Custom-designed Hall-effect strain sensors (HES) were implanted surgically onto the superficial digital flexor tendons of the forelimbs of 4 adult Thoroughbreds. Strains were recorded at various gaits, using a portable amplifer and FM cassette recorder. Strain calculations used the original length (L) as the HES position with the forelimb in the relaxed neutral position during anesthesia. A characteristic deflection in the strain cycle recording was confirmed to correspond to initial hoof contact with the ground (heel strike) by simultaneous recording of weight bearing via a footswitch. Heel strike was used as the reference point to determine the magnitude of strain change during weight bearing and nonweight bearing under various conditions. The weight-bearing strains (heel strike to maximal strain) recorded in 2 horses (with a rider) were 3.1% and 7.6% at the walk, 6.5% and 10.1% at the trot, and 11.5% and 16.6% at the gallop. Strain rate during tendon loading at the gallop was approximately 200%/s. The magnitude of strain change during nonweight bearing (minimal strain to heel strike) was smaller than during weight bearing, but also increased with faster gaits. In 3 horses led at the walk and trot, modest increases in hoof angle (baseline, 52%) resulted in small increases in the magnitude of strain change during weight bearing at the trot, but the magnitude of strain change at the walk was not affected. Results of the study indicated that the HES can be successfully adapted to provide continuous strain measurement without subjective signs of discomfort or lameness in horses during or after instrumentation.

Analysis of protein and antigen profiles of Tritrichomonas foetus isolates from cattle from 5 western states was accomplished sodium dodecyl sulfate polyacrylamide-gel electrophoresis, immunoblot, immunoprecipitation, and fluorography techniques. Total protein profiles of all isolates were compared by Coomassie brilliant blue staining of T foetus protein samples prepared by 4 protein-extraction methods. Antigenic tritrichomonas proteins were identified by immunoblot assay with polyclonal bovine or rabbit anti-T foetus serum. Additionally, [14C]glucosamine-labeled T foetus was used for total and antigenic glycoprotein analyses. Detectable differences in the composition of total proteins or antigenic tritrichomonal proteins were not observed among all isolates. However, intensity differences in some antigenic protein bands were apparent. Bovine and rabbit sera from immunized animals possessed antibodies to the same antigenic tritrichomonal proteins. Each T foetus isolate contained 4 to 7 molecular weight size classes of glycoprotein, which were labeled by [14C]glucosamine; however, only 3 to 4 glycoproteins were identified as antigens by bovine or rabbit antiserum.

Eighteen strains of Escherichia coli serogroup O115:K"V165" isolated from 1- to 8-week-old pigs with diarrhea were tested for toxigenicity, pathogenicity in pigs and mice, serum resistance, mannose-resistant hemagglutination (MRHA), F165 and other surface antigens, colicin V (Col V), aerobactin, and biotype. Twelve strains were positive for heat-stable enterotoxin (STb), MRHA-negative, and F165-negative; 5 strains were enterotoxin-negative, MRHA-positive, and F165-positive; and 1 strain was MRHA-positive, but F165- and enterotoxin-negative. Six of the 12 STb-positive strains moderately colonized the ileum of newborn colostrum-deprived pigs within 24 hours after inoculation. Two of the colonizing strains were able to induce watery diarrhea. All 12 STb-positive strains were nonpathogenic for adult mice and were serum-sensitive; 11 of 12 were Col V-negative, 9 of 12 did not produce aerobactin, and 10 of 12 belonged to biotypes other than 1 or 2. All 6 enterotoxin-negative strains colonized the small and large intestines, associated with peritoneal serosal surfaces, and induced septicemia and polyserositis in newborn colostrum-deprived pigs 1 to 2 days after inoculation. In contrast, 3 STb-positive strains poorly colonized the intestines and did not induce septicemia in pigs at 3 days after inoculation. All 6 enterotoxin-negative strains were Col V-positive, produced aerobactin, and belonged to biotype 1 or 2. Of the 5 enterotoxin-negative, F165-positive strains, only 4 were pathogenic for intraperitoneally inoculated adult mice and were serum-resistant. The enterotoxin-negative, F165-negative strain was neither serum-resistant nor mouse-pathogenic. O-agglutinable mutants of the mouse-pathogenic strains were, for the most part, no longer pathogenic for adult mice, although these strains remained unchanged for biotype and production of MRHA, F165, and Col V, and 3 of 4 mutant strains were serum-resistant. Thus, E coli strains of the same serogroup isolated from diarrheic pigs may cause either intestinal or extraintestinal disease upon reinoculation of pigs, depending on the virulence attributes produced by the strains.

Strain gauge rosettes were bonded to the dorsal, lateral, medial, and plantar aspects of the third metatarsal bone in the hind limbs of 6 ponies. The maximal compressive principal strain was approximately -600 X 10(-6) m/m, and exceeded the amplitudes of the tensile strains at all aspects of the bone. After transformation, the shear strain and the principal strains parallel and perpendicular to the bone were obtained. The first peak in the bending strain was higher in the dorsal and lateral aspects, and the second peak was higher in the medial and plantar aspects. Young modulus of elasticity was determined in a 4-point bending test at the dorsal and plantar sides; it averaged 19.5 GPa in tension and compression. Applying linear bending theory, the eccentricity of an axial force parallel or a bending force perpendicular to the bone were calculated. The position where the total force penetrated the tarsometatarsal joint surface was largely within the joint surface, indicating that the joint is merely loaded in (eccentric) compression.

