A commercial rapid-absorbed ELISA developed to detect antibodies to Mycobacterium paratuberculosis in bovine serum was modified for use with goat serum. Diagnostic sensitivity was evaluated, using a group of 163 goats from a herd with endemic paratuberculosis. Blood and fecal samples were obtained simultaneously, and prevalence of shedding of M paratuberculosis in the feces was estimated by detection of DNA of the mycobacterial insertion sequence, IS900, using a commercial test kit. Diagnostic specificity was evaluated, using blood samples from a total of 123 goats in 10 herds that were considered clinically free of paratuberculosis. The IS900 DNA was detected in 35 of the 163 goats (21%) from the infected herd. Serum antibody to M paratuberculosis was detected in 19 of the 35 IS900 DNA-positive goats, for apparent sensitivity of 54%. Serum antibody was detected in 18 of the 128 IS900 DNA-negative goats from the infected herd. Negative results for serum antibody to M paratuberculosis were obtained for all 123 goats from the herds that were considered clinically free of paratuberculosis.

Tidal breathing flow-volume (TBFV) loops were determined in a group of control horses and in horses affected with recurrent airway obstruction (heaves). The latter group was studied when the condition was in remission and under increasing amounts of airway obstruction as reflected by measurements of change in pleural pressure, pulmonary resistance, and dynamic compliance. The TBFV loops of control horses had biphasic inspiratory and expiratory patterns; peak inspiratory and peak expiratory flows were detected early in inspiration and expiration, respectively. Tidal volume was unaffected by heaves, but at all stages of heaves, respiratory frequency was increased principally because of shorter inspiratory time, and therefore, inspiratory flow rate was increased. In horses with heaves, TBFV loops did not have a biphasic pattern; peak inspiratory flow was observed late in inspiration, and peak expiratory flow was observed early in expiration. As airway obstruction became more severe, peak expiratory flow increased as pulmonary resistance increased so that, during severe airway obstruction, TBFV loops had a characteristic appearance with high peak expiratory flow early in expiration followed by low flow rate.

Two nonoverlapping clones, pOH405 and pOH632, containing cDNA inserts in the VP2 coding region of genome segment A were selected from a cDNA library prepared from the double-stranded RNA genome of the OH strain of infectious bursal disease virus (IBDV) of serotype 2. Clone pOH405, which is located in the hypervariable segment of VP2, is 328 base pairs long, has nucleotide sequence homology of 72 to 73%, and amino acid sequence homology of 64 to 67% with IBDV strains of serotype 1. Clone pOH632, which is located in the highly conserved C-terminal part of VP2, is 230 base pairs long, has nucleotide sequence homology of 87 to 88%, and amino acid sequence homology of 100% with IBDV serotype 1. The lower detection limit of 32P-labeled probes prepared from both clones was 10 ng of OH-IBDV double-stranded RNA, using high-stringency conditions of hybridization (54 C, 50% formamide) and washing (55 C, 0.015M NaCl, 0.0015M trisodium citrate, pH 7.0, with 0.1% sodium dodecyl sulfate), and autoradiography for 24 hours. Under these conditions, the dot-blot hybridization assay for detection of serotype 2 IBDV double-stranded RNA was 1,000 times more sensitive, using probe pOH632, but only 10 times more sensitive, using probe pOH405, compared with the assay for IBDV serotype 1, using the same probes. Thus, probe pOH632 could differentiate between the 2 IBDV serotypes by nucleic acid hybridization.

Disposition kinetics of indocyanine green (ICG) were used to evaluate hepatic function in healthy Beagles (group 1; n = 6) and Beagles with progressive hepatic disease induced by oral administration of dimethylnitrosamine, a hepatospecific toxin. Three classes of hepatic disease were defined by histologic features: mild (group 2; n = 5), moderate (group 3; n = 6), and severe (group 4; n = 5). Disposition of ICG was studied 3 weeks following the last dose of toxin. A rapid IV injection of 0.5 mg of ICG/kg was administered and serum samples were obtained at certain intervals during 60-minute periods. Serum ICG was analyzed by use of visible spectrophotometry. Disposition kinetics were determined from serum ICG concentrations vs 15- and 60-minute time curves and compared between one another and among groups. Data based on 60-minute time curves were not significantly different from those based on 15-minute curves. Area under the curve for ICG was greatest in group 3. Clearance of ICG was decreased and mean resident time was increased in groups 3 and 4, compared with those in groups 1 and 2. When disposition data (60 minutes) were normalized for differences in hepatic weight among dogs, group-3 mean resident time was significantly greater than that of group 4. This study supports the diagnostic benefits of using ICG disposition kinetics as a method of evaluating hepatic function in dogs with progressive liver disease.

Brain, spleen, and selected lymph nodes from sheep with clinical signs of scrapie were analyzed for presence of proteinase K-resistant protein (PrP-res). Diagnosis of scrapie on the basis of detection of PrP-res was compared with diagnosis on the basis of histologic evaluation of the brain from clinically affected or exposed sheep. Proteinase K-resistant protein was found in every brain that was histologically positive for scrapie, and in addition, was found in the brain of several clinically positive sheep that were not diagnosed as scrapie-positive by histologic evaluation. Proteinase K-resistant protein was also found in 87% of the spleens and lymph nodes from sheep that had PrP-res detected in brain homogenates. Therefore, analysis of sheep brain, spleen, or lymph nodes for PrP-res provided a diagnostic approach that was superior to histologic examination alone for detection of naturally scrapie agent-infected sheep.

