Non-invasive assessment of growth, gender and time of day related changes of respiratory pattern in healthy cats by use of barometric whole body plethysmography

The objective of this study was to establish a reference base for respiratory variables (respiratory rate [R(R)], inspiratory and expiratory time [T(i) and T(e)], peak inspiratory and expiratory pseudoflow [PIF and PEF], tidal volume [V(T)], minute ventilation [V(E)] and enhanced pause [Penh]) of healthy cats by use of barometric whole body plethysmography (BWBP). Eighteen healthy European cats (10 male, 8 female) were studied from the age of 3 to 13 months in order to assess growth- and gender-related changes of BWBP variables. Chest radiographs and bronchoalveolar lavage cytology were performed to confirm pulmonary health status. Diurnal changes were investigated every 2 h over a period of 24 h when the cats were adult. V(T), V(E), PIF and PEF significantly increased during somatic growth and were higher in males than in females, whereas R(R), T(i), T(e), T(e)/T(i) ratio, PEF/PIF ratio and Penh remained unchanged and were not affected by gender. When measured over 24 h, Penh, T(e) and T(i) were significantly increased in the early morning hours (04:00 h), whereas R(R), PIF and PEF were decreased at that time. This study provides reference values of BWBP variables for healthy male and female cats and indicates when circadian changes might be observed.     

Evaluation of respiratory function by barometric whole-body plethysmography in healthy dogs

The objective of the present study was to assess the validity of barometric whole-body plethysmography (BWBP), to establish reference values, and to standardise a bronchoprovocative test to investigate airway responsiveness using BWBP in healthy dogs. BWBP measurements were obtained from six healthy beagle dogs using different protocols: (1) during three consecutive periods (3.5min each) in two morning and two evening sessions; (2) before and after administration of two protocols of sedation; (3) before and after nebulisation of saline and increasing concentrations of carbachol and histamine both in conscious dogs and in dogs under both protocols of sedation. Enhanced pause (PENH) was used as index of bronchoconstriction. Basal BWBP measurements were also obtained in 22 healthy dogs of different breeds, age and weight. No significant influence of either time spent in the chamber or daytime was found for most respiratory variables but a significant dog effect was detected for most variables. A significant body weight effect was found on tidal volume and peak flow values (P<0.05). Response to carbachol was not reproducible and always associated with side effects. Nebulisation of histamine induced a significant increase in respiratory rate, peak expiratory flow, peak expiratory flow/peak inspiratory flow ratio and PENH (P<0.05). The response was reproduced in each dog at different concentrations of histamine. Sedation with acepromazine+buprenorphine had little influence on basal measurements and did not change the results of histamine challenge. It was concluded that BWBP is a safe, non invasive and reliable technique of investigation of lung function in dogs which provides new opportunities to characterise respiratory status, to evaluate airway hyperresponsiveness and to assess therapeutic interventions.     

Functional, inflammatory and morphological characterisation of a cat model of allergic airway inflammation

The aims of this study were to characterise a model of feline allergic airway inflammation and to test through a longitudinal investigation whether five repeated allergen exposures would lead to signs of airway remodelling that would be detectable in vivo. Eight healthy control cats and eight cats sensitised with Ascaris suum allergens were investigated. Barometric whole body plethysmography (BWBP) was used for the assessment of respiratory variables and airway responsiveness (AR). Bronchoalveolar lavage fluid (BALF) was sampled for cytology and determination of F(2)-isoprostane concentration and matrix metalloproteinase type 9 (MMP-9) activity. Thoracic radiography and bronchoscopy scores were also established. Cats were investigated prior to sensitisation and after inhalation of placebo or allergen challenge 1. BWBP measurements revealed a significant increase of enhanced pause (Penh), an index of bronchoconstriction, and AR in sensitised cats in response to allergen challenge 1. A significant increase in BALF neutrophil and eosinophil %, F(2)-isoprostane concentration and MMP-9 activity, and increased radiography and bronchoscopy scores were recorded. After a recovery period of 6 weeks, all variables except BALF MMP-9 returned to baseline values. Four further allergen challenges induced similar changes to those seen in challenge 1 and no signs of persistent changes suggestive of bronchial remodelling were detectable. The model provides an in vivo approach to functional, inflammatory and morphological changes occurring in response to single and repeated allergen exposure.     

