The Respiratory System

Histopathological Lesions Caused by Experimental Toxocara Canis and Toxascaris Leonina Infections in Farm Mink (Neovison Vison)

INTRODUCTION

Canine roundworm T. canis and T. leonina infections were investigated in experimentally infected farm mink (Neovison vison) to describe the pattern of pathological lesions in this paratenic host.

MATERIAL AND METHODS

Material and MethodsInfections in mink developed following ingestion of embryonated eggs of either parasite or mice tissue infected with both parasite species.

RESULTS

Comparative analysis of haematoxylin- and eosin-stained slides showed essential differences among the experimental groups. The lesions observed included eosinophil and mononuclear inflammatory infiltrates of the intestinal wall and local lymph nodes, inflammation and haemorrhages in liver tissues, and interstitial inflammation and mineralisation of the kidneys and lungs. Larvae migrating through the minks' bodies also caused particularly salient enlargement of lymphoid follicles in the spleen and inflammatory infiltrates of mononuclear cells in skeletal and heart muscles.

CONCLUSIONS

It is assumed that histopathological lesions appeared as a local and general host response to invasive L3 T. canis and T. leonina larvae migrating through the tissues of infected farm mink. Interestingly, mink infected with embryonated eggs had more pronounced lesions than animals infected with tissue larvae. Detailed histopathological examinations of parenchymal organs and striated muscles revealed lesions resembling those observed in other paratenic host species due to toxocarosis.

Meningoencephalitis Tuberculosa in a Holstein Cow

The gross and histopathologic lesions of meningoencephalitis tuberculosa in a 4-year-old Holstein cow showing clinical signs compatible with bovine spongiform encephalopathy are described in this report. Grossly, numerous gray to yellow, firm and caseous nodules were seen on the ventral surfaces of the brain and in the lateral and fourth ventricles. Histopathologically, foci of caseation and dystrophic mineralization were surrounded by multinucleated giant cells, epitheloid macrophages, plasma cells, lymphocytes and fibrous proliferation. Ziehl-Neelsen stains of the lesions revealed masses of slender acid-fast bacilli in the necrotic centers of lesions and within surrounding giant cells.

Extensive mast cell degranulation in bovine respiratory syncytial virus-associated paroxystic respiratory distress syndrome

Bovine respiratory syncytial virus (BRSV) infection is an important cause of outbreaks of respiratory disease among calves. This virus commonly induces mild to severe respiratory signs but, in a substantial proportion of cases, is also reported to be associated with paroxystic respiratory distress syndrome (PRDS). The pathogenesis of this 'malignant' clinical form has not been fully elucidated. The present study aimed at determining whether mast cell (MC) degranulation plays a role in the physiopathologic cascade leading to the PRDS. Paired serum samples were taken in herds during outbreaks of severe respiratory diseases (acute sera) and 3 weeks after (convalescent sera). Based on seroconversion to BRSV and clinical picture, 67 pairs of sera were selected from calves with a BRSV-associated PRDS for circulating MC tryptase determination. A MC metachromatic score was measured in post-mortem lungs from animals died from a BRSV-associated PRDS (principals) and compared with reference scores obtained from healthy lungs (controls). Levels of tryptase were significantly higher in acute sera (26.6 +/- 12.4 microg/l) compared to convalescent sera (8.4 +/- 7.8 microg/l; P<0.001). Metachromatic scores yielded significantly different results between controls and principals (P<0.01), demonstrating a significant disappearance of metachromatic granules from lung MCs in principals. Taken together, these data demonstrate the presence of an extensive MC degranulation in BRSV-associated PRDS.

Use of operon fusions in Mannheimia haemolytica to identify environmental and cis-acting regulators of leukotoxin transcription

The leukotoxin of Mannheimia haemolytica is an important virulence factor that contributes to much of the pathology observed in the lungs of animals with bovine shipping fever pneumonia. We believe that identification of factors that regulate leukotoxin expression may provide insight into M. haemolytica pathogenicity. The DNA sequence upstream of the leukotoxin operon is divergently shared by P(lapT), which transcribes an arginine permease gene. The intergenic region contains several elements that are potential sites for transcriptional modulation of the promoters. We have developed plasmid-borne chloramphenicol acetyltransferase (cat) operon fusions, as well as lktC::cat chromosomal fusions, to study transcription initiation in M. haemolytica. Using these genetic tools, we have identified cis-acting sequences and environmental conditions that modulate transcription of the leukotoxin and lapT promoters. By deletion analysis, promoters were shown to rely on sequences upstream of their -10 and -35 regions for full activity. Direct repeats of the sequence TGT-N(11)-ACA and a static bend region caused by phased adenine tracts were necessary for full activation of P(lkt). A computer-generated model of the promoter's structure shows how DNA bending brings the repeat sequences within close proximity to the P(lkt) RNA polymerase, and we hypothesize that these repeats are a binding site for an activator of leukotoxin transcription. The lktC::cat operon fusion was also used to demonstrate that, like that of other RTX toxins, leukotoxin transcription is environmentally regulated. Roles for iron deprivation and temperature change were identified.

