Muscle potentials evoked by stimulation of the sciatic nerve were evaluated in 4- and 15-week-old chickens. Each bird was anesthetized and slowly cooled externally from a normal body temperature of 40 C to 28 C, and motor nerve conduction velocities were measured at various intervals during cooling. Motor nerve conduction velocity decreased linearly with decreasing limb temperature in both groups. The rate of change in motor nerve conduction velocity per degree in 2 groups (2.13 m/s/C vs 1.84 m/s/C) fell just short of a statistically significant difference (P = 0.0508), indicating that an age-related effect on temperature-associated variation in motor nerve conduction velocity may be present.

A monoclonal antibody (MAB) against equine tumor necrosis factor-alpha (Eq TNF) was used to investigate the role of TNF in cytokine, eicosanoid, and metabolic responses of Miniature Horses given endotoxin. Plasma concentrations of interleukin 6 (IL-6), lactate, thromboxane A2 metabolite, and prostacyclin metabolite (6-keto-PGF(1 alpha)) were measured in 10 Miniature Horses given 0.25 micrograms of lipopolysaccharide (LPS; Escherichia coli O55:B5)/kg of body weight. Five horses were given Eq TNF MAB and 5 were given isotype-matched MAB as control. All horses were given 1.86 mg of antibody/kg by IV infusion, 5 minutes before LPS was given IV. Blood samples were taken 20 minutes before and at multiple intervals for 24 hours after LPS was given. Interleukin 6 bioactivity in plasma was measured, using IL-6-dependent cell line (B9). Eicosanoid activities were assessed by enzyme immunoassay, and plasma lactate concentration was determined enzymatically. Data were analyzed by ANOVA and Tukey's honest significant difference test for significant (P < 0.05) effect of treatment. Horses given Eq TNF MAB had significantly (P < 0.050) lower peak mean +/- SEM IL-6 (59 +/- 29 U/ml), lactate (16 +/- 2.00 mg/dl), and 6-keto-PGF(1 alpha) (254 +/- 79 pg/ml) values then did horses given control MAB (880 +/- 375 U/ml for IL-6; 26 +/- 0.04 mg/dl for lactate; and 985 +/- 290 pg/ml for 6-keto-PGF(1 alpha)). There was no effect of anti-TNF treatment on LPS-induced thromboxane A2 metabolite production. Tumor necrosis factor mediated IL-6, lactate, and prostacyclin responses, without affecting thromboxane production in horses given LPS.

Release of enzymes from cytoplasmic granules has been postulated to have a major role in neutrophil-mediated tissue injury. Secretion or release of primary granules, specific granules, and cytosolic enzymes by bovine neutrophils was examined by quantifying the release of beta-glucuronidase, B12-binding protein, and lactate dehydrogenase, respectively, in response to predetermined amounts of phorbol myristate acetate, calcium ionophore, and opsonized zymosan. These responses were compared with the enzyme release induced by exposure to live or dead, unopsonized or opsonized Pasteurella haemolytica. The greatest release of beta-glucuronidase, B12-binding protein, and lactate dehydrogenase was observed in neutrophils exposed to live organisms partially because of neutrophil lysis. Bovine neutrophils respond markedly to particulate agonists, live or dead, pathogenic or nonpathogenic, by a selective release of specific granules, an effect enhanced by opsonization. Particulate agonists induce minimal primary granule release other than that induced by cell death. Because bovine neutrophils contain quantitatively high numbers of specific granules, the high rate of secretion/ release in response to P haemolytica organisms could have a major role in the tissue responses that characterize the lesions of pneumonic pasteurellosis.