Bronchodilators in bronchoscopy-induced airflow limitation in allergen-sensitized cats

This study investigated the effect of bronchoscopy and bronchoalveolar lavage (BAL) on respiratory function, determined by barometric whole-body plethysmography (BWBP), of healthy and allergen-sensitized cats. Furthermore, the efficacy of inhaled bronchodilators in preventing changes in respiratory function was determined. For test 1, 18 healthy experimental cats were investigated on day 1 by BWBP. On day 2, the cats underwent BWBP after sedation (medetomidine), after anesthesia induction (propofol), and after bronchoscopy and BAL. Enhanced pause (Penh) was significantly increased after bronchoscopy and BAL (1.64 +/- 0.17 versus 1.23 +/- 0.07, P < .05). For test 2, 6 cats were sensitized to ovalbumin (OVA), 6 cats were sensitized to Ascaris suum (AS), and 6 cats served as controls. On day 0, OVA- and AS-sensitized cats underwent an inhaled allergen challenge, whereas controls were exposed to saline. On days 1 and 2, the same protocol as described for test 1 was repeated. Post-BAL Penh of the AS-sensitized cats was significantly higher than at test 1 (2.28 +/- 0.22 versus 1.69 +/- 0.33, P < .05) and was correlated with BAL fluid neutrophil count (r = 0.55, P < .05). During tests 3, 4, and 5, the same protocol as used for test 2 was applied to each cat group, with the animals being randomly treated before sedation with inhaled salbutamol (200 microg), ipratropium bromide (40 microg), or a combination of both (200 + 40 microg). Post-BAL Penh of the AS-sensitized group was significantly decreased after the salbutamol + ipratropium bromide treatment (1.56 +/- 0.18 versus 2.28 +/- 0.22, P < .05). This study suggests that bronchoscopy and BAL induce airflow limitation in cats, which is more severe in the presence of lower airway inflammation. Inhaled salbutamol + ipratropium bromide reduce BAL-induced bronchoconstriction in AS-challenged cats and might be recommended as preventive treatment of asthmatic cats undergoing bronchoscopy.     

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 reactivity measured by barometric whole-body plethysmography in healthy cats

OBJECTIVE: To assess the validity of barometric whole-body plethysmography (BWBP) as a means of monitoring airway responses to induced bronchoconstriction in healthy cats. ANIMALS: 8 healthy cats without history of bronchopulmonary disease or exposure to indoor tobacco smoke. PROCEDURE: Cats were placed into a barometric plethysmograph with an internal volume of 38 L, and air flow was recorded at baseline and after carbachol (concentrations 0.005, 0.01, 0.02, 0.05, 0.1, and 0.2%) was introduced into the chamber. A dose-response curve was generated for several flow-derived measurements, and airway reactivity was determined by interpolation of the dose-response curve for enhanced pause. RESULTS: Peak inspiratory and expiratory flows increased significantly, but respiratory rate, inspiratory and expiratory times, relaxation time, and tidal volume did not differ significantly from baseline values. Flow-derived measurements (pause, enhanced pause, and end-expiratory pause) increased significantly at carbachol concentrations > 0.02%. Baseline measurements did not correlate with indices of airway reactivity. CONCLUSIONS AND CLINICAL RELEVANCE: Airway reactivity can be measured by use of BWBP, which is noninvasive. Airway reactivity was highly variable among cats and was not a function of baseline airway caliber, suggesting that other intrinsic mechanisms may be important.     

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.     

Inhaled fluticasone reduces bronchial responsiveness and airway inflammation in cats with mild chronic bronchitis