Enhancement of clearance of bacteria from murine lungs by immunization with detoxified lipooligosaccharide from Moraxella catarrhalis conjugated to proteins

Moraxella catarrhalis strain 25238 detoxified lipooligosaccharide (dLOS)-protein conjugates induced a significant rise of bactericidal anti-LOS antibodies in animals. This study reports the effect of active or passive immunization with the conjugates or their antiserum on pulmonary clearance of M. catarrhalis in an aerosol challenge mouse model. Mice were injected subcutaneously with dLOS-tetanus toxoid (dLOS-TT), dLOS-high-molecular-weight proteins (dLOS-HMP) from nontypeable Haemophilus influenzae (NTHi), or nonconjugated materials in Ribi adjuvant and then challenged with M. catarrhalis strain 25238 or O35E or NTHi strain 12. Immunization with dLOS-TT or dLOS-HMP generated a significant rise of serum anti-LOS immunoglobulin G and 68% and 35 to 41% reductions of bacteria in lungs compared with the control (P<0.01) following challenge with homologous strain 25238 and heterologous strain O35E, respectively. Serum anti-LOS antibody levels correlated with its bactericidal titers against M. catarrhalis and bacterial CFU in lungs. Additionally, immunization with dLOS-HMP generated a 54% reduction of NTHi strain 12 compared with the control (P<0.01). Passive immunization with a rabbit antiserum against dLOS-TT conferred a significant reduction of strain 25238 CFU in lungs in a dose- and time-dependent pattern compared with preimmune serum-treated mice. Kinetic examination of lung tissue sections demonstrated that antiserum-treated mice initiated and offset inflammatory responses more rapidly than preimmune serum-treated mice. These data indicate that LOS antibodies (whether active or passive) play a major role in the enhancement of pulmonary clearance of different test strains of M. catarrhalis in mice. In addition, dLOS-HMP is a potential candidate for a bivalent vaccine against M. catarrhalis and NTHi infections.

Towards an understanding of equine pleuropneumonia: factors relevant for control

OBJECTIVE

To review relevant literature on factors associated with the development of equine pleuropneumonia.

DESIGN

A review of the literature using a range of databases including Current Contents, Medline, ChemAbstracts, Biological Abstracts and CAB and a comprehensive search strategy which involved use of keywords, author and subject category searches. Additional sources included review of articles cited by key accumulated references.

RESULTS

Since the early years of this century, many of the "gaps" in our knowledge of the pathogenesis of this disease have been filled. We now know that equine pleuropneumonia results from contamination of the lower respiratory tract with bacteria similar to the normal oropharyngeal microbiota of the horse and that transportation of any mode, especially over long distances (and consequently with no or short rest periods), is the single most important predisposing factor for this disease. This is associated with restraint of horses such that they are unable to lower their heads, which leads to increased opportunity for lower respiratory tract contamination and a reduced opportunity for clearance. Strenuous exercise also results in lower respiratory tract contamination and exercise subsequent to transportation exerts additive detrimental effects on the defenses of the lower respiratory tract.

CLINICAL IMPLICATIONS

While modern veterinary medicine and surgery have significantly reduced the death rate from pleuropneumonia, horses that develop the disease have a high probability of not returning to their prior use. This underscores the importance of developing the most effective strategies for its prevention.

Immunohistochemical detection of canine distemper virus in haired skin, nasal mucosa, and footpad epithelium: a method for antemortem diagnosis of infection

A reliable antemortem diagnostic method is needed for determining infection with canine distemper virus (CDV). The utility of immunohistochemical detection of CDV antigen was examined was examined for samples of nasal and footpad epithelium and haired skin in dogs with and without detectable CDV antigen in the lung and/or brain. Tissues from 57 dogs at risk of CDV infection were tested. Viral antigen was found in the lung and/or brain of 28 dogs. Among these dogs, viral antigen was demonstrated in the epithelial cells of the nasal mucosa in 24 of 27 dogs, in the footpad epithelium in 24 of 26 dogs, and in the haired skin of the dorsal neck in 26 of 27 dogs. Among the 29 dogs without CDV antigen in either the lung or brain, 1 dog had positive staining for viral antigen in the skin and nasal mucosa. Biopsies of haired skin of the dorsal neck, which is relatively simple to sample, can be used for immunohistochemical testing for acute and subacute infection with CDV.

