resulted in maximal serum concentrations (77.93 +/- 19.90 micrograms/ml, mean +/- SEM) and area under the concentration-vs-time curves (83.79 +/- 14.97 micrograms.h/ml) that were significantly (P < 0.05) greater than those following treatment at the 2.2-mg/kg dosage (5.05 +/- 0.50 micrograms/ml and 6.03 +/- 0.66 micrograms.h/ml, respectively). Nephrotoxicosis was not induced with either dosage regimen, and postantibiotic effects were prolonged with a higher gentamicin concentration. This study provided evidence to support the use of once-daily gentamicin treatment in adult horses.

The effects of short-term restraint stress, by means of snaring, on plasma concentrations of catecholamines, beta-endorphin, and cortisol were studied in 6 gilts. A catheter was inserted into the jugular vein, and 2 blood samples were collected before onset of stress. Thereafter, a hog snare was applied, and blood samples were collected at 0.5, 2, and 3.5 minutes after the start of snaring. Plasma epinephrine and norepinephrine concentrations increased (P < 0.001) within 0.5 minute after start of restraint and decreased thereafter. Plasma concentration of beta-endorphin increased (P < 0.05) within 2 minutes after start of restraint, whereas that of cortisol increased (P < 0.05) 3.5 minutes after start of restraint. Taken together, short-term stress, such as snaring, may increase the plasma concentration of catecholamines, beta-endorphin, and cortisol in pigs.

Objective--To determine the relative role of endogenous prostaglandin F2 alpha (PGF2 alpha) secretion in cloprostenol-induced abortion in mares that no longer require luteal progesterone secretion for maintenance of pregnancy, and to evaluate the ability of a prostaglandin cyclooxygenase inhibitor (flunixin meglumine) to prevent cloprostenol-induced abortion. Design--The effect of flunixin meglumine on PGF2 alpha secretion and outcome of pregnancy was compared between mares treated with cloprostenol only and mares treated with cloprostenol plus flunixin meglumine. Animals--Five pregnant mares, aged 4 to 15 years, of light-horse type. Procedure--Cloprostenol (250 micrograms) was administered at 24-hour intervals to 5 pregnant mares. Flunixin meglumine (500 mg, IV) was administered at 8-hour intervals starting 15 minutes before the first cloprostenol administration. Hourly blood samples were analyzed for 15-ketodihydro-PGF2 alpha, progesterone, and estrogen concentrations. Previously reported data on cloprostenol-induced abortion in 6 pregnant mares treated daily with cloprostenol only were used as historic controls. Results--The mean (+/- SEM) interval from first cloprostenol administration to fetal expulsion 56.4 (+/- 13.7) hours and number of cloprostenol administrations 3.2 (+/- 0.6) in the 5 flunixin meglumine-treated mares were not significantly different, compared with values for 6 pregnant mares treated daily with cloprostenol only, 48.6 (+/- 5.6) hours and 2.8 (+/- 0.2) cloprostenol administrations. Flunixin meglumine did not inhibit endogenous PGF2 alpha secretion. Prostaglandin F2 alpha secretion rates on the day before and day of fetal expulsion were similar in both groups. Conclusion--Flunixin meglumine at a dosage of 500 mg/animal, administered IV every 8 hours, is ineffective in modulating uterine PGF2 alpha secretion during cloprostenol-induced abortion. Clinical Relevance--Flunixin meglumine is ineffective in the modulation of prostaglandin-induced uterine PGF2 alpha secretion and, therefore, does not offer a viable alternative for the prevention of abortion in mares at risk of abortion because of systemic illness.

A cross-over study was performed in 6 healthy mixed-breed dogs and 4 healthy Beagles. Diazepam was administered per rectum to Beagles (0.5 mg/kg of body weight) and mixed-breed dogs (2 mg/kg), and IV (0.5 mg/kg) to both groups of dogs. Each dog received the drug by both routes, with a 1-week washout period between dosages. After diazepam administration, blood samples were collected to measure plasma concentration of diazepam and its active metabolites, desmethyldiazepam and oxazepam, by use of reverse-phase high-performance liquid chromatography (HPLC). Systemic availability was assessed by comparing the area under the curve for diazepam metabolites for each route of administration. Mean (+/- SD) diazepam concentrations in plasma after rectal administration were low in comparison with those obtained after IV administration, with systemic availability of only 7.4 (+/- 5.9) and 2.7 (+/- 3.2)% for the high and low dose, respectively. However, diazepam was converted to its metabolites within minutes after administration. Accounting for the total concentration of benzodiazepines (diazepam plus desmethyldiazepam and oxazepam) in plasma, systemic availability was 79.9 (+/- 20.7) and 66.0 (+/- 23.8)% for the high and low dosage, respectively. After IV administration, diazepam concentration decreased, with a half-life of only 14 to 16 minutes, but desmethyldiazepam and oxazepam concentrations decreased more slowly, with a half-life of 2.2 to 2.8 hours and 3.5 to 5.1 hours, respectively. Each of the metabolites is reported to have anticonvulsant activity. After rectal administration of the high dose, mean total benzodiazepine concentration was above 1.0 micrograms/ml within 10 minutes and was maintained above this concentration for at least 6 hours. We conclude that diazepam is absorbed after rectal administration in dogs, and that the pharmacologic effects are probably caused by the active metabolites, not the parent drug. Samples also were analyzed by use of a nonspecific commercial benzodiazepine fluorescence polarization immunoassay (FPIA). Correlation between the FPLA and HPLC assay was strongest for diazeparn (R2 = 0.84), weak for desmethyldiazepam (R2 = 0.09), and nonexistent for oxazepam. We conclude from a comparison of assays that HPLC is preferred over the FPLA method for measuring benzodiazepines in dogs.