Cytological Analysis of Bronchoalveolar Lavage Fluid in the Diagnosis of Spontaneous Respiratory Tract Disease in Dogs: A Retrospective Study

Results of cytological analysis of bronchoalveolar lavage (BAD fluid were compared with clinical diagnoses in dogs that presented with signs of respiratory disease to referral hospitals. Of 68 dogs in which a clinical diagnosis was possible, BAL cytological findings were considered definitive for the diagnosis in 17 cases (25%), supportive of the diagnosis in 34 cases (50%), and not helpful in 17 cases (25%). Findings were most often considered supportive of or definitive for the clinical diagnosis in dogs with alveolar or bronchial radiographic patterns, or the presence of pulmonary masses. BAL results among lung lobes differed in 23 of 63 dogs (37%) with diffuse radiographic patterns. Tracheal wash cytology differed from BAL fluid cytology in 45 of 66 dogs (68%). Bronchoalveolar lavage was a clinically useful procedure for the diagnostic evaluation of dogs with signs of respiratory disease.     

Injury versus inflammatory response in the lungs of rats intratracheally inoculated with bacterial lipopolysaccharide

The relationship between acute pulmonary cell injury and inflammatory response was investigated in rats killed 1, 3, and 7 days after intratracheal inoculation with bacterial lipopolysaccharide (LPS). Activities of lactate dehydrogenase (LDH) and alkaline phosphatase (AP) in bronchoalveolar lavage (BAL) fluid and bronchoalveolar cell (BAC) lysate supernatants were used as indicators of cell injury in the lung. Concentrations of protein in BAL fluid and the number and types of BAC were used as indicators of pulmonary inflammatory response. The magnitude of inflammation and cell injury was calculated as the percentage difference of cellular and biochemical values, compared with values of nontreated controls. Inoculation with LPS induced a significant and dramatic (greater than 18,000%) influx of polymorphonuclear leukocytes (PMN) and a mild (approx 250%) increase in pulmonary alveolar macrophages. A moderate, significant and time-dependent increase in LDH (up to approx 260%) and AP (up to approx 220%) was detected in BAL fluid and BAC lysate supernatants after LPS inoculations. Inoculation with saline solution alone resulted in increased PMN (approx 975%), but did not alter LDH and AP values. In all rats evaluated, protein concentrations did not change. Numbers of PMN significantly and positively correlated with activities of LDH and AP. Protein concentrations and PMN counts had a negative nonsignificant association. Evidence of further cell injury was not detected after massive influx of PMN into the bronchoalveolar space. Therefore, the cellular influx of PMN induced by LPS probably was disproportionate to the magnitude of pulmonary cell injury.     

Using urea dilution to standardise cellular and non-cellular components of pleural and bronchoalveolar lavage (BAL) fluids in the cat

A technique to standardise the analysis of cellular and non-cellular components in epithelial lining fluid (ELF) collected during saline lavage of pulmonary and pleural cavities was developed using the urea dilution method. Bronchoalveolar lavage (BAL) and pleural lavage (PL) fluids were collected from 12 clinically healthy cats. Total and differential cell counts in BAL fluid were within normal ranges for the cat, while cell counts in PL fluid were assumed to be normal based on clinical health during examination, auscultation and lactate dehydrogenase (LDH) activities being comparable with other species. The major clinical implication of this study was that nucleated cell counts within feline ELF could not be predicted from analysis of lavage fluid which suggests that calculation of the proportion of ELF in lavage fluid by the urea dilution method may be necessary to avoid misdiagnosis of health or disease in pulmonary or pleural cavities.     

Effects of inhalation of dust and endotoxin on respiratory tracts of pigs.

