Adult Beagles were used to evaluate clinical signs and serologic response after inoculation with, or exposure to, Borrelia burgdorferi. An indirect immunofluorescent assay (IFA) and 2 ELISA were used to monitor the serologic response to B burgdorferi. Feeding infected ticks on 4 dogs (group 1) failed to cause seroconversion, and SC inoculation with 500 organisms caused minimal seroconversion in 2 of 4 dogs (group 2). At 56 days, approximately 3.01 X 10(8) B burgdorferi organisms were injected IV into group-1 dogs, and intraperitoneally into group-2 dogs. A control group of 4 dogs (group 3) had noninfected ticks feed on them, and then were given IV injection of physiologic saline solution. Increases in immunoglobulin M (IgM) titers were detected in 2 of 4 group-2 dogs approximately 7 days after the initial exposure. These titers returned to negligible values 20 days later. Immunoglobulin G titers increased approximately 10 days after the initial exposure and were mildly increased 56 days later, when dogs were exposed a second time. Both the IV and intraperitoneal injections (second exposures) resulted in increased IgM titers, which in both groups eventually returned to preexposure values after approximately 2 months. Immunoglobulin G titers increased within a week after the second exposure, and in 3 dogs monitored for 8 months, returned to negligible values after the 8-month period. One control dog had a slightly increased IgG titer 24 days after the second inoculation. The possibility of urine transmission is suggested. Clinical status, hemograms, serum biochemical profiles, ECG and results of urinalyses remained normal throughout the study. Borrelia burgdorferi was not isolated from either the blood or urine of these dogs. Gross or microscopic pathologic changes were not detected on necropsy.

Concentrations of serum thyroxine (T4) and 3,5,3'-triiodothyronine (T3) were determined after the administration of freshly reconstituted thyrotropin-releasing hormone (TRH), reconstituted TRH that had been previously frozen, or thyrotropin (TSH) to 10 mature dogs (6 Greyhounds and 4 mixed-breed dogs). Thyrotropin-releasing hormone (0.1 mg/kg) or TSH (5 U/dog) was administered IV; venous blood samples were collected before and 6 hours after administration of TRH or TSH. Concentrations of the T4 and T3 were similar (P > 0.05) in serum after administration of freshly reconstituted or previously frozen TRH, indicating that TRH can be frozen at -20 C for at least 1 week without a loss in potency. Concentrations of T4, but not T3, were higher after the administration of TSH than they were after the administration of TRH (P < 0.01). Concentrations of T4 increased at least 3-fold in all 10 dogs given TSH, whereas a 3-fold increase occurred in 7 of 10 dogs given freshly reconstituted or previously frozen TRH. Concentrations of T4 did not double in 1 dog given freshly reconstituted TRH and in 1 dog given previously frozen TRH. Concentrations of T3 doubled in 5 of 10, 2 of 10, and 5 of 10 dogs given TSH, freshly reconstituted TRH, or previously frozen TRH, respectively. Results suggested that concentrations of serum T4 are higher 6 hours after the administration of TSH than after administration of TRH, using dosage regimens of 5 U of TSH/dog or 0.1 mg of TRH/kg. Additionally, results suggested that Greyhounds have lower concentrations of serum T4 than do mixed-breed dogs, but Greyhounds tend to have higher concentrations of serum T3.

Using an avidin-biotin-peroxidase complex immunoperoxidase staining method, respiratory syncytial virus (RSV) antigen was demonstrated in glutaraldehyde-fixed, parraffin-processed lung sections from calves with induced RSV pneumonia. The virus also was detected in formalin-fixed, paraffin-processed lung sections from calves with naturally occurring RSV pneumonia. Specific immunoperoxidase staining was detected within the cytoplasm of epithelial cells and syncytia in small bronchi, bronchioli, and alveoli. Staining also was detected within exudates in airway lumina and in mononuclear and multinucleate cells within alveolar lumina. Optimal intensity of staining was achieved by proteolytic enzyme treatment of lung sections, using 0 .1% pronase and overnight incubation in diluted primary antiserum. The distribution of antigen had a close correlation with presence of lesions. Antigen-staining patterns were similar in lung tissue from calves with naturally occurring and induced RSV disease.

Serologic virus neutralization tests, indirect immunofluorescence tests, and ELISA, using tissue culture-adapted feline infectious peritonitis virus (FIPV) or feline enteric coronavirus (FECV) were compared for their ability to distinguish specific virus exposure in cats. Sera of specific-pathogen-free cats inoculated with virulent or modified FIPV or FECV were used to compare the sensitivity and specificity of the homologous assays to a heterologous assay that measures antibody reactivity with transmissible gastroenteritis virus of swine. The geometric means of the serologic titers in FIPV and FECV assays were higher for FIPV- or FECV-infected specific-pathogen-free cats than the geometric means of the transmissible gastroente ritis virus assays for most groups. None of the assays was specific enough to discern the virus to which a cat had been exposed. However, the FIPV virus neutralization test appeared to be more sensitive for detection of an early response to FIPV infection than did the FIPV immunofluorescence test or FIPV-ELISA.

An indirect immunoperoxidase staining technique was evaluated for detection of Mycoplasma hyopneumoniae in formalin-fixed, paraffin-embedded porcine lung. Lungs from swine with induced (n = 4) or naturally occurring M hyopneumoniae infection (n = 31) were examined grossly, by light and immunofluorescent microscopy, and by an indirect immunoperoxidase test, using antibody raised in swine against M hyopneumoniae as the primary antibody. Organisms stained by the indirect immunoperoxidase method were identified in tissue sections as pleomorphic brown-staining structures corresponding to those observed with immunofluorescence. Mycoplasma hyosynoviae, M hyorhinis, and Acholeplasma laidlawii did not stain with the indirect immunoperoxidase method, using antibody raised against M hyopneumoniae.

