Indirect immunofluorescent antibody (IFA), latex agglutination (IA), and enzyme immunoassay (EIA) methods were compared for evaluation of the serum antibody responses of dogs experimentally and naturally exposed to spotted fever-group rickettsiae. Selected sera (obtained on days 1, 42, 53, 124, 145, 236, 255, 264, and 292) were examined from three 8-month-old female Beagles inoculated with Rickettsia rickettsii on days 34 and 250 of the study. A second group of dogs comprised three 8-month-old female Beagles inoculated with R montana on days 34 and 102. Subsequently, these dogs were inoculated with R rickettsii on day 250. Serum samples were obtained from the second group of dogs on days 1, 96, 103, 132, 180, 215, 292, and 494. A third group consisted of 21 naturally exposed dogs, from which sequentially obtained serum samples were available, and which had clinical signs compatible with Rocky Mountain spotted fever. Clinical signs of disease in dogs of the third group resolved after treatment with tetracycline (22 mg/kg of body weight, Po, q 8 h) was instituted. At least 2 sequentially obtained serum samples from each dog were tested. In general, the first sample was obtained just prior to treatment and the convalescent serum samples were obtained at weekly or greater intervals thereafter. For correlation and reactivity data, an IFA test for IgG/IgM (using heavy and light chains-specific conjugate) was used as the reference standard for comparison of results with those of the other tests,

Random fragments of DNA were obtained from a cosmid library of Salmonella agona genomic DNA. from this library, 2 fragments were chosen and pooled to probe isolates of S typhimurium obtained during an episode of salmonellosis in a veterinary medical teaching hospital. Chromosomal DNA from the Salmonella isolates was digested with restriction endonucleases, and was probed with the random fragments of chromosomal DNA. This procedure resulted in a fingerprint pattern for each isolate. We found that the method permitted discrimination between isolates involved in the disease episode and S typhimurium obtained prior to the episode. We conclude that random fragments of chromosomal DNA are useful for fingerprinting isolates of S typhimurium. Analysis of plasmid DNA obtained from the isolates was not as useful. Some isolates found to be identical by restriction site analysis, had plasmids of different molecular weight. These results indicate that plasmid analysis may not be as useful a fingerprinting tool as previously reported.

Haptoglobin (HP), an acute-phase protein, is detected in serum of cows with hepatic lipidosis (fatty liver). To assess the relevance of Hp in fatty liver, induction of Hp was examined, using conditions similar to those involving development of fatty liver in cows. Induction of Hp was achieved by a combination of dexamethasone administration (0.1 mg/kg of body weight) and 2 days' starvation. Haptoglobin appearance in serum was not associated with the increase of alpha 1-acid glycoprotein (a marker for inflammation). This treatment increased serum nonesterified fatty acids concentration and decreased serum triglycerides concentration. Protein kinase C activity was decreased in the cytosolic fractions of liver and mononuclear cells. Reduction of protein kinase C-catalyzed endogenous protein phosphorylation also was observed, particularly in the cytosolic fractions of the tissue and cells. Detection of Hp in serum of cows with fatty liver appears to be explained by the fact that Hp is induced by dexamethasone administration and starvation, which are similar to the condition responsible for fatty liver development. The change of protein kinase C-catalyzed phosphorylation was suggested to be involved in the induction of Hp in cows.

