Assessing breathing effort by barometric whole-body plethysmography and its relationship with prognosis in client-owned cats with respiratory distress.

BACKGROUND: Cats in respiratory distress have limited tolerance for manipulation, hindering clinical monitoring. Minute volume (MV) can be utilized to rate dyspnea in humans, but its relationship with respiratory distress in cats remains poorly investigated. HYPOTHESIS: Cats with respiratory distress will show higher MV per kg body weight (MV/BW) than normal cats, and the MV/BW increase will correlate with survival. ANIMALS: Fifty-two cats with respiratory distress from lung parenchymal disease, pleural space disease, lower airway obstruction (LAO), or upper airway obstruction were recruited since 2014. METHODS: This is a prospective observational study. Study cats were placed in a transparent chamber, allowing clinicians to easily observe their breathing status and record ventilation using barometric whole-body plethysmography (BWBP). Ventilatory variables of the 52 cats were compared with those of 14 historic control cats. Follow-up data, including disease category, clinical outcomes, and survival, were prospectively collected. RESULTS: Cats in respiratory distress demonstrated significantly higher MV/BW (397 mL/kg; range, 158-1240) than normal cats (269 mL/kg; range, 168-389; P < .001). Among the etiologies, cats with LAO, parenchymal, and pleural space disease exhibited higher-than-normal MV/BW trends. A cutoff value of 373 mL/kg (1.4-fold increase) indicated abnormally increased breathing efforts (sensitivity, 67%; specificity, 93%). MV/BW was independently associated with increased cardiorespiratory mortality in cats with respiratory distress (adjusted hazard ratio 1.17, 95% confidence interval [CI] 1.02-1.35; P = .03). CONCLUSIONS AND CLINICAL IMPORTANCE: Breathing efforts in cats can be noninvasively quantified using BWBP. Measurement of MV/BW could serve as a prognostic index for monitoring cats experiencing respiratory distress.

Influence of acclimatization time on parameters of barometric whole-body plethysmography in healthy adult cats.

BACKGROUND: Pulmonary function testing by barometric whole-body plethysmography (BWBP) is a long-established and well-accepted, non-invasive investigative procedure in cats. HYPOTHESIS/OBJECTIVES: To evaluate, if different acclimatization times influence the measurement parameters of BWBP in healthy adult cats. ANIMALS: 48 healthy adult cats. METHODS: In the prospective observational study, healthy cats were placed in a measuring chamber and BWBP was performed over 30 minutes. Parameters obtained during the three measurement units of 10 minutes each (T1, T2 and T3) were compared. RESULTS: All measurement parameters except for tidal volume per body weight changed significantly (p<0.05) over the three time periods. From T1-T2, the parameters minute volume per body weight (p<0.001), peak inspiratory flow per body weight (p<0.001), peak expiratory flow per body weight (p = 0.002), pause (p = 0.03), enhanced pause (p = 0.03) and quotient of peak expiratory flow divided by expiratory flow at end expiratory volume plus 50% tidal volume (p = 0.03) changed significantly. From the time interval T2-T3, only respiratory rate (p = 0.02), inspiratory time (p = 0.02), expiratory time (p = 0.04), and relaxation time (p = 0.01) changed significantly. All measurement parameters except for tidal volume per body weight changed significantly (p<0.05) between T1 and T3. Age had a significant influence on all parameters except for peak expiratory flow per body weight and peak inspiratory flow per body weight. The parameters were not influenced by sex. CONCLUSION AND CLINICAL IMPORTANCE: All measurement parameters except tidal volume per body weight were significantly affected by acclimatization time. Controlling for age and sex, there was still a significant influence of acclimatization time on all parameters except for tidal volume per body weight. Standardization of the acclimatization time for future studies would be appropriate in order to maintain comparability.

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.

Nebulization of epinephrine to reduce the severity of brachycephalic obstructive airway syndrome in dogs.

