Genetic recombination between field strains and vaccine strains of pseudorabies virus (PRV) has been suggested as a scenario that might arise from use of deletion-mutant modified-live vaccine strains, particularly those strains attenuated by deletions within the thymidine kinase (TK-) gene locus. To address this hypothesis experimentally, it is necessary to screen large numbers of PRV isolates for their TK genotype. Techniques to detect the native TK genotype are routinely used in molecular virology laboratories, but are time-consuming. We adapted the polymerase chain reaction to define the genotypic status of PRV isolates with regard to the presence or absence of deletions in the TK gene locus. Used in tandem with the existing glycoprotein-specific ELISA that discriminate between PRV-vaccinated and field strain-infected swine populations, the described technique may help to clarify whether vaccine-derived recombinants are generated under natural conditions and after normal vaccine usage.

Affinity chromatography on heparin sepharose was used to identify 2 lipolytic enzymes in heparinized plasma from horses. One enzyme was typical of hepatic triglyceride lipase (HTGL), because it was resistant to inactivation by high concentrations of NaCl, and it did not require the addition of serum for activity. The other enzyme was identified as lipoprotein lipase (LPL), because of its inactivation at NaCl concentrations in excess of 0.2M, and its dependency on addition of serum as a source of apolipoprotein C-II activator. The enzymes were purified by 347- (HTGL) and 442- (LPL) fold, with yields of 54 and 58%, respectively. The partially purified enzymes were used to design incubation conditions that gave optimal activities for each enzyme in vitro. A selective assay was then developed for direct measurement of LPL and HTGL activities in heparinized plasma from horses. Analysis of HTGL took advantage of the almost complete inactivition of LPL when serum cofactor was excluded from the assay at the NaCl concentration that gave optimal HTGL activity. Prior incubation of heparinized plasma with sodium dodecyl sulfate to inhibit HTGL was necessary for measurement of LPL, because HTGL retained 67% of its activity at the NaCl concentration required for optimal LPL activity. Activity of each enzyme was measured in heparinized plasma from 12 Shetland ponies. The mean activity +/- SD for LPL was 3.22 +/- 1.04 micromoles of fatty acids/ml of heparinized plasma/h (micromoles of FA/ml/h). The mean activity for HTGL was 4.9 +/- 1.56 micromoles of FA/ml/h. The performance of the assay was assessed by replicate analysis of pools of each enzyme with high and low activities. The intra-assay coefficient of variation ranged between 3.4 and 8.7% (n = 10), and the interassay coefficient of variation ranged between 5.2 and 10.7% (n = 7) for the same pools analyzed over 7 weeks.

The aerobic bacterial flora of the genital tract was characterized in 15 stud dogs in an 18-month study. The dogs represented 4 breeds and were from 3 kennels. Bacterial samples from the prepuce and semen were collected every month, except in connection with matings, when they were collected weekly (464 samples). The dogs that were included all mated at least once during the study. The mean pregnancy rate, litter size, and pup mortality for the bitches with which they had mated were all within normal limits. The most frequent bacteria isolated from the prepuce and semen were Pasteurella multocida, beta-hemolytic streptococci, and Escherichia coli. There was a tendency for breeds to differ in frequency of the most common bacterial species. Bacterial culture yielded no aerobic growth in 14.2% of the preputial samples and 69.8% of the semen samples. Bacteria were transferred between dog and bitch at mating. In this study of healthy breeding dogs, neither the fertility of the dog nor that of the bitch was affected by the bacteria transferred.