OBJECTIVE: To assess the effects of inhalation of feed flour dust and dustborne endotoxin on respiratory tracts of pigs. ANIMALS: 29 healthy Belgian Landrace pigs. PROCEDURE: Pigs housed in an environmental chamber were exposed for 6 days to feed flour dust (1 to 15 mg/m3) and dustborne endotoxins (50 to 2,500 ng/m3). Effects were evaluated by measuring albumin concentration, lactate dehydrogenase (LDH) activity, cell composition of nasal lavage (NL) and bronchoalveolar lavage (BAL) fluids and blood, and percentages of CD4+ and CD8+ T lymphocytes in blood and lavage fluids. Dustborne endotoxin was obtained by mixing endotoxins from Escherichia coli (serotype O127:B8) with feed flour before spraying the flour in the environmental chamber. RESULTS: Exposure did not affect cell composition of NL fluid or blood. Total cell counts of BAL fluids were increased in all groups exposed to dust. Macrophage counts were increased in pigs exposed to inhalable dust concentrations as low as 4.4 mg/m3, and lymphocyte counts were increased in groups exposed to high dust concentrations. Percentages of CD4+ and CD8+ T lymphocytes in blood and lavage fluids were unchanged. In all dust-exposed groups, albumin content of BAL fluid was increased, whereas LDH activity was unaffected. Macrophage and lymphocyte infiltration and edema in the bronchi were identified by light microscopy. Effects attributable to E. coli endotoxin exposure were not identified. CONCLUSIONS: Inhalation of feed flour dust did not affect nasal mucosa but did induce bronchial airway inflammation. Dustborne endotoxins did not have effects attributable to endotoxin alone.     

Comparison of results of thoracic radiography, cytologic evaluation of bronchoalveolar lavage fluid, and histologic evaluation of lung specimens in dogs with respiratory tract disease: 16 cases (1996-2000)

OBJECTIVE: To compare results of thoracic radiography, cytologic evaluation of bronchoalveolar lavage (BAL) fluid, and histologic evaluation of biopsy and necropsy specimens in dogs with respiratory tract disease and to determine whether histologic evaluation provides important diagnostic information not attainable by the other methods. DESIGN: Retrospective study. ANIMALS: 16 dogs. PROCEDURE: BAL fluid was classified as normal, neutrophilic, eosinophilic, mononuclear, mixed, neoplastic, or nondiagnostic. Radiographic abnormalities were classified as interstitial, bronchial, bronchointerstitial, or alveolar. Histologic lesions were classified as inflammatory, fibrotic, or neoplastic, and the predominant site of histologic lesions was classified as the alveoli, interstitium, or airway. RESULTS: The predominant radiographic location of lesions correlated with the histologic location in 8 dogs. Of 11 dogs with histologic evidence of inflammatory disease, 8 had inflammatory BAL fluid. Of the 2 dogs with histologic evidence of neoplasia, 1 had BAL fluid suggestive of neoplasia, and the other had BAL fluid consistent with septic purulent inflammation. Two dogs without any histologic abnormalities had mononuclear or nondiagnostic BAL fluid. Two dogs with histologic evidence of fibrosis had mononuclear or mixed inflammatory BAL fluid. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that although thoracic radiography, cytologic evaluation of BAL fluid, and histologic evaluation of lung specimens are complementary, each method has limitations in regard to how well results reflect the underlying disease process in dogs with respiratory tract disease. Lung biopsy should be considered in cases where results of radiography and cytology are nondiagnostic.     

Changes in blood and bronchoalveolar lavage fluid components in calves with experimentally induced pneumonic pasteurellosis

Pneumonic pasteurellosis was experimentally induced in calves by inoculation of 5 x 10(8) Pasteurella haemolytica organisms into the right diaphragmatic lung lobe. Blood and bronchoalveolar lavage fluid samples were obtained prior to inoculation and at postinoculation hour (PIH) 2, 4, and 6. Calves developed acute lung injury, characteristic of pneumonic pasteurellosis. Lesions were found only in the right diaphragmatic lobe. By PIH 4, significant (P less than 0.01) increases were detected in lavage fluid total cell count, neutrophil count, total protein and albumin concentrations, and alkaline phosphatase (ALP) and lactic dehydrogenase (LD) activities. Myeloperoxidase and elastase activities did not increase. Neutrophil depletion ameliorated the lung lesions and prevented the increase in lavage fluid cell count, total protein, and albumin concentrations and ALP and LD activities. Treatment with the iron chelator, deferoxamine mesylatehydroxyethyl starch, attenuated the increase in total protein and albumin concentrations and ALP and LD activities at PID 4, but not PIH 6. Treatment with a neutrophil function inhibitor, pentoxifylline, prevented the increase in lavage fluid neutrophil numbers, but accentuated the increase in total protein and albumin concentrations, and ALP, LD, myeloperoxidase, and elastase activities.     