Cellular and humoral responses in the respiratory tract of goats following intranasal stimulation using formalin-killed Pasteurella haemolytica A2

A study to determine the immunoglobulin and cellular responses in the respiratory tract of goats following intranasal exposures to formalin-killed Pasteurella haemolytica A2 was carried out. Forty-two goats were divided into two groups. Goats in Group 1 were subjected to double intranasal exposures to formalin-killed P. haemolytica A2 while goats in Group 2 were the unexposed control. Prior to and at weekly intervals post-exposure, three goats from each group were killed, serum samples were collected while the lungs were flushed with 50 ml normal saline before the right apical lobes were fixed in 10% buffered formalin. Both serum and lung lavage fluid were subjected to enzyme-linked immunosorbent assay (ELISA) to determine the levels of IgA, IgM and IgG while the formalin-fixed tissues were examined histologically. IgA levels in the lung lavage fluid increased rapidly to reach a significantly (p < 0.05) high level as early as Week 2 post-exposure and remained significantly (p < 0.05) high throughout the study period. The IgM levels increased at an intermediate rate to reach a significantly (p < 0.05) high level at Week 3 post-exposure before they decreased to an insignificant (p > 0.05) level the following week and the weeks thereafter. IgG levels increased gradually and only reached a significantly (p < 0.01) high level at Weeks 5 and 6 of the study. The size of the bronchus-associated lymphoid tissue (BALT) and the number of lymphocytes in BALT increased significantly from Week 2 and remained high thereafter. However, differences in the numbers of BALT were insignificant (p > 0.05) initially before becoming significantly (p < 0.05) high at Weeks 5 and 6. The BALT responses were parallel to those of imunoglobulins in the lung lavage fluid.

Phenotypic characterization of lymphocyte subpopulations in horses affected with chronic obstructive pulmonary disease and in normal controls

The alterations in lymphocyte subsets in chronic obstructive pulmonary disease (COPD) in the horse were investigated by using monoclonal antibodies to identify CD3+, CD4+, CD8+, and surface immunoglobulin positive (sIg+) lymphocytes in peripheral blood, bronchoalveolar lavage fluid (BALF), and pulmonary biopsy frozen tissue sections. COPD-affected horses (n = 5) and normal controls (n = 5) were sampled prestabling and 14 days poststabling, at which time the COPD-affected horses wee exhibiting clinical signs of COPD. The peripheral blood absolute CD4+ lymphocyte count was significantly elevated in the COPD-affected horses pre- and poststabling. The CD4:CD8 ratio in peripheral blood of COPD-affect horses was unaffected by stabling, but the same ratio in the control horses was significantly decreased. These findings support a hypothesis of deficient regulation of a systemic immune response to indoor air in the COPD-affected horses. A large population of leukocytes in pulmonary biopsy immunohistochemical sections from both groups of horses appeared to be CD3+ CD4- CD8-, an uncommon phenotype in both the peripheral blood and BALF.

Lesions of acute inhaled lethal ricin intoxication in rhesus monkeys

Five unimmunized adult rhesus monkeys weighing 5.9-6.3 kg were challenged with a precalculated, inhaled dose of 20.95-41.8 micrograms/kg of aerosolized ricin. Two males and three females either died or were killed at the onset of respiratory distress between 36 and 48 hours post-ricin inhalation and were necropsied. Consistent gross and microscopic lesions were confined to the thoracic cavity. All monkeys had multifocal to coalescing fibrinopurulent pneumonia, diffuse necrosis, and acute inflammation of airways, and nearly diffuse alveolar flooding, with peribronchovascular edema. All monkeys also had purulent tracheitis, fibrinopurulent pleuritis, and purulent mediastinal lymphadenitis. One male monkey and one female monkey had bilateral adrenocortical necrosis. We attributed the cause of death to asphyxiation following massive pulmonary alveolar flooding. The lesions of acute inhaled ricin intoxication in rhesus monkeys closely resembled those lesions reported in rats with acute inhaled ricin intoxication.

Contagious bovine pleuropneumonia in northern Tanzania, culture confirmation and serological studies

After an absence of about 25 years contagious bovine pleuropneumonia (CBPP) appeared again in 1990 in Tanzania. It was preceded by a spread in Kenya to an area bordering Tanzania. Due to the frequent cattle movements across the border it was soon introduced into Loliondo in northern Tanzania. One month after the first cases, CBPP was suspected in a total of 9 herds comprising 1,500 cattle. However, few animals showed clear clinical signs and frequent antibiotic treatment at an early stage further obscured the clinical picture. In one herd with acute cases, the diagnosis was confirmed by autopsy and Mycoplasma mycoides subsp. mycoides, SC type, was isolated. From this herd several serum samples were positive in the complement fixation test and gave high absorbance values in an ELISA with M. mycoides subsp. mycoides antigen. From 5 other herds with suspected cases blood samples were negative by the complement fixation test but in the enzyme-linked immunosorbent assay at least one in each herd was positive.