The effects of prolonged plasmapheresis of cattle on total and antigen-specific immunoglobulin production were evaluated. Five adult cows were hyperimmunized by repeated IV administration of live, logarithmic-phase Pasteurella haemolytica A1 organisms. Three of the cows underwent plasmapheresis daily for 3 weeks. From 2 cows, serum was only obtained periodically. Anti-P haemolytica antibody was assayed by indirect hemagglutination and a kinetic-augmented, antigen-capture ELISA for capsular polysaccharide and lipopolysaccharide/outer membrane protein antigens. Total serum immunoglobulin concentration was determined for IgM, IgG1, and IgG2 by primary radial immunodiffusion. Anti-P haemolytica A1 activity increased rapidly after immunization. After beginning plasmapheresis, the antigen-specific antibody activities remained nearly constant. In general, antilipopolysaccharide/outer membrane protein activity (in terms of concentration) was higher than anti-capsular polysaccharide activity and was not affected as much by the plasmapheresis. Total serum Ig concentration decreased transiently by a small amount after beginning plasmapheresis.

Nonvaccinated pregnant cows were segregated retrospectively into 2 groups following inoculation with Brucella abortus stain 2308. One group resisted infection (resistant cows) and the other group developed active infections (susceptible cows) and subsequently aborted. Mammary gland macrophages collected from the 2 groups of cows were compared, using in vitro functional assays. In a chemiluminescence assay, mammary gland macrophages from resistant cows produced significantly (P = 0.014) higher oxidative burst activity than did macrophages from susceptible cows. Macrophages from resistant cows had significantly (P = 0.038) greater bacteriostatic activity against B abortus than did macrophages from susceptible cows. Differences in lysosomal enzymatic activity or Fc receptor expression were not observed for macrophages from the 2 groups of cows. Differences in macrophage function may be one factor responsible for natural resistance to Brucella infection in cattle.

Diacetoxyscirpenol (DAS) was given IV to pigs (0, 0.5, and 1.0 mg/kg of body weight), cattle (0 and 0.5 mg/kg), and dogs (0 and 0.5 mg/kg). Blood was collected and hemograms were done at 0.5-hour intervals for 8 hours. The animals were euthanatized at 8 hours after treatment, and bone marrow samples were taken and examined by light microscopy. Moderate to severe necrosis of bone marrow hematopoietic elements was found in animals given DAS. The sequential increase in the type and number of abnormal cells in the blood suggested a successive destruction of the hematopoietic elements. A marked left shift in the neutrophil population was found in animals given DAS. Metarubricytes and large platelets were found in the blood of animals given DAS. Lymphocytes were replaced with immature cells. Pathologic changes were most severe in the pigs given a dosage of 1.0 mg of DAS/kg. The order of species sensitivity to DAS was pigs greater than dogs much greater than cattle.

Subclinical Toxoplasma gondii infection was induced in young and adult cats by oral administration of tissue cysts. An antibody-capture ELISA to detect anti-Toxoplasma IgM-class antibodies in the serum of cats was developed. The serologic response to experimental infection was followed in the 2 groups of cats by use of anti-Toxoplasma IgM and IgG detection. This study shows that anti-Toxoplasma IgM-class antibody titers develop early in the course of experimental infection in cats and that the combination of IgM- and IgG-class antibody titer measurement can aid in the detection of recent subclinical toxoplasmosis.

We compared the ability of 3 alpha 2-adrenoreceptor antagonists, idazoxan (0.05 mg/kg), tolazoline (2 mg/kg), and yohimbine (0.2 mg/kg) to reverse xylazine (0.3 mg/kg)-induced respiratory changes and CNS depression in 6 ewes. Once weekly, each ewe was given a random IV treatment of xylazine, followed in 5 minutes by either an antagonist or 0.9% NaCl solution. Xylazine alone caused recumbency for 54.2 +/- 5.3 minutes (mean +/- SEM). Xylazine also increased respiratory rate and decreased PaCO2 for at least 45 minutes, but did not significantly change arterial pH or PaCO2. Idazoxan and tolazoline were equally effective in reversing the respiratory actions of xylazine; however, yohimbine was less effective in reducing the respiratory rate and was ineffective in antagonizing the decreased PaO2. Idazoxan and tolazoline decreased the duration of xylazine-induced recumbency to 6.3 +/- 0.6 and 9.5 +/- 2.3 minutes, respectively, whereas yohimbine did not significantly change this effect of xylazine. Thus, at the dosages studied, idazoxan and tolazoline appeared to be more effective than yohimbine in reversing the respiratory and CNS depressant actions of xylazine in sheep.

Effectiveness of 2 pentavalent leptospiral vaccines containing Leptospira interrogans serovar hardjo was evaluated for protection of steers from infection with serovar hardjo type hardjo-bovis. The hardjo component of 1 vaccine was prepared from serovar hardjo type hardjoprajitno. The hardjo component of the other vaccine was prepared from serovar hardjo type hardjo-bovis. Two steers were vaccinated once and 4 steers were vaccinated twice with the pentavalent vaccine containing type hardjoprajitno. Four steers were vaccinated once and 4 steers were vaccinated twice with the pentavalent vaccine containing type hardjo-bovis. Four steers were maintained as non- vaccinated controls. Steers given vaccine containing type hardjo-bovis developed higher mean serum microscopic agglutination titers against serovar hardjo than steers given vaccine containing hardjoprajitno. Six months after the first vaccination, all steers were challenge-exposed on 3 occasions by conjunctival instillation of 10(7) serovar hardjo type hardjo-bovis organisms, and on 1 occasion by conjunctival instillation of urine from a steer shedding hardjo-bovis. All control and all vaccinated steers became infected and shed serovar hardjo type hardjo-bovis in the urine. Lesions were detected in kidneys of 3 of 4 nonvaccinated control steers, 5 of 6 steers given hardjoprajitno vaccine, and 6 of 8 steers given hardjo-bovis vaccine. Leptospires were detected in kidneys of 4 of 4 control steers and 13 of 14 vaccinated steers.