Foals with the Ca blood group antigen on their RBC were given colostrum with anti-Ca antibodies (6 foals) or colostrum without anti-Ca antibodies (6 foals). The PVC were determined at birth and 2, 4, and 6 days after birth for the foals in each group. Significant differences were not observed for the PCV between the 2 groups, indicating that foals were not adversely affected by ingesting colostrum with the anti-Ca antibody. Standardbred mares without the Aa blood group antigen were evaluated to determine whether production of anti-Ca antibodies influenced production of anti-Aa antibodies. Of 266 mares without the Aa antigen, 3 of 61 (5%) mares without the Ca blood group antigen produced anti-Aa antibodies and 43 of 205 (21%) with the Ca blood group antigen produced anti-Aa antibodies. These 2 groups of mares were significantly (p = 0.006) different; Ca-negative mares were less likely to produce antibodies to Aa than were mares with the Ca blood group antigen. This observation was consistent with a hypothesis of antibody-mediated immunosuppression of immune response to the As blood group antigen by antibodies to the Ca blood group antigen, ie, when a mare is exposed to her foal's RBC and already has antibodies to the Ca blood group antigen on the foal's RBC, then she is less likely to initiate an immune response to the Aa blood group antigen also on the foal's RBC.

Cardiovascular effects and pulmonary gas exchange were compared during conventional mechanical ventilation (CMV) and interrupted high-frequency, positive-pressure ventilation (IHFPPV) in 6 anesthetized ponies in dorsal recumbency. When the peak airway pressure (Paw) was held constant at control values attained during CMV (18 to 20 cm of H2O), and the ventilator frequency of IHFPPV was varied over the range, 2.5 to 12.5 Hz, significant (P less than 0.05) changes from control values were observed only in the ratio of dead-space volume to tidal volume (VD/VT) and in the respiratory minute volume (VE). The mean +/- SEM) carbon dioxide excretion (VCO2) was 2.12 +/- 0.1 ml/kg/min during IHFPPV. Dead-space ventilation ranged from 40 to 73.7% of total ventilation and increased directly with increasing frequency. The VE also increased, from 89 ml/kg/min at a ventilatory frequency of 2.5 Hz to 145 ml/kg/min at a frequency of 12.5 Hz. Maintaining the frequency of IHFPPV constant at 12.5 Hz and increasing the Paw over the range of 5 to 30 cm of H2O caused significant (P less than 0.05) changes in arterial partial pressure of O2 (PaO2), VCO2, pulmonary shunt fraction (QS/QT), VE, arterial-alveolar differences in oxygen tension (AaDO2), VD/VT, and cardiac output, compared with CMV. The PaO2 and the VCO2 increased linearly with increasing Paw. With increasing Paw, VD/VT decreased directly with increasing Paw from 98 to 69.3%. Gas exchange at a Paw of 15 cm of H2O during IHFPPV was equivalent to conditions at Paw of 20 cm of H2O during CMV. At a higher Paw during IHFPPV, improvements over control values were observed in gas exchange.

The effect of glucocorticoids on early follicular growth in sows undergoing normal estrous cycles was evaluated by administration of dexamethasone during the middle of the luteal phase. Plasma specimens were obtained for measurement of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and estradiol-17 beta concentrations. Fifteen sows were used. Control sows (n = 5) were given physiologic saline solution twice daily from day 9 to day 14 of the estrous cycle. Sows of the second group (n = 5) were given dexamethasone (30 microgram/kg of body weight, IM) similarly, and those of the third group (n = 5) were given dexamethasone plus gonadotropin-releasing hormone (GnRH+ 50 microgram at 6-hour intervals, IV). Plasma specimens, obtained twice daily from day 8 through day 26, indicated that progesterone production and luteal regression were not inhibited by any of the 3 treatment regimens. Although preovulatory plasma estradiol concentration increased in control sows, such was not observed in the sows treated with dexamethasone or dexamethasone plus GnRH (P less than 0.01). Ovulation, with formation of corpora lutea, occurred in gilts given saline solution. Dexamethasone administration resulted in persistence of 19 to 41 follicles/ovary (2 to 4 mm in diameter), and dexamethasone-plus-GnRH treatment resulted in 6 to 18 follicles/ovary (5 to 6 mm in diameter). Plasma was obtained at 15-minute intervals for 12 hours to compare the effect of treatmenton hormone concentrations on day 12 of the estrous cycle with the values on day 8. Glucocorticoid administration had no significant effect on mean concentration, final concentration excluding those hormone concentrations that constituted part of a pulse (referred to as base line), number of pulses, pulse amplitude, and area under the pulse for either gonadotropin. Addition of GnRH to dexamethasone treatment significantly (P less than 0.01) increased all plasma LH values, but only base-line concentration of FSH. For estradiol, pulse amplitude and mean pulse area were increased (P less than 0.05), and although the frequency of pulses was not significantly altered, base-line concentration in glucocorticoid-treated sows was significantly reduced, compared with that of control sows. In sows treated with GnRH plus dexamethasone, the pulse frequency of estradiol was significantly (P less than 0.01) increased, but pulse area and amplitude were similar to those of sows given saline solution. Dexamethasone treatment was associated with an increase in mean and base-line concentrations of progesterone. The results suggest that high midcycle glucocorticoid concentrations (1) do not inhibit luteal function or regression, (2) have little influence on LH and FSH secretion during the middle of the luteal phase, (3) alter the pattern of estradiol secretion, (4) are associated with the persistence of small ovarian follicles, and (5) result in the development of fewer but larger follicular structures when GnRH is administered concurrently.