OBJECTIVE: To determine the preoperative and postoperative effect of nebulized epinephrine on brachycephalic obstructive airway syndrome (BOAS) severity in dogs. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Thirty-one client-owned pugs, French bulldogs, and English bulldogs with moderate to severe BOAS. METHODS: Whole body barometric plethysmography was used to determine BOAS severity (BOAS index; 0%-100%) prior to and after nebulization with 0.05 mg/kg epinephrine diluted in 0.9% saline preoperatively. The same protocol was repeated postoperatively (within 24 hours of surgery). RESULTS: Five dogs were excluded because they did not tolerate nebulization, and postoperative data were available for 13 dogs. Epinephrine nebulization resulted in a decreased BOAS index across all breeds of dog both before (9.6% [3.1% to -30.2%], n = 26) and after surgery (14.3% [0.9% to -24.3%], n = 13). The preoperative reduction in BOAS index was greater (17.3% [1.8% to -27.4%]) in dogs with a baseline BOAS index >70% (P = .006) and in pugs (16.9% [0.8% to -27.4%]) compared with French bulldogs (5.2% [3.1% to -30.2%], P = .03). Simple linear regression was used to identify a positive relationship between baseline BOAS index and reduction in BOAS index for pugs (n = 10, P = .001). Nausea was noted as a side effect in four dogs. CONCLUSION: Nebulized epinephrine reduced the BOAS index of dogs in this study. This effect was clinically significant in preoperative dogs with a BOAS index >70% and in dogs recovering from surgery. CLINICAL SIGNIFICANCE: This study provides evidence to support the use of nebulized epinephrine in the perioperative management of BOAS-affected dogs.

Validation of exercise testing and laryngeal auscultation for grading brachycephalic obstructive airway syndrome in pugs, French bulldogs, and English bulldogs by using whole-body barometric plethysmography.

OBJECTIVE: To determine whether the sensitivity of clinical examination for assessing upper airway disease severity in 3 breeds of brachycephalic dogs can be improved by incorporating an exercise test (ET) or by auscultation of a laryngeal stridor to predict laryngeal collapse. STUDY DESIGN: Prospective clinical study. ANIMALS: Client-owned brachycephalic dogs (n = 44 ET; n = 57 laryngeal stridor assessment). METHODS: In the first part of the study, clinical examinations were performed at rest and after 5-minute walk and 3-minute trot tests, and a grade reflective of brachycephalic obstructive airway syndrome (BOAS) severity was assigned. Whole-body barometric plethysmography was used as a comparative, objective measure of disease severity. In the second part of the study, the degree of laryngeal collapse present in dogs undergoing BOAS surgery was compared to pre-exercise and postexercise laryngeal stridor detected during functional testing. RESULTS: The sensitivity of clinical examination for BOAS diagnosis was 56.7% pre-ET, 70% after a 5-minute walk test, and 93.3% after a 3-minute trot test. The sensitivity of laryngeal stridor as a predictor of laryngeal collapse was improved after exercise (70%) compared with before exercise (60%). Specificity of laryngeal stridor for laryngeal collapse was 100% (pre-exercise and postexercise). CONCLUSION: The sensitivity of clinical examination for BOAS diagnosis was improved by inclusion of an ET, particularly the 3-minute trot test. Audible laryngeal stridor was highly specific but only moderately sensitive for laryngeal collapse. CLINICAL SIGNIFICANCE: Inclusion of a 3-minute trot test and careful auscultation for laryngeal stridor are recommended during BOAS assessment of brachycephalic dogs.

Whole-Body Barometric Plethysmography Characterizes Upper Airway Obstruction in 3 Brachycephalic Breeds of Dogs.

BACKGROUND: A novel test using whole-body barometric plethysmography (WBBP) was developed recently to diagnose brachycephalic obstructive airway syndrome (BOAS) in unsedated French bulldogs. HYPOTHESIS/OBJECTIVES: The hypotheses of this study were: (1) respiratory characteristics are different between healthy nonbrachycephalic dogs and brachycephalic dogs; and among pugs, French bulldogs, and bulldogs; and (2) obesity and stenotic nares are risk factors for BOAS. The main objective was to establish a diagnostic test for BOAS in these 3 breeds. ANIMALS: A total of 266 brachycephalic dogs (100 pugs, 100 French bulldogs, and 66 bulldogs) and 28 nonbrachycephalic dogs. METHODS: Prospective study. Exercise tolerance tests with respiratory functional grading, and WBBP were performed on all dogs. Data from WBBP were associated with functional grades to train quadratic discriminant analysis tools to assign dogs to BOAS+ and BOAS- groups. A BOAS index (0-100%) was calculated for each dog. Receiver operating characteristic (ROC) curves were used to evaluate classification ability. RESULTS: Minute volume was decreased significantly in asymptomatic pugs (P = .009), French bulldogs (P = .026), and bulldogs (P < .0001) when compared to nonbrachycephalic controls. Respiratory characteristics were different among breeds and affected dogs had a significant increase in trace variation. The BOAS index predicted BOAS status for each breed with 94-97% (95% confidence interval [CI], 88.9-100%) accuracy (area under the ROC curve). Both obesity (P = .04) and stenotic nares (P = .004) were significantly associated with BOAS. CONCLUSIONS AND CLINICAL IMPORTANCE: The WBBP can be used as a clinical tool to diagnose BOAS noninvasively and objectively.