Serum liver enzyme activities in healthy Miniature Schnauzers with and without hypertriglyceridemia

OBJECTIVE: To determine whether hypertriglyceridemia in healthy Miniature Schnauzers is associated with high serum liver enzyme activities. DESIGN: Cross-sectional study. ANIMALS: 65 Miniature Schnauzers with serum triglyceride concentrations within the reference range (group 1), 20 Miniature Schnauzers with slightly high serum triglyceride concentrations (group 2), and 20 Miniature Schnauzers with moderately to severely high serum triglyceride concentrations (group 3). PROCEDURES: Questionnaires regarding each dog's medical history were completed, and serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and G-glutamyltransferase (GGT) activities were measured. RESULTS: Median serum ALP activity was significantly higher in group 3 than in group 1 or 2 dogs, but was not significantly higher in group 2 than in group 1 dogs. Median serum ALT activity was significantly higher in group 3 than in group 1 dogs, but was not significantly different between any of the other groups. Compared with group 1 dogs, group 2 and 3 dogs were significantly more likely to have high serum ALP activity (odds ratio, 26.2 and 192.6, respectively). Group 3 dogs also were significantly more likely to have high serum ALT activity (odds ratio, 8.0), serum AST activity (odds ratio, 3.7), and serum GGT activity (odds ratio, 11.3), compared with group 1 dogs. Group 3 dogs were significantly more likely (odds ratio, 31.0) to have > or = 2 high serum liver enzyme activities than were group 1 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that moderate to severe hypertriglyceridemia was associated with high serum liver enzyme activities in Miniature Schnauzers.     

Thoracic radiography,bronchoalveolar lavage cytopathology,and pulmonary parenchymal histopathology: a comparison of diagnostic results in 11 cats

The purpose of this study was to compare the diagnostic results and value of thoracic radiography, bronchoalveolar lavage (BAL) fluid cytopathology, and lung histopathology in 11 cats with spontaneous respiratory disease in which radiography and cytopathology were inadequate in establishing a definitive diagnosis. In these cats, radiographic patterns were characterized as bronchial (n=6), interstitial (n=3), and alveolar (n=2); other features included hyperinflation (n=3), bronchiectasis (n=2), pleural fissure lines (n=2), pulmonary nodules (n=2), atelectasis (n=1), and a tracheal mass (n=1). Bronchoalveolar lavage fluid was unremarkable in two cats. Abnormal BAL fluid showed inflammation (n=5), hemorrhage (n=2), epithelial hyperplasia (n=1), or was suspicious for neoplasia (n=1). Histopathological evaluation revealed inflammation (n=8), neoplasia (n=2), and vascular congestion (n=1). The predominant radiographic location of disease correlated with the same histopathological location in seven cats, and the cytopathological class of BAL fluid was consistent with the histopathological class of disease in seven cats. There was poor correlation between the types of cells found in the BAL fluid and the pathologist's prediction of the types of cells likely to be found in the BAL fluid based on the amount and type of airway cellularity seen on histopathological examination. The results of this study suggest that in some cats, BAL fluid cytopathology does not always correlate with the type of pulmonary disease identified on histopathology. In respiratory diseases where radiography and cytopathology fail to provide a definitive diagnosis, histopathological examination of the lung may be necessary.     

