The sensitivity of an indirect enzyme-linked immunosorbent assay (ELISA) for bovine IgG serum antibody to Pasteurella haemolytica was compared with that of an indirect hemagglutination (IHA) test. Pasteurella haemolytica serotypes were grown in a chemically defined cell culture medium, and soluble antigens released into the growth medium were used in the ELISA and IHA test. An ELISA with serotype-1 antigen consistently detected antibody in sera that were positive by IHA test (correlation, 99%). Sera reacting with serotype-1 ELISA antigens also reacted with ELISA antigens prepared from other serotypes. Although ELISA titers determined by the 2 methods were approximately linear. Titer increases detected in paired serum samples by either test were similar. The ELISA was more sensitive than was the IHA in detecting colostral IgG antibody in serum of newborn calves. The ELISA uses a simple, stable antigen preparation and detects antibody to P haemolytica serotypes that commonly infect cattle.

Tissue specimens from muscle, liver, kidney, and injection sites were collected, and serum was obtained from 3 calves euthanatized on each of posttreatment days 5 and 22. Calves were treated with 6.7, 13.4, or 20 mg of oxytetracycline (OTC)/kg of body weight, IM, once daily for 3 days; these dosages are 1, 2, and 3 times the label dose, respectively. One control calf was euthanatized on each of posttreatment days 5 and 22. In treated male calves killed 2 days after the last injection, OTC residues were detected in all tissues and serum, using high-performance liquid chromatography. Tissues from all injection sites also were considered positive for antimicrobial residues, using swab test on premises (STOP), microbial inhibition test (MIT), and thin-layer chromatography-biautography (TLCB) test. Kidney tissues from a calf given 13.4 mg of OTC/kg and kidney and liver tissues from a calf given 20 mg of OTC/kg also were considered positive, using the MIT and TLCB. Results of the STOP only were considered positive for the liver and kidney of a calf given 20 mg of OTC/kg, but substitution of Saskatoon antibiotic medium-3 for the original medium (antibiotic medium-5) allowed the STOP to detect residues in these tissues from all treated calves. In female calves killed 19 days after the last injection, the STOP, MIT, and TLCB procedures revealed positive results for tissues from some injection sites, but revealed negative results for other tissues. High-performance liquid chromatographic analyses detected OTC in tissues from injection sites from all treated calves, in muscle and liver from a calf given 20 mg of OTC/kg, and in kidneys from calves given 13.4 or 20 mg of OTC/kg. The STOP, MIT, and TLCB procedures lacked the sensitivity of high-performance liquid chromatography for detection of OTC residues. However, the STOP procedure with Saskatoon antibiotic medium-3 did perform appropriately in that it failed to detect label doses in tissues from injection sites, but did detect 2 and 3 times extralabel doses after the recommended withdrawal time, and results were considered positive for all tissues after 2 days of withdrawal. A significant (P less than 0.05) loss of OTC was not observed after samples were stored at -20 C for 80 days. The highest concentration of OTC residues persisted in kidneys and tissues from injection sites.

A study was performed to assess the effect of xylazine HCl (0.1 mg/kg of body weight, IV) in heifers maintained at thermoneutrality (18 C, 42% humidity) or under heat stress (33 C, 63% humidity) conditions. Xylazine caused 50 and 70% decreases in serum insulin concentrations in the thermoneutral and heat-stressed heifers, respectively. Xylazine-induced hypoinsulinemia was associated with hyperglycemia. In the thermoneutral group, serum glucose concentrations increased from a basal concentration of 75 mg/dl to 150 mg/dl after 15 minutes. In the heat stress group, the serum glucose concentration increased from 65 mg/dl to 105 mg/dl. Hyperglycemia peaked at 2 hours and remained high for 6 hours after xylazine administration. Heat-stressed heifers took a longer time (107 minutes) to stand than did heifers under thermoneutral conditions (41 minutes). The time to regain sensation to pain was significantly prolonged in heat-stressed heifers. Xylazine had no effect on body temperature and respiration rate in heifers under the thermoneutral conditions, whereas it markedly induced hyperthermia and suppressed respiration rate in the heat-stressed heifers. Furthermore, the pulse rate was slightly decreased in thermoneutral heifers and was markedly decreased in the heat-stressed heifers.