This study investigated the effect of inhaled fluticasone on lower airway inflammation and bronchial responsiveness (BR) to inhaled carbachol in cats with very mild, chronic bronchitis (n = 5) that were compared with healthy cats serving as controls (n = 6). Chest radiographs, BR tests performed non-invasively by barometric whole body plethysmography (BWBP) and bronchoalveolar lavage (BAL) were performed before and after treatment. BR was quantified by calculating the concentration of carbachol inducing bronchoconstriction (C-Penh300%), defined as a 300% increase of baseline Penh, an index of bronchoconstriction obtained by BWBP. BAL fluid was analyzed cytologically and the oxidant marker 8-iso-PGF2alpha was determined. At test 1, healthy cats and cats with bronchitis were untreated, whereas for test 2 inhalant fluticasone (250 microg once daily) was administrated for 2 consecutive weeks to cats with bronchitis. Control cats remained untreated. Inhaled fluticasone induced a significant increase in C-Penh300% and a significant decrease of BAL fluid total cells, macrophages, neutrophils and 8-iso-PGF2alpha in cats with bronchitis, whilst untreated control cats did not show significant changes over time. This study shows that a 2-week fluticasone treatment significantly reduced lower airway inflammation in very mild bronchitis. BR could be successfully monitored in cats using BWPB and decreased significantly in response to inhaled fluticasone. 8-Iso-PGF2alpha in BAL fluid was responsive to treatment and appeared as a sensitive biomarker of lower airway inflammation in cats.     

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.     

Effect of short-term oral and inhaled corticosteroids on airway inflammation and responsiveness in a feline acute asthma model

The objective of this study was to investigate whether high-dose inhaled fluticasone propionate (FP), alone or in combination with salmeterol (SAL), is as effective as oral prednisolone in reducing airway inflammation and obstruction in cats with experimentally-induced acute asthma. Six cats sensitised to Ascaris suum (AS) were enrolled in a prospective controlled therapeutic trial and underwent four aerosol challenges, at 1-month intervals with AS allergen. The allergen - stimulated animals received four consecutive days treatment with either oral prednisolone at 1mg/kg twice daily, 500 μg of FP inhaled twice daily, or a combination of FP/SAL at 500 μg/50 μg inhaled twice daily, respectively, according to a randomised cross-over design. Treatment-related changes in lung function, airway responsiveness (AR) and bronchoalveolar lavage fluid (BALF) cytology were assessed. Barometric whole-body plethysmography (BWBP) was used for the assessment of respiratory variables and AR. No significant differences in respiratory rate or Penh (an estimate of airflow limitation measured by BWBP) were detected among treatment groups. Allergen-induced airway hyper-responsiveness was significantly inhibited by all three steroid treatments (P<0.05). The mean BALF eosinophil percentage (±SEM) was lower after oral and inhaled corticosteroid treatment and these changes were significant for groups receiving prednisolone and the FP/SAL combination. Findings suggest high-dose FP, particularly in combination with SAL, is effective in ameliorating airway inflammation and hyper-responsiveness in this model of acute feline asthma, and highlight the potential use of these drugs in cats experiencing acute exacerbations of the naturally occurring disease.     

Pulmonary function testing in small animals

Pulmonary function testing (PFT) may be used to help provide objective information concerning the respiratory system in dogs and cats. Available techniques for PFT include spirometry, tidal breathing flow-volume loop analysis, barometric whole-body plethysmography, dynamic and static compliance, and lung and upper airway resistance. The information gained from PFT may help both in patient management and also in gaining understanding of the pathophysiology of the pulmonary system.     

CARDIAC AND PULMONARY ARTERY MENSURATION IN FELINE HEARTWORM DISEASE

A retrospective study was undertaken to quantify thoracic radiographic changes in cats with heartworm diseases, ( Dirofilaria immitis ). Using a blinded study format, the cardiac silhouette, thoracic cavity and pulmonary arteries were measured from thoracic radiographs of 21 cats with feline heartworm disease and 30 cats without known cardiac or pulmonary vessel pathology. Measured data were normalized to the thoracic cavity or bony structures within the radiographic field of view. The measurements were compared between the two groups of cats using an unpaired, two-tailed Student's t -test, with a p value of < 0.05 being considered significant. Cats with feline heartworm disease had enlargement of the craniocaudal aspect of the cardiac silhouette and normalized cardiac:thoracic ratio (p < 0.05) on the lateral view. Also, there was significant enlargement of the central and peripheral caudal lobar pulmonary arteries and their normalized ratios (p < 0.05) in the heartworm infected cats as visualized on the ventrodorsal projection. Tortuosity of the pulmonary arteries was seen in three of the 21 infected cats. Eleven of the 21 cats with feline heartworm disease had pulmonary parenchymal changes. Based on the present study, central and peripheral pulmonary artery enlargement as viewed on the ventrodorsal radiograph was the single best radiographic indicator of feline heartworm disease.     

