Sequence of cardiovascular changes leading to pulmonary edema in swine fed culture material containing fumonisin

OBJECTIVES: To determine the sequence of cardiovascular and blood gas changes induced by ingestion of fumonisin-containing culture material in swine and to examine the temporal relationship of these changes to plasma sphinganine and sphingosine concentrations. ANIMALS: 12 healthy castrated pigs (38 to 50 kg). PROCEDURE: Pigs were instrumented to permit cardiovascular monitoring and collection of blood samples. Baseline values were obtained, and pigs were randomly assigned to 1 of 2 groups. Control pigs (n = 6) were fed a standard grower diet, whereas culture material that contained 20 mg of fumonisin B1/kg of body weight was added to the feed of treated pigs (n = 6) each day. Hemodynamic data, results of arterial and mixed venous blood gas analyses, and plasma sphinganine and sphingosine concentrations were recorded every 12 hours until treated pigs were euthanatized because of impending death from pulmonary edema. RESULTS: Sphinganine and sphingosine concentrations were increased in plasma of treated pigs within 24 hours of initial fumonisin exposure and continued to increase dramatically until euthanasia. Fumonisin-treated pigs had increased respiratory rate, mean pulmonary artery pressure, and pulmonary artery wedge pressure, along with decreased heart rate and cardiac output in the 12-hour period before euthanasia. Fumonisin-treated pigs also had systemic arterial hypotension, arterial and mixed venous hypoxemia, metabolic acidosis, decreased oxygen delivery, and increased oxygen consumption immediately before euthanasia. CONCLUSIONS AND CLINICAL RELEVANCE: Fumonisin-induced pulmonary edema in swine is probably caused by acute left-sided heart failure. Onset of hemodynamic changes was associated with plasma sphinganine concentration > or = 2.2 microM/L and plasma sphingosine concentration > or = 1 microM/L.     

Characterization of Salmonella Typhimurium isolates associated with septicemia in swine

Salmonella Typhimurium is frequently isolated from pigs and may also cause enteric disease in humans. In this study, 33 isolates of S. Typhimurium associated with septicemia in swine (CS) were compared to 33 isolates recovered from healthy animals at slaughter (WCS). The isolates were characterized using phenotyping and genotyping methods. For each isolate, the phage type, antimicrobial resistance, and pulsed-field gel electrophoresis (PFGE) DNA profiles were determined. In addition, the protein profiles of each isolate grown in different conditions were studied by Coomassie Blue-stained sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot. Various phage types were identified. The phage type PT 104 represented 36.4% of all isolates from septicemic pigs. Resistance to as many as 12 antimicrobial agents, including some natural resistances, was found in isolates from CS and WCS. Many genetic profiles were identified among the PT 104 phage types. Although it was not possible to associate one particular protein with septicemic isolates, several highly immunogenic proteins, present in all virulent isolates and in most isolates from clinically healthy animals, were identified. These results indicated that strains associated with septicemia belong to various genetic lineages that can also be recovered from asymptomatic animals at the time of slaughter.     

Fumonisin B1 levels associated with an epizootic of equine leukoencephalomalacia

During the fall of 1989, an episode of equine leukoencephalomalacia involved 18 of 66 purebred Arabian horses at a breeding/training stable in Arizona. Of the 18 horses affected, the condition was fatal in 14. These horses, as well as 48 unaffected horses, had been fed a diet containing a substantial amount of white corn screenings. Gross pathologic findings included liquefactive necrosis in parts of the cerebral white matter and hemorrhagic foci of various sizes in the brain stem. Histopathologic findings included rarefied white matter with pyknotic nuclei and eosinophilic cytoplasm. Thin-layer chromatography, high-performance liquid chromatography, and gas chromatography/mass spectroscopy were utilized to identify and quantitate fumonisin B1 in 3 samples of corn from the farm. Concentrations of fumonisin B1 range from 37 to 122 ppm. Fumonisin B2 was also detected. Using information on diet, animal weights, and feeding practices, estimates of total fumonisin B1 dosage were determined. This is the first definitive report on equine leukoencephalomalacia and associated fumonisin B1 concentrations.     

Pulmonary edema and hydrothorax in swine produced by fumonisin B1, a toxic metabolite of Fusarium moniliforme

Pulmonary edema and hydrothorax were observed in mature swine that died approximately 5 days after consuming corn screenings. These postmortem observations were reproduced in younger swine (16-24 kg) that died within 1 week when fed the corn screenings under experimental conditions. Additionally, pulmonary edema and hydrothorax occurred in a pig (7.1 kg) that died after receiving 4 daily intravenous injections of fumonisin B1. A fungus was isolated from the corn screenings that is identical to Fusarium moniliforme MRC-826 in colony morphology and under microscopic examination.     

