Hematologic and serum biochemical values were determined in 174 llamas of all age groups and both sexes from ranches in California and Nevada. Compared with hematologic values for horses and cattle, llama erythrocytes were more numerous (10.1 to 17.3 x 10(6)/microliter), but the PCV was lower (25 to 45%) because the smaller elliptical cells pack tighter. The mean corpuscular volume was half that of horses and cattle (22 to 29.5 fl). The mean corpuscular hemoglobin concentration was higher (38.9 to 46.2 g/dl), and the mean corpuscular hemoglobin slightly lower (9.6 to 12.6 pg). Most serum biochemical values were similar to those of cattle and horses, with the exception of triiodothyronine (48 to 468 ng/dl) and thyroxin (9.8 to 30 microgram/dl), which are up to 10 times higher than values for other domestic species.

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.

The arrhythmogenic dose of epinephrine (ADE) was determined in heartworm-infected and noninfected (control) dogs during thiamylal-induced and halothane-maintained anesthesia to assess the myocardial sensitization. The ADE in heartworm-infected dogs (2.42 +/- 0.26 micrograms/kg of body weight) was significantly lower than that for the controls (3.36 +/- 0.29 micrograms/kg). After 2 weeks, ADE was determined again in these dogs after atropine treatment. Atropine treatment lowered the ADE to 1.76 +/- 0.33 micrograms/kg and 1.77 +/- 0.19 micrograma/kg in heartworm-positive and negative dogs, respectively. After 2 weeks more the ADE was determined after administration of prazosin, an alpha 1-antagonist. Only 2 of 6 controls and 3 of 6 heartworm-positive dogs had arrhythmias after a threefold increase of ADE. The mean ADE in the dogs that responded to treatment were 7.4 micrograms/kg and 7.2 micrograms/kg for heart worm-positive and negative dogs, respectively. The findings of this study indicated that ADE in heartworm-infected dogs were lower than those in the control dogs, which makes the heartworm-infected dogs more vulnerable to arrhythmia during anesthesia. Atropine did not protect the dogs of either group. However, prazosin protected the dogs of both groups by significantly increasing the threshold of the ADE. On the basis of our findings, to reduce the risk of arrhythmia, we suggest that routine screening of dogs for heartworm infection be done before anesthetics are used.

A serologic survey was conducted to determine the prevalence of antibodies to alcelaphine herpesvirus-1 (AHV-1) in captive exotic ruminants within the United States. Forty-six percent of the members of the subfamily Alcelaphinae (wildebeest, topi, hartebeest) in the family Bovidae had virus-neutralizing antibody to AHV-1. Other subfamilies of Bovidae with high prevalence of virus-neutralizing antibodies to AHV-1 included Hippotraginae (oryx and addax) and Caprinae (sheep and goats), with prevalence of 45% and 29%, respectively. Herpesviruses that have been isolated from captive exotic ruminant species, including healthy animals and those with clinical malignant catarrhal fever at the Oklahoma City Zoo and the San Diego Zoo/Wild Animal Park, were analyzed by DNA restriction enzyme analysis and blot hybridization. Variation has been detected among the genomes of several malignant catarrhal fever virus isolates obtained from various exotic species of ruminants, using the DNA restriction enzymes BamHI and HindIII. The DNA of these virus isolates is distinct from that of bovine herpesviruses 1, 2, and 4, as demonstrated by restriction enzyme analysis and nucleic acid hybridization. On the basis of restriction enzyme analysis and nucleic acid hybridization data, the DNA from each of the putative alcelphine herpesvirus isolates examined, except for the topi virus isolate, had a high degree of DNA sequence similarity with the original AHV-1 isolate, WC-11, from a blue wildebeest.

