A study was conducted to determine whether serum interleukin-6 (IL-6) activity increased in horses during experimentally induced endotoxemia and whether serum IL-6 activity correlated to changes in clinical or laboratory data. Six clinically normal horses were given endotoxin iv (30 ng/kg of body weight) in 0.9% NaCl solution over 1 hour. Five of these and 1 additional horse served as controls and were given only 0.9% NaCl solution. Venous blood, for determination of serum IL-6 activity and WBC count, was collected before and at various times through 8 hours after the start of endotoxin or NaCl infusion. Rectal temperature and heart and respiratory rates were recorded throughout the study period. Serum IL-6 activity was determined by bioassay of proliferation of the B13.29 clone B.9 hybridoma cell line. From 1.5 through 5 hours after start of the infusion, serum IL-6 activity was significantly (P < 0.05) increased in horses given endotoxin. Mean peak serum IL-6 activity was observed between 3 and 4 hours. In response to endotoxin infusion, horses became lethargic, tachycardic, and febrile. Leukopenia developed by 1 hour, followed by leukocytosis at 8 hours. Significant (P < 0.05) positive association and linear correlation were apparent between mean serum IL-6 activity and mean rectal temperature in the group of horses that were given endotoxin. Changes from baseline were not evident in any of the clinical or laboratory values in horses given only NaCl solution.

The effects of Actinobacillus (Haemophilus) pleuropneumoniae and its metabolites on the oxygenation activity of porcine pulmonary alveolar macrophages (PAM) were studied, using a chemiluminescence technique. Actinobacillus pleuropneumoniae strains of serotypes 2, 3, and 9 in a dose of 1, 10, and 100 colony-forming units/ macrophage first stimulated the oxygen radical production of PAM. After having reached a peak value, oxygenation activity decreased, finally resulting in total suppression of PAM. All these effects were neutralized by homologous convalescent pig sera that had been adsorbed onto inactivated A pleuropneumoniae strains. Moreover, cross-neutralization was shown between serotypes 2 and 3. Inactivated A pleuropneumoniae strains did not influence the oxidative activity of PAM. Undiluted and lower dilutions of sterile A pleuropneumoniae culture supernatants were toxic for PAM, whereas higher dilutions of the supernatants stimulated oxygen radical production of the macrophages. These effects were heat-sensitive and were neutralized by homologous convalescent pig sera. Cross-neutralization was shown between serotypes 2 and 3. These findings indicated that stimulation and inhibition of the oxygenation activity of PAM are attributable to heat-sensitive metabolites produced by A pleuropneumoniae.

The effect of dietary copper deficiency on T-cell mitogenic responsiveness and phenotypic profile of blood mononuclear cells (MNC) in weaned pigs was examined. Outbred, weaned pigs were fed a semipurified diet containing adequate (6.4 mg/kg of body weight) or deficient (0.8 mg(kg) amounts of Cu. Pigs fed the low Cu diet for 10 weeks had markedly decreased concentrations of Cu in liver and plasma, and hypertrophic hearts. In vitro reactivity of MNC from Cu-deficient pigs to phytohemagglutinin and concanavalin A was significantly suppressed. This functional impairment was not associated with a decrease in the percentages of T cells, CD4 or CD8 cell subsets, or B cells. Expression of SLA-DQ and SLA-DR class II major histocompatibility complex (MHC) antigens was increased by Cu deficiency, the former significantly. Unlike rodents, in which inadequate Cu nutriture induces functional T cell deficiency that is associated with a decrease in the CD4 T-cell subset, swine fed inadequate Cu diets for 10 weeks had no changes in MNC subsets yet clearly manifested functional impairment of T-cell responses.