Differential cell counts in canine cytocentrifuged bronchoalveolar lavage fluid: a study on reliable enumeration of each cell type

Background: Bronchoalveolar lavage (BAL) allows cell recovery from the lower respiratory tract; differential cell counts of BAL fluid gives important information in the assessment of various bronchial and pulmonary diseases. To the best of our knowledge no study has investigated the relation between the number of cells counted and the reproducibility of BAL fluid differential cell counts. Objective: The purpose of this study was to investigate using statistical methods how many cells should be counted in cytocentrifuged BAL fluid preparations in order to obtain a reliable enumeration of each cell type. Methods: BAL fluid samples from dogs with suspected bronchopulmonary disease were obtained during fiberoptic bronchoscopy with a standardized protocol. Differential cell counts were performed on May–Grünwald–Giemsa‐stained cytocentrifuged preparations by 2 independent observers. Reproducibility for the enumeration of each cell type was expressed as the intraclass correlation coefficient. We considered a threshold level of ≥0.90 to be high and a threshold level of ≥0.85 to be adequate. Results: Forty BAL fluid samples were included in the study. For neutrophils, alveolar macrophages, and eosinophils high reproducibility was reached by counting 200 cells; adequate reproducibility was reached for lymphocytes and bronchial epithelial cells by counting 500 cells. Conclusions: A 500‐cell differential count is required for all types of cells to be quantified with adequate reproducibility in canine cytocentrifuged BAL fluid samples.     

Comparison of bronchoalveolar lavage and respiratory secretion cytology in horses with clinically diagnosed chronic pulmonary disease

Thirty-nine horses and 3 ponies underwent a thorough respiratory examination and were grouped as follows: healthy (4 horses and 1 pony); mild chronic pulmonary disease (CPD 11 horses); moderate CPD (16 horses and 1 pony); and severe CPD (8 horses and 1 pony). Bronchoalveolar lavage (BAL) fluid collected from all animals and respiratory secretions (RS) obtained from 39 of these animals were evaluated cytologically and the results were compared. It was concluded that cytological examination of either BAL fluid or RS was useful in diagnosing various equine pulmonary diseases. The only advantage that BAL offered over RS sampling was in cases in which there was no RS available in the trachea. In addition, the severity of the CPD did not always correlate with either RS or BAL cytology.     

Use of a modified stomach tube for bronchoalveolar lavage in dogs

A technique that did not require use of a bronchoscope for bronchoalveolar lavage (BAL) in dogs was developed. An inexpensive, readily available 16-F Levin-type stomach tube was modified for the procedure. The technique was effective for collecting BAL fluid in 9 dogs that ranged from 9.3 to 26.2 kg (20.5 to 57.6 lb). Recovered fluid was consistent with fluid collected bronchoscopically. Mean recovery volume was 84/125 ml (67%), mean WBC counts were high (> 300 cells/microl), and > 70% of cells were macrophages. Complications from use of the technique were not detected on the basis of pulse oximetry, thoracic radiography, and clinical observation. This effective, simple, and safe technique for BAL can be readily performed in clinical settings that do not have bronchoscopic capabilities. It also provides a less costly alternative than bronchoscopic BAL.     

Quantitative bacterial cultures and cytological examination of bronchoalveolar lavage specimens in dogs

Cytology and quantitative bacterial cultures of lower respiratory tract secretions are widely used in human medicine to differentiate airway infection from simple bacterial colonization. A retrospective study was conducted to determine the usefulness of quantitative aerobic cultures and Gram stain intracellular bacteria counts from bronchoalveolar lavage (BAL) specimens in dogs in diagnosing lower respiratory tract infection (LRTI) and to determine whether chronic bronchitis is associated with marked bacterial growth in dogs. The threshold determined to define clinically relevant bacterial growth was 1.7 x 10(3) colony-forming units per milliliter of BAL fluid. We used this threshold and found that diagnostic sensitivity and specificity were 86% and 100%, respectively. With a threshold for infection of >2 intracellular bacteria observed in any of 50 fields, microscopic examination of Gram stain BAL preparations had a sensitivity of 71% and a specificity of 97% in establishing LRTI. There was a high correlation between bacterial morphology on BAL Gram stain and bacterial cultures. Combining the results of intracellular bacteria counts from the BAL Gram stain with those from the quantitative cultures, the sensitivity in diagnosing LRTI was 87% and the specificity was 97%. BAL quantitative cultures as well as quantitating intracellular bacteria on Gram stain BAL cytology were revealed to be useful in identifying LRTI in dogs. Chronic bronchitis does not appear to be associated with marked bacterial growth in dogs.     