Respiratory tract infections are prevalent in foals, yet the frequency with which the distal airways are affected in chemical episodes of respiratory tract disease has not been evaluated to our knowledge. The objective of the study was to determine the incidence of distal respiratory tract infection (DRTI) in foals on a sample of Thoroughbred breeding farms (n = 10) in Ontario. In a pilot study, clinical criteria commonly used to select foals for antimicrobial treatment (detection of abnormal lung sounds, plus nasal discharge, cough, fever, tachypnea, and/or lethargy) were found to segregate foals with and without endoscopically confirmed DRTI. Mucopurulent exudate and bronchial erythema were observed more frequently (P < 0.005), bronchial lavage total cell count and neutrophil concentration were significantly (P < 0.005) higher, and intracellular cocci were recovered significantly (P < 0.01) more often from bronchial lavage samples of affected foals (n = 8) than of controls (n = 8). These clinical criteria were used to identify cases in a cohort of Thoroughbred foals (n = 219) from May 1 to October 30, 1991. Case morbidity adjusted for clustering was 82 +/- 5% (95% confidence limits, 72 to 92%). Most (74%) episodes of clinical DRTI were detected in july and August, and equal numbers were detected before (53%) and after (47%) weaning of foals. Of 178 cases, 66 (48%) were selected at random for endoscopy and bronchial lavage. Grade-II pharyngeal lymphoid hyperplasia was observed commonly (60% of foals); auditory tube diverticulum (guttural pouch) discharge was observed in 18 of 86 (21%) foals, and guttural pouch infection was confirmed in 6 of 7 foals examined endoscopically. Endoscopically confirmed DRTI, defined as visual detection of bronchial exudate with microscopic detection of intracellular cocci and markedly high neutrophil count in bronchial lavage samples, was confirmed in 75 of 86 (87%) cases tested. These data indicate that DRTI might be reliably diagnosed by auscultation during a simple rebreathing exercise. The syndrome of DRTI was extremely common in Thoroughbred foals, characterized by marked inflammation of visible airways and cytologic evidence of bacterial infection. Risk factors for clinical (undifferentiated) DRTI were not identified in this study.

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.

The effects of exogenous platelet-activating factor (PAF) were determined in anesthetized ponies. Administration of PAF induced a decrease in cardiac index that resulted in systemic hypotension. This was followed by tachycardia, hypertension, and a return of cardiac index to baseline. Pulmonary arterial pressure increased markedly because of pulmonary vasoconstriction. Exogenous PAF also caused leukopenia and thrombocytopenia. The specific PAF receptor antagonist (WEB 2086) blocked all PAF-induced changes. Flunixin meglumine, a cyclooxygenase inhibitor, abolished the pulmonary hypertension and tachycardia, and attenuated the systemic hypotension but did not change the PAF-induced peripheral cellular changes. The PAF antagonist also inhibited platelet aggregation induced by PAF in vitro. The PAF-induced changes are similar to those reported after endotoxin exposure in horses.

Using polyclonal rabbit and monoclonal mouse anti-dog IgE antibodies, we developed ELISA for measurement of ragweed-specific IgE in canine serum. In the ELISA, microtitration plates were coated with ragweed extract and sequentially incubated with canine serum, purified monoclonal or polyclonal anti-dog IgE, and conjugated goat antibody to mouse IgG or rabbit IgG. Serum ragweed-specific IgE values were measured by the 2 ELISA in serum samples from 60 ragweed-allergic dogs and in serum from 10 control dogs. Passive cutaneous anaphylaxis (PCA) tests were performed on these sera to compare results with those of the ELISA, Mean coefficient of variation between assays was 0.20 +/- 0.10 for the assay using the polyclonal antibody and was 0.17 +/- 0.10 for that using monoclonal antibody. Sensitivity was 0.6 U/ml for the ELISA, using polyclonal antibody, and 2.5 U/ml for the ELISA, using monoclonal antibody. Serum ragweed-specific IgE values measured by the 2 ELISA strongly correlated with PCA titers (P < 0.0000), but the ELISA using polyclonal antibody had higher correlation with PCA titer (r = 0.84) than the ELISA using monoclonal antibody (r = 0.59). The geometric mean ragweed-specific IgE value measured by the 2 ELISA and by PCA testing, was significantly higher (P < 0.0000) in allergic dogs than in control dogs. The 2 ELISA were specific, sensitive, and reproducible for measurement of ragweed-specific IgE in canine serum.

