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.

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.

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.

Serologic analyses and virus isolation studies were carried out to determine the role of bovid herpesvirus-4 (BHV-4) in infections in cattle, principally those of the reproductive tract. Serologic analyses were performed, using an indirect fluorescent antibody test on thoracic fluid specimens from aborted fetuses and on sera from 3 sources of adult cattle. Virus isolation was attempted from field cases of abortion, early embryo death, and postpartum vulvovaginitis/metritis, using uterine discharge and buffy coat preparations obtained from cows and tissues obtained from aborted fetuses. Of 420 fetal thoracic fluid specimens examined, 5 were positive for BHV-4 antibodies. Seventeen percent of adult cattle from 2 sources ie, clinically normal herds and abattoir cattle, were seropositive for BHV-4 antibodies. Cattle from a third source, 4 herds with high incidence of reproductive tract disorders, had a seroprevalence rate between 36 and 88%. Two isolates of BHV-4 were also obtained from this group. the overall incidence of BHV-4 antibodies in clinically normal cattle was higher than previously recognized, with relatively higher prevalence in herds having reproductive problems (chi-squared = 156.5, P less than 0.005). At least 10% of the BHV-4 antibody-positive sera did not have neutralizing antibody against bovine viral diarrhea virus and/or bovid herpesvirus-1, both important causes of bovine reproductive tract disorders.

Urinary protein loss was determined in 12 healthy cats. Voided urine was collected and protein quantitated by the Coomassie blue method. Mean protein loss for all cats was 12.65 mg/kg24 h (5.45 SD). Protein loss for male cats (n=6) was 16.62 mg/kg24 h (3.3 SD), which was significantly different (P less than 0.01) from 8.69 mg/kg/24 h (4.09 SD) for females (n = 6). A single urine protein-creatinine ratio correlated well with the total urinary protein loss in mg/kg/24 h. The correlation coefficient for the protein-creatinine ratio in voided urine (UPCV) vs 24-hour urinary protein (UP-24) loss was 0.968, and that for the protein-creatinine ratio in urine obtained by cystocentesis (UPCC) vs UP-24 was 0.945. The regression equations were UPCV = 0.02145 + 0.02338 x UP-24 (mg/kg), and UPCC = 0.02667 + 0.02133 x UP-24 (mg/kg). Using the mean value plus 3 SD of urinary protein loss from the healthy cats in this study, a healthy cat would be expected to have a urinary protein loss of less than 29 mg/kg/24 h. A protein-creatinine ratio from a single urine sample provides an accurate estimate of urinary protein loss in healthy cats.

Fluctuations of serum vitamin E (alpha-tocopherol), cholesterol, and total lipids were monitored in 12 horses at 3-hour intervals for 72 hours. Mean coefficients of variation were 12, 5, and 15%, respectively. Statistical analyses were used to conclude that instrumentation error was accountable for only a small portion of the vitamin E variation. Results indicated that a single serum sample assay is an unsatisfactory indicator of vitamin E status in horses. These data have clinical application in the evaluation of horses suspected to be affected with equine degenerative myeloencephalopathy. The large variance of serum total lipids and the lack of correlation of it with serum vitamin E over time preclude the use of vitamin E/serum total lipids ratio in assessing vitamin E status.

Nutritional alterations were evaluated in 9 horses before surgery and 3 weeks, 3 months, and 6 months (4 total trials) after sham operation (group 1; n = 3) or extensive large colon resection (group 2; n = 6). Feed and fecal analyses were performed to determine apparent digestion of dry matter, organic matter, crude protein, calcium, phosphorus, magnesium, potassium, manganese, zinc, copper, and iron, and true digestion of dry matter, organic matter, crude protein, total plant cell wall, hemicellulose, cellulose, and lignin. Additional fecal and metabolic variables included the percentage of fecal water (water in the feces), total fecal water, metabolic organic matter, metabolic crude protein, and metabolic nitrogen. A CBC and standard series of biochemical tests were performed. Large colon resection decreased (P less than 0.05) the true digestion of dietary crude protein and cellulose and apparent digestion of phosphorus, and it increased the fecal metabolic matter and water loss. Total fecal output increased 45% and total fecal water increased 55%. Phosphorus digestion was decreased (P less than 0.05) in group-2 horses, but effects of this were not detected on analysis of blood variables or on physical examination. Nevertheless, after extensive large colon resection, horses can regain body weight lost after surgery and have no overt physical changes when fed an alfalfa pellet diet that meets greater-than-maintenance requirements. Ad libitum water access is suggested, because these horses may have to consume 2 gal/day more than would normal horses.