Experimental evidence indicates that maintenance of urinary pH less than or equal to 6.4 is the single most effective means of preventing feline struvite crystalluria or urolithiasis of noninfectious causes. This may be accomplished by dietary acidification, but must be moderated to avoid potential adverse effects of excessive acidification, including bone demineralization, negative calcium balance, potassium depletion, and renal disease. Effects of chronic dietary phosphoric acid supplementation on acid-base balance and on mineral and bone metabolism were investigated in adult, domestic cats. One group of 6 cats was fed a basal, naturally acidifying diet without added acidifiers, and another group of 6 cats was fed 1.7% dietary phosphoric acid. Changes observed during 12 months of study included development of noncompensated metabolic acidosis, increased urinary calcium excretion, and lower but positive calcium balance in cats of both groups. Urinary pH decreased in cats of both groups, but was significantly (P < 0.05) and consistently maintained less than or equal to 6.4 in cats given dietary phosphoric acid. Urinary phosphorus excretion increased in cats of both groups, but was significantly (P < 0.05) greater in phosphoric acid-supplemented cats, leading to lower overall phosphorus balance as well. Potassium balance decreased in cats of both groups, but was only transiently negative in the phosphoric acid-supplemented cats midway through the study, and normalized at positive values thereafter. Plasma taurine concentration was not affected by dietary acidification, and remained well within the acceptable reference range for taurine metabolism. Double labeling of bone in vivo with fluorescent markers was followed by bone biopsy and histomorphometric measurement of several static and dynamic variables of bone formation. Overall indices of bone formation decreased in cats of both groups with age and confinement, but were not affected by dietary phosphoric acid supplementation. Dietary supplementation with phosphoric acid used as the principal inorganic P source to achieve moderate and stable degree of urinary acidification, did not appear over the course of 1 year, to have induced adverse effects on mineral, bone, or taurine balance in these adult domestic cats.

Cerebrospinal fluid and serum were obtained from 16 clinically normal adult cows (11 dairy, 5 beef). Sodium, potassium, magnesium, total protein, and albumin concentrations, osmolality, and lactate dehydrogenase and creatine kinase activities, were quantified in CSF and serum. Total and differential cell counting, protein electrophoresis, and IgG quantification were performed on CSF. Statistical analyses of these variables, including mean, SEM, range, and 95% confidence intervals, were performed. Effects of blood contamination were evaluated, and were found to be negligible for all measured constituents. Correction factors for CSF creatine kinase and lactate dehydrogenase activities accounting for cellular contamination were developed. Total nucleated cell count was similar to counts in CSF of other species, but higher than values in healthy people. Differential leukocyte count in CSF was similar to that reported in CSF of other domestic animals: mostly lymphocytes, fewer monocytoid cells, and scant neutrophils. Cerebrospinal fluid protein concentration was higher than concentration reported for dogs, goats, and people, but was similar to values reported for horses. Beef cows had higher CSF total protein concentration than did dairy cows; also, beef cows had higher CSF gamma-globulin concentration. The concentration of sodium in CSF was slightly higher than the value in serum, and potassium concentration was lower than the value in serum. In contrast to studies of human beings, CSF osmolality was generally less than serum osmolality in the cows studied. Reference values for CSF electrolyte concentrations and osmolality are useful for diagnosis of salt poisoning and for assessment of the effects of fluid therapy. Magnesium concentration was lower in CSF, compared with serum. Reference values may be useful for diagnosis of grass tetany. Glucose concentration in CSF was variable, compared with serum concentration; sometimes, it was similar, lower, or even higher than serum glucose concentration. This variation reflects a more complete equilibration of glucose between CSF and blood, owing to the lower and more stable blood glucose concentration in cows. Creatine kinase activity in CSF was markedly less than, and was not correlated with, serum creatine kinase activity. Cerebrospinal fluid lactate dehydrogenase activity was markedly lower than serum lactate dehydrogenase activity. Compared with lactate dehydrogenase, creatine kinase activity had a wider range in these healthy cows; therefore, the former enzyme has higher specificity and sensitivity for diagnosis of diseases affecting the CNS.

Four balance trials were conducted in 3 groups of 5 calves each at 0, 4, 8, and 14 weeks after initial inoculation with Ostertagia ostertagi. Group-1 calves were inoculated with 100,000 third-stage larvae (L3) of O. ostertagi/wk for 14 weeks. Group-2 calves were inoculated with 10,000 L3/wk for 14 weeks, and group-3 calves were not inoculated. Effects of infection on apparent digestibilities of dry matter and nitrogen, and balances of nitrogen and water were evaluated. Neither clinically apparent (group 1) nor subclinical (group 2) O. ostertagi infections had observable effects on the apparent digestibility of dry matter. Subclinical infection also had no significant effects on nitrogen digestibility or nitrogen and water balance. Clinically apparent infection, however, decreased the apparent digestibilities of nitrogen significantly (P < 0.05) at 4, 8, and 14 weeks after inoculation, and decreased nitrogen balance at 4 and 8 weeks after inoculation. Group-1 calves also had lower water intake, fecal-water excretion, and apparent water balance, but higher urinary water output at 4, 8, and 14 weeks after inoculation.

