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.

Purified O chain of Brucella abortus was passively attached to polystyrene to differentiate antibody responses of cattle vaccinated with B abortus strain 19 from those of naturally infected cattle. In the indirect assay, using O polysaccharide as antigen, a single serum dilution was used and mouse monoclonal antibody to bovine L chain conjugated with horseradish peroxidase was the detection reagent. Measurable antibody was not found in sera of vaccinated cattle, except for 3 sera from cattle that were persistently infected with strain 19. Sera from 25 cattle infected with pathogenic strains contained antibody on the basis of results of indirect enzyme immunoassay, using smooth lipopolysaccharide or O chain as antigens, or results of competitive enzyme immunoassay, using the O-chain antigen. Results in sera from calves with experimentally induced Yersinia enterocolitica serotype 0:9 infection or inoculated with a low dose of B abortus strain 2308 were comparable with those in sera of cattle that were vaccinated with strain 19. The data correlated with those from competitive enzyme immunoassay, using one serum dilution and horseradish peroxidase-conjugated mouse monoclonal antibody to smooth lipopolysaccharide. On the basis of results of the indirect enzyme immunoassay, all sera (except those samples obtained before inoculation) contained antibody to smooth lipopolysaccharide.

Water vapor-saturated air was delivered to 12 healthy housed horses for 2 hours daily for 5 days. Treatment had no effect on tracheal mucus transport rate, bronchoalveolar lavage total and differential cell counts, blood cell counts, or plasma fibrinogen concentration.

A study on erythrocyte distribution was performed on 10 healthy, nonstressed adult white Pekin ducks. Results indicated 2 populations of erythrocytes, with average mean corpuscular volumes of 128.37 fl/cell and 308.50 fl/cell. Variations in erythrogram patterns were evident over time, when comparing specimens from different ducks or the same duck. There were 5 patterns of cell number/volume distribution observed between the 2 cell populations when all ducks were studied. Females had a greater change than did males when population density and volume percentage comparisons were made on erythrocyte compartments.

The effects of canine parvovirus (CPV) infection in dogs with hemolytic anemia was compared with the clinical effects of human parvovirus-induced aplastic anemia in human beings with chronic regenerative anemias. Phenylhydrazine was used to induce a transient, severe, hemolytic anemia in dogs to evaluate the effects of CPV infection on rapidly dividing bone marrow precursors. Erythrocyte colony-forming unit bone marrow cultures and cytologic examination of bone marrow were used to determine the effects of CPV infection on erythroid bone marrow precursors. The induced hemolytic anemia regenerated rapidly and although the bone marrow was infected, it was determined that CPV infection did not induce a detectable decrease in erythroid progenitors in dogs with severe hemolytic anemia.

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.

A transretinal method for recording the summed potentials generated by photoreceptors of the isolated canine retina in vitro is reported. Pieces from 10 retinas of 5 clinically and visually normal dogs were maintained in a recording chamber and superperfused with a modified cell culture medium. Sodium glutamate added to the medium eliminated electrical responses from retinal glia and allowed the summed receptor potentials to be recorded. The response to flashes of light consisted of a negative potential, which increased in amplitude in a graded manner and in complexity with increased stimulus intensity. The response was similar in waveform to that reported in other vertebrate species, using intracellular and extracellular techniques. This method of recording the mass transretinal receptor potentials in vitro will be of value for investigating abnormal photoreceptor functions in dogs in the early stages of inherited retinal degeneration.

Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity in the duodenum, right ventral colon, cecal body, and cecal apex were measured in 6 conscious healthy horses for 60 minutes during and for 120 minutes after IV infusion of 0.9% NaCl solution (control) or fenoldopam. There were no significant changes in these measurements during or after infusion of 0.9% NaCl (saline) solution. Fenoldopam, a selective dopamine- 1 receptor agonist, was administered in saline solution at dosages of 0.01, 0.05, and 0.1 ug/kg/min. Intravenous infusion of fenoldopam at 0.01 ug/kg/min significantly increased heart rate, but did not change average carotid arterial pressure or lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at both 0.05 and 0.1 ug/kg/min significantly increased heart rate, significantly decreased average carotid arterial pressure, and significantly increased lateral cecal arterial blood flow. Intravenous infusion of fenoldopam at 0.01, 0.05 and 0.1 ug/kg/min did not significantly change the mechanical activity measured by the area under the strain gauge defection curve for the duodenum, right ventral colon, cecal body, or cecal apex. These results suggest that dopaminergic-1 receptors are present on the colonic vascudopaminergic-1 receptors exist on the visceral smooth muscle of the duodenum, right ventral colon, cecal body, or cecal apex of horses.

A porcine rotavirus isolate was titrated in neonatal colostrum-fed and colostrum-deprived pigs. The stock rotavirus suspension had a titer of 10 /ml and was in its fifteenth cell culture passage in MA-104 cells. Fourteen colostrum-fed pigs were orally inoculated with dilutions of the stock virus suspension ranging from undiluted to 10-5. These pigs did not develop notable clinical signs during the 7-day experimental trial and no pathologic changes were found in intestine, liver, lung, kidney, spleen, or brain. However, rotavirus was detected in feces of the colostrum-fed pigs, using virus isolation and electron microscopic techniques. Rotavirus was also isolated from lung, brain, or spleen of 4 of 12 of these pigs. Sixteen colostrum-deprived pigs were orally inoculated with dilutions of the stock virus suspension ranging from 10-1 to 10-8. Diarrhea developed in 10 of 12 pigs that were given up to the 10-6 dilution. Seven of these 12 pigs died because of the severity of diarrhea. Pigs that died of rotavirus-induced diarrhea had severe villus loss in the jejunum and ileum. Villi of the small intestine of colostrum-deprived pigs that survived the severe diarrhea were within normal limits at the end of the 7-day trial. The colostrum-deprived pigs that were inoculated with a dilution less than 10-6 and survived past 96 hours underwent seroconversion. Rotavirus was detected by virus isolation and electron microscopy in the feces of all colostrum-deprived pigs that survived beyond 18.5 hours after inoculation. Virus was isolated from lungs, brain, or spleen of 12 of 16 colostrum-deprived pigs.

Functional capabilities of morphologically mature (segmented) and immature granulocytes (neutrophils and eosinophils) from bone marrow from cows were studied and compared with similar activities of segmented granulocytes from blood. Phagocytosis of Escherichia coli and postphagocytic oxidative metabolic stimulation, measured by nitroblue tetrazolium (NBT) reduction, were evaluated simultaneously. Phagocytosis was observed readily in segmented neutrophils, neutrophilic bands, and metamyelocytes and rarely in myelocytes. Phagocytosis was not seen in promyelocytes and myeloblasts. Neutrophilic bands and metamyelocytes were phagocytically less active than were segmented neutrophils. Washed segmented bone marrow neutrophils possessed phagocytic activity similar to that of blood neutrophils, whereas the activity of unwashed segmented bone marrow neutrophils was markedly less than that of blood neutrophils. Reduction of NBT was observed only in blood segmented neutrophils and bone marrow segmented neutrophils; the magnitude of NBT reduction was significantly (P = less than 0.005) less in bone marrow neutrophils than in blood neutrophils. Eosinophils were phagocytically less competent than were neutrophils. The NBT reduction was observed only in eosinophils from blood, but not in eosinophils from bone marrow.