Gross and light-microscopic features of ovine pulmonary hydatidosis and verminous pneumonias in Morocco

Verminous pneumonias appear to be common in sheep in Morocco, therefore, a systematic study was undertaken to classify the pulmonary changes induced by various parasites in Morocco. A total of 613 pairs of lungs with parasitic pneumonias were diagnosed in 1152 young and adult sheep either slaughtered at two abattoirs in Morocco (487 out of 1152 sheep) or received at necropsy services (126 out of 1152 sheep) over a 15-month period. Based on gross and microscopic findings, four types of pulmonary changes were classified. Included were those associated with: 1. The larvae of Taenia echinococcus (Echinococcus granulosus (canine tapeworm); 520 out of 613 lungs (84.8%)); 2. Muellerius capillaris (450 out of 613 lungs (79.9%)); 3. Protostrongylus rufescens (375 out of 613 lungs (61.1%)); and 4. Dictyocaulus filaria (285 out of 613 lungs (46.4%)). Mixed infestations, involving the presence of two, three, or four species of parasites in the same lung, were encountered in 325 out of 613 (53%) lungs studied. Red-to-brownish consolidated areas, confined to the cranial parts of the lung, were observed frequently in some lungs affected with M. capillaris and P. rufescens. In most of the lungs, co-existent emphysematous, atelectatic, and abscessed areas were seen.

Distemper skin lesions in a dog

Skin lesions were studied in a 3-year-old male Maltese dog with distemper. Hyperkeratosis and parakeratosis with vesicles and pustule formation were the outstanding features of the skin lesions around the eye, nose, and mouth. Multinucleated syncytial giant cells together with nuclear and cytoplasmic inclusion bodies containing viral particles and viral antigen were scattered in the epidermis, and epidermal appendages. These findings suggest a direct viral attack on the skin.

Requirement for transcription factor IRF-1 in NO synthase induction in macrophages

Production of nitric oxide (NO) by macrophages is important for the killing of intracellular infectious agents. Interferon (IFN)-gamma and lipopolysaccharide stimulate NO production by transcriptionally up-regulating the inducible NO synthase (iNOS). Macrophages from mice with a targeted disruption of the IFN regulatory factor-1 (IRF-1) gene (IRF-1-/- mice) produced little or no NO and synthesized barely detectable iNOS messenger RNA in response to stimulation. Two adjacent IRF-1 response elements were identified in the iNOS promoter. Infection with Mycobacterium bovis (BCG) was more severe in IRF-1-/- mice than in wild-type mice. Thus, IRF-1 is essential for iNOS activation in murine macrophages.

Distribution of antigen in cattle infected with rinderpest virus

Five Holstein heifers (approximately 8 months of age and weighing 225-275 kg) were inoculated subcutaneously with 1,000 TCID50 of rinderpest virus, virulent Kabete O strain. They become clinically ill 2 to 5 days post-inoculation, with fever (40 C to 41.5 C), conjunctivitis, and diarrhea. All were euthanatized when moribund at 6 days postinoculation. The following tissues were collected in formalin, embedded in paraffin, and subsequently subjected to histopathologic and immunohistochemical examination: tongue, buccal mucosa, soft palate, esophagus, rumen, abomasum, duodenum, jejunum with and without Peyer's patch, ileum, cecum, proximal colonic lymphoid patch, spiral colon, eyelid, gall bladder, spleen, tonsil, trachea, lungs, and numerous lymph nodes. Immunohistochemical examination was accomplished using a primary rabbit anti-rinderpest antibody, and either a peroxidase-diaminobenzidine or alkaline phosphatase-Vector Red detection substrate system. In the lymph nodes, spleen, and tonsil, depletion of lymphocytes from all areas was extensive, with antigen most prominent in persisting reticular cells throughout the tissues. In the intestine, necrotizing and ulcerative changes in the mucosa were extensive and widespread. Damage was most severe in areas overlying lymphoid patches. In both small and large intestine, antigen was distributed predominantly in epithelial cells, histiocytic cells in the lamina propria, and in remaining reticular cells of lymphoid patches. In oral mucosa, there were multiple ulcerations and numerous multinucleate syncytial cells, both containing and without antigen. Lungs and trachea had subtle yet consistent necrosis of epithelial cells, with antigen often distributed in a circumferential manner in epithelium of bronchioles.