Simultaneous visual inspection for barometric whole-body plethysmography waveforms during pulmonary function testing in client-owned cats.

OBJECTIVES: For the purpose of applying a barometric whole-body plethysmography (BWBP) device as a routine clinical tool in client-owned cats, the objective of this study was to evaluate the methodological importance of simultaneous visual inspection (SVI) of graphic tracing. METHODS: To investigate the effect of SVI on the results obtained, 50 client-owned cats were included. Breath-by-breath analysis was conducted with BWBP software, and a commonly used rejection setting was chosen for automatic elimination (AE) of non-breath artefactual waveforms, according to tidal volume (TV), inspiratory and expiratory time, and the difference between inspiratory and expiratory volumes. During 10 mins of data recording, SVI for BWBP waveforms was performed to record manually time periods that were free of any artefacts. The two datasets derived from AE alone (AEA method) and AE plus SVI (SVI-AE method) were compared. The inter-observer effect on the process of SVI was evaluated on six cats. RESULTS: There were statistically significant differences (P <0.001) between the AEA and SVI-AE datasets for most BWBP parameters. Bland-Altman analysis of the parameter-enhanced pause (Penh) showed heterogeneous variances, indicating less agreement when the Penh values were large. Intra-individual coefficients of variation of Penh were significantly higher with the AEA method than with the SVI-AE method (61.1% vs 34.7%, respectively; P <0.001). Inter-observer agreement on the SVI process was excellent, and no statistically significant differences between the two observers were found for any BWBP parameters obtained by the SVI-AE method (P >0.05). CONCLUSIONS AND RELEVANCE: Visual inspection for BWBP waveforms in real time can reliably identify stable breathing signals in client-owned cats. The obtained results were significantly different when the SVI method was used in addition to AE. In the interpretation of BWBP parameters or comparison of measurements among studies, whether an SVI methodology was applied should be considered.

Characterisation of Brachycephalic Obstructive Airway Syndrome in French Bulldogs Using Whole-Body Barometric Plethysmography.

Brachycephalic obstructive airway syndrome (BOAS) is an important health and welfare problem in several popular dog breeds. Whole-body barometric plethysmography (WBBP) is a non-invasive method that allows safe and repeated quantitative measurements of respiratory cycles on unsedated dogs. Here respiratory flow traces in French bulldogs from the pet population were characterised using WBBP, and a computational application was developed to recognise affected animals. Eighty-nine French bulldogs and twenty non-brachycephalic controls underwent WBBP testing. A respiratory functional grading system was used on each dog based on respiratory signs (i.e. respiratory noise, effort, etc.) before and after exercise. For development of an objective BOAS classifier, functional Grades 0 and I were considered to have insignificant clinical signs (termed here BOAS-) and Grades II and III to have significant signs (termed here BOAS+). A comparison between owner-perception of BOAS and functional grading revealed that 60 % of owners failed to recognise BOAS in dogs that graded BOAS+ in this study.WBBP flow traces were found to be significantly different between non-brachycephalic controls and Grade 0 French bulldogs; BOAS- and BOAS+ French bulldogs. A classifier was developed using quadratic discriminant analysis of the respiratory parameters to distinguish BOAS- and BOAS + French bulldogs, and a BOAS Index was calculated for each dog. A cut-off value of the BOAS Index was selected based on a receiver operating characteristic (ROC) curve. Sensitivity, specificity, positive predictive value, and negative predictive value of the classifier on the training group (n=69) were 0.97, 0.93, 0.95, and 0.97, respectively. The classifier was validated using a test group of French bulldogs (n=20) with an accuracy of 0.95. WBBP offers objective screening for the diagnosis of BOAS in French Bulldogs. The technique may be applied to other brachycephalic breeds affected by BOAS, and possibly to other respiratory disease in dogs.

Pulmonary function in obese vs non-obese cats.

