Objective-To develop polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis for molecular typing of strains of Streptococcus zooepidemicus and to use the new typing method to analyze a collection of isolates from the respiratory tract of Thoroughbreds. Sample Population-10 strains of S zooepidemicus, 65 isolates from the respiratory tract of 9 yearlings following long distance transportation, and 89 isolates from tracheal aspirates of 20 foals with pneumonia. Procedure-Phenotypic variations in the SzP protein were detected by western immunoblot analysis. Using PCR-RFLP analysis, genotypes were obtained with primer sets from the SzP gene, followed by restriction endonuclease digestion of the amplicons. Results-Unique genotypic patterns were obtained with a primer set designed from both ends of the structural gene and the restriction endonuclease Dde I. Forty-five isolates from the lymphoid tissue within the pharyngeal recess (ie, pharyngeal tonsil) of yearlings included 10 SzP genotypes and SzP phenotypes. Isolates from the trachea of each yearling were of a single genotype that was also present among isolates from the pharyngeal tonsil of the same horses. Isolates from tracheal aspirates of foals belonged to 14 genotypes. Conclusion and Clinical Relevance-Analysis of the SzP gene by use of PCR-RFLP was effective for molecular typing of strains of S zooepidemicus in the study of respiratory tract disease in horses. Results of PCR-RFLP analysis indicate that a single strain of S zooepidemicus can migrate from the pharyngeal tonsil to the trachea at a high rate in horses undergoing long distance transportation.

Objective-To determine plasma concentrations of adrenocorticotrophic hormone (ACTH) and alpha-melanocyte stimulating-hormone (α-MSH) in healthyferrets and ferrets with hyperadrenocorticism. Animals-16 healthy, neutered, privately owned ferrets, 28 healthy laboratory ferrets (21 sexually intact and 7 neutered), and 28 ferrets with hyperadrenocorticism. Procedures-Healthy ferrets were used for determination of reference plasma concentrations of ACTH and alpha-MSH. Diagnosis of hyperadrenocorticism was made on the basis of history, clinical signs, urinary corticoid-to-creatinine ratios, ultrasonography of the adrenal glands, and macroscopic or microscopic evaluation of the adrenal glands. Blood samples were collected during isoflurane anesthesia. Plasma concentrations of ACTH and α-MSH were measured by radioimmunoassay. Results-Plasma concentrations of ACTH in 23 healthy neutered ferrets during the breeding season ranged from 4 to 145 ng/L (median, 50 ng/L). Plasma concentrations of α-MSH in 44 healthy neutered or sexually intact ferrets during the breeding season ranged from < 5 to 617 ng/L (median, 37 ng/L). Reference values (the central 95% of the values) for ACTH and α-MSH were 13 to 100 ng/L and 8 to 180 ng/L, respectively. Plasma concentrations of ACTH and α-MSH in ferrets with hyperadrenocorticism ranged from 1 to 265 ng/L (median, 45 ng/L) and 10 to 148 ng/L (median, 46 ng/L), respectively. These values were not significantly different from those of healthy ferrets. Plasma ACTH concentrations of sexually intact female ferrets in estrus were significantly higher than those of neutered females. Conclusions and Clinical Relevance-Ferrets with hyperadrenocorticism did not have detectable abnormalities in plasma concentrations of ACTH or α-MSH. The findings suggest that hyperadrenocorticism in ferrets is an ACTH and α-MSH-independent condition.

Objective-To evaluate the effect of 2 cyclooxygenase (COX)-2 inhibitors on contractile activity of the circular smooth muscle layer of the equine dorsal and ventral colon. Sample Population-Samples of the dorsal and ventral colon obtained from 10 healthy horses. Procedure-Full-thickness tissue samples were collected from the dorsal colon in the area of the diaphragmatic flexure and the ventral colon in the area of the sternal flexure. Samples were cut into strips oriented along the fibers of the circular muscle layer and mounted in a tissue bath system for determination of contractile strength. Incremental amounts of etodolac, nabumetone, and indomethacin ere added, and contractile activity was recorded. Results-Response of the dorsal and ventral colon to nonsteroidal anti-inflammatory drugs (NSAIDs) was variable. Indomethacin induced the greatest reduction in contractile activity, followed by nabumetone. For etodolac, the difference from baseline values was only significantly reduced at the highest concentration used (1 × 10(-5)M) for the ventral colon. Conclusions and Clinical Relevance-The NSAIDs that are designed to target the COX-2 isoform appeared to have variable effects on the contractile activity of the equine dorsal and ventral colon. Etodolac appeared to have the least effect on contractile activity, compared with the effects attributable to nabumetone, and would potentially have the fewest adverse effects relative to motility of the dorsal and ventral colon.