Infected cell types in ovine lung following exposure to bovine respiratory syncytial virus

Sixteen adult sheep (ten females, six males obtained from a closed flock at National Animal Disease Center, Ames, IA) were experimentally infected with bovine respiratory syncytial virus strain 375 (BRSV), and lung tissues were stained for viral antigen. Two infected sheep were euthanatized at each of the following post-inoculation times: 12, 24, 36, 48, 72, 96, 144, and 192 hours. Lung, nasal turbinates, trachea, right cranial bronchial and mediastinal lymph nodes, liver, and spleen were collected for histologic evaluation. An indirect immunoperoxidase technique was performed on routine paraffin-embedded sections of lung tissue, trachea, turbinates, and bronchial and mediastinal lymph nodes to determine the location of the BRSV antigen. For lung tissue from each sheep 400 light microscopic fields at 160x magnification were examined for staining for BRSV antigen. Lung tissue was also collected for virus and bacterial isolation. Daily serum samples were taken for determination of anti-BRSV titers. Severe respiratory disease was not produced in any sheep. Bovine respiratory syncytial virus was isolated from lung tissue collected from all sheep up through 144 hours post-inoculation. At 12 hours post-inoculation (case No. 2) respiratory syncytial virus antigen was detected in bronchiolar epithelium and a mononuclear cell within an alveolar space. Lung tissue from the sheep necropsied between 24 and 144 hours post-inoculation (case Nos. 3-14) contained BRSV antigen in bronchiolar epithelium, type I pneumocytes, type II pneumocytes, alveolar macrophages, and mononuclear cells within alveolar spaces. Macrophages staining for viral antigen were rare. Bronchiolar and type I epithelial cells comprised the majority of infected cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental reproduction of pneumonia in gnotobiotic pigs with porcine respiratory coronavirus isolate AR310

The pathogenicity of porcine respiratory coronavirus (PRCV) isolate AR310 was determined for gnotobiotic pigs. PRCV-AR310 was isolated from the intestines of a nursery pig from a herd with endemic transmissible gastroenteritis. The AR310 isolate was plaque purified and cell culture propagated, passed once in a gnotobiotic pig, then used as inoculum for a gnotobiotic pig pathogenicity study. Eight pigs were inoculated oronasally with 2 x 10(6) plaque-forming units of PRCV-AR310. Eight pigs served as controls and received cell culture medium. Two pigs from each group were necropsied at 3, 5, 10, and 15 days postinoculation (DPI). There was moderate multifocal to coalescing reddish tan consolidation of 60% of the lung by 10 DPI. Microscopic examination revealed a necrotizing and proliferative bronchointerstitial pneumonia characterized by necrosis, squamous metaplasia, dysplasia, proliferation of airway epithelium, mononuclear cell infiltration of alveolar septa, mild type II pneumocyte proliferation, and lymphohistiocytic alveolar exudation. The microscopic lesions were mild by 3 DPI, moderate by 5 DPI, severe by 10 DPI, and mostly resolved by 15 DPI. No lesions were observed in the intestines of these pigs. There was no clinical respiratory disease. Control pigs remained normal and had no lesions. PRCV was isolated from the lungs but not from the intestines of inoculated pigs. PRCV was not isolated from the lungs or intestines of control pigs. PRCV was also isolated from the nasal and rectal swabs of inoculated but not of control pigs.

Histopathologic lesions in sea otters exposed to crude oil

Following the Exxon Valdez oil spill in Prince William Sound, Alaska, sea otters (Enhydra lutris) that appeared to be contaminated with oil, that were in danger of becoming contaminated, or that were behaving abnormally were captured and taken to rehabilitation centers. Exposure to oil was assessed by visual examination when otters arrived at the centers. Degree of oil exposure was graded according to the following criteria: oil covering greater than 60% of the body--heavily contaminated; oil covering 30-60% of the body--moderately contaminated; oil covering less than 30% of the body or light sheen on fur--lightly contaminated. If there was no oil visible, otters were considered uncontaminated. Tissues from 51 oil-contaminated sea otters (14 males, 37 females) and from six uncontaminated sea otters (three males, three females) that died in rehabilitation centers were examined histologically. Among oil-contaminated sea otters, 19/46 had interstitial pulmonary emphysema, 13/40 had gastric erosion and hemorrhage, 11/47 had centrilobular hepatic necrosis, 14/47 had periportal to diffuse hepatic lipidosis, and 10/42 had renal tubular lipidosis. Of the uncontaminated sea otters, 1/6 had gastric erosion and hemorrhage and 1/6 had diffuse hepatic lipidosis. Histologic examinations were performed on tissues from five sea otters (three males, two females) found dead with external oil present 15 to 16 days after the spill. Periportal hepatic lipidosis and renal tubular lipidosis were found in 3/5, and interstitial pulmonary emphysema was found in 1/5. Tissues from six apparently normal sea otters (four males, two females) collected from an area not affected by an oil spill were examined histologically, and none of these lesions were found. We conclude that interstitial pulmonary emphysema, centrilobular hepatic necrosis, and hepatic and renal lipidosis of sea otters were associated with exposure to crude oil. Gastric erosion and hemorrhage may have been associated with stress of captivity and/or oil exposure.

