Storage alters feline bronchoalveolar lavage fluid cytological analysis

Pitfalls in Respiratory Tract Cytopathology

BACKGROUND

Cytopathology is integral to the investigation and diagnosis of respiratory disease, and, in the last decade or so, transbronchial needle aspiration by endobronchial ultrasound has made possible diagnosis and staging of malignant thoracic tumours at a single procedure. In addition, interventional teams increasingly include cytopathologists and cytotechnologists who, by providing rapid onsite evaluation, ensure efficient sampling of intrathoracic targets with the ultimate goal of accurate diagnosis as well as sufficient material for comprehensive predictive testing. Nonetheless, "traditional" cytological investigations such as bronchial washings, brushings, and lavages are still carried out for investigation of both suspected neoplastic and non-neoplastic conditions, and all these procedures still produce specimens in which florid benign cells mimic malignancy, while truly neoplastic cells lurk quietly in the background. Furthermore, even when neoplasia is not suspected, issues in preparation and interpretation may render a final assessment inaccurate and, therefore, clinically unhelpful or misleading. In this overview, we have tried to adopt a format partly modelled on the passage of a specimen from clinical acquisition to laboratory endpoint, thus taking in potential pitfalls in communication, clinical interaction, transport, and clinic-based preparation, as well as in morphology, immunocytochemistry, and suitability for predictive testing. It is not exhaustive but highlights areas that may frequently be encountered or are part of our personal experience.

SUMMARY

The account highlights potential pitfalls in respiratory cytopathology at key stages of the process from acquisition to reporting and presents these in both flow diagram and tabular form. We hope this is useful for the increasingly collaborative roles of cytotechnologist and cytopathologist and their wider involvement in the clinical investigative teams.

KEY MESSAGES

Correct clinical and radiological information is crucially important and promotes the correct acquisition and processing of cytopathological specimens. Cross-discipline collaborative working ensures the most efficient use of the specimen such that diagnoses and predictive tests are performed on optimal material, reducing the potential for misinterpretation. Nonetheless, even with optimal material, morphological mimics and atypical antigen expression may mislead and render accurate diagnosis challenging.

Correlation of clinical and radiographic variables in cats with lower airway disease

BACKGROUND

Feline lower airway disease (FLAD) is frequently associated with radiographic abnormalities.

OBJECTIVES

To evaluate whether radiographic changes in cats with naturally occurring FLAD improve with treatment and if radiographic changes correlate with clinical signs.

ANIMALS

Twenty-four client-owned cats newly diagnosed with FLAD, based on medical history, typical clinical signs, radiographic findings, and examination of bronchoalveolar lavage fluid, were included in the prospective study.

METHODS

At 2 examination time points (days 0 and 60), an owner questionnaire, clinical examination, and thoracic radiography were carried out. Information from the questionnaire and clinical examination were evaluated on the basis of a 12-point clinical score. Radiographs were assessed using a 10-point radiographic score. Individual treatment was given to all cats over the study period, based on severity of the disease and compliance of the cat. Clinical and radiographic scores were compared statistically for both examination time points and evaluated for correlation.

RESULTS

All cats showed radiographic abnormalities at initial presentation. In addition to significant improvement in clinical variables, the total radiographic score improved significantly (P = .01) during the study period, with significant improvement in the severity of bronchial (P = .01) and interstitial lung pattern (P = .04). Improvement of the clinical and radiographic score was not correlated.

CONCLUSION AND CLINICAL IMPORTANCE

In addition to clinical signs, repeated radiographic examination can be used as a diagnostic tool to evaluate treatment response in cats with FLAD.

Evaluation of barometric whole-body plethysmography for therapy monitoring in cats with feline lower airway disease

OBJECTIVES

Feline lower airway disease (FLAD) is a common respiratory condition in cats. Traditionally, response to therapy is monitored only by evaluation of clinical signs and radiographic examination of the lungs. Barometric whole-body plethysmography (BWBP) is considered a non-invasive, well-tolerated form of measuring airway reactivity in cats. The aim of the study was to assess pulmonary function testing by BWBP for non-invasive evaluation of response to therapy in cats with FLAD and to investigate whether BWBP parameters correlate with clinical severity.

MATERIAL AND METHODS

The prospective study included 25 client-owned cats, diagnosed with FLAD on the basis of their medical history, clinical signs, radiographic findings, and bronchoalveolar lavage fluid (BALF) examination. At three time points (day 0, 14, and 60), a standardised owner questionnaire, a clinical examination and BWBP measurements were carried out. Results of the questionnaire and the clinical examination were evaluated using a clinical 12-point score. Individual therapy was administered to all patients after diagnosis, based on the severity of disease and compliance of the cat.

