Distribution of pulmonary nerves immunoreactive for either substance P or calcitonin gene-related peptide was determined, using immunohistochemical methods on healthy lungs from adult equids. The overall patterns of distribution of substance P and calcitonin gene-related peptide-like immunoreactivity were similar. Distribution of immunoreactive nerves was not uniform throughout the lungs; nerve fibers immunoreactive for these peptides were more frequently observed near the hilus of the lung than in the caudal lobes or in the periphery of the lung. Nerve fibers mununoreactive for substance P or calcitonin gene-related peptide were most abundant in the propria of the trachea and large airways, particularly within and directly below the airway epithelium, they were also frequently associated with bronchial and pulmonary vessels. Presence of nerve fibers immunoreactive for substance P and calcitonin gene-related peptide in peribronchial neural ganglia indicated that these sensory nerves may modulate parasympathetic regulation of pulmonary function. Nerve fibers immunoreactive for substance P and calcitonin gene-related peptide were, therefore, well placed to detect inhaled agents and to contribute to the pulmonary response to irritants and pathogens.

Inoculation of 53 ewes after 35, 45, 60, or 80 days of gestation with bluetongue virus serotypes 10, 11, 13, or 17, or with epizootic hemorrhagic disease virus serotypes 1 or 2, resulted in overt clinical disease in the 47 ewes inoculated with bluetongue virus but not in the 6 ewes inoculated with epizootic hemorrhagic disease virus. None of the lambs produced by these ewes had developmental defects or any evidence of persistence of viremia.

The in vitro activity of trimethoprim (TMP) and 9 sulfonamides and their combinations in 6 concentration ratios was tested against 62 Salmonella strains isolated from horses over a 3-year period in the Netherlands, using the agar-dilution method. Most of the isolates were S typhimurium strains (n = 52); the others were S heidelberg (n = 3), S hadar (n = 2), S thompson (n = 2), S enteritidis (n = 1), S infantis (n = 1), and S derby (n = 1). The minimal TMP concentration at which 50% of the Salmonella strains were inhibited (MIC50) was 0.12 micrograms/ml. Sulfachlorpyridazine (SCP; MIC50, 16 micrograms/ml), sulfamethoxazole (SMX; MIC50, 32 micrograms/ml), and sulfadiazine (SDZ; MIC50; 32 micrograms/ ml) were the most potent of the sulfonamides tested. The antimicrobial effect of the sulfonamides, in combination with TMP (additive, synergistic, or antagonistic), was expressed by the fractional inhibitory concentration (FIC) index. Concentrations of SDZ and SCP with TMP had marked synergism at all tested TMP-to-sulfonamide concentration ratios (1:1 to 1: 160; FIC index, 0.10 to 0.50); SMX had synergy with TMP at all ratios, except 1:1 (FIC index, 0.10 to 0.27). Sulfamethazine, sulfamerazine, sulfadoxine (SDX), sulfatroxazole, sulfadimethoxine, and sulfacetamide had MIC50 greater than their breakpoint MIC value and are, therefore, less potent drugs. However, synergy with TMP was found for these less potent sulfonamides at certain concentration ratios, depending on the sulfonamide used. Sixteen Salmonella strains were resistant to TMP, all sulfonamides, and TMP-sulfonamide combinations; 14 of these strains were S typhimurium phage type 200, 1 was S typhimurium phage type 61, and I was S typhimurium phage type 10. Four additional Salmonella strains were resistant to the sulfonamides alone (1 S typhimurium phage type 171 and 3 S typhimurium strains that could not be biotyped). Results of this study indicate that SDZ, SCP, and SMX are the best sulfonamides to combine with TMP for treatment of salmonellosis in equids, because they are the most potent sulfonamides and have strong synergism with TMP at a wide range of TMP-to-sulfonamide concentration ratios.

Diamine oxidase (DAO), an enzyme of small intestinal origin, is released from mucosal storage sites by IV administration of heparin, to yield the plasma postheparin DAO (PHD) curve. The PHD curve is diminished when mucosal surface area is lost, and baseline (without heparin) plasma DAO activity increases when mucosal storage sites are damaged. Plasma DAO activity was measured after 2 doses of heparin were administered Iv in healthy, conscious horses. In anesthetized horses, the PHD curve was studied: during sham small intestinal surgery, and during venous strangulation obstruction (VSO) of the distal 50% of the small intestine. In a third group of anesthetized horses, baseline plasma DAO activity (without heparin) was measured during vso of the distal 50% of the small intestine for 90 minutes, followed by reperfusion for 90 minutes. Postheparin plasma DAO curves in conscious horses were similar to those reported in other species Horses with VSO had a similar PHD curve as did sham-operated controls at all times, except at 15 minutes, when plasma DAO activity was significantly (P < 0.05) greater in the vso group. Horses with VSO and reperfusion had no change in baseline plasma DAO activity throughout the study. Peritoneal fluid DAO activity remained low throughout the study, but increased slightly in horses with VSO that received heparin, possibly because of DAO from extravasated blood in the peritoneal fluid. Results indicated that the plasma DAO response to IV administered heparin in horses is similar to that in other mammals, but, unlike other species, baseline and postheparin DAO activities did not change as expected after small intestinal vascular obstruction and mucosal injury. There may be additional sources of DAO in horses, the type of injury induced was not of sufficient magnitude to affect storage sites of DAO, or the circulatory changes induced by vso might have altered tissue delivery of heparin.