A slaughterhouse survey of lung lesions in goats

A survey of the lungs from 4284 goats killed at a slaughterhouse in the North Island of New Zealand during the winter of 1990 revealed only ten cases of non-parasitic bronchopneumonia. However, 41% of the lungs had lesions consistent with infection by Muellerius capillaris, 33% with Dictyocaulus filaria, and 8% with both species. The prevalence of parasitic lesions increased with age. The carcasses of goats with mild to severe Dictyocaulus filaria lesions were from 0.81 to 1.52 kg lighter than those without the lesions (p<0.001). The carcasses of goats with more than ten nodular (Muellerius capillaris) lesions were 0.75 kg lighter than those without the lesions (p<0.001). Twelve sets of lungs had lesions of chronic bronchiectasis. Nematode larvae were seen in the bronchial lumina of three of them. The microscopic appearance varied from a moderate dilatation of occluded bronchi which retained an intact epithelium, to large foreign-body granulomas where the remaining bronchial outlines were barely discernible. Multiple, very discrete, fibrous pleural plaques were found on the caudal lobes in two cases. Plaques of this morphology have not been described previously in the veterinary literature. Pleural adhesions were found in 350 cases (8.2%). The relatively higher frequency of pleurisy versus non-parasitic pneumonia suggests that pneumonia in goats in the North Island of New Zealand completely resolves in most cases.

Retrospective study of testicular degeneration in raccoons with canine distemper infection

A 6-year (1985-1990) retrospective survey of raccoons with canine distemper infection and an outbreak of the disease in 1988 on South Island, South Carolina, are described. During this epizootic, 3 male raccoons with the clinical disease had gross testicular lesions that, on histopathologic examination, revealed severe diffuse degeneration and mineralization of seminiferous tubules. The testicular pathology of canine distemper in raccoons has not been previously reported.

Pulmonary inflammation associated with aspirated meconium and epithelial cells in calves

"Meconium aspiration syndrome" is a condition resulting in respiratory distress and the occasional death of newborn human beings. A retrospective study was conducted on 52 calves that were submitted for postmortem examination to the Atlantic Veterinary College, Charlottetown, Prince Edward Island, Canada. These calves died of infectious and noninfectious diseases within the first 2 weeks of life due to a variety of causes. The most common cause of death was infectious enteric disease. Histologic examination of lungs revealed that 42.5% of calves had evidence of meconium, squamous cells, or keratin in the lung. There was considerable variation in the magnitude of histologic changes in lungs containing aspirated material. Typically, affected lungs had only a few inconspicuous pieces of meconium, keratin, and squamous cells within bronchoalveolar spaces. Sporadically, the entire lumen of airways was obliterated by aspirated material. Lungs with aspirated material had a mild but diffuse alveolitis characterized by exudation of a few neutrophils, macrophages, and occasional multinucleated giant cells. Obstruction of small airways and focal atelectasis were also observed. Similar lesions have been reported in human meconium aspiration syndrome. It is concluded that histologic changes similar to those of human meconium aspiration syndrome occur commonly in calves that die within 2 weeks of birth. Further studies involving healthy age-matched calves are required to evaluate the clinicopathologic significance of meconium aspiration in this species.

Pathologic and immunocytochemical studies of morbillivirus infection in striped dolphins (Stenella coeruleoalba)

Hundreds of striped dolphins (Stenella coeruleoalba) died along the Spanish Mediterranean coast during the second half of 1990. We necropsied 58 dolphins. Partial collapse of the lungs with patchy atelectasis, subcutaneous edema, icterus, and stomatitis were the most prominent gross morphologic changes. Histologically, a bronchiolo-interstitial pneumonia was the most frequent lesion (72% of the animals). It was characterized by hyperplasia of alveolar epithelial type II cells and formation of multinucleate syncytia in alveolar and bronchiolar lumina. Other prominent lesions were encephalitis (69%), lymphoid depletion, and formation of multinucleate syncytia in the cortex of lymph nodes. The distribution of morbillivirus antigen was investigated in 23 well-preserved dolphins using a monoclonal antibody against the hemagglutinin glycoprotein of phocine distemper virus. Positive immunostaining was found in brain (77%), in lung (70%), and in mesenteric (61%), mediastinal (47%), and prescapular (45%) lymph nodes. Phocine distemper virus antigen was demonstrated less frequently in trachea, stomach, biliary epithelium, intestine, kidney, and mammary gland. Necrotizing-hemorrhagic pneumonia and encephalitis due to Aspergillus fumigatus were seen in three dolphins, whereas two animals had lesions of toxoplasmosis. Changes in our dolphins were similar to those caused by distemper in seals and porpoises. The origin of the dolphin virus and the relationships among dolphin, seal, and porpoise morbilli viruses are unknown.