Obesity is a risk factor in the development of several respiratory diseases. Lung volumes tend to be decreased, especially expiratory reserve volume, increasing expiratory flow limitation during tidal breathing. Barometric whole-body plethysmography is a non-invasive pulmonary function test that allows a dynamic study of breathing patterns. The objective of this study was to compare pulmonary function variables between obese and non-obese cats through the use of barometric whole-body plethysmography. Nine normal-weight and six obese cats were placed in the plethysmograph chamber, and different respiratory variables were measured. There was a significant decrease in tidal volume per kilogram (P = 0.003), minute volume per kilogram (P = 0.001) and peak inspiratory and expiratory flows per kilogram (P = 0.001) in obese cats compared with non-obese cats. Obesity failed to demonstrate a significant increase in bronchoconstriction index variable enhanced pause (Penh), as previously reported in humans and dogs. The results show that feline obesity impairs pulmonary function in cats, although a significant increase in bronchoconstriction indexes was not observed. Non-invasive barometric whole-body plethysmography can help characterise mechanical dysfunction of the airways in obese cats.

Inhaled budesonide therapy in cats with naturally occurring chronic bronchial disease (feline asthma and chronic bronchitis).

OBJECTIVES: To describe the long term use of inhaled budesonide in cats with naturally occurring asthma and chronic bronchitis and to measure its effects. METHODS: Owners of 43 cats diagnosed with asthma or chronic bronchitis, which had been prescribed 400 µg of inhaled budesonide twice daily, were contacted and information was retrieved by a questionnaire. Nineteen cats still receiving inhaled budesonide after more than 2 months were re-evaluated clinically and underwent barometric whole body plethysmography and adrenocorticotropic hormone-stimulation testing. RESULTS: In 20 of the cats, therapy had been withdrawn by the owners. Cats (n=23) still receiving inhaled budesonide improved clinically and 19 cats that were reevaluated had significantly lower basal PENH (P=0·048) and higher PCPenh300 (P=0·049) values than before treatment. Corticosteroid-induced side effects were not observed in any cats but hypothalamic-pituitary-adrenal axis suppression was detected in 3 of 15 cases. CLINICAL SIGNIFICANCE: Treatment with inhaled budesonide was well tolerated, resulting in improvement of clinical signs and barometric whole body plethysmography parameters. Although inhaled budesonide therapy was found to cause suppression of the hypothalamic-pituitary-adrenal axis in some cats, no cats showed clinical signs attributable to corticosteroid side effects.

Correlation of bronchoalveolar eosinophilic percentage with airway responsiveness in cats with chronic bronchial disease.

OBJECTIVES: To retrospectively assess the relationship between bronchoalveolar lavage fluid analysis and lung function parameters as assessed by means of barometric whole body plethysmography and airway responsiveness testing in cats with chronic bronchial disease and to evaluate the potential application of barometric whole body plethysmography and airway responsiveness testing to distinguish between eosinophilic and non-eosinophilic bronchitis. METHODS: Twelve cats presented for chronic bronchial disease with complete bronchoalveolar lavage fluid and barometric whole body plethysmography data were identified. Cats were retrospectively assigned to eosinophilic bronchitis or non-eosinophilic bronchitis groups on the basis of bronchoalveolar lavage fluid eosinophil percentage (threshold 17%). Airway responsiveness was quantified by calculating the concentration of carbachol-inducing bronchoconstriction (C-Penh-300), defined as a 300% increase of basal enhanced pause (Penh). RESULTS: Log Penh was significantly higher and C-Penh-300 significantly lower in eosinophilic bronchitis cats compared to non-eosinophilic bronchitis cats (P=0·031 and P=0·032, respectively). Bronchoalveolar lavage fluid eosinophil percentage was moderately correlated with log Penh (P=0·012, r=0·70) and showed a weak inverse correlation with C-Penh-300 (P=0·047, r=-0·58). CLINICAL SIGNIFICANCE: This study provides supportive evidence of a correlation between airway eosinophilic inflammation and plethysmographic measures of bronchoconstriction and airway responsiveness. Further investigation of the use of barometric whole body plethysmography to differentiate between forms of chronic bronchial disease in cats is indicated.

Assessment of routine procedure effect on breathing parameters in mice by using whole-body plethysmography.