Non-invasive assessment of airway responsiveness in healthy and allergen-sensitised cats by use of barometric whole body plethysmography

This study aimed at determining whether airway responsiveness (AR) tests performed by use of barometric whole body plethysmography (BWBP) were repeatable in cats and to what extent AR was affected by the nebulization protocol used, the age of the animals, the inflammatory status of the airways and prior bronchodilator treatment. Repeatability of AR was tested on two occasions in 30 healthy cats. The concentration of carbachol inducing a 300% increase of the enhanced pause (Penh)--an estimator of airflow limitation--was calculated (C-Penh300) and did not differ significantly between the two tests (0.035+/-0.017% compared to 0.034+/-0.016%) and was significantly and positively correlated. The comparison between rapidly and slowly increasing carbachol concentrations was performed in ten healthy cats and showed a significantly lower C-Penh300 (%) when slowly increasing concentrations were used (0.037+/-0.013% compared to 0.039+/-0.015%, P<0.05). A significant age-related increase of C-Penh300 was evidenced by performing AR tests in 15 healthy cats at 12, 18, 24 and 30 months (12 months: 0.026+/-0.008%, 18 months: 0.031+/-0.009%, 24 months: 0.038+/-0.01%, 30 months: 0.043+/-0.014%, P<0.05). C-Penh300 significantly decreased in 12 Ascaris suum-sensitised cats after allergen exposure (0.026+/-0.016% compared to 0.033+/-0.016%, P<0.05) and was negatively correlated with the granulocyte percentage of bronchoalveolar lavage fluid (r=-0.36, P<0.01). Compared with a placebo inhalation, pre-treatment with inhaled salbutamol significantly increased C-Penh300 in four healthy cats (0.093+/-0.021% compared to 0.036+/-0.004%, P<0.05). This study provides evidence that AR determination by use of BWBP is promising as non-invasive indicator of lower airway inflammation or for monitoring response to bronchodilator treatment.     

Structural and ultrastructural changes in the lungs of cats Felis catus (Linnaeus, 1758) experimentally infected with D. immitis (Leidy, 1856)

Clinical signs are seldom observed in feline heartworm disease, and the pathophysiological changes in the lungs of infected animals remain undefined. The goal of this study was to evaluate the structural and ultrastructural changes in the lungs of cats experimentally infected with Dirofilaria immitis. Six healthy cats were each infected with two adult heartworms by intravenous transplantation (Receptor Group, RG). The control group consisted of two uninfected animals kept under the same conditions as the RG. At 42 days after transplantation, all cats were euthanized and necropsied for worm recovery and collection of lung samples for examination by light microscopy (LM) and transmission electron microscopy. By LM, lung sections from the six infected cats exhibited bronchial and bronchiolar lesions. Alterations in all tissues of the pulmonary arteries were observed in the infected animals. In conclusion, cats infected experimentally with D. immitis developed lesions in their lungs as a consequence of arterial disease and intense interstitial pneumonia.     

Clinical evolution and radiographic findings of feline heartworm infection in asymptomatic cats

Clinical manifestations of heartworm disease in cats are variable; most cats seem to tolerate the infection well for extended periods. Heartworm-infected cats may undergo spontaneous self-cure due to the natural death of parasites without any symptomatology, or they may suddenly show dramatic and acute symptoms. Sudden death in apparently healthy cats is not a rare event. Thoracic radiographs are important tool for the diagnosis of cardiopulmonary disease. However, thoracic abnormalities are often absent or transient and highly variable in heartworm-infected cats. Findings, such as enlargement of the peripheral branches of the pulmonary arteries, with a varying degree of pulmonary parenchymal disease and hyperinflation, are the most typical features consistent with infection. A field study was performed for cats referred to the Veterinary Hospital Città di Pavia from January 1998 to December 2001 for routine health examinations and procedures to evaluate the clinical evolution and radiographic findings of feline heartworm infection. Thirty-four asymptomatic cats diagnosed with feline heartworm infection by antibody and antigen tests together with an echocardiogram that allowed worm visualization were included in the follow-up study. Cats were routinely examined every 3 months from the time of heartworm diagnosis until the outcome (self-cure or death). Self-cure was defined as no positive serology for heartworm antigens and no visualization of worms by echocardiography. A final examination for antibodies was carried after 12 months as a final confirmation of self-cure. Twenty-eight cats (82.4%) self-cured; including 21 that showed no clinical signs of infection throughout the study. Six cats died. The most common clinical features observed were acute respiratory symptoms and sudden death. Infection lasted over 3 years in the majority of the cats enrolled in the study. Thoracic radiograph appearance was variable, and the most commonly observed findings were focal and diffuse pulmonary parenchymal abnormalities.     

