Interpretation of multisegment bronchoalveolar lavage in cats (1/2001-1/2011)

Reactions to environmental allergens in cats with feline lower airway disease

Objectives

Aeroallergens have been discussed as potential triggers for feline asthma (FA), which can be induced experimentally by allergen sensitization. To date, only few studies have investigated reactions to environmental allergens in cats with naturally occurring feline lower airway disease (FLAD). The aim of the study was to compare results of intradermal testing (IDT) and serum allergen-specific immunoglobulin E-(IgE) testing (SAT) in cats with FLAD, and to investigate possible associations with allergen exposure.

Material and methods

Eight cats with eosinophilic airway inflammation (EI), ten cats with mixed inflammation (MI), six with neutrophilic inflammation (NI), and 24 healthy cats (HC) were included. Cats diagnosed with FLAD were assigned to the different inflammatory groups based on bronchoalveolar lavage fluid (BLAF) cytology. SAT was performed in all cats; IDT was only carried out in cats with FLAD. Information about the cats' environment and potential allergen exposure was obtained using an owner questionnaire.

Results

In comparison to 83% of HC with positive reactions on SAT only 52% of cats with FLAD had positive responses (p = 0.051). Significantly more positive reactions per cat were detected on IDT than on SAT (p = 0.001). No significant difference was found for positive reactions per cat on SAT when compared between HC, NI, EI, and MI (p = 0.377). Only "slight" agreement was found for most allergens when reactions obtained in both tests in cats with FLAD were compared, except for "moderate" agreement for English plantain (k = 0.504) and Alternaria alternata (k = 0.488). Overall, no clear association between the cats' environment and allergen reactions were detected.

Conclusions and clinical importance

Interpretation of allergy test results in cats with FLAD should be done in the context of clinical signs and individual factors.

Intradermal testing and serum allergen-specific IgE-testing in cats with naturally occurring feline bronchial disease

OBJECTIVES

While feline asthma (FA) is considered to be of allergic origin, the etiology of feline chronic bronchitis (CB) to date is unknown. Aim of the study was to compare the results of intradermal testing (IDT) and serum testing for allergen-specific immunoglobulin E (SAT) in cats diagnosed with FA and CB.

MATERIAL AND METHODS

Twenty-seven client-owned cats with clinical signs, suggestive of feline inflammatory bronchial disease (FBD) were prospectively enrolled in the study. Patients were assigned to 3 groups based on results of bronchoalveolar-lavage-fluid (BALF)-cytology: FA (n=8), CB (n=10), or cats with a physiological BALF cytology (PB; n=9). A standardized IDT for 27 allergens was performed in all cats. In addition, allergen-specific IgE was measured in serum samples using an FcεRIα-ELISA. The number of positive reactions in both tests was compared between groups, and agreement between test results of both tests was evaluated.

RESULTS

Regarding the number of positive reactions, no statistically significant difference was detected between groups in IDT (p=0.65) and SAT (p=0.51). When comparing the 2 test systems, a weak correlation was found for the allergens Tyrophagus putrescentiae (k=0.256), Dermatophagoides farinae (k=0.276), and rye (k=0.273). The most commonly observed reactions were to house dust mites, storage mites, rye and nettle in IDT and to sheep sorrel, storage mites, and house dust mites in SAT.

CONCLUSION AND RELEVANCE

IDT and SAT in cats with feline inflammatory bronchial disease (FBD) cannot be used interchangeably for allergen detection. Sensitization to environmental allergens can occur in cats with and without airway inflammation. Therefore, a positive test result should always be assessed in context with clinical signs and allergen exposure.

Serum Allergen-Specific Immunoglobulin E in Cats with Inflammatory Bronchial Disease

