Blood samples were obtained from 20 bison (Bison bison) from a ranch in northern lower Michigan, as well as from 20 free-ranging bison of the same sex and similar age from the Badlands National Park in South Dakota. Hematologic and serum biochemical values were determined. The values were comparable in both groups, except for those for BUN, aspartate transaminase, and phosphorus, which were significantly (P < 0.001) higher in the ranched bison than in the free-ranging bison. These differences were attributed to nutritional effects. Impact of age on blood characteristics was assessed in the ranched bison only by comparing values from calves weighing less than 185 kg with those from bison weighing more than 185 kg. Calves had significantly (P < 0.001) higher values for phosphorus and RBC counts and lower total protein values than adults. Adult bison had higher eosinophil and neutrophil counts with lower numbers of lymphocytes, suggestive of a stress leukogram, whereas calves had the typical bovine neutrophil:lymphocyte ratio.

The directional (chemotactic) and random migration activities of neutrophils from cows and newborn and 2-week-old calves were determined by use of the chemotaxis-under-agarose assay. Blood samples were stored for 2, 24, or 48 hours and at 4 or 25 C before testing. During the assay, cells were incubated at 17, 27, or 37 C. The assay was found suitable for testing the directional and random migration activities of neutrophils from cattle. Directional migration of neutrophils was diminished (P < 0.05) when cells were incubated at 17 or 27 C, compared with data from incubation at 37 C. Random migration of neutrophils was unaffected by test incubation temperature. Significant (P < 0.05) differences were found between cows and calves regarding the percentage number and viability and the directional and random migration activities of neutrophils. Neutrophils from cows were adversely affected to a greater extent by prolonged sample storage times or low storage temperature than were neutrophils from calves. Results indicate that a sample storage time of up to 24 hours, a sample storage temperature of 25 C, and a test incubation temperature of 37 C provided optimal conditions for testing the migratory activities of neutrophils from cattle.

A study was conducted to develop valid estimates of lymphocyte count (LC; cells per microliter) of individual, clinically normal dairy cattle. Estimated weighted regression was used on repeated measures of individual LC to examine 6 models predicting LC as a function of age in cattle not infected with bovine leukemia virus. The generalized growth curve model of analysis of variance was used to estimate intercepts, slopes, and prediction limits for the models and to compare the LC-to-age relationship between Holstein and Guernsey breeds. The best-fitting model (P = 0.0001) with the narrowest prediction interval was LC = 4,414.4 - 84.6X, where X = (age - 48) if age less than or equal to 48 months, and X = 0 if age > 48 months, and 163.6 and 8.1 are the SE of the estimates, respectively. Upper one-sided 95%-predicted normal LC tended to be higher than estimates derived from traditional hematologic keys that use confidence limits of mean LC. Difference was not found in the LC-to-age relationship between the Holstein and Guernsey cattle (P = 0.67). Results of this study provided estimates of normal LC that are more specific in diagnosing lymphocytosis in individual cattle.

The effect of age and training status on the pharmacokinetics of flunixin meglumine was evaluated in 16 Thoroughbreds. Horses were assigned to 1 of 3 groups on the basis of age and training status: group A (n = 6), horses in active training and less than or equal 5 years old; group B (n = 5), horses out of training for a minimum of 6 weeks and less than or equal to 5 years old; and group C (n = 5), horses out of training for at least 2 years and greater than or equal to 9 years old. After administration of 500 mg of flunixin meglumine IV, multiple serum and urine samples were obtained over 24 hours and assayed for flunixin by high-performance liquid chromatography. Although the mean distribution rate constant and volume of distribution were similar for the 3 groups, mean total body clearance and elimination rate constant were significantly (P < 0.05) greater and half-life significantly (P < 0.01) less in groups A and B, compared with group C. Differences in pharmacokinetic values were not observed between the horses in groups A and B. In addition, the changes in clearance, elimination rate constant, and half-life of flunixin were found to significantly (P < 0.05) correlate with age. The results of this investigation indicated that age, but not training status, influences disposition of flunixin meglumine in Thoroughbreds.

The antiviral activity of recombinant DNA-derived bovine alpha 1-1 interferon on an established swine testicular cell line and primary testicular cell cultures derived from swine of various ages (2 days, 3 weeks, and 5 weeks) was determined. Bovine interferon induced a dose-dependent increase in 2-5A synthetase in testicular cells, regardless of the source of the cells. Furthermore, interferon inhibited replication of vesicular stomatitis virus to an equivalent extent in all testicular cell cultures. The results indicate that 2-5A synthetase is a reliable marker of interferon activity in swine testicular cell cultures and that the induction of 2-5A synthetase and antiviral effects of recombinant bovine interferon in primary testicular cell cultures are not dependent on the age of the donor animal.