Effects of cadmium chloride inhalation on airflow limitation to histamine, carbachol and adenosine 5'-monophosphate assessed by barometric whole body plethysmography in healthy dogs

The effects of pharmacological bronchoprovocation on airflow patterns and surrogate respiratory parameters assessed by barometric whole body plethysmography (BWBP) were investigated in healthy dogs, previously exposed to cadmium chloride inhalation. BWBP-derived respiratory variables were calculated (1) at baseline and (2) following nebulisation of increasing concentrations of histamine, carbachol and adenosine 5'-monophosphate (AMP) until enhanced pause (PENH) increased to 300% of baseline (PCPENH300). Bronchoalveolar lavage fluid (BALF) cytology before (BCC) and after (ACC) cadmium chloride inhalation revealed cadmium-induced airway inflammation. Neutrophils increased from 6.7 +/- 7.3% (728 +/- 104/microL) BCC to 77.8 +/- 8.6% (3255 +/- 1407/microL) ACC. PCPENH300 for all three agonists significantly decreased ACC (means+/-SD) as follows: PCPENH300(histamine) 0.72 +/- 0.28 mg/mL BCC, and 0.35 +/- 0.31 mg/mL ACC (P<0.02); PCPENH300(carbachol) 0.34 +/- 0.16 mg/mL BCC, and 0.064 +/- 0.032 mg/mL ACC (P<0.02); PCPENH300(AMP) 1000 mg/mL BCC, and 415 +/- 398 mg/mL ACC (P<0.03). The only clinical sign shown was coughing. It was concluded that airway hyperresponsiveness after induced airway inflammation can be determined by BWBP in conscious small sized dogs. BWBP could be a suitable technique to study the respiratory effects of urban environmental pollution in pets.     

Prevalence of Dirofilaria immitis infection among shelter cats

OBJECTIVE: To determine prevalence of Dirofilaria immitis infection among shelter cats. DESIGN: Cross-sectional study. ANIMALS: 239 cats euthanatized at an animal shelter in southeastern Michigan. PROCEDURE: A gross necropsy focusing on the thoracic cavity, heart, lungs, and pulmonary vessels was performed within 5 hours after cats were euthanatized. Blood was collected directly from the heart of cats found to be infected and tested, using a filter test for microfilariae. Serum was tested for D immitis antigens by use of 2 antigen detection kits and for D immitis-specific antibodies by use of 2 antibody detection kits. RESULTS: Cats ranged from approximately 4 months to 15 years old. Adult D immitis were found in 6 (2.5%) cats. Blood could not be recovered from 1 of the cats with heartworm infection. For the 5 other cats, results of the filter test were negative, and results of both antigen and both antibody tests were positive. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cats living in an urban area in the northern part of the United States have a low prevalence of adult D immitis infection. However, this is likely to be an underestimate of the true prevalence of infection, because no attempts were made to identify cats infected with larval or juvenile stages of D immitis.     