Foremilk, residual milk, and blood samples were studied for 10 days during acute mastitis episodes induced by endotoxin infused via the teat canal. Quarter milk and blood samples were collected frequently for 3 days after the infusion and thereafter once or twice daily. Leukocyte concentration in milk and blood was determined by flow cytometry. Within 2 hours after infusion of the endotoxin, clinical mastitis was observed. Total leukocyte concentration and proportion of neutrophils increased significantly (P < 0.05) by postinfusion hour (PIH) 2 in foremilk and by PIH 4 in residual milk. From PIH 2, serum albumin content and N-acetyl-beta-D-glucosaminidase activity were significantly increased in both fractions. Neutrophils were the predominant leukocyte population in both fractions until PIH 59. From PIH 72, lymphocytes were the predominant cell population until PIH 175 in foremilk and until PIH 223 in residual milk. Serum albumin content and N-acetyl-beta-D-glucosaminidase activity in residual milk was significantly lower than in foremilk from PIH 4 to 24 and from PIH 24 to 59, respectively. Regarding total and differential leukocyte counts, values for the 2 fractions followed the same pattern throughout the course of inflammation, probably owing to frequent sample collection. Total and differential cell counts tended to differ between the fractions during some periods, although differences were not statistically significant. When samples were taken less frequently, the total leukocyte concentration in residual milk was higher than that in foremilk. Although sample collections were frequent, clustering of immature neutrophils was not observed in the cytofluorogram of blood leukocytes in this study. Residual milk seems to be the fraction that best reflects the condition in the quarter at the particular time when the milk sample is taken. Results also indicate that residual milk reflects the condition of the secretory tissue, as well as the lower regions of the gland.

Sonographic observations were made of the image mean gray scale (MGS) of the flexor tendons and ligaments in the left and right metacarpal regions of each of 10 clinically normal horses. In images made in the dorsal and sagittal planes, the MGS was measured at multiple sites in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament (AL), and suspensory ligament (SL), and at single sites in the medial and lateral limbs of the SL, and the palmar ligament. Relative sonographic brightness of each tendon and ligament was calculated by dividing the value of its MGS by the mean value for the MGS of images of 3 soft tissue equivalent phantoms. When a multivariate repeated-measures of ANOVA of the relative brightness values was statistically significant (P < 0.05), Tukey's method of multiple comparisons was used to determine which values were significantly different from each other. In the dorsal plane, the SL was significantly brighter than the DDFT, SDFT, and AL; relative brightnesses of the DDFT and SDFT were similar, as were those of the SDFT and AL. In the sagittal plane, the SL again was the significantly brightest structure, followed by the Al, and similar brightnesses of the DDFT and SDFT. In dorsal images made 25 cm distal to the accessory carpal bone, relative brightnesses of the SDFT, DDFT, and the medial and lateral limbs of the SL were similar. In images made 30 cm distal to the accessory carpal bone, relative brightness of the palmar ligament was significantly (P < 0.05) less than that of the SDFT and DDFT in the dorsal plane, but not in the sagittal plane, where it was significantly greater. Relative brightness values represented a unique sonographic characteristic of each structure and, in the future, may provide further insights into tendon and ligament structure and function.

Monoclonal antibodies were prepared against 40- and 56- to 64-kd antigens of Chlamydia pecorum strain Maeda, which was isolated from a cow with pneumonia. Using the monoclonal antibodies, 5 strains of C pecorum, 25 strains of mammalian and 19 strains of avian C psittaci, 1 strain of C pneumoniae, and 3 strains of C trachomatis were analyzed for immunologic reactivity by use of the indirect immunofluorescent test. Monoclonal antibody analysis revealed immunologic relatedness between C pecorum and mammalian strains of C psittaci, which were completely differentiated from the other avian strains. Bovine strains were distinguished from ovine strains. Antigenic diversity mm observed for bovine and ovine strains. Feline- and guinea pig-derived strains were shown to be immunologically different from bovine and ovine strains. Results provide the basis for typing and epidemiologic study of bovine and ovine strains of C pecorum and C psittaci.