Affinity chromatography on heparin sepharose was used to identify 2 lipolytic enzymes in heparinized plasma from horses. One enzyme was typical of hepatic triglyceride lipase (HTGL), because it was resistant to inactivation by high concentrations of NaCl, and it did not require the addition of serum for activity. The other enzyme was identified as lipoprotein lipase (LPL), because of its inactivation at NaCl concentrations in excess of 0.2M, and its dependency on addition of serum as a source of apolipoprotein C-II activator. The enzymes were purified by 347- (HTGL) and 442- (LPL) fold, with yields of 54 and 58%, respectively. The partially purified enzymes were used to design incubation conditions that gave optimal activities for each enzyme in vitro. A selective assay was then developed for direct measurement of LPL and HTGL activities in heparinized plasma from horses. Analysis of HTGL took advantage of the almost complete inactivition of LPL when serum cofactor was excluded from the assay at the NaCl concentration that gave optimal HTGL activity. Prior incubation of heparinized plasma with sodium dodecyl sulfate to inhibit HTGL was necessary for measurement of LPL, because HTGL retained 67% of its activity at the NaCl concentration required for optimal LPL activity. Activity of each enzyme was measured in heparinized plasma from 12 Shetland ponies. The mean activity +/- SD for LPL was 3.22 +/- 1.04 micromoles of fatty acids/ml of heparinized plasma/h (micromoles of FA/ml/h). The mean activity for HTGL was 4.9 +/- 1.56 micromoles of FA/ml/h. The performance of the assay was assessed by replicate analysis of pools of each enzyme with high and low activities. The intra-assay coefficient of variation ranged between 3.4 and 8.7% (n = 10), and the interassay coefficient of variation ranged between 5.2 and 10.7% (n = 7) for the same pools analyzed over 7 weeks.

Zoometric measurements and bioelectrical impedance analysis were evaluated as methods of body composition determination in healthy cats. Zoometric and impedance measurements were taken on 22 anesthetized adult cats of various ages, genders, breeds, and body weights. The cats were then euthanatized. The bodies were processed through a tissue homogenizer and free-catch specimens were taken, freeze-dried, and analyzed for total body water, protein, fat, potassium, and ash content. Stepwise regression analysis was implemented to identify statistically significant relationships between the chemically determined dependent variables (total body water, protein, potassium, fat-free mass, fat mass, and percent body fat) and the zoometric measurements, with or without bioelectrical impedance analysis. Statistical analysis revealed high correlations between the dependent variables and the corresponding predicted values of those variables. Body weight alone was a poor predictor of body composition in these cats. On the basis of these findings, we suggest that zoometric and bioelectrical impedance measurements may serve as practical, noninvasive, simple, and accurate methods for estimating body composition in domestic cats.

Quantitative immunodiffusion in one dimension was performed in 6-mm Duran tubes containing a 1% Nobel agar solution and various dilutions of antisera. A series of dilutions of pure myoglobin in equine sera as well as plasma from horses with rhabdomyolysis were tested. Standard curves were prepared of the migration distance of the formed precipitate from the meniscus of the gel after 3, 6, 12, and 24 hours. The clearest line of precipitate was formed with a 1:20 dilution of antisera in agar. Standard curves were nonlinear and plasma myoglobin could be detected at 2 micrograms of myoglobin/ml or greater. The test was optimal, with an error of 5.6%, when read at 24 hours at approximately 25 C. Tubes with agar could be stored for 6 months at 4 C without affecting the accuracy of the test. The specificity of myoglobin for skeletal or cardiac muscle, and its rapid clearance from serum after muscle necrosis, make it ideally suited for evaluating acute muscle damage and for testing the susceptibility of horses for rhabdomyolysis following an exercise test.

The pharmacokinetics and bioavailability of enrofloxacin were determined after IV and IM administration of 5 mg/kg of body weight to 6 healthy adult rabbits. Using nonlinear least-squares regression methods, data obtained were best described by a 2-compartment open model. After IV administration, a rapid distribution phase was followed by a slower elimination phase, with a half-life of 131.5 +/- 17.6 minutes. The mean body clearance rate was 22.8 +/- 6.8 ml/min/kg, and the mean volume of distribution was 3.4 +/- 0.9 L/kg. This large volume of distribution and the K12/K21 ratio close to 1, indicated that enrofloxacin was widely distributed in the body, but not retained in tissues. After a brief lag period (6.2 +/- 2.86 min), IM absorption was rapid (4.1 +/- 1.3 min) and almost complete. The mean extent of IM absorption was 92 +/- 11%, and maximal plasma concentration of 3.04 +/- 0.34 micrograms/ml was detected approximately 10 minutes after administration.