RESULTS

The total clinical score significantly improved over the entire study period (p<0.001). Significant improvement was detected for the frequency of coughing (p = 0.009), respiratory distress (p = 0.001), lung auscultation findings (p = 0.002), and general condition and appetite (p = 0.045). The BWBP parameter Penh, an indicator of bronchoconstriction, improved significantly under initial therapy between day 0 and 14 (p = 0.009). A significant correlation between Penh and the severity of auscultation findings was seen on day 0 (r = 0.40; p = 0.013).

CONCLUSION

The study supports the role of Penh as a non-invasive parameter for monitoring initial treatment response in cats with FLAD. Further studies are needed to address whether other BWBP parameters might be suitable for non-invasive therapy monitoring of FLAD. Clinical evaluation is always essential in cats with FLAD to evaluate treatment response.

Constrictive bronchiolitis obliterans with a presumptive etiology of preceding feline herpesvirus infection in a cat

Background

Bronchiolar disorders are rarely recognized in cats. Constrictive bronchiolitis obliterans is characterized by concentric peribronchiolar fibrosis and inflammation of the bronchioles, but the underlying causes remain poorly understood in current small animal medicine.

Case presentation

A 9-year-old cat presented with paroxysmal tachypnea, infrequent cough and persistent labor breathing. Thoracic radiography showed lung hyperinflation and bronchointerstitial pattern, and pulmonary function assessment revealed flow limitation in the late-expiratory phase and poor response to short-acting bronchodilator. Dorsally distributed subpleural ground glass opacities with distinct margin and tree-in-bud opacities were observed on lung high-resolution computed tomography. The cat underwent bronchoalveolar lavage (BAL) and showed severe neutrophilic inflammation. Feline herpesvirus was the only pathogen detected in the BAL fluid. Multiple therapeutic attempts were unsuccessful and the cat died 8 weeks after the initial presentation. Necropsy revealed the infiltration of inflammatory cells, obstruction of the bronchiolar lumen, and submucosal concentric fibrosis suggesting constrictive bronchiolitis obliterans. Combining the pre- and post-mortem findings, as well as the time from symptom onset or BAL to necropsy, constrictive bronchiolitis obliterans was possibly triggered by a preceding feline herpesvirus infection in this case.

Conclusions

The history of nonvaccinated status, lower airway neutrophilic inflammation, and presence of feline herpesvirus in the BAL fluid without coexistence of other pathogens led to the presumption that constrictive bronchiolitis obliterans was induced by a preceding feline herpesvirus infection in this cat. The pathological changes of bronchiolitis obliterans induced by a preceding feline herpesvirus infection could be different from that of cats with acute herpesvirus pneumonia, such as intranuclear inclusions would disappear over time and were no longer found 7–10 days after inoculation. The presence of patchy distribution of subpleural ground glass opacities on lung high-resolution computed tomography should raise the suspicion of peribronchiolar fibrosis. Clinical awareness of bronchiolar disorders as a differential diagnosis is important in cats with lung hyperinflation and labored breathing who show poor reversibility to bronchodilator.

An observational study of the role of indoor air pollution in pets with naturally acquired bronchial/lung disease

Background

Indoor air pollution (IAP) is an emerging issue for both human and veterinary patients under the concept of ‘One Health’. The association between IAP and respiratory disease in companion animals has been reported.

Objectives

The present study investigated the relationship between quantifiable indoor air quality and clinical characteristics of naturally acquired bronchial/lung disease in pet dogs and cats.

Methods

A total of 36 clinical cases (20 dogs and 16 cats) with naturally acquired bronchial/lung disease were prospectively recruited. Lower airway samples were collected and analysed, and clinical signs and the information from pulmonary function testing were examined. Indoor air quality was estimated by the average concentration of particles measuring ≤2.5 μm (PM2.5, μg/m³) and volatile organic compounds (VOC, ppm) in the animals’ domestic microenvironments.

Results

Exposure to IAP was not found to be correlated with the severity of clinical signs, pulmonary function changes or bronchoalveolar lavage fluid cytology in cats with bronchial/lung disease. However, a hypercellular response in canine lower airways was found to be associated with poor indoor air quality, including unacceptable indoor PM2.5 levels (>35 μg/m³) or increases in VOC concentration (>1 ppm) in places most commonly frequented by the dogs in the home.

Conclusions

Poor indoor air quality may exacerbate airway disease in pets and should not be ignored in modern society.

Analysis of the effects of storage temperature and contamination on aerobic bacterial culture results of bronchoalveolar lavage fluid

BACKGROUND

Storage temperature of bronchoalveolar lavage fluid (BALF) impacts cytological evaluation. The effect of storage temperature before bacterial culture has not been evaluated.

OBJECTIVES

To assess whether BALF storage temperature alters aerobic bacterial culture results.

ANIMALS

Eight healthy, male, intact, purpose-bred Beagles.