Spinal-evoked potentials were recorded from 2 litters of clinically normal mixed-breed dogs between 35 and 300 days of age. Summated responses to tibial nerve stimulation were recorded from percutaneous needle electrodes placed at L7-S1, L4-5, T13-L1, C7-T1, and the cisterna cerebellomedullaris. The ulnar nerve was stimulated with recordings at C7-T1 and the cisterna cerebellomedullaris. Amplitudes did not change significantly with age, but were significantly (P < 0.05) different between various recording sites. On day 35, segmental and overall (L7-cisterna cerebellomedullaris) conduction velocities were less than half of the adult values. Spinal cord conduction velocities increased with age, reaching adult values at approximately 9 months of age. It was determined that quadratic equations best predicted the conduction velocities during maturation.

Reference blood chemical values were determined for 65 male and 61 female ostriches (Struthio camelus) 1 month to 72 months of age. Plasma values of glucose, total protein, triglycerides, cholesterol, uric acid, urea, bilirubin, creatinine, osmolality, electrolytes, and enzyme activity were determined. In general, differences in various values appeared mainly among age groups and less so between sexes. Older ostriches had lower plasma glucose values and enzyme activity than did younger ostriches. High plasma sodium and chloride concentrations in young ostriches correlated with high plasma osmolalities. Plasma calcium values were lower in laying ostriches. Uric acid concentrations were markedly higher than were urea concentrations in all ostriches.

Erythromycin (EM) pharmacokinetic variables were studied after IV administration of the drug (10 mg/kg of body weight) to 1-, 6-, and 15-day-old pigs. With advancing age, from 1 day to 15 days after birth, half-life of EM became shorter (3.0 hours to 1.4 hour), whereas apparent volume of distribution, total body clearance (CLt), and intrinsic clearance became greater: 0.68 to 3.28 (L/kg), 0.15 to 1.42 (L/h/kg), and 1.81 to 3.56 (L/h/kg), respectively. The percentage of plasma protein binding of EM decreased from 91 to 56%, correlating well with volume of distribution and CLt values. The altered binding percentage depended on plasma alpha1-acid glycoprotein (AGP) concentration, but not on albumin concentration. With advancing age, plasma AGP concentration was markedly decreased from approximately 6,000 microgram/ml to 700 microgram/ml. Despite a twofold increase in intrinsic clearance with advancing age, CLt increased ninefold, implying that the decreased protein binding contributed to the increase of CLt more preferentially than did maturational development of elimination capacity. Therefore, the altered protein binding of EM attributable to the change in plasma AGP concentration could be a major causal factor of the age-related pharmacokinetic variables of EM in pigs.

We defined methods for use of luminol-dependent chemiluminescence (LDCL) and superoxide anion (O2-) production as parameters of the oxidative metabolism of neutrophils isolated from 1.5- to 5-week-old neonatal calves. We determined how variations in blood sample handling, agonist preparation, individual variability, and age of calves influenced the LDCL and O2- responses to certain agonists, and defined concentrations of soluble and particulate agonists that maximally stimulated the oxidative metabolism of bovine neutrophils. Oxidative responses, particularly LDCL, were characterized by marked dayto-day variability, differed greatly within and between calves, were partially age-dependent, and were partially dependent on the individual agonist. Superoxide anion production had substantially less variability. We compared the in vitro oxidative (LDCL and O2-) responses of neutrophils isolated from neonatal calves stimulated by defined concentrations of the agonists-latex, phorbol myristate acetate, calcium ionophore, and opsonized zymosan-with responses to formylated oligopeptides and zymosan-activated serum, and to live, dead, live opsonized, and dead opsonized Pasteurella haemolytica organisms. Opsonization of particulates, pathogenic or nonpathogenic, enhanced the LDCL and O2- responses of stimulated neutrophils although P haemolytica was a less potent stimulant of oxidative functions than were nonbiological agonists. We conclude that the generation of reactive oxygen species by bovine neutrophils in response to P haemolytica is highly dependent on the presence of opsonins and is greatly enhanced in live vs killed bacteria. Futhermore, the in vitro generation of reactive oxygen species, including O2- by stimulated neutrophils, may be of biologic importance if similar events occur in vivo, and could have a major role in the pathogenesis of the acute lung injury associated with pneumonic pasteurellosis.

Heart and body weights were obtained from 230 Greyhounds during necropsy. Sex and age were recorded for each Greyhound. Twenty-nine racing and 21 nonracing Greyhounds among the 230 dogs were compared. Heart-to-body weight ratio was calculated. Statistical analysis was done to determine the effects of age, sex, and racing on heart and body weights and heart-to-body weight ratio. In adult Greyhounds, mean +/- SD body weight was 28.4 +/- 3.1 and 31.5 +/- 2.8 kg, heart weight was 355.6 +/- 52.8 and 381.4 + /-50.8 g, and heart-to-body weight ratio was 1.3 +/- 0.2 and 1.2 +/- 0.2% for females and males, respectively. Heart and body weights were significantly different between sex and age groups and among nonracing and racing males. However, heart-to-body weight ratio was not significantly different among age, sex, or racing groups.