The etiology of feline inflammatory bronchial disease is poorly understood. This study compares the degree of allergen-specific serum IgE responses between cats with feline asthma, chronic bronchitis, mixed inflammation, and clinically healthy cats (HCs). The retrospective case-control study used serum from eighteen cats with eosinophilic inflammation (EI), ten with neutrophilic inflammation (NI), six with mixed inflammation (MI), and fourteen HCs. Affected cats were categorized into groups based on bronchoalveolar lavage cytology. The measurement of IgE for 34 different allergens including fungal organisms, weeds, grasses, trees, mites, and insects was performed using an indirect ELISA. Positive reactions to allergens were detected in the serum of 17/18 cats with EI, 8/10 with NI, 6/6 with MI, and 11/14 HCs (p = 0.364). When overall positive reactions were compared between groups, cats with MI (p = <0.01) had significantly more positive reactions against mite allergens than HCs. Blood eosinophils inversely correlated with the absolute amount of allergen-specific serum IgE expressed in ELISA absorbance units (EAs) (p = 0.014). Sensitization against dust mites seems to be more prevalent in cats with MI. However, positive IgE reactions can be observed in healthy and diseased cats, and, therefore, need to be interpreted in the light of clinical findings and environmental conditions of individual patients.

Comparison of the respiratory bacterial microbiome in cats with feline asthma and chronic bronchitis

Objectives

While feline chronic bronchitis (CB) is known as neutrophilic bronchial inflammation (NI), feline asthma (FA) is defined as an eosinophilic airway inflammation (EI). Feline chronic bronchial disease refers to both syndromes, with similar clinical presentations and applied treatment strategies. Recent studies described alterations of the microbiota composition in cats with FA, but little is known about the comparison of the lung microbiota between different types of feline bronchial disease. The study aimed to describe the bacterial microbiota of the lower respiratory tracts of cats with FA and CB and to identify potential differences.

Methods

Twenty-two client-owned cats with FA (n = 15) or CB (n = 7) confirmed via bronchoalveolar-lavage (BALF)-cytology were included. Next-generation sequencing analysis of 16S rRNA genes was performed on bacterial DNA derived from BALF samples. QIIME was used to compare microbial composition and diversity between groups.

Results

Evenness and alpha-diversity-indices did not significantly differ between cats with FA and CB (Shannon p = 0.084, Chao 1 p = 0.698, observed ASVs p = 0.944). Based on a PERMANOVA analysis, no significant differences were observed in microbial composition between animals of both groups (Bray-Curtis metric, R-value 0.086, p = 0.785; unweighted UniFrac metric, R-value −0.089, p = 0.799; weighted Unifrac metric, R-value −0.072, p = 0.823). Regarding taxonomic composition, significant differences were detected for Actinobacteria on the phylum level (p = 0.026), Mycoplasma spp. (p = 0.048), and Acinetobacteria (p = 0.049) on the genus level between cats with FA and CB, with generally strong interindividual differences seen. There was a significant difference in the duration of clinical signs before diagnosis in animals dominated by Bacteriodetes (median 12 months, range 2–58 months) compared to animals dominated by Proteobacteria (median 1 month, range 1 day to 18 months; p = 0.003).

Conclusions and relevance

Lung microbiota composition is very similar in cat populations with spontaneous FA and CB besides small differences in some bacterial groups. However, with disease progression, the lung microbiome of cats with both diseases appears to shift away from dominantly Proteobacteria to a pattern more dominated by Bacteriodetes. A substantial proportion of cats tested positive for Mycoplasma spp. via sequencing, while none of them tested positive using classical PCR.

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.

Clinicopathologic and radiographic features in 33 cats with aspiration and 26 cats with bronchopneumonia (2007-2017)

Background

Aspiration pneumonia (AP) and bronchopneumonia (BP) are poorly characterized diseases in cats that share clinical similarities to inflammatory airway disease (IAD).

Objectives

Describe clinicopathologic, radiographic, and microbiologic features in cats with AP and BP and compare findings to those in cats with IAD.

Animals

Thirty‐three cats with AP and 26 with BP; 44 cats with IAD.

Methods

Retrospective case‐control study. Results extracted for all cats included signalment, physical examination findings, historical details, and potential risk factors for aspiration. Diagnostic test results were summarized including CBC, bronchoalveolar (BAL) fluid analysis and microbial culture. Radiographs were reviewed in masked fashion and scored for severity. Results of BAL fluid analysis were assessed for evidence of septic inflammation.

Results

Cats with AP were less likely to be presented for evaluation of cough (P < .001) and more likely to be hypothermic (P = .01) than were cats with IAD or BP. Median duration of signs was significantly shorter in cats with AP (12 days) compared to cats with BP or IAD (270 and 180 days; P = .01). Radiographically, cats with AP were more likely to have an alveolar pattern and higher total score than were cats with BP or IAD. Mycoplasma spp. were the organisms most commonly cultured from BAL fluid in cats with BP, but were not cultured from any cats with AP.