METHODS

Prospective, controlled investigation. Samples of BALF were collected sterilely. Half of each sample was reserved for controls, and half was inoculated with 10⁴ colony forming units per milliliter (cfu/mL) Bordetella bronchiseptica and 10² cfu/mL Escherichia coli. Control and inoculated samples each were separated into 4 aliquots (1 plated immediately; 3 stored at 4, 24, or 37°C, respectively, for 24 hours before aerobic bacterial culture). Colony counts were compared across treatments for each organism.

RESULTS

In inoculated samples, a statistical difference could not be detected in growth of E. coli or B. bronchiseptica between the baseline culture and BALF stored at 4°C for 24 hours before culture. However, for E. coli, growth in cfu/mL at both 24 and 37°C was higher compared to baseline (P < .05) and compared to 4°C (P < .05). For B. bronchiseptica cfu/mL, growth at 37°C was significantly different (P = .003) compared to both baseline and 4°C.

CONCLUSIONS AND CLINICAL IMPORTANCE

Samples of BALF may be stored at 4°C for 24 hours before culture without substantially altering culture results. Inappropriate storage or shipment temperature (room temperature or exposure to heat) can result in overgrowth of E. coli or B. bronchiseptica, which could alter clinical decisions.

Effects of on-slide fixation on the cell quality of cytocentrifuged equine bronchioalveolar lavage fluid

BACKGROUND

During bronchoalveolar lavage fluid (BALF) sample preparation in horses, several technical aspects can affect sample variability. To date, the effects of different fixatives on prepared equine BALF films have been insufficiently investigated.

OBJECTIVES

This study aimed to determine the effect of various on-slide fixation methods on cell quality, including spray fixation of wet films, and acetone and methanol fixation of air-dried samples in comparison with unfixed, air-dried films.

METHODS

Cytocentrifuged BALF samples from 5 horses were fixed in a wet state using a commercially available fixation spray. They were also fixed with acetone or methanol after air-drying using standard protocols or were air-dried with no fixation. After different postfixation storage durations and temperatures, the samples were stained with May-Grünwald Giemsa or immunocytochemistry stains. Subsequently, differential cell counts (DCCs) were performed, cell areas were measured, and cell morphologies and immunocytochemical staining intensities were assessed semiquantitatively.

RESULTS

Optimal cell morphology results were achieved with the wet-spray fixation method. Acetone and methanol fixation, especially when performed at -20°C, caused reduced cell morphology quality, thereby significantly altering DCCs. For storage of unstained samples for 1 week at room temperature, no significant changes in cell morphology were observed for either fixation method. Wet-spray fixation resulted in enhanced preservation of macrophage, granulocyte, and mast cell sizes compared with air-drying techniques. Immunocytochemical staining of unfixed and acetone-fixed samples was the most intense.

CONCLUSIONS

Wet-spray fixation resulted in the best preservation of cellular morphology and less cell shrinkage compared with unfixed specimens and is, therefore, recommended for BALF cytology.

Functional phenotype and its correlation with therapeutic response and inflammatory type of bronchoalveolar lavage fluid in feline lower airway disease

Background

Currently, functional assessment to monitor therapeutic response in feline lower airway disease (FLAD) has limited application.

Objectives

To evaluate if expiratory indices derived from pseudo‐tidal breathing flow‐volume loop (pTBFVL) representing lower airway obstruction would decrease after clinical improvement and to investigate the correlation between functional phenotype and inflammatory cell type in bronchoalveolar lavage (BAL) fluid.

Animals

Nineteen client‐owned cats with FLAD.

Methods

Prospective observational study. Functional assessment with pTBFVL indices (eg, peak to mid‐expiratory flow; PEF/EF50) and conventional barometric whole body plethysmography (BWBP) parameters (eg, enhanced pause) was carried out before receiving treatment. BAL was performed to analyze inflammatory cell types. Signs were assessed by scoring. The cats were treated with glucocorticoids daily and functional testing was repeated.

Results

Loop indices PEF/EF50 and PEF/EF25 were significantly decreased after treatment (P < .001). Conventional BWBP parameters were not significantly different before and after treatment. Cats with PEF/EF50 > 1.51 before treatment had a significantly higher granulocyte (eosinophil plus neutrophil) percentage in BAL fluid (P = .014). Granulocyte percentage in BAL fluid was strongly correlated with PEF/EF25 (P = .001, r_s = 0.74) and moderately correlated with PEF/EF50 (P = .022, r_s = 0.57), whereas eosinophil or neutrophil percentage alone had no significant correlation with functional parameters.

Conclusions and Clinical Importance

Functional parameters including PEF/EF50 and PEF/EF25 can be used for monitoring therapeutic response. The presence of airflow limitation during mid‐ to late expiration is affected by the overall extent of granulocyte infiltration.