Effects of 4-ipomeanol on bovine parainfluenza type 3 virus-induced pneumonia in calves

Previous research has demonstrated that 4-ipomeanol toxicosis can enhance the severity of para-influenza virus-induced pneumonia in mice. The objectives of this study were to determine whether calves are susceptible to 4-ipomeanol-induced enhancement of parainfluenza type 3 viral pneumonia and to determine whether 4-ipomeanol alters pulmonary replication of parainfluenza virus. Male Holstein calves were injected with either 4-ipomeanol (3 mg/kg) or vehicle (polyethylene glycol) 3 days prior to intratracheal inoculation with either parainfluenza virus or sham inoculum of culture medium. Calves in the four treatment groups (ipomeanol-parainfluenza, ipomeanol-medium, vehicle-parainfluenza, and vehicle-medium) were necropsied at 5 days after inoculation with parainfluenza virus or medium. The lungs were studied by correlated methods of light and electron microscopy, digitizing morphometry and pulmonary lavage to quantitate the severity of pneumonia. Pulmonary viral titers were determined, and viral antigen was identified in the lung by immunoperoxidase technique. The calves in the ipomeanol-virus treatment group had over a 9-fold higher (P less than 0.05) volume density of virus-induced interstitial pneumonia than did the calves in the other three treatment groups. This 4-ipomeanol-enhanced viral pneumonia was associated with significantly greater (P less than 0.05) numbers of pulmonary macrophages and neutrophils in the lavage fluid and higher (P less than 0.05) pulmonary titers of pulmonary infectious parainfluenza virus. Four-ipomeanol-enhanced viral pneumonia was characterized in part by extensive hyperplasia of type II alveolar epithelial cells and by dense aggregates of macrophages and neutrophils in alveolar spaces and interalveolar septa. The results indicate that 4-ipomeanol exacerbates interstitial pneumonia in calves induced by bovine parainfluenza type 3 virus.

Expression and kinetics of induced procoagulant activity in bovine pulmonary alveolar macrophages

Leukocytes, especially macrophages, are important cellular mediators of fibrin deposition and removal at tissue sites of inflammation. Pulmonary fibrin deposition is a prominent feature of bovine acute lung injury; therefore, we studied the resting and stimulated procoagulant responses of bovine pulmonary alveolar macrophages (PAM) and peripheral blood neutrophils (PMN). Freshly isolated normal PAM and PMN expressed negligible procoagulant activity. PAM stimulated with endotoxin lipopolysaccharide (LPS), 4 beta-phorbol 12-myristate 13-acetate (PMA) and bovine recombinant interleukin-1 beta (rBIL-1 beta) exhibited protein synthesis- and dose-dependent enhancement of procoagulant activity in 8-h cultures. Bovine recombinant granulocyte macrophage-colony stimulating factor (rBGM-CSF) and recombinant human gamma-interferon (rHIFN-gamma) did not induce procoagulant activity. The kinetics of LPS- and PMA-enhanced PAM procoagulant activity differed: LPS-induced enhancement developed earlier and more rapidly than PMA-induced enhancement. Pasteurella haemolytica LPS was more potent than Escherichia coli LPS in enhancing PAM procoagulant activity, while dexamethasone decreased both baseline and LPS- or PMA-stimulated activity by approximately 50%. PAM procoagulant activity resulted from tissue factor expression. Bovine PMN produced negligible procoagulant activity when stimulated, and are thus unlikely to be major contributors to procoagulant activity in bovine lung. Activity inhibitory to bovine tissue factor was present in both calf and adult sera, and was partly dependent on the presence of factor X for activity. Rapid induction of bovine PAM procoagulant activity by inflammatory mediators, and subsequent resistance to degradation, may thus combine to promote an alveolar microenvironment permissive to fibrin deposition in bovine acute lung injury.