Conclusion and Clinical Importance

Pneumonia must be distinguished from IAD in cats with cough and AP should be considered in cats with acute onset of tachypnea.

Serum immunoglobulin E responses to aeroallergens in cats with naturally occurring airway eosinophilia compared to unaffected control cats

BACKGROUND

Eosinophilic airway disease in cats is sometimes described as allergic in origin, but controversy exists in the documentation of allergy in cats and the utility of allergy testing for respiratory tract diseases.

OBJECTIVE

To examine serum immunoglobulin E (IgE) response to aeroallergens in cats with airway eosinophilia.

ANIMALS

Fifteen cats with idiopathic eosinophilic airway inflammation and 9 control cats.

METHODS

Prospective, case-control study. Surplus serum from cats with airway eosinophilia documented by bronchoscopic bronchoalveolar lavage was submitted for IgE measurement using ELISA polyclonal antibody methodology. Responses for regional allergens (fungal organisms, weeds, grasses, trees, mites, insects) were assessed. Results were reported as ELISA absorbance units with scores 0 to 79 considered negative, scores between 80 and 300 considered intermediate, and scores >300 considered positive.

RESULTS

Cats with airway eosinophilia had significantly more positive serum IgE responses (25/720) than did healthy controls (5/432, P = .02); however, the number of cats with positive IgE responses (5/15) did not differ from controls (1/9, P = .35). The allergen that most commonly resulted in positive serum IgE response in cats with airway eosinophilia was dust mite (n = 4) followed by 2 types of storage mites (n = 3 each). No control cat tested positive for these allergens.

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum IgE production against aeroallergens was found in some cats with eosinophilic airway inflammation, but the number of affected cats with positive results did not differ from controls. Further investigation in cats with eosinophilic, mixed, and neutrophilic airway disease in comparison to control cats is warranted.

Comparison of signalment, clinical, laboratory and radiographic parameters in cats with feline asthma and chronic bronchitis

OBJECTIVES

Feline asthma (FA) and feline chronic bronchitis (CB) are common respiratory conditions in cats, frequently referred to as 'feline lower airway disease'. However, the aetiologies of both inflammatory airway diseases are probably different. Little is known about the differences in signalment, clinical signs, laboratory abnormalities and radiographic features between cats with these two airway diseases. The aim of the study was to investigate whether certain parameters can help in differentiating between both diseases, as distinguished by airway cytology.

METHODS

Seventy-three cats with FA and 24 cats with CB were included in the retrospective study. Inclusion criteria were compatible clinical signs and a cytological evaluation of bronchoalveolar lavage fluid indicating either FA (eosinophilic inflammation) or CB (neutrophilic inflammation) without cytological or microbiological evidence of bacterial infection. Parameters of signalment, physical examination, haematology and thoracic radiographs of both disease groups were compared statistically (P <0.05).

RESULTS

The median age of cats with FA was 6 years, and was 7.5 years in cats with CB (P = 0.640). The most commonly reported clinical signs in both groups were a cough (95% FA/96% CB; P = 1.000), pathological pulmonary auscultatory sounds (82% FA/79% CB; P = 0.766) and dyspnoea (73% FA/79% CB; P = 0.601). Abnormal radiographic lung patterns were detected in 94% of cats with FA and 91% with CB (P = 0.629), respectively. Blood eosinophilia was significantly more common in cats with FA (40%) compared with CB (27%) (P = 0.026).

CONCLUSIONS AND RELEVANCE

The study indicates that a differentiation of FA and CB by means of signalment, a single clinical sign, and haematological and radiographic findings is not possible.

Clinical features and radiographic findings in cats with eosinophilic, neutrophilic, and mixed airway inflammation (2011-2018)

Background

Idiopathic inflammatory airway disease (IAD) in cats often is described as asthmatic (eosinophilic) or bronchitic (neutrophilic), but this designation requires collection of airway fluid and it fails to consider cats with mixed airway inflammation.

Objective

To identify clinical features that would differentiate inflammatory disease types.