A significant (P less than 0.0001) positive correlation was demonstrated between left ventricular internal chamber dimension in diastole or systole and body weight, body surface area, cycle length, and the square root of cycle length. On the basis of adjusted coefficients of determination, multiple regression analysis, using body weight or body surface area and cycle length or the square root of cycle length, was superior to separate simple regression with these variables in accounting for variations in left ventricular internal chamber dimensions. Shortening fraction had a significant (P less than 0.0001) negative correlation and left ventricular free wall measurements had a significant (P less than 0.0001) positive correlation to body weight and body surface area. For these echocardiographic variables, correlation to the square root of cycle length was insignificant (P greater than 0.05), and a multiple regression model was not helpful in developing confidence intervals. Septal wall measurements were not correlated with body weight, body surface area, cycle length, or the square root of cycle length.

Twenty-four male domestic shorthair cats were used to evaluate the acute and chronic effects of a single, toxic but sublethal, orally administered dose of chlorpyrifos. A dose of 10 mg/kg of body weight did not induce clinical signs of toxicosis, but a dosage of 40 mg/kg induced clinical signs of toxicosis, and 1 of 12 cats died. Chlorpyrifos given at a dosage of 0.1 mg/kg to 2 cats reduced whole blood and plasma cholinesterase (Che) activities to values obtained after cats were given doses that induced clinical signs of toxicosis. Regeneration time for whole blood and plasma Che activities ranged from 7 to 28 days. Brain Che activity was considerably decreased in 1 cat that died 4.5 hours after dosing, but was normal in all others at 28 days after dosing. Other than decreased Che activity, significant changes were not seen in hematologic or serum biochemical values. Toxin-related lesions were not seen during macroscopic or microscopic examination.

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.

Effects of ventriculectomy and prosthetic laryngoplasty on upper airway flow mechanics and blood gas tensions in exercising horses with induced left laryngeal hemiplegia were assessed. Five adult horses were trained to stand, trot (4.5 m/s), and gallop (7.2 m/s) on a treadmill (6.38? incline). Inspiratory and expiratory airflows (VImax, VEmax, respectively) were measured using a 15.2-cm diameter pneumotachograph in a face mask. Inspiratory and expiratory transupper airway pressures (PuI, PuE respectively) were determined as pressure differences between barometric pressure and lateral tracheal pressure. Blood collected from exteriorized carotid arteries was analyzed for PaO2, PaCO2, pH, hemoglobin (Hb) content, and HCO3-values. Heart rate (HR) was determined with an HR monitor. Measurements were made with horses standing, trotting, and galloping before left recurrent laryngeal neurectomy (LRLN; base line), 14 days after LRLN, 30 days after ventriculectomy (44 days after LRLN), and 14 days after prosthetic laryngoplasty (58 days after LRLN). Before LRLN (base line), increasing treadmill speed for horses from standing to the trot and gallop progressively increased HR, respiratory frequency, VImax, VEmax, PuI, PuE, Hb, and PaCO2 values and decreased PaO2 pH, and HCO3- values; inspiratory and expiratory impedances were unchanged. After LRLN, inspiratory impedance and PuI were significantly (P < 0.05) increased in horses at the trot and gallop, and PaCO2 was significantly increased in horses at the gallop. The VImax and respiratory frequency were significantly (P < 0.05) decreased in horses at the gallop. Left recurrent laryngeal neurectomy had no effect on PuE VEmax, HR, PaO2, pH, Hb or expiratory impedance values. Ventriculectomy failed to improve upper airway flow mechanics induced by LRLN, whereas prosthetic laryngoplasty restored upper airway flow mechanics to base-line values.

Red blood cells from 6 Pygmy goats were determined to be significantly (P less than 0.01) more susceptible to osmotic lysis and mechanical stress than were RBC from 6 Toggenburg goats. Differences in RBC size and shape and adenosine 5'-triphosphate concentration between the 2 breeds were not significant. The differences observed in the in vitro tests may be attributable to differences in RBC membrane composition.

Experiments concerned with the immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia:Sindbis virus were conducted. The WR strain of the recombinant vaccinia:Sindbis virus was found to be infective for calves and mildly pathogenic, resulting in local tissue reaction. It was not transmissible to other calves. Also, it was found to be immunogenic when inoculated intradermally into calves, and antibody was produced against the parent vector virus (vaccinia) and the Sindbis antigen. Recombinant virus given IV to calves induced no detectable clinical signs, nor did the calves develop neutralizing antibodies. Furthermore, second-passage lesion material containing up to 10(7) tissue culture infective doses of the recombinant virus failed to induce development of lesions or illness in intradermally inoculated calves, and virus could not be recovered from the inoculation sites. In this series of experiments, this vaccinia recombinant given intradermally was immunogenic, mildly pathogenic at the local injection site only, and was not transmissible to contact animals, thus demonstrating the potential efficacy and safety of the WR strain of vaccinia virus when used as a live vector system in cattle.

During the 1986 lambing season, 33 Michigan sheep producers submitted all lambs that had died before weaning to the Michigan State University Diagnostic Laboratory for necropsy. Inductively coupled argon plasma emission spectroscopy was used to measure 22 elements in the liver of 888 of the lambs submitted. Mean concentrations of each element were established and compared with literature values of established deficient, normal, and toxic concentrations. Mean values in milligrams per kilogram of wet weight were as follows: A1, 3.843; As, less than 1; Ba, 0.176; Ca, 128.2; Cr, 0.778; Cu, 56.82; Fe, 491.6; Hg, less than 2; K, 2,150; Mg, 138.4; Mn, 2.776; Mo, 0.489; Na, 1,384; P, 2,583; Pb, 1,453; Sb, less than 1; Tl, less than 5; Zn, 68.31. In only 11 lambs did the liver contain As, B, Cd, Co, Hg, Sb, Se, or Tl in detectable concentrations.