We used whole-body plethysmography to investigate the effect of restraint, ear marking, tail vein and retroorbital blood sampling, and tail clipping on respiration in Balb/c × TCR-HA +/- F1 hybrid mice (F1h). Baseline values of breathing parameters were determined. During the experiment, mice experienced a procedure and then plethysmographic recordings were obtained immediately and at 4, 24, and 48 h afterward. Baseline breathing parameters showed significant differences between sexes. Restraint affected minute volume differently than did handling in male mice and to a lesser extent in female mice. Ear marking significantly changed minute volume compared with handling but not restraint in male mice and in the opposite manner in female mice. Tail vein blood sampling changed minute volume in a significant manner compared with restraint but not compared with handling in both sexes. Retroorbital blood sampling significantly changed minute volume compared with values for both handling and restraint in male mice but only compared with handling in female mice. Tail clipping modified minute volume significantly compared with handling in male mice and compared with restraint in both sexes. Analysis of data showed that routine procedures affect minute volume in mice depending on invasiveness of maneuver and in a sex-biased manner for as long as 24 h after the procedure. Our experiment shows that procedures performed on laboratory mice can change respiratory parameters and can be investigated by plethysmography.

Evaluation of pulmonary function in European land tortoises using whole-body plethysmography.

The aim of this study was to evaluate the use of whole-body plethysmography as a non-invasive method to determine the respiratory parameters and profiles in two tortoise species belonging to the genus Testudo. Pulmonary functions and volumetric parameters were determined in 10 adults of Testudo hermanni and in seven Testudo marginata animals, using whole-body plethysmography. A profile pattern was regularly observed: an inspiratory flow peak, an expiratory peak, an apnoea phase and a second expiratory peak, previous to the beginning of the next respiratory cycle. Positive and significant correlation was observed between the inspiratory time, weight and length of the tortoises. Larger tortoises showed a higher time of inhalation. The peak of inspiratory flow was correlated with the sex, being longer in the females. T. marginata had an inspiratory time longer than that of T. hermanii. In T. hermanii, differences related to the sex were observed in the tidal volume, peak inspiratory flow, peak expiratory flow, expiratory flow of 50 per cent and enhanced pause, which could be related to the smaller size of males. The results suggest that additional information on new technologies currently used in pet medicine or even in human medicine should be developed and adjusted as alternative ways to support the rehabilitation of turtles and tortoises.

Evaluation of pulmonary function variables by using plethysmography in cats with respiratory disease associated to Dirofilaria immitis.

Heartworm Associated Respiratory Disease (HARD) is a pulmonary syndrome that results from the vascular and parenchymal inflammatory response associated with the arrival and death of Dirofilaria immitis in the distal pulmonary arteries. Barometric whole-body plethysmography (BWBP) is a non-invasive pulmonary function test (PFT) that allows a dynamic study of breathing patterns and is useful to study airway disease and the response to different treatments. The aim of this prospective non-blinded study was to compare respiratory function variables between healthy cats and HARD cats (seropositive to D. immitis) by use of BWBP. Twenty-five healthy cats and six HARD cats were put into the plethysmograph chamber and different respiratory variables were measured. The results were analyzed and compared between the two groups of animals. There were significant differences for bronchoconstriction index variables Pause (P-value<0.001) and enhanced pause (P-value<0.001), minute volume (P-value<0.05) and tidal volume (P-value<0.05) between healthy and HARD cats. There were no significant differences in respiratory rate and inspiratory and expiratory times between both groups of animals. The results obtained in our study support that HARD cats show significant differences in pulmonary function variables obtained by BWBP due to an acute inflammatory response at bronchial, vascular and parenchymal level. This PFT could be a useful method to facilitate the diagnosis of pathological states of bronchoconstriction in HARD cats.

Effects of obesity on lung function and airway reactivity in healthy dogs.

The present study investigated the effects of bodyweight (BW) gain on respiratory function and airway responsiveness in healthy Beagles using barometric whole body plethysmography (BWBP). Six adult dogs were examined before and after a fattening diet. The high-energy diet induced a mean increase in BW of 41±6%. BWBP basal parameters were recorded prior to airway reactivity testing (using increasing concentrations of histamine nebulisations). An airway responsiveness index (H-Penh300) was calculated as the histamine concentration necessary to reach 300% of basal enhanced pause (Penh, bronchoconstriction index). The same dogs underwent a doxapram hydrochloride (Dxp) stimulation testing 2 weeks later. Basal measurements showed that obese dogs had tidal volume per kg (TV/BW) that was significantly decreased whilst respiratory rate (RR) increased significantly. H-Penh300 decreased significantly in obese Beagles, indicating increased bronchoreactivity. Dxp administration induced a significant increase in TV/BW, minute volume per kg (MV/BW), peak inspiratory and expiratory flows per kg (PIF/BW and PEF/BW) in both normal and obese dogs although the TV/BW increase was significantly less marked in the obese group. In conclusion, obesity induced changes in basal respiratory parameters, increased bronchoreactivity and a blunted response to Dxp-induced respiratory stimulation. This combination of basal respiratory parameters, bronchoreactivity testing and pharmacological stimulation testing using non-invasive BWBP can help characterize pulmonary function and airway responsiveness in obese dogs.