Four healthy cats were given clindamycin orally in daily doses of 25 or 50 mg/kg of body weight for 6 weeks. Significant change in Factor-VII activity was not found, compared with pretreatment values. In 2 cats tested, toxin produced by Clostridium difficile was not detected in fecal samples obtained before treatment and at 6 weeks after treatment, suggesting that intestinal overgrowth by C difficile did not develop. Results of the study seemed to indicate that orally administered clindamycin does not measurably reduce synthesis of vitamin K-dependent clotting factors in healthy cats.

The pharmacokinetic determinants of doxycycline were calculated after a single IV administration of the drug (20 mg/kg of body weight) in 5 Angus calves with mature rumen function and 4 Holstein calves with immature rumen function. Doxycycline disposition was best described by means of an open 2-compartment model. Median elimination half-life was 14.17 hours (Angus) and 9.84 hours (Holstein). Mean (+/- SEM total body clearance was 1.07 (+/- 0.06) and 2.20 (+/- 0.21) ml/min/kg in Angus and Holstein calves, respectively. Mean extent of doxycycline binding to serum proteins was 92.3% (+/- 0.8%). The large steady-state volume of distribution (1.31 +/- 0.11 L/kg in Angus and 1.81 +/- 0.24 L/kg in Holstein calves), despite the small free fraction in serum, suggested a relatively unrestricted access of drug into the intracellular compartment and/or appreciable tissue binding. Results of mass spectrometric analysis of serum and urine from calves administered doxycycline IV revealed absence of biotransformation, because only parent drug could be detected. Thus, doxycycline may be a valuable antibiotic for use in food animals pending further studies on tissue residues, safety, and efficacy.

Eight healthy nonstressed calves were inoculated with Pasteurella haemolytica serotype 1, by instilling a broth culture into the middle nasal meatus of the left nostril. The inoculated left nostrils shed P haemolytica from the ventral nasal meatus at a steady rate for a mean of 7 days, whereas the uninoculated right nostrils of the same calves shed P haemolytica sporadically and in lower concentrations. The duration, frequency, and concentration of P haemolytica shed from the inoculated nostrils was significantly (P less than 0.05) greater than from the nostrils of other healthy calves that had been exposed by instilling the culture into the ventral nasal meatus of both nostrils in a previous study. The concentration of antibodies (IgG, IgA, and IgM) to P haemolytica increased significantly (P less than 0.05) in serum and nasal secretions after exposure. Four weeks after initial P haemolytica exposure, calves were exposed to infectious bovine rhinotracheitis virus and became clinically ill. Four calves were induced to shed P haemolytica from both nostrils by the virus infection; thus, they were harboring the bacterium and were susceptible to active recolonization. Four calves were not induced to shed P haemolytica. The apparent reason was not that they were resistant to active colonization, but that they were no longer harboring the bacterium, because they became active shedders after they were reinfected with P haemolytica.

Phagocytic and oxidative metabolic activities of bovine blood neutrophils were determined in the presence of glycolytic (NaF) and cytoskeletal (colchicine, cytochalasin B, and prostaglandin E1) inhibitors. Phagocytosis and postphagocytic oxidative metabolic activity, measured by nitroblue tetrazolium reduction, were determined using zymosan, Escherichia coli, Staphylococcus aureus, or Streptococcus agalactiae. Sodium fluoride (1.25 micromolar to 1.25 mM concentrations) did not significantly (P greater than 0.05) inhibit phagocytosis of S aureus and Str agalactiae, whereas phagocytosis of zymosan and E coli was significantly (P less than 0.05) inhibited only at 1.25 mM concentration. Colchicine at 1.25 nM to 1.25 micromolar conce ntrations significantly inhibited phagocytosis of zymosan and E coli, but not of S aureus and Str agalactiae. Cytochalasin B at 1.25 nM to 1.25 micromolar concentrations significantly inhibited phagocytosis of zymosan and all 3 bacteria, whereas prostaglandin E1 was noninhibitory at similar concentrations. Nitroblue tetrazolium reduction, in general, was not significantly affected by NaF and cytoskeletal inhibitors.

Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity of the circular and longitudinal muscle layers of the cecal body were measured in 7 conscious healthy horses during IV infusion of physiologic saline solution for 60 minutes (control), during a 60-minute IV infusion of dopamine (at dosages of 1, 2.5, and 5 microgram/kg/min), and for 60 minutes after IV infusion of dopamine. The mean values for lateral cecal arterial blood flow during IV infusion of dopamine at a dosage of either 1 or 2.5 microgram/kg/min were not significantly different from the mean values for lateral cecal arterial blood flow during IV infusion of saline solution. The mean values for lateral cecal arterial blood flow, however, were significantly greater during IV infusion of dopamine at a dosage of 5 microgram/kg/min than the mean values for lateral cecal arterial blood flow during IV infusion of saline solution. Intravenous infusion of dopamine at 1 and 2.5 microgram/kg/min did not significantly change the mean values for carotid arterial pressure. In contrast, the mean values for carotid arterial pressure were significantly less during IV infusion of dopamine at dosages of 2.5 and 5 microgram/kg/min than during infusion of saline solution. The mean values for heart rate were not significantly altered by infusion of dopamine at a dosage of either 1 or 2.5 microgram/kg/min, but infusion of dopamine at a dosage of 5 microgram/kg/min significantly increased heart rate. Intravenous infusion of dopamine at dosages of either 1 or 5 microgram/kg/min did not significantly change the mechanical activity of the circular muscle layer of the cecal body, as measured by the area under the strain gauge deflection curve. Conversely, the mechanical avtivity of the circular muscle layer of the cecal body was significantly reduced by IV infusion of dopamine at a dosage of 2.5 microgram/kg/min. This reduction of circular muscle mechanical activity by dopamine infusion was attributable to a significant decrease in the total duration of contractions. The mechanical activity of the longitudinal muscle layer was not significantly altered by infusion of dopamine at any dose. These results suggest that IV infusion of dopamine at a dosage of 5 microgram/kg/min increased lateral cecal arterial blood flow by either increasing cardiac output or dilating the lateral cecal artery, an effect most likely mediated by dopaminergic or beta-adrenergic receptors. In addition, dopamine had a biphasic effect on contractile activity of the equine cecum.

In 2 studies, the effects of dietary aflatoxin (AF) and deoxynivalenol (DON) were evaluated in growing crossbred barrows. The first study consisted of 4 treatments of 5 barrows each (6 weeks old) at dosages of 0 mg of DON and AF (control), 2.5 mg of DON/kg of feed, 0.75 mg of AF/kg of feed, and 2.5 mg of DON + 0.75 mg of AF/kg of feed. Pigs were fed their respective diets for 21 days. Treatment with DON caused decreases in weight gains, but no other treatment-related differences could be attributed to diets. In a second study, the experimental design consisted of 4 treatments of 5 barrows each (6 weeks old) at dosages of 0 mg of DON and AF (control), 3 mg of DON/kg of feed, 3 mg of AF/kg of feed, and 3 mg of DON + 3 mg of AF/kg of feed fed ad libitum for 28 days. The pigs were observed twice daily for clinical signs, hematologic and serum biochemical measurements were made weekly, and body weights and feed consumption were determined weekly. Body weight gains were significantly depressed by the AF and the AF + DON treatments for days 7, 14, 21, and 28. Body weights and body weight gains were only slightly reduced in the DON treatment. Changes in serum enzymatic activities of alkaline phosphatase, aspartate transaminase, creatine kinase, and gamma-glutamyl transferase were noticed in pigs given treatments with AF alone and those given AF + DON. Total iron binding capacity and serum total protein, albumin, cholesterol, BUN, and glucose concentrations were decreased, whereas prothrombin and activated thromboplastin times were increased by AF and AF + DON treatments. Lesions in the AF-treated groups were compatible with a diagnosis of aflatoxicosis. The control and DON-treated pigs had no abnormalities. These data provide a description of the effects of dietary AF and DON, singly and in combination, in growing barrows.