The effect of low-dose challenge of immunity with pseudorabies virus (PRV) on subunit-vaccinated pigs was studied in 2 experiments. In the first experiment, we studied the effect of challenge dose on the antibody response to an early excreted 98-kilodalton PRV-glycoprotein that was used as a diagnostic antigen in the ELISA. In the second experiment, we studied the effect of low doses of virus on the establishment of latent infections in subunit-vaccinated pigs. The relationship of virus exposure dose and vaccine dose to the response of pigs to diagnostic antigen was studied in 18 pigs. Two groups of 3 pigs were vaccinated with a total of 200 micrograms of a lectin-derived PRV subunit vaccine over a 5-week period. Two groups of 3pigs were similarly vaccinated with a total of 100 micrograms. Two groups of 3 pigs served as nonvaccinated controls. One group of pigs from each of the preceding categories was intranasally exposed to 10(6.0) and 10(2.7) plaque-forming units (PFU) of virus. Antibody to diagnostic antigen was detected by the ELISA and radioimmunoprecipitation 3 to 7 days earlier in pigs exposed to 10(6.0) PFU, demonstrating that the size of the virus challenge dose affects the antibody response to diagnostic antigen. The establishment of latent infections by low PRV doses and the ability to detect these infections was studied in 10 subunit-vaccinated pigs. Each pig was intranasally exposed to 10(2.3) PFU of virus (day 0). The serum virus-neutralizing antib ody titer of these pigs increased to their highest level 14 to 21 days after exposure and then steadily decreased through day 113, indicating absence of viral recrudescence. All pigs were treated with dexamethasone for 4 consecutive days, beginning on day 113. Latent infections were identified in 8 of 10 pigs on the basis of recovery of virus and/or 2 log2 or greater increases in serum virus-neutralizing titer. Antibody to diagnostic antigen was initially detected in the 8 latently infected pigs on day 14 or 21 and continued to be detected through days 21, 46, 53, 110, and 113 in 1, 2, 1, 1, and 3 pigs, respectively. The antibody titer to diagnostic antigen increased in 6 of the 8 latently infected pigs after dexamethasone treatment. However, antibody to diagnostic antigen was not detected by ELISA in the remaining 2 latently infected pigs, despite increases in serum virus-neutralizing titers in both pigs and the recovery of reactivated virus from one pig. The failure to consistently detect antibody to diagnostic antigen in latently infected pigs suggests that diagnostic tests using nonvaccine diagnostic antigen may be suitable only for detecting infections in vaccinated herds, but not in individual pigs.

Strangulation obstruction was induced in anesthetized ponies for periods of 2 and 3 hours by clamping 45-cm segments of jejunum and associated veins (venous strangulation obstruction) and arteries and veins (arterial and venous strangulation obstruction). Four segments were studied in each of 7 ponies allowed to survive 12 hours, 2 segments in a pony that was allowed to survive 1 hour, and 1 segment in each of 10 ponies allowed to survive 42 days after the strangulation periods ended. Fifteen minutes after the periods of strangulation obstruction ended, the viability of test segments was assessed by clinical judgment (40 segments), fluorescein fluorescence (40 segments), and Doppler ultrasound (32 segments). Because thetest segments were normal at necropsy in long-term survivors, all segments were designated as viable. The overall accuracy of the methods used to predict viability was 88% for Doppler ultrasound and 53% each for clinical judgment and fluorescein fluorescence (P less than 0.005). Failures in the last 2 techniques could be attributed to their tendency to score venous strangulation obstruction segments as nonviable (90% for each). Doppler ultrasound was 94% accurate in these segments.

Comparisons were made among rapid latex agglutination test and conventional biochemical tests used to identify Streptococcus agalactiae and Staphylococcus aureus. Ninety-eight streptococci and 149 staphylococci isolated from bulk tank milk were tested. Sensitivity and specificity for the latex agglutination test used for identification of Str agalactiae were 97.6 and 98.2%, respectively. Sensitivity and specificity for the latex agglutination test used for identification of S aureus were 90.2 and 67.5%, respectively. Of 25 staphylococci considered false-positive by the latex agglutination test, 14 (56%) were considered tube coagulase-positive. Fifteen staphylococci considered false-positive by latex agglutination test had biotypes representative of S hyicus or S xylosus.

The umbilical arteries urachus, and umbilical vein were scanned ultrasonographically in 13 clinically normal foals that ranged in age from 6 hours to 4 weeks. Sonograms were obtained using a 7.5-MHz sector scanner transducer placed across the midline of the ventral portion of the foal's abdominal wall. The umbilical vein was scanned from the umbilical stalk to its entrance into the hepatic parenchyma. The mean (+/- SD) diameter of the umbilical vein was 0.61 +/- 0.20 cm immediately cranial to the umbilical stalk, 0.52 +/- 0.19 cm midway between the umbilicus and liver, and 0.6 +/- 0.19 cm at the liver. The urachus and umbilical arteries were scanned from the umbilical stalk to the apex of the urinary bladder and had a mean total diameter of 1.75 +/- 0.37 cm at the bladder apex. The umbilical arteries also were scanned along either side of the bladder and had a mean diameter of 0.85 +/- 0.21 cm. These measurements and the ultrasonographic appearance of the internal umbilical structures from clinically normal foals can be used as references to diagnose abnormalities of the umbilical structures in neonatal foals.