Using urea dilution to standardise components of pleural and bronchoalveolar lavage fluids in the dog

AIM: To develop a technique to estimate the volume of epithelial lining fluid (ELF) obtained during bronchoalveolar lavage (BAL) and pleural lavage (PL) in the dog, using the urea dilution method. METHODS: BAL and PL fluids were obtained by saline lavage of pulmonary and pleural cavities of nine clinically healthy mixed-breed dogs immediately after euthanasia. Cell counts in the BAL and PL fluids were measured using standard techniques. The concentration of ELF in each lavage fluid was calculated from the relative concentration of urea in plasma and in each type of lavage fluid. Cell counts in ELF were then calculated. RESULTS: There were substantially higher cell counts in ELF compared to BAL or PF fluid. However, nucleated cell counts in ELF could not be predicted from cell counts in BAL or PL fluid. CONCLUSIONS AND CLINICAL RELEVANCE: These results suggest that accurate assessment of cellular or non-cellular components in lavage fluids should include a calculation of the proportion of ELF recovered, using a method such as urea dilution.     

Using urea dilution to standardise components of pleural and bronchoalveolar lavage fluids in the dog

AIM: To develop a technique to estimate the volume of epithelial lining fluid (ELF) obtained during bronchoalveolar lavage (BAL) and pleural lavage (PL) in the dog, using the urea dilution method.

METHODS: BAL and PL fluids were obtained by saline lavage of pulmonary and pleural cavities of nine clinically healthy mixed-breed dogs immediately after euthanasia. Cell counts in the BAL and PL fluids were measured using standard techniques. The concentration of ELF in each lavage fluid was calculated from the relative concentration of urea in plasma and in each type of lavage fluid. Cell counts in ELF were then calculated.

RESULTS: There were substantially higher cell counts in ELF compared to BAL or PF fluid. However, nucleated cell counts in ELF could not be predicted from cell counts in BAL or PL fluid.

CONCLUSIONS AND CLINICAL RELEVANCE: These results suggest that accurate assessment of cellular or non-cellular components in lavage fluids should include a calculation of the proportion of ELF recovered, using a method such as urea dilution.     

The importance of interleukin-8 as a neutrophil chemoattractant in the lungs of cattle with pneumonic pasteurellosis.

Interleukin-8 (IL-8), an in vitro and in vivo neutrophil chemoattractant, is expressed at high levels in the lesions observed in bovine pneumonic pasteurellosis. Because of the role of neutrophils in the pathogenesis of pneumonic pasteurellosis, we investigated the relative importance of IL-8 as a neutrophil chemoattractant in this disease. Bronchoalveolar lavage (BAL) fluid was harvested from calves experimentally infected with bovine herpesvirus-1 and challenged with Mannheimia haemolytica. Neutrophil chemotactic activity was measured in pneumonic BAL fluid samples treated with a neutralizing monoclonal antibody to ovine IL-8, and compared to the activity in samples treated with an isotype-matched control antibody. Bronchoalveolar lavage fluid was analyzed at a dilution which induced a half-maximal response, and the concentrations of antibody were optimized in a preliminary experiment. Following incubation of replicate samples of diluted pneumonic bovine BAL fluid with 70 microg/mL of IL-8-neutralizing antibody or control antibody, the neutrophil chemotactic activities of the samples were determined using an in vitro microchemotaxis assay. Overall, pretreatment of BAL fluid samples with neutralizing anti-IL-8 antibody reduced neutrophil chemotactic activity by 15% to 60%, compared to pretreatment with control antibody. This effect was highly significant (P < 0.001), and was present in 5 of 5 samples. These data indicate that IL-8 is an important neutrophil chemoattractant in calves with pneumonic pasteurellosis, but that mediators with actions redundant to those of IL-8 must also be present in the lesions.     