Serologic recognition of common lipopolysaccharide core antigens has been related to enhanced resistance to gram-negative bacterial disease in several species. Class-specific titers (IgG, IgM) were determined by direct ELISA, using intact Escherichia coli (J5) as a plate antigen. Serum samples were obtained from 224 neonatal swine between the ages of 36 and 60 hours. The mean (+/- SEM) log(10) IgG titer against gram-negative core antigens was 1:1,713 +/- 0.4718 and the mean log(10) IgM titer was 1:202 +/- 0.5644. The IgG titer was directly related with litter size, birth weight, and serum total IgG concentration; IgM titer was directly related with dam parity and serum total IgG concentration.

Atracurium (0.4 mg/ml in isotonic NaCl solution) was administered by IV infusion to 7 healthy adult horses for 2 hours. Over the 2-hour period, a 95 to 99% reduction of train-of-four hoof-twitch response was maintained by 0.17 +/- 0.01 mg of atracurium/kg of body weight/h, for a total of 161 +/- 6 mg of atracurium (mean +/- SEM) for horses 1 to 4, 6, and 7. Horse 5, a mare in estrus, required 0.49 mg of atracurium/kg/h to maintain comparable relaxation. Hoof-twitch recovery time from 10 to 75% of baseline strength was 19.8 +/- 2.5 minutes for all horses. The 10 to 75% recovery time for horse 5 was 18 minutes. Recovery time from discontinuation of halothane until standing was 86 +/- 14 minutes (range, 55 to 165 minutes). Horse 5 had a 165-minute recovery. Regarding recovery from anesthesia, 3 recoveries were rated as excellent, 1 recovery good, and 2 recoveries as fair. Horse 5 laid quietly until she stood with 1 strong, smooth effort.

The effects of single IV administered doses of dexamethasone on response to the adrenocorticotropic hormone (ACTH) stimulation test (baseline plasma ACTH, pre-ACTH cortisol, and post-ACTH cortisol concentrations) performed 1, 2, and 3 days (experiment 1) or 3, 7, 10, and 14 days (experiment 2) after dexamethasone treatment were evaluated in healthy Beagels. In experiment 1, ACTH stimulation tests were carried out after administration of 0, 0.01, 0.1, 1, and 5 mg of dexamethasone/kg of body weight. Dosage greater than or equal to 0.1 mg of dexamethasone/kg decreased pre-ACTH plasma cortisol concentration on subsequent days whereas dosages greater than or equal to 1 mg/kg also decreased plasma ACTH concentration. Treatment with 1 or 5 mg of dexamethasone/kg suppressed (P less than 0.05) post-ACTH plasma cortisol concentration (on day 3 after 1 mg of dexamethasone/kg; on days 1, 2, and 3 after 5 mg of dexamethasone/kg). In experiment 2, IV administration of 1 mg of dexamethasone/kg was associated only with low (P less than 0.05) post-ACTH plasma cortisol concentration in dogs on day 3. In experiment 2, pre-ACTH plasma cortisol and ACTH concentrations in dogs on days 3, 7, 10, and 14 and post-ACTH plasma cortisol concentration on days 7, 10, and 14 were not affected by dexamethasone administration. The results suggest that, in dogs a single IV administration. The results suggest that, in dogs, a single IV administered dosage of greater than or equal to 0.1 mg of dexamethasone/kg can alter the results of the ACTH stimulation test for at least 3 days. The suppressive effect of dexamethasone is dose dependent and is not apparent 7 days after treatment with 1 mg of dexamethasone/kg. The magnitude of the decrease in post-ACTH plasma cortisol concentration did not exceed 35% (compared with control values), regardless of the dose of dexamethasone used.