Fiberoptic bronchoscopy was performed in pigs to assess bacterial contamination of bronchoalveolar lavage fluids (BALF) obtained by use of the method and to determine the aerobic bacterial species in bronchoalveolar airways of healthy pigs. Bacterial contamination of BALF caused by insertion of the bronchoscope was evaluated, using a chromogenic bacterial tracer strain, and was found to be 0.22% of total colony-forming units (CFU), with range between 0 and 1.6%. A total of 164 pulmonary-healthy pigs from 6 closed herds were selected. The BALF obtained from these pigs were examined bacteriologically. Bacteria could not be isolated from 10.4% of all BALF; 5.5% of the BALF samples yielded pure cultures; and 84.1% yielded mixed aerobic bacterial growth. In BALF from 29.2% of the pigs, less than or equal to 5 X 10(2) CFU of bacteria/ml were isolated. The total number of bacteria in BALF from 50% of the pigs varied between 5 X 10(2) and 10(3) CFU/ml; 10.4% of BALF samples contained between 10(3) CFU/ml and 5 X 103 CFU/ml. More than 1 bacterial species were isolated from a single lung lavage of 84.1% of the pigs. Up to 6 species were isolated from a single BALF sample. A total of 443 bacterial isolates were differentiated into 25 bacterial genera and species. Samples of BALF yielded staphylococci (67.6%: Staphylococcus hyicus from 13.4% of the samples and S aureus from 2.4%), alpha-hemolytic streptococci (49.4%), Escherichia coli (42.1%), non-hemolytic streptococci (26.2%), Klebsiella spp (18.3%), micrococci (12.8%), and Coryneformes (11.0%). Other bacterial species were found, but less frequently. In our study, BALF from all pigs yielded < 5 X 103 CFU/ ml. Thus, low numbers of bacteria known to be facultative pathogens were isolated from BALF without causing detectable pneumonia.

Development of an arthroscopic approach to the caudal pouches of the equine stifle has been necessary because cranial approaches do not allow access to articular lesions in the caudal aspect of the joint. Therefore, the anatomy of the caudal region was examined in 52 cadaver limbs by use of gross dissection, x-ray-computed tomography, fluoroscopy, or arthroscopy. Additionally, using arthroscopic techniques developed in equine cadaver limbs, 3 stifles from 2 anesthetized horses were arthroscopically explored. Fluoroscopy was used to verify needle placement for joint injection and filling patterns of each femorotibial joint. The medial femorotibial joint sac (n = 4) held a mean +/- SD 41.67 +/- 5.77 ml of injection fluid, and the lateral femorotibial joint sac (n = 4) held a mean 61.67 +/- 2.89 ml of injection fluid. Vital structures that inadvertently could be damaged during arthroscopy of the caudal pouches of the stifle included the peroneal nerve (located approx 7 cm caudal to the lateral collateral ligament), the popliteal artery and vein (situated directly between the medial and lateral femoral condyles), and the lateral femoral condyle (most often traumatized during arthroscopy). The tendon of the popliteus muscle, which is contiguous with the joint capsule of the caudal pouch of the lateral femorotibial joint, made arthroscopic exploration of this pouch particularly difficult.

Drug-metabolizing enzyme activities were measured in livers from calves fed commercial milk replacer (nonfunctioning rumen [veal]), and those fed milk replacer supplemented with whole grain and hay from the first week of age (functioning rumen [ruminating calves]). After birth, cytochrome P450 and its NADPH-dependent reductase activities remained unchanged in veal calves; in ruminating calves they increased almost 50%. Cytochrome P450-mediated reactions, such as aniline hydroxylase activity, tripled in ruminating calves, but remained unchanged in veal calves. In both groups of calves, coumarin hydroxylase and 7-ethoxycoumarin 0-deethylase activities increased after birth, but maturation rates and activity values in ruminating calves were considerably greater than those of veal calves. The aminopyrine N-demethylase activity for veal calves was equal to that of calves with functioning rumen. Uridine diphosphoglucuronic acid glucuronyl transferase and glutathione-S-transferase activities also were higher in calves with functioning rumen than in veal calves. This increased activity in calves with functioning rumen probably represents a response to environmental exposure to xenobiotics. Compared with rumen-functional calves, bob veal (0 to 3 weeks old) and fancy veal (15 to 19 weeks old) calves fed commercial milk replacer have a significantly (P = 0.05) diminished capacity for metabolizing drugs and other xenobiotics. From a regulatory perspective, the variance in drug-metabolizing enzyme activities within these different market classes of calves suggests that specific studies designed to determine drug residue-depletion times in veal calves may be needed.