Levator ani and coccygeus muscle estrogen and androgen receptors were measured in 6, healthy, greater than or equal to 5-year-old, noncastrated, male Beagles (controls) and in 24 dogs with perineal hernia. Estrogen and androgen receptor analyses were performed on levator ani and coccygeus muscle specimens obtained from control dogs at the time of castration; contralateral levator ani and coccygeus muscle specimens were assayed 2 months after castration. During herniorrhaphy of dogs with perineal hernia, levator ani (noncastrated, n = 12; castrated, n = 7) and/or coccygeus (noncastrated, n = 5; castrated, n = 4) muscle biopsy specimens were obtained for estrogen and androgen receptor analyses. For estrogen and androgen receptor assays, each muscle biopsy specimen was homogenized in Tris-EDTA-glycerol buffer, and centrifuged at 30,000 X g; extracts were used for binding with ligands: [3H]methyltrienolone (3H-R1881) for androgen receptors, and [3H]estradiol-17 beta for estrogen receptors. Extracts were incubated overnight at 0 to 4 C. Nonspecific binding was estimated, using 100-fold concentration of cold ligands. Bound and free hormones were separated, using hydroxylapatite batch assay. Receptor numbers for each tissue were calculated as femtomoles (fmol) per milligram of protein. Quantified data were compared between precastration and postcastration controls, using a paired t-test. One-way ANOVA and Bonferroni post-hoc test were used to compare values for precastration controls, postcastration controls, castrated dogs with perineal hernia, and noncastrated dogs with perineal hernia. Significance was set at P < 0.05. Estrogen receptors were not detected. Androgen receptors were characterized by Scatchard analysis (dissociation constant = 3.16 to 6.6 nM R1881, receptor number = 23 to 175 fmol/mg of protein). Post castration controls had significantly higher numbers of androgen receptors in levator ani and coccygeus muscles than did precastration controls. Dogs with perineal hernia (castrated and noncastrated) had lower numbers of androgen receptors than did either control group. The paucity of androgen receptors in pelvic diaphragm muscles of dogs with perineal hernia, compared with controls, suggests that decreases in quantity of androgen receptors contribute to the etiopathogenesis of perineal hernia in dogs.

Restriction endonuclease patterns of genomic fragments separated by use of pulsed-field gel electrophoresis were used to differentiate Brucella abortus strain RB51, a rifampin-resistant mutant of the standard virulent strain 2308, from other brucellae. Results were compared with results obtained by use of standard methods for characterizing brucellae. Electrophoretic patterns of the ATCC type strains allowed identification of the strains to the level of species. Genomic profiles of B abortus biovars 1, 2, and 4 were similar, as were those of biovars 5, 6, and 9. The profile of biovar 3 was similar to that of biovars 5, 6, and 9, except for a missing band at 93 kb and additional bands at 65 and 67 kb. A different fingerprint was detected in B abortus strain RB51, using the pulsed-field gel electrophoresis patterns of genomic DNA digested with restrictive endonuclease Xba I. The profile of B abortus strain RB51 contained a band at 104 kb, as opposed to a 109-kb fragment within profiles of B abortus isolates from naturally infected cattle, bison, and elk. Despite known biochemical and biological differences between RB51 and its parent strain (2308), restriction endonuclease analysis results were similar.

Blood flow to the semitendinosus muscle was studied in 12 dogs after ligation of either the proximal or distal vascular pedicle and elevation of the muscle from its normal position. Using 25-micrometer-diameter radioactive microspheres, flow was measured at rest, h and 18 days after muscle elevation and pedicle ligation. Mean blood flow in the proximal region of the muscle 6 and 18 days after ligation of the caudal gluteal (proximal) pedicle was not significantly different from mean blood flow calculated in the middle and distal regions of the muscle. There was also no significant difference in mean blood flow among proximal, middle, and distal regions of the muscle, 6 and 18 days after ligation of the distal caudal femoral (distal) pedicle. There was significantly (P < 0.05) increased blood flow between group-A (ligation of caudal gluteal artery) and group-C (operated-control) muscles, 6 and 18 days after surgery. There was no loss of muscle fiber striations or nuclei, or presence of fibrous tissue that might have indicated ischemic necrosis in any of the experimental groups. These results indicate that the entire semitendinosus muscle can be sustained by the blood flow from either of its 2 vascular pedicles, which reinforces its potential as a muscle flap.

Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors' knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.

Because caffeine is metabolized by the hepatic P-450 cytochrome oxidase system, clearance of caffeine is an excellent quantitative test of hepatic function in human beings. It is currently used in much the same way that creatinine clearance is used to assess renal function. Caffeine clearance was measured in lactating dairy cows initially to determine the suitability of caffeine clearance as an indicator of hepatic function in cattle. Pharmacokinetic variables of caffeine were studied in 6 adult lactating dairy cows after IV administration of a single dose of caffeine sodium benzoate (2 mg of caffeine/kg of body weight). Caffeine concentration was analyzed by use of an automated enzyme immunoassay. The lower limit of detection of the assay for caffeine in serum was 0.079 micrograms/ml. Serum caffeine concentration-time curves best fit an open two-compartment pharmacokinetic model. Harmonic mean elimination half-life was 3.8 (range, 2.6 to 6.9) hours, and total clearance was 0.118 (range, 0.090 to 0.197) L/kg/h. Milk caffeine concentration was similar to serum concentration 1.5 to 24 hours after caffeine administration. Adverse effects were not observed in cows given caffeine.