Clinical course, diagnostic findings and necropsy diagnosis in dyspneic cats with primary pulmonary parenchymal disease: 15 cats (1996–2002)

Objective: Correlate the necropsy diagnosis with the history, diagnostic findings, and clinical course of dyspneic cats with primary lung parenchymal disease. Design: Retrospective study. Setting: Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania. Animals: Client‐owned cats over 6 months of age hospitalized in the Intensive Care Unit (ICU) with a primary problem of respiratory distress that had pulmonary parenchymal disease on thoracic radiographs, and a complete necropsy. Interventions: None. Measurements and main results: Cats included were assigned into 2 groups based on the pulmonary histopathology: inflammatory (n=8) and neoplastic (n=7) disease. No statistical difference was found between the groups with regard to age, body weight, clinical signs, duration of clinical signs, physical examination findings, thoracic radiography, duration of hospitalization, treatment, and outcome. Cats with neoplasia had a statistically higher mean total white blood cell count (26.60 k/μL±10.41) than those with inflammatory lung disease (11.59 k/μL±4.49; P=0.026). Cats with bacterial or viral pulmonary disease had a significantly shorter median duration of illness (5 days, range 1–7 days) than all other cats (30 days, range 7–365 days; P=0.0042). Ultrasound guided pulmonary fine‐needle aspiration (FNA) provided an accurate diagnosis in 5/5 cases. Conclusions: Forty‐seven percent of cats with pulmonary parenchymal disease had neoplasia. The clinical diagnosis was difficult to obtain ante‐mortem; lung FNA appeared to be the most helpful diagnostic tool in these cases.     

Physiological and haematological findings and clinical observations in a model of acute systemic anaphylaxis in Dirofilaria immitis-sensitised cats

OBJECTIVE: This study aims to understand the pathophysiology of anaphylaxis in Dirofilaria immitis-sensitised cats by analysing objective physiological and haematological measurements after challenge. DESIGN: Nineteen healthy D immitis-naive cats were sensitised using weekly injections of aluminium hydroxide-adjuvanted D immitis antigen, administered subcutaneously over 6 weeks. After sensitisation, cats (n = 16) were anaesthetised and challenged with intravenous D immitis antigen. A control group (n = 3) was sham-challenged using intravenous sterile 0.9% saline. Systolic blood pressure (measured non-invasively/indirectly), respiratory rate, degree of dyspnoea, blood O2 saturation, expired CO2, and heart rate and were measured immediately before and at 10 to 15 min intervals after challenge until terminal apnoea occurred or euthanasia at 140 mins post-challenge. Blood was collected for complete blood count immediately before and at 10, 20 and 35 mins after challenge. Clinical observations were recorded as they occurred. RESULTS: Antigen-challenged cats were divided into two groups: acute (apnoea occurred within 25 mins of challenge) and subacute (breathing at 25 mins after challenge). In both groups, the degree of dyspnoea increased and blood O2 saturation and blood pressure decreased. Respiratory rate increased in the subacute group. Expired CO2 decreased in both Ag-challenged and control groups. Haematocrit increased in the subacute group. Neutrophil count decreased in the acute group and platelet count decreased in the subacute group. Eosinophil count decreased in the subacute and control groups. Sustained dyspnoea and gastrointestinal signs were the most common clinical manifestations of anaphylaxis in the antigen-challenged cats. CONCLUSIONS: Intravenous challenge with D immitis antigen in sensitised cats results in dyspnoea, hypoxaemia and systemic hypotension accompanied by haemoconcentration.     

Hematologic and radiographic changes in cats after inoculation with infective larvae of Dirofilaria immitis.

Hematologic and radiographic findings in 15 domestic cats inoculated with 25, 100, or 200 to 400 infective larvae of Dirofilaria immitis and in 5 uninoculated cats were compared. Eosinophilia and leukocytosis developed 3 to 5 months after inoculation; packed cell volume and hemoglobin values were similar for inoculated cats and controls. Changes detected in radiographs of inoculated cats were: (1) increased visualization of the pulmonary arteries; (2) right-side cardiac enlargement; and (3) diffuse to focal areas of density in the pulmonary parenchyma. At least one of these lesions was visible radiographically by 3 to 7 months after inoculation in all 15 cats. The severity of changes was not directly proportional to the number of infective larvae inoculated, adult worm burden, or age of cat. However, male cats had more severe cardiopulmonary lesions than did females, and cats that had microfilaremia during the course of infection had more severe pulmonary lesions, as determined radiographically. Parenchymal densities decreased in 8 of the 15 inoculated cats 6 to 14 months after inoculation. Cardiac enlargement was detected radiographically in 10 of the inoculated cats. Enlargement of the pulmonary arteries was the most consistent sign of D immitis infection; it developed and persisted in 12 cats found to be infected at necropsy.