An immunohistochemical study of the pneumonia caused by peste des petits ruminants virus

Ten goats were inoculated with peste des petits ruminants virus, a paramyxovirus closely related to rinderpest virus. All goats developed severe clinical disease, 8/10 having coughing or dyspnea as prominent clinical signs. In addition, all of the goats had stomatitis and diarrhea. Histopathologic and immunohistochemical studies were done only on the respiratory tracts. Pathologic changes ranged from mild multifocal bronchiolitis and bronchitis to severe bronchointerstitial pneumonia. Lesions were more severe in anteroventral than caudal lobes. The histologic nature of the viral process in the goat lungs had many features in common with the processes of pneumonia in dogs, due to canine distemper, or pneumonia in human beings, due to measles virus. Immunohistochemical staining of formalin-fixed, paraffin-embedded respiratory tract tissue was performed using an indirect system with rabbit anti-rinderpest virus serum, biotinylated anti-rabbit antibody, streptavidin-alkaline phosphatase, and nitroblue tetrazolium chromogen. Staining was sensitive, highlighting the presence of viral antigen in both lung and trachea of all goats. Viral antigen was found in both cytoplasm and nucleus of tracheal, bronchial, and bronchiolar epithelial cells, type II pneumocytes, syncytial cells, and alveolar macrophages. In general, the amount of staining correlated directly with the severity of the inflammatory process.

Histopathologic and immunocytochemical studies of distemper in harbor porpoises

During 1988 thousands of harbor seals (Phoca vitulina) died in European seas as a result of morbillivirus infection. Six harbor porpoises (Phocoena phocoena) found stranded on the coast of Northern Ireland in late 1988 were submitted to our laboratory for necropsy. Pneumonia was the main necropsy finding in three of these animals. Microscopic lung lesions characterized by necrosis of bronchial and bronchiolar epithelium and infiltration of alveoli with leukocytes, lymphoid cells, macrophages, and multinucleate syncytia were seen in all six porpoises. Cytoplasmic and nuclear acidophilic inclusions characteristic of morbillivirus infection were common in bronchial and bronchiolar epithelial cells and in alveolar macrophages and syncytia. Brain alterations included degeneration and necrosis of neurons, microglial infiltration, and perivascular cuffing. There were cytoplasmic and nuclear acidophilic inclusions in many neurons. Immunoperoxidase staining of morbillivirus antigen was seen in many tissues including lung, brain, spleen, and urinary bladder. Alterations in our porpoises were similar to those seen in distemper in seals and many species of terrestrial mammals. Systemic viral disease has not previously been documented in Cetacea.

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.

Cor pulmonale in an Angus cow

Cor pulmonale was diagnosed in a 4-year-old beef cow at pasture. Clinical and pathological evidence for the diagnosis included ventral oedema, respiratory distress, chronic interstitial pneumonia and cardiac failure. The cause of the pneumonia was not identified.

Evaluation of ethylenediaminetetraacetic acid, tetrasodium salt dihydrate (EDTA)-Tween 20 treatment versus protease digestion of formalin-fixed tissue sections for detection of bovine respiratory syncytial virus antigen in infected ovine lung

The efficacy of protease and ethylenediaminetetraacetic acid, tetrasodium salt dihydrate (EDTA)-Tween 20 in unmasking bovine respiratory syncytial virus (BRSV) antigens in formalin-fixed lung tissue was compared using avidin-biotin immunoperoxidase procedure. Tissues were taken from experimentally infected lambs. BRSV antigen stained in both techniques. Treatment with EDTA-Tween 20 resulted in more intense staining of BRSV infected cells, more uniform cytoplasmic staining, less non-specific background, and superior cellular detail in comparison to protease digestion.

Histopathologic and immunocytochemical studies of distemper in seals

Thousands of harbor seals (Phoca vitulina) died in European seas during 1988. Respiratory distress and oculonasal discharge were common clinical signs. We necropsied 76 affected seals. The main necropsy finding was severe pneumonia. Microscopic lung changes were characterized by proliferation of type II pneumocytes, filling of alveolar lumina with serofibrinous exudate, leukocytes, and macrophages, and necrosis of bronchial and bronchiolar epithelium. Intracytoplasmic and intranuclear acidophilic inclusion bodies characteristic of morbillivirus infection were seen in bronchial and bronchiolar epithelial cells. Microscopic lesions of non-suppurative demyelinating encephalitis were seen in the brain. There was degeneration and necrosis of neurons, focal gliosis, perivascular cuffing, and patchy demyelination. Many neurons and astrocytes contained intracytoplasmic and intranuclear inclusions. Using an immunoperoxidase technique, we detected morbillivirus antigen in many tissues including lung, brain, spleen, and urinary bladder. The origin of the seal morbillivirus is unknown.

Upper respiratory tract infection in mouse and rats

Spontaneous aspergilloma in the para-nasal cavities of 2 rats, and a chronic granuloma with grains, caused by Gram-positive cocci in the maxillary sinus of a mouse, are reported.

Cryptococcosis of the nasopharynx in mice and rats

An attempt to infect the upper respiratory tract of mice and rats with various bacteria and fungi by intranasally instillation was performed. Cryptococcus neoformans was the only agent to invade the tissue. The infection was limited to the nasopharynx, a phenomenon which probably indicates the presence of a specific chemotaxis or receptor.