Stimulation of alpha 2 adrenergic receptors inhibits colonic motility and may constrict some peripheral vascular beds. Endotoxemia elicits release of sympathetic neurotransmitters and increases sympathetic nerve activity, which may result in stimulation of alpha 2 adrenergic receptors. The objective of this study was to determine whether blockade of alpha 2 adrenergic receptors would restore cecal motility and blood flow during endotoxemia in horses. Strain-gauge force transducers and ultrasonic flow probes were used to measure cecal and colonic mechanical activity and lateral cecal arterial blood flow. Intravenous infusion of endotoxin (cumulative dose of 0.03 mg/kg) significantly decreased cecal and right ventral colon contractile activity and lateral cecal arterial blood flow. Slow IV infusion of yohimbine (cumulative dose of 75 micrograms/kg) significantly attenuated those effects of endotoxin. On the basis of our findings, we concluded that endotoxemia causes cecal and proximal colonic ileus and cecal hypoperfusion via a mechanism that involves alpha 2 adrenergic receptors.

A study was done to determine whether radiographic-distraction measurement of coxofemoral joint (hip) laxity at 4 and 8 months of age can serve as a predictor of hip dysplasia in older Labrador Retrievers. The method of Smith, Biery, and Gregor was used for radiologic examination of hips and for evaluation of radiographs. Mean (+/- SEM) distraction laxity (ie, distraction index) for 10 adult disease-free dogs was 0.29 +/- 0.05, whereas a group of 8 dogs with dysplastic hips had mean distraction index of 0.60 +/- 0.10 (P < 0.05). Mean distraction index at 4 months of age for 11 pups of 4 litters from matings between dogs with normal hips was 0.39 +/- 0.07, and was 0.54 +/- 0.04 for 31 pups of 7 litters from matings between dogs with hip dysplasia. The distraction index and, thus, joint laxity at that age was significantly (P = 0.0351) different for the 2 groups. The distraction index at 4 months correlated positively with the distraction index at a later age at necropsy (r = 0.43; P = 0.0289). Distraction index < 0.4 at 4 months of age predicted normal hips in 88% of cases and distraction index > 0.4 predicted hip dysplasia in 57% of the dogs. Logistic regression modeling indicated that the odds of a hip being normal decreased with increasing distraction index, and thus, with increasing joint laxity. The logistic regression models provided a reasonable mathematical description of the data. Based on the logistic model of the data, distraction indexes between 0.4 and 0.7 at either 4 or 8 months of age were not associated strongly enough with evidence of disease to be clinically reliable in predicting, on an individual basis, the outcome for dysplastic hip conformation when dogs were older. Index > 0.7 was associated with high probability for developing dysplastic joints and distraction index < 0.4 predicted normal hips with high probability.

The cellular response induced in the host animal by endotoxin contributes greatly to the morbidity and mortality of gram-negative infections in bovine neonates. We characterized the temporal sequence, magnitude, and duration of mediator release during endotoxemia and evaluated the effect of endotoxin dose and method of administration. Thromboxane B2 (TxB2), and 6-keto prostaglandin F(1 alpha) (PGF 1 alpha) concentrations and tumor necrosis factor (TNF), and interleukin-1 beta (IL-1 beta) activities were measured in 34 newborn calves given Escherichia coli endotoxin at dosage of 0 (saline solution), 0.2, 2.0, or 20 micrograms/kg of body weight, either by IV administered bolus or infusion over 50 minutes. In all groups and at each lipopolysaccharide dosage, mediators peaked in this sequence; TxB2 and TNF, followed by PGF 1 alpha, then IL-1 beta. Neither dose nor method of administration affected the sequence of mediator release. The magnitude of eicosanoid response to endotoxin was dose-dependent. During induced endotoxemia, duration and/or magnitude of mediator response reflected the dose of endotoxin administered, indicating that the outcome of endotoxemia, in neonatal calves, may be related to the amount of circulating endotoxin.

Combined blood pool and delayed images produced by use of 99mTc-methylene diphosphonate (99mTcMDP) were evaluated as an objective measurement of the response of equine joints with osteochondral defects to postoperative exercise and intra-articularly administered polysulfated glycosaminoglycan (PSGAG). Osteochondral defects (approx 2.4 X 0.9 cm) were induced arthroscopically in the dorsodistal radial carpal bones of 18 ponies. These ponies were randomized (while balancing for age [range 2 to 15; median, 5.0; mean, 5.1 years]) to 2 treatment groups. Nine ponies were assigned to be exercised, and 9 were stall-rested. Six ponies in each group were administered PSGAG (250 mg) in 1 joint (medicated) and lactated Ringer's solution (LRS) in the contralateral joint. The 3 remaining ponies in each group were administered LRS in both joints (nonmedicated). Medication was given at surgery, then weekly for 4 weeks. The exercise protocol (begun at postoperative day 6 and conducted twice daily) started with 30 minutes walking (approx 0.7 m/s), and, by postoperative month 3, the ponies were being walked for 15 minutes and trotted (approx 1.6 m/s) for 25 minutes. Simultaneous dorsal images of both carpi were made 2 to 3 minutes after IV administration of 99mTcMDP (blood pool image) and 90 to 120 minutes later (delayed image). Scintimetry, in counts per minute per pixel per millicurie, was done before, and at 1, 2, 4, 8, 10, 13, and 17 weeks after surgery, prior to euthanasia. Radionuclide uptake on blood pool images decreased faster than that on delayed images, in which uptake remained high for 17 weeks. This indicated that bone was metabolically active for at least 17 weeks after surgery. Exercise significantly (P < 0.05) decreased uptake on the blood pool images of medicated joints up to 1 month after surgery. Thus, exercise (in the presence of PSGAG) probably had a transient, beneficial effect on soft tissues of the joint. Exercise, without PSGAG, promoted increased bone remodeling, because the highest uptake on delayed images was observed in exercised, nonmedicated ponies up to 3 months after surgery. This was consistent with development of osteoarthritis in these ponies. Medication alone stimulated bone remodeling, and data indicated that an identical effect may take place in contralateral LRS-injected joints, because of systemic circulation of the drug. However, the combination of exercise and medication appeared to moderate the independent effects of each. The combination of exercise and medication in individual joints resulted in notably (P < 0.05) decreased bone remodeling. Medication caused a decrease in bone remodeling in exercised ponies, indicating a protective effect against development of osteoarthritis.