Animals

Forty‐nine cats with nonspecific airway inflammation identified by bronchoscopic bronchoalveolar lavage (BAL) between 2011 and 2018 were evaluated.

Methods

This is a retrospective study. Cats were categorized by BAL differential cytology as having eosinophilic (eosinophils >20% with neutrophils <14%, or eosinophils >50%), mixed (eosinophils 20%‐50% and neutrophils >14% or discordant inflammation from 2 BAL sites), or neutrophilic (neutrophils >14% and eosinophils <20%) inflammation. Type and duration of presenting complaints, signalment, body condition score, respiratory rate, CBC results, bronchoscopy, BAL results (% recovery, total nucleated cell count, differential cell count), and radiographic findings were compared among groups.

Results

Idiopathic IAD was diagnosed in 49 cats, with BAL eosinophilic inflammation in 23, mixed inflammation in 14, and neutrophilic inflammation in 12. Cough was the predominant presenting complaint with no difference in duration of signs among groups (median, 5.5 months). Respiratory rate and effort also did not differ. Cats with eosinophilic inflammation were significantly younger (4.4 ± 3.3 years) than those with neutrophilic (8.0 ±5.6 years) or mixed inflammation (7.5 ± 4.0 years; P = .03). Results of CBC and interpretation of radiographic findings did not differ among groups.

Conclusions and Clinical Importance

Substantial overlap exists in clinical and radiographic findings in cats with various forms of idiopathic airway inflammation.

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.

Evaluation of Bronchoscopy and Bronchoalveolar Lavage Findings in Cats With Aelurostrongylus abstrusus in Comparison to Cats With Feline Bronchial Disease

The cat lungworm Aelurostrongylus abstrusus is a cause of lower respiratory tract disease worldwide. Bronchoscopy and bronchoalveolar lavage (BAL) are important tools for diagnosing respiratory diseases in cats. Therefore, the aim of the study was to investigate the usefulness of bronchoscopy and BAL in the diagnosis of A. abstrusus. Findings from bronchoscopic examination and BAL of 24 naturally infected cats were evaluated and compared with those of 12 cats with idiopathic Feline Bronchial Diseases (FBDs). Data were analyzed using Mann-Whitney or Fisher's exact tests. No significant bronchoscopic differences were detected between cats with aelurostrongylosis and FBDs in bronchial mucus, nodular lesions, and airway collapse. On the other hand, airway hyperemia, epithelial irregularities, and bronchial stenosis were observed more frequently in cats affected by FBDs than aelurostrongylosis, while bronchiectasis was found only in cats infected by A. abstrusus. Neutrophilic, eosinophilic, lymphocytic, and mixed inflammation were recorded in both groups. Bacteria or bacterial DNA was identified regardless of the presence or absence of A. abstrusus with no significant differences between groups. Larvae of A. abstrusus were cytologically detected in 5 of the 24 cats (20.8%) with aelurostrongylosis. These results indicate that, although some findings on bronchoscopic examination (i.e., bronchiectasis) can be described more frequently in cats infected by A. abstrusus, bronchial alterations and cytological findings in aelurostrongylosis are not specific unless larvae are observed and overlap with those of other feline airway diseases.

Bronchoalveolar lavage fluid lymphocytosis in 104 dogs (2006-2016)

BACKGROUND

Bronchoalveolar lavage (BAL) fluid cytology and culture are used to characterize respiratory diseases in dogs. Little is known about disorders associated with increased numbers of lymphocytes in BAL fluid.

OBJECTIVE

To evaluate duration of clinical signs and detection of specific respiratory diagnoses in dogs with BAL lymphocytosis.

ANIMALS

One-hundred four client-owned dogs evaluated for respiratory signs.

METHODS

Medical records of dogs that had >300 cells/μL and >20% lymphocytes on a differential cell count of BAL fluid between January 1, 2006, and January 1, 2016, were reviewed retrospectively. Cases were evaluated for the duration of clinical signs and respiratory diagnoses, including aspiration injury, infectious or inflammatory respiratory disease, and airway collapse.