Objective-To evaluate the effect of prolonged water exposure on tissue mass and solutes of outer and inner layers of the stratum medium, sole, frog, and the stratum medium (SMZA) zona alba layer of horses' hooves. Specimen Population-10 hooves from 10 horses without foot abnormalities. Procedure-Hoof wall tissue specimens were obtained and immersed for 10 days in distilled deionized water. Serial changes in mass were recorded during the immersion period. Subsequently, osmolarity and Na+, K+, Cl-, and protein concentrations of the immersion solution were quantified. Results-Fully cornified outer hoof wall, sole, and frog epidermal structures increased in mass, whereas the SMZA lost mass when immersed in water. All hoof structures had a variable loss of crystalloids during immersion, but none of the specimens lost proteins. The frog epidermis was distinct in that total solute lost during immersion could not be ascribed to Na+, K+, and Cl-. Conclusions and Clinical Relevance-Data support a 2-compartment model for the fully cornified outer stratum medium, frog, and sole that permits the exchange of crystalloids, but not proteins, across the cell membrane and infers that topical agents containing proteins cannot benefit the hoof. The unique osmotic behavior of the SMZA relative to other hoof structures suggests the hypothesis that it is composed of transitional epithelial cells. The solutes lost from frog epithelium are interpreted to reflect its unique lipid composition.

Objective-To evaluate the effect of controlled exposure to inhaled lipopolysaccharides (LPS) on the pulmonary inflammatory response of anesthetized pigs. Animals-Forty-seven 8- to 12-week-old domestic pigs. Procedure-Pigs were anesthetized with pentobarbital, instrumented for measurement of cardiopulmonary function, and randomly assigned to receive saline (0.9% NaCl) solution or 0.25, 0.5, or 1.0 µg of LPS/kg/h for 2 or 6 hours via nebulization through the endotracheal tube. Cardiopulmonary variables were measured, ex vivo neutrophil superoxide production determined, and postmortem assessment for pulmonary neutrophil influx and modulation of adhesion molecule (E-selectin) expression was done. Results-Mild changes in cardiopulmonary function were observed in response to inhaled LPS in the 2- and 6-hour groups. In pigs inhaling LPS (0.5 or 1.0 µg/kg/h) for 6 hours, there was significant pulmonary neutrophil influx observed postmortem. An increase in expression of E-selectin on pulmonary endothelial cells after 6 hours of LPS inhalation (0.5 µg/kg/h) was also observed. In contrast, there was no significant influx of neutrophils or expression of E-selectin in lungs from pigs inhaling LPS for 2 hours. Conclusion and Clinical Relevance—Inhalation of LPS resulted in localized pulmonary inflammation characterized by neutrophil influx and increased expression of the endothelial cell adhesion molecule, E-selectin. It may be possible to relate our experimental findings to the clinical consequences of airborne LPS exposure in swine confinement facilities.

Objective-To determine the effect of caprine arthritis-encephalitis virus (CAEV) infection on expression of interleukin-16 (IL-16). Animals-6 goats experimentally infected with CAEV and 6 age-matched healthy uninfected control goats. Procedure-Peripheral blood mononuclear cells (PBMCs) and synovial membrane cells from infected and control goats cultured with or without phytohemagglutinin were analyzed for IL-16 mRNA by use of a reverse transcriptase-polymerase chain reaction assay with goat-specific primers, after cloning and sequencing of a 384-bp fragment of the goat IL-16 gene. Synovial fluid, serum, and culture supernatants of PBMCs and synovial cells of control and CAEV-infected goats were analyzed for IL-16 by use of an ELISA. Results-The 384-bp product was 86% homologous to the corresponding human IL-16 nucleotide sequence. Higher expression of IL-16 mRNA in PBMCs (unstimulated or stimulated with phytohemagglutinin) was detected in samples from CAEV-infected goats, compared with control goats, but the difference was not significant. Synovial membrane cells infected in vitro had higher expression than uninfected control cells. Higher IL-16 concentration was detected in synovial fluid, serum, and culture supernatants of PBMCs of infected goats than in samples from control goats. Conclusions and Clinical Relevance-Infection with CAEV increases expression of IL-16, a proinflammatory and chemotactic cytokine. This cytokine appears to be constitutively expressed at low concentrations in normal uninfected PBMCs and synovial membrane cells. Increased production of IL-16 in CAEV infection may partly be responsible for increased lymphoid cell infiltrations observed in arthritic joints and other tissues of CAEV-infected goats.

Objective-To compare cardiopulmonary responses during anesthesia maintained with halothane and responses during anesthesia maintained by use of a total intravenous anesthetic (TIVA) regimen in horses. Animals-7 healthy adult horses (1 female, 6 geldings). Procedure-Each horse was anesthetized twice. Romifidine was administered IV, and anesthesia was induced by IV administration of ketamine. Anesthesia was maintained for 75 minutes by administration of halothane (HA) or IV infusion of romifidine, guaifenesin, and ketamine (TIVA). The order for TIVA or HA was randomized. Cardiopulmonary variables were measured 40, 60, and 75 minutes after the start of HA or TIVA. Results-Systolic, diastolic, and mean carotid arterial pressures, velocity time integral, and peak acceleration of aortic blood flow were greater, and systolic, diastolic, and mean pulmonary arterial pressure were lower at all time points for TIVA than for HA. Pre-ejection period was shorter and ejection time was longer for TIVA than for HA. Heart rate was greater for HA at 60 minutes. Minute ventilation and alveolar ventilation were greater and inspiratory time was longer for TIVA than for HA at 75 minutes. The PaCO2 was higher at 60 and 75 minutes for HA than for TIVA. Conclusions and Clinical relevance-Horses receiving a constant-rate infusion of romifidine, guaifenesin, and ketamine maintained higher arterial blood pressures than when they were administered HA. There was some indication that left ventricular function may be better during TIVA, but influences of preload and afterload on measured variables could account for some of these differences.