A study was conducted to determine whether serum interleukin-6 (IL-6) activity increased in horses during experimentally induced endotoxemia and whether serum IL-6 activity correlated to changes in clinical or laboratory data. Six clinically normal horses were given endotoxin iv (30 ng/kg of body weight) in 0.9% NaCl solution over 1 hour. Five of these and 1 additional horse served as controls and were given only 0.9% NaCl solution. Venous blood, for determination of serum IL-6 activity and WBC count, was collected before and at various times through 8 hours after the start of endotoxin or NaCl infusion. Rectal temperature and heart and respiratory rates were recorded throughout the study period. Serum IL-6 activity was determined by bioassay of proliferation of the B13.29 clone B.9 hybridoma cell line. From 1.5 through 5 hours after start of the infusion, serum IL-6 activity was significantly (P < 0.05) increased in horses given endotoxin. Mean peak serum IL-6 activity was observed between 3 and 4 hours. In response to endotoxin infusion, horses became lethargic, tachycardic, and febrile. Leukopenia developed by 1 hour, followed by leukocytosis at 8 hours. Significant (P < 0.05) positive association and linear correlation were apparent between mean serum IL-6 activity and mean rectal temperature in the group of horses that were given endotoxin. Changes from baseline were not evident in any of the clinical or laboratory values in horses given only NaCl solution.

Concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in serum samples obtained from 100 dogs. Groups (n = 25/group) consisted of sexually intact and ovariohysterectomized bitches and sexually intact and castrated male dogs. Mean (+/- SD) concentrations of LH in the serum of sexually intact and ovariohysterectomized bitches were 1.2 (+/- 0.9) and 28.7 (+/- 25.8) ng/ml, respectively. Mean concentrations of FSH in the serum of sexually intact and ovariohysterectomized bitches were 98 (+/- 49) and 1,219 (+/- 763) ng/ml, respectively. Mean concentrations of LH in the serum of sexually intact and castrated male dogs were 6.0 (+/- 5.2) and 17.1 (+/- 9.9) ng/ml, respectively. Mean concentrations of FSH in the serum of sexually intact and castrated male dogs were 89 (+/- 28) and 858 (+/- 674) ng/ml, respectively. In addition to history, physical examination results, and other laboratory values, the measurement of serum gonadotropin concentrations may aid in determining whether dogs have been neutered.

A subcutaneous soft tissue infection model in calves was used to study the in vivo response of Pasteurella haemolytica to erythromycin and dexamethasone. Two tissue chambers were implanted SC in each of 12 calves. At 45 days after implantation, all tissue chambers were inoculated with an erythromycin-sensitive strain of P haemolytica. Starting 24 hours after inoculation, calves were allotted to 4 groups of equal size and a 2 X 2-factorial arrangement of treatments was applied: 3 calves were given erythromycin (30 mg/kg of body weight, IM, for 5 days), 3 calves were given dexamethasone (0.05 mg/kg, IM, for 2 days), 3 calves were given erythromycin and dexamethasone, and the remaining calves served as nontreated controls. Chamber fluids were tested daily, and the response to treatment was measured. Neither erythromycin nor dexamethasone affected viability or growth of bacteria within tissue chambers. Dexamethasone had no effect on the influx of neutrophils into infected chambers. Despite repeated administration of a high dose of erythromycin and attainment of adequate concentration in serum, erythromycin concentration in chamber fluids did not exceed the minimal inhibitory concentration established in vitro. These results indicate that the clinical efficacy of erythromycin against P haemolytica sequestered in consolidated pneumonic lesions may not be well correlated with predictions based on serum pharmacokinetic and in vitro susceptibility data.

A Latin square design was used to compare the effects of laxatives and a corresponding volume of water on gastrointestinal tract function in 4 healthy horses. Horses were intragastrically infused with each of the following: dioctyl sodium sulfosuccinate (DSS; 50 mg/kg of body weight); magnesium sulfate (0.5 g/kg-low dosage); magnesium sulfate (1.0 g/kg-high dosage); and an equal volume of water (6 L) given as a control infusion. From 5 to 33 hours after the high dosage of magnesium sulfate, feces were slightly softer than usual in all horses. In 1 horse, DSS caused mild colic, hyperpnea, and diarrhea from 0.3 to 3 hours after administration. After aH laxative treatments and the control infusion, fecal output, fecal water, number of defecations, and fecal water percentage were greater during the first 6 and 12 hours, compared with each subsequent 6-hour period (P < 0.05). The high dosage of magnesium sulfate had greater effect on fecal output and fecal water than did the low dosage and control infusion (P < 0.05). However, this effect preceded arrival of the liquid transit marker, polyethylene glycol, and magnesium at their highest concentrations in feces by 12 to 18 hours. Compared with the control infusion, none of the laxative treatments affected excretion of polyethylene glycol and plastic particulate markers, nor did they increase water consumption. It was concluded that the response to intragastric infusions may involve reflex mechanisms in the gastrointestinal tract and that these responses could be used for treatment of colon impactions. Under conditions of this study, DSS was not a sufficiently effective laxative to outweigh the risk of toxic effects at recommended doses. Although DSS and the low dosage of magnesium sulfate may not provide a greater laxative effect than did an equal volume of water, the high dosage of magnesium sulfate should be more effective.