An ELISA was developed and tested to detect antibodies to Eperythrozoon suis in swine. Results were compare with those of the indirect hemagglutination (IHA) test. Antigen isolated from swine heavily infected with E suis was used for both tests. Comparison of the ELISA with the IHA test revealed a significant (P < 0.001) correlation between results. Of 114 samples obtained from 9 swine infected with E suis, 8 7.7% were seropositive (titer greater than or equal to 200) via the ELISA, and 80.7% were seropositive (titer greater than or equal to 20) via the IHA test. The sensitivity of the ELISA was greater than that of the IHA test. All blood samples obtained from specific-pathogen-free swine tested negative for E suis antibody. Cross-reactions were not observed between E suis antigen and antisera against various swine and cattle disease agents using ELISA. We concluded that the ELISA may be used for rapid and effective diagnosis of infection with E suis in swine.

An ion chromatographic method was used to simultaneously determine nitrate and nitrite ions in biological samples. Ultrafiltration was used to produce a protein-free filtrate. Chloride interferences were eliminated by precipitation as the silver salt. Detection limits and average recoveries were 0.5 mg/L and 102% for nitrate and 0.2 mg/L and 78% for nitrite, respectively. Nitrate concentration was 2.1 +/- 1.8 mg/L and 4.9 +/- 0.8 mg/L in serum and ocular fluid of healthy cattle, respectively; nitrite was not detected. A severe case of nitrate poisoning in cattle was described and used to study the concentrations of nitrate and nitrite in samples obtained under natural conditions. Nitrate concentration of acutely poisoned cattle was 35% lower in ocular fluid at 158.1 +/- 51.4 mg/L, than in serum at 256.3 +/- 113.4 mg/L. Nitrite was not detected, because of the long processing time (> 3 hours) required for samples obtained in the field. A gradual decrease in ocular fluid nitrate of 29.4% at 24 hours, 25.9% at 36 hours, 51.6% at 48 hours, and 73.2% at 60 hours was observed; however, concentrations remained diagnostically significant (73.2 mg/L) 60 hours after death. Twenty-four hours after poisoning, the serum nitrate concentration of severely ill (52.7 +/- 51.9 mg/L) and moderately affected (12.4 +/- 5.7 mg/L) cattle that survived was indicative of the severity of clinical signs previously observed. Nitrate in serum and ocular fluid was stable in samples stored for 24 hours at 23 C, 1 week at 4 C, and 1 month at -20 C.

An ELISA was used to detect IgG, IgM, and complement (C3) on the surface of canine erythrocytes. Erythrocytes were placed in wells of a microtitration plate and incubated with affinity purified, alkaline phosphatase-conjugated anti-canine IgG, IgM, or C3. Results of the ELISA were compared with the direct antiglobulin test (DAT) by preparing standard reference curves from canine blood type A erythrocytes that had been incubated with serial dilutions (1:2 to 1:8,192) of canine anti-A serum. The ELISA detected increased erythrocyte-bound immunoglobulin and complement at two- to fourfold dilutions greater than thoe required for positive results with the DAT. The ELISA required small sample and reagent volumes and detected lower concentrations of immune components than did the DAT.

Swine herds suspected to be infected with Leptospira interrogans serovar bratislava were vaccinated with bacterins containing 5 or 6 leptospiral serovars in which serovar bratislava was the unique component. The principal diagnostic feature indicating an infection by this organism was demonstration of antibody against serovar bratislava in sera from stillborn pigs. For 1 breeding cycle after vaccination of herds on 3 farms, 255 of 266 (95.9%) sows and gilts given the 6-serovar bacterin farrowed. In contrast, 233 of 311 (74.9%) sows and gilts given the 5-serovar bacterin farrowed. These results, as evaluated by analysis of variance techniques, showed a significant improvement (P less than 0.01) in reproductive performance for groups vaccinated against serovar bratislava.

When incubated with solutions of hydrogen peroxide, erythrocytes of stress-susceptible pigs produced more by-products of lipid peroxidation (as measured as thiobarbituric acid-reactive substances [TBARS]) than did erythrocytes from stress-resistant pigs. Using this technique, discrimination between the 2 pig types was absolute at hydrogen peroxide concentrations of 0.9 and 1.5%. This was in contrast to other methods of identifying stress-susceptible pigs, such as osmotically induced erythrocyte lysis and the determination of plasma pyruvate kinase and creatine kinase activities, for which considerable overlap of data was observed between pig types. The increased TBARS production by erythrocytes was further evidence for the existence of an antioxidant abnormality in stress-susceptible pigs. However, because there were no discernible differences in the major blood antioxidant-related values between stress-susceptible and stress-resistant pigs, the nature of the defect remains unclear. The production of TBARS by erythrocytes when incubated with hydrogen peroxide provides an improved method for identifying stress-susceptible pigs.