Airway hyperresponsiveness to adenosine 5'-monophosphate in feline chronic inflammatory lower airway disease.

Airway hyperresponsiveness is a key feature of human asthma and chronic bronchitis and response to the indirectly acting agonist adenosine 5'-monophosphate (AMP) is thought to reflect underlying airway inflammation. To examine whether airway responsiveness testing (ART) with AMP may be used to differentiate healthy cats from those with asthma (FA) and chronic bronchitis (CB), 24 cats (9 FA, 6 CB, 9 controls) underwent ART with AMP at concentrations of 0.1, 1, 10, 100 and 500mg/mL using barometric whole body plethysmography. The defined endpoint of ART, an increase in enhanced pause (Penh) exceeding 300% of the post-saline value (baseline), was reached in 9/15 patients (7 FA, 2 CB), but in none of the controls. Mean Penh (±SD) at baseline (BL) was 0.49±0.16 for cases, and 0.54±0.16 for controls, and was significantly increased after AMP challenge in clinical cases (2.62±2.20), but not in controls (0.63±0.30, P<0.05). After separating responder (R) and non-responder (NR) cases, a more pronounced difference after challenge was found (R: 3.96±1.84, NR: 0.6±0.21, P<0.001). The provocative concentration of the agonist that increased Penh to 300% of BL (PC Penh 300) in R cases was 52.98±48.04mg/mL AMP. Age had no influence on the responder status or PC Penh 300. It was concluded that AMP challenge may offer a new method for the identification of cats with lower inflammatory airway disease, and possibly for monitoring disease progression or response to therapy.

Respiratory pattern in awake rats: effects of motor activity and of alerting stimuli.

Our aim was to assess the impact of motor activity and of arousing stimuli on respiratory rate in the awake rats. The study was performed in male adult Sprague-Dawley (SD, n=5) and Hooded Wistar (HW, n=5) rats instrumented for ECG telemetry. Respiratory rate was recorded using whole-body plethysmograph, with a piezoelectric sensor attached for the simultaneous assessment of motor activity. All motor activity was found to be associated with an immediate increase in respiratory rate that remained elevated for the whole duration of movement; this was reflected by: i) bimodal distribution of respiratory intervals (modes for slow peak: 336+/-19 and 532+/-80 ms for HW and SD, p<0.05; modes for fast peak 128+/-6 and 132+/-7 ms for HW and SD, NS); and ii) a tight correlation between total movement time and total time of tachypnoea, with an R(2) ranging 0.96-0.99 (n=10, p<0001). The extent of motor-related tachypnoea was significantly correlated with the intensity of associated movement. Mild alerting stimuli produced stereotyped tachypnoeic responses, without affecting heart rate: tapping the chamber raised respiratory rate from 117+/-7 to 430+/-15 cpm; sudden side move--from 134+/-13 to 487+/-16 cpm, and turning on lights--from 136+/-12 to 507+/-14 cpm (n=10; p<0.01 for all; no inter-strain differences). We conclude that: i) sniffing is an integral part of the generalized arousal response and does not depend on the modality of sensory stimuli; ii) tachypnoea is a sensitive index of arousal; and iii) respiratory rate is tightly correlated with motor activity.

Description of original endoscopic findings and respiratory functional assessment using barometric whole-body plethysmography in dogs suffering from brachycephalic airway obstruction syndrome.