Fatal pulmonary edema in white-tailed deer (Odocoileus virginianus) associated with adenovirus infection.

Sporadic sudden deaths in adult white-tailed deer occurred from November 1997 through August 1998 on an Iowa game farm. Three of the 4 deer necropsied had severe pulmonary edema, widespread mild lymphocytic vasculitis, and amphophilic intranuclear inclusion bodies in scattered endothelial cells in blood vessels in the lung and abdominal viscera. Immunohistochemistry with bovine adenovirus 5 antisera and transmission electron microscopy demonstrated adenoviral antigen and nucleocapsids, respectively, within endothelial cells. Adenovirus was isolated in cell culture from 1 of the affected deer. The isolate was neutralized by California black-tailed deer adenovirus antiserum. These findings indicate that adenovirus should be considered in the differential diagnosis of both black-tailed and white-tailed deer with pulmonary edema and/or hemorrhagic enteropathy.     

Characterization of an avian cholera epizootic in wild birds in western Nebraska

Avian cholera killed an estimated 2500 birds in western Nebraska and eastern Wyoming from 28 November 1985 to late January 1986. Wild mallards (Anas platyrhynchos) suffered the most losses. Other wild waterfowl, wild turkeys (Meleagris gallopavo), a few domestic fowl, and a bald eagle (Haliaeetus leucocephalus) also died. Pasteurella multocida serotype 1 was the predominant isolate from these carcasses. Cold, wet weather persisted throughout the outbreak, but daily losses in the flock of 50,000 mallards using the area were low. Pasteurella multocida was isolated from nasal swabs of 35 of 37 cattle from a feedlot in which many of these mallards were feeding. Eighty percent of the cattle isolates had antigenic characteristics of serotype 3 or serotype 3 with cross-reactivity. Isolates from wild mallards, wild turkeys, and the bald eagle were virulent to game-farm mallards when inoculated subcutaneously, but P. multocida isolates from cattle were not.     

Ruminal and plasma concentrations of 3-methylindole associated with tryptophan-induced pulmonary edema and emphysema in cattle.

Five Hereford cows were given an intraruminal dose of L-tryptophan (0.35 g/kg of body weight), and 2 cows were used as controls. Of the 5 treated cows, 3 developed clinical signs of interstitial pul monary edema, and emphysema and severe pulmonary lesions were seen at necropsy after 96 hours. Another cow developed moderate clinical signs and pulmonary lesions, and the remaining cow had few clinical signs and mild pulmonary lesions. The severity of clinical signs in each cow was related to the severity of pulmonary lesions at necropsy. The 3-methylindole (3MI) was present in ruminal fluid and plasma within 6 hours after administration of tryptophan, and the concentrations increased to 3.0 and 9.0 mug/ml within 12 to 24 hours. Severity of pulmonary lesions was related to maximal concentration and duration of 3MI in the plasma. At necropsy, gross lesions were characterized by diffuse, pulmonary edema and interstital emphysema; and the lungs were dark red, firm, and heavier than normal. Predominant microscopic changes included accumulation of proteinaceous residue, hypertrophy and hyperplasia of alveolar lining epithelium, thickening of alveolar septums, and emphysematous thickening of interstitial tissues. These changes were similar to previously reported 3MI-induced pulmonary lesions. The presence of 3MI in ruminal fluid and plasma after administration of tryptophan and the relationship between concentration of 3MI and severity of clinical signs indicate that 3MI is the principal metabolite of ruminal fermentation which leads to the development of acute pulmonary edema and emphysema in cattle given tryptophan.     

Lymphoma associated with an epizootic of lymphocytic choriomeningitis in Syrian hamsters (Mesocricetus auratus).

A hamster-associated epizootic of lymphocytic choriomeningitis (LCM) virus infection in medical center personnel at the University of Rochester in 1973 necessitated prompt termination of the Syrain hamster colony. Necropsies were performed on 130 hamsters, blood speciments were obtained from 60 for serotest, and viral isolation procedures were done on 47. Active virus infection, as shown by virus isolation, was associated with the presence of lymphoreticular infiltrate in liver and kidney. Intraabdominal lymphoma was seen only in groups of hamsters from which LCM virus was isolated, but LCM virus was not isolated from many of the hamsters with lymphoma. Although frequency of intraabdominal lymphoma could be markedly increased in LCM-positive hamsters treated with 7,12-dimethylbenz(a)anthracene, lymphoma was not induced in LCM-negative hamsters with this carcinogen.     