RESULTS

Dogs ranged in age from 0.5 to 16 years (median, 7.9 years) and had a median body weight of 11.4 kg (range, 2.0-42.7 kg). Eosinophilic lung disease was documented in 13 of 104 dogs (Group 1) and airway neutrophilia associated with infectious or inflammatory disease was found in 59 of 104 dogs (Group 2). Lymphocytosis alone in BAL fluid was described in 32 dogs (Group 3). Duration of cough did not differ among groups, but airway collapse was significantly more common in dogs with solitary lymphocytosis than in those with other types of inflammation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lymphocytosis in BAL fluid is common in dogs and, in many cases, likely represents a common response to airway injury, independent of the type or duration of insult. It is unknown whether airway collapse leads to lymphocytosis or if the inflammatory process causes airway collapse.

Tracheobronchial brush cytology and bronchoalveolar lavage in dogs and cats with chronic cough: 45 cases (2012-2014)

Background

Animals with chronic cough can have normal bronchoalveolar lavage fluid cytology when small airway disease is absent. Cytology of a tracheobronchial brushing can detect inflammation in larger airways; however, evaluation of this technique has been limited in veterinary medicine.

Objective

To compare airway brush cytology to bronchoalveolar lavage fluid analysis in dogs and cats with chronic cough.

Animals

Forty dogs and five cats undergoing bronchoscopic investigation of chronic cough.

Methods

Prospective study. Bronchoscopy and bronchoalveolar lavage were performed followed by tracheobronchial brushing of central airways. Results of cytologic assessment of BAL fluid and brush cytology were compared for the presence or absence of inflammation and concordance of inflammatory cell type.

Results

Brush cytology detected central airway inflammation in 34 of 40 (85%) dogs with inflammatory BAL fluid. However, the type of inflammation reported differed in 23 of 34 dogs. In five cats with inflammation in BAL fluid, brush cytology detected inflammation in four; the type of inflammation was discordant in all cats.

Conclusions and clinical relevance

Brush cytology has good agreement with BAL regarding the presence of inflammation, although the type of inflammation detected with the different sampling techniques commonly varies. Brush cytology can provide supplementary information to BAL, and additional studies will provide further information on the role of tracheobronchial brush cytology in the diagnosis and management of respiratory conditions.

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.

Comparison of manual and suction pump aspiration techniques for performing bronchoalveolar lavage in 18 dogs with respiratory tract disease

Background

Different aspiration techniques to retrieve bronchoalveolar lavage fluid (BALF) affect sample quality in healthy dogs. Studies evaluating these techniques in dogs with respiratory disease are lacking.

Objectives

To compare sample quality of BALF acquired by manual aspiration (MA) and suction pump aspiration (SPA).

Animals

Eighteen client‐owned dogs with respiratory disease.

Methods

Randomized, blinded prospective clinical trial. Manual aspiration was performed with a 35‐mL syringe attached directly to the bronchoscope biopsy channel and SPA was performed with a maximum of 50 mmHg negative pressure applied to the bronchoscope suction valve using the suction trap connection. Both aspiration techniques were performed in each dog on contralateral lung lobes, utilizing 2 mL/kg lavage volumes per site. Samples of BALF were analyzed by percentage of retrieved infusate, total nucleated cell count (TNCC), differential cell count, semiquantitative assessment of slide quality, and diagnosis score. Data were compared by paired Student's t‐test, Wilcoxon signed‐rank test, chi‐squared test, and ANOVA. Cohen's kappa coefficient was used to assess agreement.

Results

The percentage of retrieved BALF (P = .001) was significantly higher for SPA than MA. Substantial agreement was found between cytologic classification of BALF obtained with MA and SPA (kappa = 0.615). There was no significant difference in rate of definitive diagnosis achieved with cytologic assessment between techniques (P = .78).

Conclusions and Clinical Importance

Suction pump aspiration, compared to MA, improved BALF retrieval, but did not significantly affect the rate of diagnostic success of bronchoalveolar lavage (BAL) in dogs with pulmonary disease.