The clinical features of brachycephalic airway obstructive disease in 11 brachycephalic dogs are described in this study. The respiratory strategy was assessed before (n=11) and after (n=6) surgery using barometric whole-body plethysmography (BWBP), with the relationship between BWBP variables and the severity of the clinical signs assessed by the use of a respiratory score based on clinical, radiographic and endoscopic findings. Partial collapse of the left main bronchus was a common finding not previously described as part of the brachycephalic airway obstructive disease syndrome. Epiglottic cysts, laryngeal granulomas and nasopharyngeal turbinates in English Bulldogs were other previously unreported findings. No significant correlation between the respiratory score and any of the BWBP variables was detected. Compared to healthy dogs, brachycephalic dogs had a significantly lower Te/Ti ratio (expiratory time over inspiratory time), peak inspiratory flow (PIF) per kg bodyweight (BW), significantly higher peak expiratory flow (PEF) per kgBW, PEF/PIF, and enhanced pause. These variations are compatible with upper airway obstructions primarily in the extrathoracic airways. Following surgery, a significant decrease in PEF/PIF was detected. The study showed that BWBP could be used to characterise the respiratory strategy in brachycephalic dogs before and after surgery.

A pilot study comparing the antispasmodic effects of inhaled salmeterol, salbutamol and ipratropium bromide using different aerosol devices on muscarinic bronchoconstriction in healthy cats.

This study compared the duration and magnitude of the antispasmodic effects of salmeterol (SLM), salbutamol (SAL), ipratropium bromide (IB) and the combination of SAL and IB (SAL/IB) against carbachol-induced bronchoconstriction in healthy cats, and investigated the gain in efficacy using a two or fourfold increase in drug dosages. The drug regimens used were: (1) SLM 25 microg, SAL 100 microg, IB 20 microg and SAL/IB 100 microg/20 microg for bronchodilators delivered by a metered-dose inhaler (MDI); (2) SAL 3.75 mg and IB 62.5 microg for nebulised (NEB) medications. To monitor the bronchodilator effect, airway responsiveness was assessed at different time points using barometric whole-body plethysmography and calculation of the concentration of inhaled carbachol inducing a 300% increase of baseline Penh (enhanced pause), an estimator of airflow limitation. Maximum C-Penh300 was recorded 15 min after NEB SAL, IB MDI, NEB IB and 1h after SAL MDI and 4h after SLM MDI, respectively. C-Penh300 was significantly different from control values (without treatment) up to 24h for SLM MDI, 8h for IB MDI and 4h for other drugs. In terms of efficacy, SAL/IB MDI showed a synergistic antispasmodic effect at 15 min, 4h and 8h after administration. A fourfold increase of the initial dose of IB MDI and NEB IB significantly increased C-Penh300. Despite a fourfold dose increase, SLM displayed the weakest degree of bronchoprotection compared to other bronchodilators. The study provides evidence that inhaled bronchodilators are efficient at preventing muscarinic-induced bronchospasm in healthy cats and that SAL and IB appear to be short-acting bronchodilators in contrast to SLM.

Comparison of barometric whole body plethysmography and its derived parameter enhanced pause (PENH) with conventional respiratory mechanics in healthy Beagle dogs.

The purpose of the study was to compare barometric whole body plethysmography (BWBP) and its derived parameter, enhanced pause (PENH), with conventional respiratory mechanics measurements. Resistance (RL), dynamic compliance (Cdyn) and pleural pressure changes were measured in six healthy anaesthetised Beagle dogs using a pneumotachograph and oesophageal balloon technique consecutive to BWBP-derived variables. Upper airway airflow limitation was established (1) by a filter or (2) by insertion of a narrow endotracheal tube. Bronchoconstriction was induced by nebulisation of carbachol at increasing concentrations until PENH exceeded 300% baseline. Upper airway narrowing significantly increased resistance (baseline RL 2.0+/-0.3, RL filter 11.8+/-3.2, RL luminal narrowing 21.1+/-2.3cm H(2)O/L/s; P <0.03), whereas PENH did not change significantly (baseline PENH 0.55+/-0.17, PENH filter 0.49+/-0.10; PENH luminal narrowing 0.50+/-0.18; P >0.05). Carbachol-induced bronchoconstriction caused a significant increase in PENH (baseline PENH 0.43+/-0.14, PENH carbachol 2.62+/-2.14; P <0.02) and resistance (baseline RL 2.1+/-0.3, RL carbachol 28.8+/-13.0 cm H2O/L/s; P <0.01), and a pronounced drop in compliance (baseline Cdyn 163.3+/-73.9, Cdyn carbachol 9.7+/-2.9mL/cmH2O; P <0.02). It was concluded that BWBP detects airflow limitation due to bronchoconstriction but not due to upper airway obstruction in healthy dogs. BWBP represents a valid, although not very sensitive screening tool for respiratory function testing.