Brain stem auditory evoked potential (BAEP) testing with air-conducted click stimuli can be used to diagnose sensorineural deafness in dogs if conductive deafness can be ruled out. Detection of conductive deafness can be performed by recording BAEP elicited by a vibratory stimulus transducer placed against the skull. Air- and bone-conducted BAEP were compared in dogs, varying bone stimulator placement, click polarity, and stimulus intensity. Optimal bone stimulator placement was determined to be over the mastoid process, followed by the mandible and the zygomatic arch. Condensation polarity clicks gave responses preferable to those elicited by rarefaction or alternating polarity. Bone-conducted BAEP peak latencies were significantly longer than air-conducted latencies after correction of the latencies for the air conduction time accompanying air-conducted stimuli. Significant differences between stimulus modalities were not seen for BAEP peak amplitudes or interpeak latencies. Latency-intensity and amplitude-intensity regressions had similar effects for both modalities: latencies decreased and amplitudes increased as stimulus intensity increased.

Paired CSF and serum samples were obtained from 109 rhesus macaques aged 1 to 18 years. The CSF and serum IgG and albumin concentrations were determined, using radial immunodiffusion; CSF total protein and glucose were determined, using colorimetric methods; and Na, K, and Cl concentrations were determined, using ion-specific electrodes. The CSF protein values were lower than those reported for nonhuman primates, and this finding was confirmed by results of agar gel electrophoresis. Animal age and sex had no significant effects on CSF composition, but serum IgG concentration increased with age. Concentrations of total protein, albumin, and IgG were greater, and concentrations of glucose and potassium were lower in CSF obtained from the lumbar rather than the cisternal site. Composition of CSF was not significantly altered by contamination with blood at values up to 10,000 RBC/microliter. The CSF albumin quotient, IgG quotient, and IgG index were determined and differed markedly from values reported for human beings, indicating that the properties and specificity of the blood-brain barrier may be species-specific.

Pili have been implicated as virulence factors that result in increased infectivity of Moraxella bovis, the causative agent of infectious bovine keratoconjunctivitis (IBK). Healthy calves' eyes were inoculated with I- or Q-piliate or nonpiliate M bovis Epp63 to compare the pathogenicity of these isogenic variants. Pathogenicity was determined by the rate of persistent M bovis infection and the prevalence of clinical IBK. Inoculation with M bovis expressing the Q pili resulted in the highest frequency of infection and IBK whereas I-piliate M bovis elicited a lower rate and nonpiliate M bovis did not result in infection. In vivo pilin gene rearrangement and pilin-type switching were evaluated by DNA hybridization and immunoblot. Gene rearrangement and type switching varied dependently, and were observed only in eyes inoculated with Q-piliate M bovis. This study suggests that Q pili are specific for colonization of bovine corneal epithelium, whereas I pili enable maintenance of an established infection.

An antigen-capture ELISA was used to detect bluetongue virus (BTV) from blood of infected sheep. A rabbit-origin capture antibody and a mouse-origin detection antibody combined with biotin-avidin amplification were used for the assay. The antigen-capture ELISA could not detect virus directly from the blood of infected sheep because of low virus titer. To enhance detection, virus from infected blood was amplified in cell culture. Virus could then be detected from cell culture supernatant fluids, using the ELISA. This amplification step increased the sensitivity of the assay comparable to that of assays performed in cell culture measuring cytopathic effects. The ELISA procedure was specific for BTV and did not mistakenly identify the antigenically related epizootic hemorrhagic disease virus. The antigen-capture ELISA permitted indirect quantitation and identification of BTV from the blood of infected sheep.

Virologic and pathologic investigations were done on prednisolone-treated bitches with a history of canine herpesvirus (CHV) infection. Reactivation of CHV was demonstrated in 5 Beagle bitches after daily administration of 600 mg of prednisolone for 5 days. The reactivation was confirmed in 4 of 5 bitches. Canine herpesvirus was recovered from nasal, oral, vaginal, and ocular secretions on the 5th to 2lst days after initiation of treatment with prednisolone, and also from nasal mucosa and tonsil tissues. Results indicated that latent CHV infections develop and that the virus may be reactivated, without clinical signs, in dogs with a history of CHV infection.

Free, autogenous, full-thickness skin grafting was performed on 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). The percentage of viable graft on day 10 was higher, but not significantly so, in DEF-HES-treated dogs (mean +/- SD, 72.6 +/- 24.8%; median 76.5%) than in HES-treated dogs (mean +/- SD, 46.7 +/- 34.3%; median, 48.8%). A trend for a positive correlation between the percentage of viable graft (on day 10) and the percentage of original graft area (on day 28) was observed in HES- and DEF-HES-treated dogs; this trend was significant in HES-treated dogs (P = 0.012). Both groups had significant positive correlation between percentage of viable graft on day 10 and percentage of haired skin on day 28 (HES, P = 0.000002; DEF-HES, P = 0.0148). A unique finding in DEF-HES treated dogs was the consistent observation of foamy macrophages in the dermis adjacent to the grafts, in deep subcutaneous tissue below the grafts, and in normal dermis.