Live Pasteurella haemolytica biotype A, serotype 1 isolates (n = 3) and Escherichia coli K-12, strain W3110, were reacted with bovine pulmonary lavage cell (PLC) suspensions. The comparative effects of the different bacteria on the functional and metabolic activity of alveolar macrophages (AMO) in the PLC suspensions were assessed simultaneously by use of 51Cr release, luminol-dependent chemiluminescence (LDCL), and AMO bactericidal assays. The bovine PLC reponsed differently to E coli, than to the 3 P haemolytica isolates in each of the 3 experimental test systems; however, responses to each of the P haemolytica isolates were not found to be significantly different. Unopsonized live P haemolytica cells adversely affected the functional and metabolic response of PLC, whereas there was no evidence of a cytotoxic (cytocidal) influence of E coli. A difference in 51Cr release for reaction mixtures containing E coli and P haemolytica was not detected at zero time; however, at each subsequent time, reaction mixtures phagocytically stimulated with P haemolytica had significantly increased amount of 51Cr release (P less than 0.05), compared with those mixtures containing E coli. Bovine AMO in the PLC suspensions were able to effectively kill E coli in vitro, but were unable to prevent survival and subsequent growth of P haemolytica. The luminol-dependent chemiluminescence profiles for reaction mixtures phagocytically stimulated with E coli provided evidence of sustained production of oxygen radicals with antimicrobial capabilities by bovine AMO in the PLC. Production of these highly reactive antimicrobial oxidants appeared initially in cultures containing P haemolytica but, subsequently, their production declined precipitously and ceased altogether.

Basal serum triiodothyronine (T3) and tetraiodothyronine (T4) concentrations have not been established for the llama (Lama glama). In addition, changes in T3 and T4 concentrations in response to thyroid-stimulating hormone (TSH) administration have not been determined, making clinical evaluation of problems referable to thyroid dysfunction difficult. In study 1, basal T3 and T4 concentrations were determined in serum samples collected from 132 clinically healthy llamas. The llamas were allotted to 3 groups: mature intact or neutered males (group I, n = 25), nonpregnant sexually mature females (group II, n = 21), and pregnant females (group III, n = 86). A mean concentration and a 95% confidence interval were computed for each group. An analysis of variance (ANOVA) indicated that a single confidence interval range (0.45 to 4.18, mean = 1.37 ng T3/ml) adequately defined the normal T3 concentrations for all groups. An ANOVA indicated that the T4 concentrations for the female populations (groups II and III) could be combined with a normal confidence interval range of 39 to 204 ng/ml (mean = 88 ng/ml), whereas a separate range (70 to 220 ng/ml, mean = 124 ng/ml) was determined for the male population. An ANOVA indicated that a single confidence interval range (0.0066 to 0.0321, mean = 0.0146) adequately defined the normal T3/T4 ratio for all groups. In study 2, T3 and T4 concentrations were evaluated in 10 healthy llamas immediately preceding and at 2, 4, 6, 8, and 24 hours after the IV administration of 3 IU of TSH/44 kg of body weight. The T3 and T4 concentrations were significantly higher by 2 hours after TSH administration in both groups. Peak T3 and T4 concentrations were observed at 4 and 8 hours, respectively, after TSH administration. When normalized with respect to serum T3 concentrations in samples collected immediately prior to TSH administration, the maximal increase in predicted T3 concentration was 4.06-fold (80% confidence interval range = 2.99- to 5.50-fold) at 4 hours after TSH administration. The maximal increase in predicted normalized T4 concentration was 2.32-fold (80% confidence interval range = 1.76- to 3.05-fold) at 8 hours after TSH administration. The TSH-stimulated increases in T3 and T4 concentrations at 4 hours were clearly distinguishable from values in samples obtained before TSH administration.