Cell-mediated immunity was evaluated in intestinal, respiratory, and systemic lymphoid tissues of pigs exposed when 11 days old to virulent transmissible gastroenteritis virus (TGEV), attenuated TGEV, or porcine respiratory coronavirus (PRCV), 3 antigenically related porcine coronaviruses with distinct enteric and respiratory tissue tropisms. Mononuclear cells were prepared from mesenteric lymph nodes (MLN), bronchial lymph nodes (BLN), and spleens of pigs and tested for virus-specific responses by use of lymphocyte proliferation assays. Vigorous MLN and BLN proliferation responses to virulent TGEV and PRCV, respectively, at postinoculation days 8 to 24 were strongly associated with prior detection of TGEV in rectal swab samples and PRCV in nasal swab samples. Gastrointestinal disease and intestinal virus replication, assessed on the basis of rectal virus shedding, were almost exclusively found in the virulent TGEV-inoculated pigs, even though virulent TGEV and a high dose of attenuated TGEV elicited the highest proliferation responses in MLN. Pigs exposed to PRCV or attenuated TGEV did not have clinical signs of disease, and only 1 pig given a high dose of attenuated TGEV shed virus in feces. Porcine respiratory coronavirus replicated in the respiratory tract after either oronasal or aerosol inoculation of virus and induced strong BLN, but not MLN, proliferation responses. A high dose of attenuated TGEV (4 X 10(8) plaque-forming units) was more effective than a lower dose of attenuated TGEV (7 X 10(6) plaque-forming units) in eliciting significant lymphocyte proliferation in MLN and BLN. Cellular immune function, assessed on the basis of mitogen-induced proliferation of lymphocytes, was comparable for all 3 sources of lymphocytes and was not adversely affected by exposure to any of the pigs. The tissue tropism of TGEV and PRCV was associated with induction of virus-specific cell-mediated immune responses, as evidenced by substantial lymphocyte proliferation responses in MLN and BLN, mucosa-associated lymph nodes adjacent to the primary sites of virus replication. The failure of PRCV strain ISU-1 to replicate in the intestinal tract correlated with poor virus-specific cellular immune responses in MLN.

An ELISA, using purified flagellin of Borrelia burgdorferi as the solid-phase antigen, was used to measure antibody concentrations to B burgdorferi in dairy cattle in Wisconsin. Serum obtained from 5,060 cows in 160 randomly selected herds in the state were tested. Serum from an additional 2,600 cattle in Barron County, Wis, a county with a high annual incidence of B burgdorferi infections in human beings, was also tested. Only 7% of the cows that were tested, but 66% of the herds that were tested, were seropositive for B burgdorferi. Sixteen percent of the herds had a prevalence of 15% seropositive cows, whereas 50% of the herds had a prevalence of 1 to 14% seropositive cows. Seropositive herds were concentrated in the west-central part of Wisconsin. An association existed between the geographic location of seropositive herds and counties in which B burgdorferi infection of human beings was acquired (P < 0.05) as well as the geographic location of seropositive herds and the geographic distribution of Ixodes scapularis (P < 0.05). Barron County, in which B burgdorferi infection is endemic, had a significantly (P < 0.05) higher percentage of seropositive cows (17%) than did the state of Wisconsin (7%).

A specific, sensitive, reverse-phase high-performance liquid chromatographic assay for acepromazine, with analytic sensitivity as low as 5 ng/ml of plasma, and electrochemical detection with an oxidation potential of 0.7 V, was used to study the pharmacokinetics of acepromazine given at a dosage of 0.15 mg/kg of body weight in horses. The relation between effect and pharmacokinetics of the drug was examined. The effects studied included those on blood pressure, pulse, PCV, measures of respiration function, and sedation. Intravenously administered doses led to a biphasic concentration decay pattern with an alpha-phase distribution half-life of < 3 minutes. The beta-phase half-life was in the range of 50 to 150 minutes. The CNS effects peaked at 20 minutes after administration, and the hemodynamic effects peaked at 100 minutes. In all horses, the most sensitive variable was the PCV, which decreased by up to 20% (P < 0.0001). Systolic, diastolic, and mean blood pressures decreased (P < 0.0001); heart rate was unchanged (P > 0.05). Neither blood gas tensions nor blood pH changed noticeably (P > 0.05). In all horses studied, acepromazine had a significant (P < 0.0001) sedative effect, as observed by posture and alertness. None of the observed pharmacodynamic effects correlated well with plasma acepromazine concentration. These effects persisted beyond the time of detectable acepromazine concentration, indicating that they might be caused by active metabolites, or that their timing could result from complex pharmacokinetic compartment influences.