Reproduction of edema disease of swine with purified Shiga-like toxin-II variant.

Twenty-one weaned Yorkshire-Landrace pigs were injected intravenously with graded doses of purified Shiga-like toxin-II variant (edema disease toxin). In a preliminary study, three pigs (Nos. 1, 2, 3) were injected with 48, 24, and 12 ng, respectively, of SLT-IIv/kg of body weight. Subsequently, three groups (Nos. 4, 5, 6) of six pigs each were injected with 6, 3, and 1.5 ng, respectively, of SLT-IIv/kg of body weight. Severe clinical signs and histologic lesions characteristic of edema disease developed in pigs Nos. 1, 2, and 3, and all six pigs in group No. 4. Eight of these pigs were euthanatized in extremis (mean time to death was 34 hours) and one died of the disease (52 hours). Moderate signs and lesions of edema disease were observed in all pigs in group No. 5, and three pigs were euthanatized (mean time to euthanasia was 42 hours). Mild signs and lesions were observed in three pigs in group No. 6. The most common gross pathologic changes were edema of the eyelids, submucosa of the stomach, and mesentery of the spiral colon and hemorrhage of the colon and cerebellum. Microscopic lesions were associated with vascular injury and included vessel necrosis, perivascular edema and hemorrhage, and superficial colonic and cecal erosions. The vascular lesions were observed in the cerebellar folia, submucosa and mucosa of the stomach, cecum, colon, and sporadically in the retina. None of the clinical signs associated with endotoxin were observed.     

Risk factors associated with transmissible gastroenteritis in swine.

Commercial production data base records from 2 Illinois farms, on which epizootic or enzootic transmissible gastroenteritis (TGE) was experienced, were accessed for an epidemiologic study. Risk factors investigated were sow parity, source of sows, location of farrowing crates, and breeding practices. At farm 1, an epizootic was experienced; at farm 2, an epizootic of TGE followed by enzootic TGE was experienced. Initially, crude risk ratios were calculated for these risk factors, and the crude risk ratios were subsequently adjusted for confounders and interactions, using multiple logistic regression techniques. After adjustment, parity-3 sows were 2.3 times more likely to have litters with TGE than were sows of all other parities on farm 1, and parity-1 sows were 2.6 times more likely to have litters that experienced TGE than were sows of all other parities on farm 2. A single boar on each farm was linked to increased likelihood of a sow's litter contracting epizootic TGE on each farm. Enzootic TGE was maintained by the periodic influx of outside-source gilts on farm 2; these gilts were 2.2 times more likely to have litters with TGE than were sows derived from farm 2. Sows housed in farrowing crates located under the cold air inlet of farm 2 were 1.7 times as likely as sows located in other rows to have litters with enzootic TGE.     

Microorganisms associated with pneumonia in slaughter weight swine.

The lungs of 334 pigs were obtained from two slaughter plants in Minnesota and examined in detail. Macroscopic and microscopic evaluation, direct fluorescence for Mycoplasma hyopneumoniae and bacterial culture were done on all of them and a subsample of 50 were selected for virus culture. Mycoplasma hyopneumoniae, Pasteurella multocida and Haemophilus spp. were detected in 24.0%, 34.1% and 27.0% of the lungs, commonly in conjunction with each other. One isolate of Haemophilus pleuropneumoniae serotype 2 was detected and this represents the first report of its presence in the United States. No virus was detected in any of the lungs. Lungs with both M. hyopneumoniae and Pasteurella multocida had the greatest amount of macroscopic pneumonia (9.8% of the lung). Lungs with M. hyopneumoniae or P. multocida alone had 4.9% and 5.2% of the lung involved with pneumonia respectively. Lungs with Haemophilus sp. Taxon "minor group" had 3.8% of the lung involved which was not significantly different from lungs with none of these organisms being detected (1.6%). There was a positive correlation between the extent of M. hyopneumoniae infection, as scored by FAT and the amount of macroscopic pneumonia present (r = 0.46; P less than 0.001). Likewise, there was a positive correlation between the estimated concentration of P. multocida present, as scored by the relative number of colonies on blood agar and the amount of macroscopic pneumonia present (r = 0.60; P less than 0.001). Microscopically, the amount of lymphoreticular proliferation, polymorphonuclear cells and alveolar macrophages were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)