Objective-To purify and partially characterize various isoforms of canine pepsinogen (PG) from gastric mucosa. Sample Population-Stomachs obtained from 6 euthanatized dogs. Procedure-Mucosa was scraped from canine stomachs, and a crude mucosal extract was prepared and further purified by use of weak anion-exchange chromatography, hydroxyapatite chromatography, size exclusion chromatography, and strong anionexchange chromatography. Pepsinogens were characterized by estimation of molecular weights, estimation of their isoelectric points (IEPs), and N-terminal amino acid sequencing. Results-Two different groups of canine PG were identified after the final strong anion-exchange chromatography: PG A and PG B. Pepsinogens differed in their molecular weights and IEP. Pepsinogen B appeared to be a dimer with a molecular weight of approximately 34,100 and an IEP of 4.9. Pepsinogen A separated into several isoforms. Molecular weights for the various isoforms of PG A ranged from 34,200 to 42,100, and their IEPs ranged from 4.0 to < 3.0. The N-terminal amino acid sequence for the first 25 amino acid residues for PG A and B had good homology with the amino acid sequences for these proteins in other species. Conclusions and Clinical Relevance-Canine PG B and several isoforms of canine PG A have been purified. Availability of these PGs will facilitate development of immunoassays to measure PG in canine serum as a potential diagnostic marker for gastric disorders in dogs.

Objectives-To evoke and measure the nociceptive withdrawal reflex (NWR) by use of electromyographic recordings and to score the behavioral nociceptive responses to electrical pulses in standing nonsedated horses. Animals-10 adult horses. Procedure-The lateral palmar digital nerve of the forelimb was transcutaneously stimulated, and surface electromyographic responses were recorded from the ulnaris lateralis, extensor carpi radialis, and common digital extensor muscles. Stimuli consisted of a 25-millisecond train of 5 constant-current pulses delivered by a computer-controlled stimulator. The 80- to 250-milliseconds poststimulation interval was analyzed to detect the NWR. The current intensity was increased in steps of 0.5 mA until the NWR threshold intensity (It) was reached. The stimulus at It was repeated twice. Latency and amplitude of the NWR, together with the behavioral reaction of horses, were analyzed. The latter was scored according to a scale from 0 (no reaction) to 5 (vigorous reaction). Finally, 3 suprathreshold stimuli at 1.2 × It were analyzed. Results-The median It to elicit NWR was 2.5 mA. Median onset latency of the NWR was 96.0 milliseconds at It and 89.6 milliseconds for suprathreshold stimuli. The amplitude of the reflexes was higher for suprathreshold stimulations, and behavioral reactions were slightly stronger when stimulus intensity increased. Conclusions and Clinical Relevance-Results of our study indicate that it is possible to record NWR in conscious standing horses, to define a reflex threshold, and to measure reflexes in response to increasing stimulus intensity.

Objective-To evaluate the effect of 2 oxytocin products administered to sows at the onset of fetal expulsion on the integrity of umbilical cords, meconium staining, and piglet mortality. Animals-2099 neonatal pigs. Procedure-180 parturient sows were randomly assigned to 3 stratified groups of 60 sows each. Two groups of sows were injected IM at the onset of fetal expulsion with 1 of 2 oxytocin commercial products (20, 40, or 50 U for sows weighing 120 to 150 kg, 151 to 250 kg, or ≥ 251 kg, respectively). Control sows were treated IM with saline (0.9% NaCl) solution. Farrowing time, expulsion intervals, and numbers of stillborn and liveborn piglets were recorded for each sow. Piglets were evaluated for inspiratory effort, heart rates, and degree of meconium staining of skin (nonstained, and moderately or severely stained). Umbilical cords were classified as normal in appearance, edematous, congested, hemorrhagic, or ruptured. Results-Oxytocin-treated sows had a significant decrease in farrowing time and expulsion intervals and also had a significantly higher number of stillborn piglets per litter, compared with control sows. The number of piglets per litter with ruptured and hemorrhagic umbilical cords was significantly greater in oxytocin- treated sows, compared with control sows. In near-death stillborn piglets, oxytocin treatment significantly decreased inspiratory efforts at birth and increased the rate and severity of meconium staining, compared with saline treatment. Conclusions and Clinical Relevance-Oxytocin given to sows at the onset of fetal expulsion significantly increases the rate of fetal distress, anoxia, and intrapartum death in piglets.