Some enzyme interrelationships in serum and organs of Egyptian camel

In 7 normal healthy Egyptian one-humped camels aged 3-4 years, the relationships were studied between enzyme activities of lactic dehydrogenase (LDH), creatine phosphokinase (CPK), alkaline phosphatase (ALP), acid phosphatase (ACP), and cholonesterase (CHE) of serum and organs as well as between ACP and ALP and between LDH and CPK. Liver, heart, kidney, and spleen tissue samples as well as serum were analysed for total enzyme activity. The following results were obtained: --The heart was the organ with the highest activities of ALP, LDH, and CPK, and it contained high values of CHE, whereas the lowest activities of all enzymes were recorded from serum. The spleen exhibited of the highest activity of ACP. --Each of the serum enzymes ALP, LDH, and CHE were in strong inverse relationship with the corresponding enzymes in the liver. Strong inverse relationships existed also between serum LDH and kidney LDH as well as between CPK in serum and heart. --Direct relationships were remarkable serum LDH and that of spleen and heart as well as between serum ACP and that of liver and heart. --Interrelationships were inverse between ACP and ALP in liver, kidney, and heart, but weak direct interrelationships were characteristic between the 2 enzymes in serum and spleen. --LDH was inversely interrelated with CPK in serum and heart.     

Concentration of enrofloxacin and its active metabolite in alveolar macrophages and pulmonary epithelial lining fluid of dogs

The purpose of this study was to determine the concentration of enrofloxacin and its active metabolite, ciprofloxacin, in alveolar macrophages (AM) and epithelial lining fluid (ELF) of the lungs in comparison to plasma concentrations in healthy dogs. Eleven dogs were given a single oral dose (5 mg/kg) of enrofloxacin. Four hours later, plasma and bronchoalveolar lavage (BAL) fluid were collected. Cells were separated from the BAL fluid and lysed for determination of drug concentrations within AM. Supernatant was used to determine concentrations of drugs in ELF. Drug assays were performed by high-performance liquid chromatography.
  The concentration of enrofloxacin (mean ± SD) was 0.33 ± 0.14 μg/mL in plasma, 3.34 ± 2.4 μg/mL in AM and 4.79 ± 5.0 μg/mL in ELF. The concentration of ciprofloxacin was 0.42 ± 0.26 μg/mL in plasma, 1.15 ± 1.03 μg/mL in AM and 0.26 ± 0.26 μg/mL in ELF. Mean concentrations of both drugs in AM were greater than in plasma (AM to plasma ratio, 10.3 for enrofloxacin and 4.7 for ciprofloxacin). Mean concentrations of enrofloxacin, but not ciprofloxacin, in ELF were greater than in plasma (ELF to plasma ratio, 13.5 for enrofloxacin and 0.52 for ciprofloxacin). Enrofloxacin concentrations in AM and ELF largely exceeded the MICs of the major bacterial pathogens and surpassed by about two times the breakpoint MIC of that drug, and ciprofloxacin concentrations in AM surpassed the MIC of many susceptible organisms. These results suggest that sufficient antimicrobial activity is present in AM and ELF of dogs following oral administration of enrofloxacin to be effective in the treatment of lower respiratory tract infections involving susceptible organisms.     