Efficacy of oral administration of 20 mg of triclaben-dazole/kg of body weight was evaluated against 12-week Fascioloides magna infections in 12 sheep, each inoculated orally with 250 viable metacercariae. From 6 sheep treated with triclabendazole, 1 immature F magna was recovered, whereas 116 F magna with a mean length of 19 +/- 6.5 mm were recovered from 6 untreated control sheep. Efficacy of triclabendazole was 99.14%. Signs of toxicosis or illness were not observed in the sheep.

Wick catheters were used to measure intracompartmental pressures of the extensor carpi radialis muscles and long heads of the triceps brachii muscles of 7 horses maintained under halothane anesthesia during controlled ventilation. Horses were positioned in left lateral recumbency on a water bed for 4 hours. Using a crossover design, 6 of the 7 horses were subjected to normotensive and hypotensive anesthesia on separate occasions. Hypotension was achieved by increasing the inspired halothane concentration. Hematologic and biochemical measurements were determined at designated intervals before, during and for 7 days after each anesthetic episode. Under hypotensive conditions, 2 horses developed severe, generalized myositis and were euthanatized. Three of the 5 other horses developed swelling of the downside masseter muscle, 4 demonstrated mild extensor deficits of the downside forelimb, and 1 had a severe extensor deficit of the uppermost hind limb. As a group, the hypotensive horses had markedly increased activities of serum enzymes (creatine kinase, aspartate transaminase, and blood lactate) and abnormalities in calcium-phosphorus homeostasis. Lameness or enzyme alterations were not observed in normotensive horses. Altough the intracompartmental pressure values were markedly increased in the muscle bellies of the compressed limbs of all horses, there was a statistically significant difference in intracompartmental pressures between the downside or compressed muscle compartments of the extensor carpi radialis of hypotensive and normotensive horses. High concentrations of halothane may predispose anesthetized horses to postanesthetic myositis, even when protective padding is used. Intracompartmental muscle pressure, as measured by the wick catheter, may not be a reliable predictor of equine postanesthetic lameness.

We tested the hypothesis that lymphocytes from swine with susceptibility to malignant hyperthermia (MH) had increased sensitivity to the membrane-perturbing effects of halothane that increase cytoplasmic calcium. Cytoplasmic concentration of ionized calcium in lymphocytes isolated from blood was determined in the presence and absence of halothane for 10 Pietrain X Poland China swine that were susceptible to MH and 20 Yorkshire swine that were resistant to MH. Calcium was determined by dual-emission spectrofluorometry and by measuring the ratio of free to calcium-bound form of the fluorescent calcium dye Indo-1. Mean values for calcium concentrations in lymphocytes from MH-susceptible (MHS) swine were 80% less than control values (40.5 +/- 38.8 and 185.3 +/- 91.6 nmol/L; P less than 0.01). Untreated lymphocytes from MHS swine accumulated calcium at half the rate observed for controls. Exposure to 1 mmol/L halothane resulted in a 3-fold increase of free calcium concentration to 127.9 +/- 81.9 nmol/L in the lymphocytes of MHS swine, but had no significant effect on lymphocytes from control swine (225.0 +/- 91.4; P less than 0.01). Exposure to 2 mmol/L halothane resulted in a 6-fold increase of free calcium concentration to 255.9 +/- 91.4 nmol/L in lymphocytes from MHS swine and a 63% increase in lymphocytes from controls (303.8 +/- 116). The rate of halothane-induced increase in cytosolic calcium was 13 times greater in lymphocytes from MHS swine, compared with controls. These data indicated that the molecular defect that results in halothane-hypersensitivity and is characteristic of muscle of MHS swine also occurs in lymphocytes from MHS swine.

The relationships of various iron-related analytes were evaluated in 95 dogs. Liver and spleen nonheme iron content was determined coulometrically on acid-digested tissue specimens. Serum iron concentration and total iron-binding capacity also were measured coulometrically, whereas serum ferritin concentration was measured by ELISA. Significant (P less than 0.0002) correlation was found between serum ferritin concentration and nonheme iron stores. Significant correlation was not found between nonheme iron stores and serum iron concentration or total iron-binding capacity. Serum ferritin concentration should provide a convenient and relatively noninvasive means of estimating iron stores in dogs.