In each of 5 groups of dogs, 0.05 ml of 1 of the following solutions was injected into the anterior chamber of both eyes: phosphate-buffered saline solution, 0.001 microg of prostaglandin F2 alpha (PGF2 alpha), 0.01 microg of PGF2 alpha, 0.1 microg of leukotriene D4 (LTD4), and 1 microg of LTD4. A 10% solution of sodium fluorescein was injected IV (14 mg/kg of body weight) at the same time, and pupil size, intraocular pressure, and anterior chamber fluorescence were measured for 1 hour after injections. In a dose-dependent manner, Pgf2 alpha was a potent miotic. A significant effect on intraocular pressure was not detected when the groups given PGF2 alpha were compared with the control group. When compared with LTD4, PGF2 alpha Significantly (P < 0.05) increased the breakdown of the blood-aqueous barrier, as evidenced by increased fluorescein leakage into the anterior chamber. Leukotriene D4 caused a decrease in pupil size only at 5 minutes, compared with that of the control group. Intraocular pressure was greater (but not significantly) in the group given 1 microg of LTD4.

We evaluated the effect of anticoagulant (lithium heparin, sodium heparin, or none) and type of autoanalyzer on selected blood biochemical values of the loggerhead sea turtle (Caretta caretta). More differences were observed between the analytes in serum and those in the 2 types of plasma than were observed between the 2 types of plasma. Differences in electrolyte concentrations were not significant when plasma from sodium-heparinized blood was compared with plasma from lithium-heparinized blood. Serum is not recommended for reptilian studies because clot formation is unpredictable and because the time required for clotting may allow substantial changes in the chemical composition of the sample. For most determinants, values varied more between the 2 types of autoanalyzers than among the 3 anticoagulant treatments. These sources of variation must be considered when performing comparative studies.

Incidence of seroconversion to caprine arthritis-encephalitis virus (CAEV) was determined for 1,194 goats on 11 dairies, using 2 repeated annual herd tests for CAEV. Current life table methods were used to compare age-specific incidence of seroconversion for pasteurized milk-raised and unpasteurized milk-raised goats. Logistic regression models were used to determine the risk factors associated with CAEV seroconversion, and to estimate odds ratios for seroconversion for various factor levels. Goats raised by unpasteurized milk-feeding methods were 2.5 to 6.7 times more likely to seroconvert than were goats raised by pasteurized milk-feeding methods, depending on the method of comparison. Similarly, 61.6 to 85.0% of seroconversions in yearling goats possibly were attributable to unpasteurized milk feeding. Among yearling goats, CAEV seroconversion was associated with feeding method, breed, and source of goat (herd of origin) when the effect of dairy was considered. In addition to the 6.7 times greater risk of seroconversion for unpasteurized milk-raised goats, yearling goats of the Saanen and Toggenburg breeds were 2.2 and 3.3 times, respectively, more likely to seroconvert than were Alpine yearling goats. Yearling goats purchased from another source were less likely to seroconvert than were yearlings raised on the dairy where they were studied. Among goats > 1 year old, age was associated with risk of seroconversion. Goats that were 3 years old or were > 4 years old were 1.7 and 3.2 times, respectively, more likely to seroconvert than were 2-year-old goats, when adjusted for effect of dairy. The effects of dairy were significant (P less than or equal to 0.001) in yearling and older goats.