Serum alkaline phosphatase activity in Scottish Terriers versus dogs of other breeds

OBJECTIVE: To determine whether Scottish Terriers have higher serum alkaline phosphatase (ALP) activities and a higher prevalence of diseases commonly associated with high serum ALP activity than do dogs of other breeds. DESIGN: Retrospective case-control study. ANIMALS: 85 Scottish Terriers and 340 age-matched control dogs that were not Scottish Terriers. PROCEDURE: Medical records were reviewed, and data for year of evaluation, age, sex, breed, serum ALP activity, and final diagnosis were recorded. RESULTS: Scottish Terriers had a significantly higher mean serum ALP activity than did control dogs (1,520 U/L vs 306 U/L). Regardless of breed, dogs that had a disease commonly associated with high serum ALP activity had a significantly higher mean serum ALP activity than did dogs without such diseases (1,304 U/L vs 427 U/L). Scottish Terriers were 2.4 times as likely to have a disease commonly associated with high serum ALP activity than were control dogs, but Scottish Terriers with diseases commonly associated with high serum ALP activity had a significantly higher mean ALP activity than did control dogs with such diseases (2,073 U/L vs 909 U/L), and Scottish Terriers without such diseases had a significantly higher mean serum ALP activity than did control dogs without such diseases (1,349 U/L vs 228 U/L). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that Scottish Terriers have higher serum ALP activities than do dogs of other breeds. Although Scottish Terriers also have a higher prevalence of diseases associated with high serum ALP activity, this alone did not explain the higher mean serum ALP activity in the breed.     

Comparison of direct sampling and brochoalveolar lavage for determining active drug concentrations in the pulmonary epithelial lining fluid of calves injected with enrofloxacin or tilmicosin

Antibiotic distribution to interstitial fluid (ISF) and pulmonary epithelial fluid (PELF) was measured and compared to plasma drug concentrations in eight healthy calves. Enrofloxacin (Baytril^® 100) was administered at a dose of 12.5 mg/kg subcutaneously (SC), and tilmicosin (Micotil^® 300) was administered at a dose of 20 mg/kg SC. PELF, sampled by two different methods—bronchoalveolar lavage (BAL) and direct sampling (DS)—plasma, and ISF were collected from each calf and measured for tilmicosin, enrofloxacin and its metabolite ciprofloxacin by HPLC. Pharmacokinetic analysis was performed on the concentrations in each fluid, for each drug. The enrofloxacin/ciprofloxacin concentration as measured by AUC in DS samples was 137 ± 72% higher than in plasma, but in BAL samples, this value was 535 ± 403% (p < .05). The concentrations of tilmicosin in DS and BAL samples exceeded plasma drug concentrations by 567 ± 189% and 776 ± 1138%, respectively. The enrofloxacin/ciprofloxacin concentrations collected by DS were significantly different than those collected by BAL, but the tilmicosin concentrations were not significantly different between the two methods. Concentrations of enrofloxacin/ciprofloxacin exceeded the MIC values for bovine respiratory disease pathogens but tilmicosin did not reach MIC levels for these pathogens in any fluids.     

Alterations in the bovine bronchoalveolar lavage proteome induced by dexamethasone

Stressors such as transportation, weaning and co-mingling increase susceptibility to bacterial pneumonia in cattle and are associated with elevated levels of endogenous glucocorticoids. To determine the effect of glucocorticoids on the proteins expressed in the fluid lining the respiratory tract, bronchoalveolar lavage (BAL) was performed on cattle treated with dexamethasone or saline and proteins were resolved by two-dimensional electrophoresis (2-DE). Significant changes in expression were observed for 9 of the 363 detected spots, and the identities of these proteins were determined by mass spectrometry. Consistent with the initiation of an acute phase response, the expression of alpha-1-acid glycoprotein (orosomucoid) and alpha-1-antitrypsin was increased and alpha-2-HS-glycoprotein (fetuin) was decreased in the BAL fluid of dexamethasone-treated cattle. In addition, dexamethasone induced the expression of two hydrophobic ligand-binding proteins, adipocyte-fatty acid binding protein and odorant binding protein (OBP), as well as the proteins alpha-enolase, cofilin-1 and immunoglobulin J chain. OBP mRNA expression in bronchial biopsies was quantified by real-time RT-PCR and the 6-fold higher levels of expression observed in dexamethasone- versus saline-treated animals correlated with the changes observed in OBP protein level. These findings demonstrate glucocorticoid-dependent changes in the protein composition of the epithelial lining fluid of the respiratory tract, identifying proteins potentially integral to respiratory disease susceptibility.