Immunoglobulin E is produced in response to parasitic nematodes that undergo blood and tissue migrations. Results of our previous studies indicated that IgE and IgG respond to Dirofilaria immitis in experimentally infected dogs. To determine the association between treatment with the larvicide, diethylcarbamazine (DEC), and antibody responses and to examine the potential influence of infection with a nonfilarid intestinal nematode on isotype-specific immune responses, we monitored, by use of isotype-specific ELISA, separate IgE and IgG responses against D immitis in 4 groups (A-D) of 8 dogs experimentally coinfected with D immitis and Ancylostoma caninum. All dogs were monitored from 2 weeks before inoculation with D immitis, through postinoculation (PI) week 20. Group-B dogs received a daily regimen of 6.6 mg of DEC/kg of body weight. Group-C dogs received 4.95 mg of oxibendazole/kg daily. Group-D dogs received DEC and oxibendazole, equivalent to the daily doses given to dogs of groups B and C. All dogs given oxibendazole had no A caninum at necropsy. Of the groups receiving DEC, 3 group-B dogs each had 1 to 2 D immitis at necropsy. When results of chronologic IgE determination for all groups were statistically compared, only groups B and C had significant (P = 0.0148 and P << 0.00005, respectively) increases in IgE values. Group-C dogs had the highest IgE values from PI week 10 until the end of the study, whereas IgG values were statistically identical to those of group-A dogs. Group-B dogs given only DEC and having the least number of D immitis of all groups, had IgE values that peaked at PI week 6; values were significantly (P = 0.0002) higher than those for all other groups. In Group-B dogs, IgG values increased significantly (P << 0.00005) only at PI week 20 and were significantly (P << 0.00005) decreased after PI week 6, compared with values for all other groups. Group D containing 6 dogs infected with 1 to 18 D immitis found at necropsy had IgE values between those of group-B dogs and those of non-DEC-treated groups at PI week 6. There was no difference in IgG values between 3 groups at PI week 6, and IgE values were found to be a better correlator than were IgG values to the number of D immitis larvae killed in the tissues during this period. All differences in IgG and IgE values not only correlated with treatment status and number of D immitis adults found at necropsy, but also with the developmental stage of D immitis commonly present in the groups at each time point and the number of adult D immitis found at necropsy.

The percentage of limb contact time spent in braking and propulsion was determined for the forelimbs and hind limbs of Greyhounds at 2 walk speeds and 3 trot speeds. Limb contact times decreased significantly (P < 0.05) as velocity increased between each velocity range. At a slow walk (0.92 to 1.03 m/s), braking and propulsion were 56.1 and 43.6% of contact time in the forelimbs and 41.6 and 58.1% of contact time in the hind limbs, respectively. At a fast walk (1.06 to 1.17 m/s), braking and propulsion were 56.7 and 43.5% of contact time in the forelimbs and 41.5 and 58.4% of contact time in the hind limbs, respectively. There was no significant difference in the percentage of contact time that the forelimbs and hind limbs spent in braking and propulsion between the 2 walk velocities. At the slow trot (1.5 to 1.8 m/s), braking and propulsion were 56.8 and 43% of contact time in the forelimbs and 30.1 and 67.6% of contact time in the hind limbs, respectively. At the medium trot (2.1 to 2.4 m/s), braking and propulsion were 55.9 and 43.5% of contact time in the forelimbs and 33.8 and 63.2% of contact time in the hind limbs, respectively. At the fast trot (2.7 to 3.0 m/s), braking and propulsion were 57.2 and 43% of contact time in the forelimbs and 37.5 and 61.1% of contact time in the hind limbs, respectively. Braking percentage increased and propulsive percentage decreased significantly (P < 0.05) in the hind limbs between the slow and fast trot speeds. There was no significant difference in the percentage of forelimb contact time spent in braking and propulsion between the walk and the trot gaits or among the 3 trot velocities.