Detection of feline Mycoplasma species in cats with feline asthma and chronic bronchitis

Little is known about the aetiology of inflammatory lower airway disease in cats. The aim of this study was to investigate the role of Mycoplasma species in cats with feline asthma (FA) and chronic bronchitis (CB). The study population consisted of 17 cats with FA/CB, and 14 sick cats without clinical and historical signs of respiratory disease, which were euthanased for various other reasons. Nasal swabs, nasal lavage and bronchoalveolar lavage fluid (BALF) samples were taken from patients from both groups. Mycoplasma species culture with modified Hayflick agar and Mycoplasma polymerase chain reaction (PCR) were performed on all samples followed by sequencing of all Mycoplasma species-positive samples for differentiation of subspecies. PCR testing detected significantly more Mycoplasma species-positive BALF samples than Mycoplasma culture (P = 0.021). When cats with oropharyngeal contamination were excluded from comparison, the numbers of Mycoplasma species-positive BALF samples in the group with FA/CB (6/17) and the control group (4/9) were not significantly different (P = 0.6924). While all nasal samples of the cats with FA/CB were negative for Mycoplasma organisms, five samples in the control group (P = 0.041) were positive on PCR. Sequencing revealed Mycoplasma felis in all PCR-positive samples. Mycoplasma species can be detected in the lower airways of cats with FA/CB, as well as in the BALF of sick cats without respiratory signs. Further studies are warranted to investigate the possibility that Mycoplasma species represent commensals of the lower respiratory tract of cats.

Functional assessment of expiratory flow pattern in feline lower airway disease

Feline lower airway disease (FLAD) is a chronic respiratory disease of which there is a lack of information on functional assessment in current veterinary medicine. The purposes of this study were to investigate expiratory pattern and evaluate the diagnostic utility of functional parameters in cats with FLAD. Thirty-three client-owned cats (23 FLAD cats and 10 control cats) were studied. Under quiet tidal breathing, pseudo-tidal breathing flow-volume loop (pTBFVL) was obtained from a barometric whole body plethysmography (BWBP) device. There were significant differences in the shapes of expiratory, but not inspiratory, curves between FLAD and control cats. The incidence of the presence of concave expiratory curve indicating lower airway obstruction was 74% in FLAD cats. To assess the diagnostic utility of pTBFVL indices in cats with FLAD, area under the receiver-operator curve was 0.86 for PEF/EF50 (peak expiratory flow divided by expiratory flow at end expiratory volume plus 50% tidal volume); a cuff-off value of PEF/EF50 >1.51 distinguished normal from FLAD (73.9% sensitivity, 100% specificity). There were no significant differences in traditionally measured BWBP parameters (ie, enhanced pause) between cats with and without FLAD in the present study. In conclusion, underlying change on expiratory flow pattern during natural tidal breathing existed in FLAD cats, and selected pTBFVL indices were useful in discriminating FLAD from normal cats. Tidal breathing pattern depicted by pseudoflow-pseudovolume loops from a BWBP system could be a non-invasive tool for functional assessment in client-owned cats.

Lower respiratory tract endoscopy in the cat

Practical relevance:

Respiratory endoscopy is a useful diagnostic tool to evaluate the airways for the presence of mass lesions or foreign material while allowing for sample collection for cytologic and microbiologic assessment. While bronchial disease (eosinophilic or neutrophilic) is the most common lower respiratory disease identified in cats, infectious, anomalous and neoplastic conditions can clinically mimic inflammatory bronchial disease. Diagnostic imaging is unable to define the etiology for clinical signs of cough, tachypnea or respiratory difficulty, necessitating visual evaluation and collection of airway samples. Endoscopy allows intervention that can be life-saving and also confirmation of disease, which is important given that life-long medication is likely to be required for management of inflammatory airway disease.

Patient group:

Cats with either airway or pulmonary disease benefit from laryngoscopy, tracheoscopy and bronchoscopy to determine an etiologic diagnosis. In the best situation, animals that require these procedures present early in the course of disease before clinical decompensation precludes anesthetic intervention. However, in some instances, these tests must be performed in unstable cats, which heightens the risk of the procedure. Cats that do not respond to empiric medical therapy can also benefit from bronchoscopic evaluation.

Clinical challenges:

Due to the small size of feline airways and the tendency for cats to develop laryngospasm, passage of endoscopic equipment can be difficult. Bronchoconstriction can lead to hemoglobin desaturation with oxygen and respiratory compromise.

Evidence base:

This article reviews published studies and case reports pertaining to the diagnostic approach to feline respiratory disease, focusing specifically on endoscopic examination of the lower airways in cats. It also discusses appropriate case selection, equipment, endoscopic techniques and visual findings based primarily on the authors’ experiences.