Demographic, clinical, and radiographic features of bronchiectasis in dogs: 316 cases (1988-2000)

Severe bronchiectasis resulting from chronic bacterial bronchitis and bronchopneumonia in a jungle cat

Bronchiectasis is irreversible bronchial dilation that can be congenital or acquired secondary to chronic airway obstruction. Feline bronchiectasis is rare and, to our knowledge, has not been reported previously in a non-domestic felid. An ~10-y-old female jungle cat (Felis chaus) was presented for evaluation of an abdominal mass and suspected pulmonary metastasis. The animal died during exploratory laparotomy and was submitted for postmortem examination. Gross examination revealed consolidation of the left caudal lung lobe and hila of the cranial lung lobes. Elsewhere in the lungs were several pale-yellow pleural foci of endogenous lipid pneumonia. On cut section, there was severe distension of bronchi with abundant white mucoid fluid. The remaining lung lobes were multifocally expanded by marginal emphysema. Histologically, ectatic bronchi, bronchioles, and fewer alveoli contained degenerate neutrophils, fibrin, and mucin (suppurative bronchopneumonia) with rare gram-negative bacteria. Aerobic culture yielded low growth of Proteus mirabilis and Escherichia coli. There was chronic bronchitis, marked by moderate bronchial gland hyperplasia, lymphoplasmacytic inflammation, and lymphoid hyperplasia. The palpated abdominal mass was a uterine endometrial polyp, which was considered an incidental, but novel, finding. Chronic bronchitis and bronchopneumonia should be considered as a cause of bronchiectasis and a differential diagnosis for respiratory disease in non-domestic felids.

CT features of feline cystic bronchiectasis forming mass lesions

Case series summary

Cystic bronchiectasis was diagnosed in three cats with known histories of chronic coughing using CT and histopathology. CT of the lungs revealed large space-occupying lesions that compressed and displaced unaffected pulmonary parenchyma and vessels. The masses were soft tissue attenuating in two cases and gas-cavitated with areas of dependent fluid in one case. All three cats were found to have mineral attenuating material in lesions and in other dilatated airways. Generalized bronchial wall thickening was also present and indicative of chronic lower airway disease. These findings were supported by histopathology showing inflammatory changes and dilatated airways in the collected tissues. In the two cases in which post-contrast CT series were acquired, the lesions had rim-enhancement.

Relevance and novel information

Cystic bronchiectasis is a rare presentation of bronchiectasis in cats and may mimic a pulmonary mass lesion, which could be mistaken for neoplasia or abscessation. The lack of central enhancement or presence of gas cavitation on CT, concurrent presence of diffuse bronchial wall thickening, other areas of bronchiectasis and the presence of broncholithiasis may alert the clinician to the possibility of cystic bronchiectasis related to chronic lower airway disease.

Retrospective study of 1050 dogs with respiratory symptoms in Japan (2005-2020)

BACKGROUND

Few studies have investigated the incidence of respiratory diseases based on anatomical sites or the relationship between breed and these diseases.

OBJECTIVE

The objective of this study was to investigate the prevalence of canine respiratory diseases among dogs in Japan, with relationship to the breed.

METHODS

We retrospectively reviewed the medical records of dogs with respiratory symptoms and calculated the odds ratio (OR) to evaluate the relationship between breed and disease.

RESULTS

A total of 1050 dogs with respiratory symptoms were included in this study. Miniature dachshunds were the most common breed affected by respiratory diseases. Among tracheobronchial diseases, there was a significant association between some small breeds and tracheobronchial collapse, miniature dachshunds (OR: 4.44, 8.43, 95% confidence interval [CI]: 3.17-6.22, 4.33-16.0) and chronic bronchitis and bronchiectasis. Among nasal diseases, miniature dachshunds (OR: 27.2, 95% CI: 16.8-44.8) and golden retrievers (OR: 21.0, 95% CI: 6.43-69.3) were the most affected by non-infectious rhinitis and nasal aspergillosis, respectively. Brachycephalic obstructive airway syndrome was the most common disease among pharyngeal and laryngeal diseases, with a relationship with breed being found in some brachycephalic breeds, and Pomeranians (OR: 2.7, 95% CI: 1.42-5.17).

CONCLUSIONS

Respiratory diseases in dogs are strongly correlated with popular breeds in Japan. Miniature dachshunds, in particular, are associated with many respiratory diseases, which may differ from international reports. Thus, this result may help in the early detection, prevention, treatment, and elucidation of the pathophysiology of canine respiratory diseases.

Specialists' approach to tracheal collapse: survey-based opinions on diagnostics, medical management, and comorbid diseases

OBJECTIVE

To describe the current standard of care among specialists for the routine diagnostic evaluation and medical management of stable tracheal collapse in dogs, identifying gaps between practice and scientific evidence to facilitate the development of future prospective studies. A secondary objective was to describe the perceived incidence of selected comorbid disorders in dogs with tracheal collapse and the diagnostic tests performed to evaluate for those disorders.

SAMPLE

180 veterinary specialists in 22 countries.

PROCEDURES

An electronic survey was sent to 4 specialty listservs to target diplomates. Respondents completed multiple-choice and free-response questions related to the diagnostic evaluation and treatment of a theoretical stable dog with suspected tracheal collapse.

RESULTS

Most respondents routinely utilized radiography, tracheobronchoscopy, and fluoroscopy to diagnose tracheal collapse and performed airway sampling, sedated airway examination, and echocardiograms to rule out comorbidities. The most frequently perceived comorbid disorders included chronic bronchitis, bronchomalacia, and myxomatous mitral valve disease. Respondents most often prescribed opioid antitussives, glucocorticoids, anxiolytics, and antibiotics as treatments. Less frequently, they utilized bronchodilators and nonopioid medications for cough.

CLINICAL RELEVANCE

Despite a lack of published guidelines, specialists have similar approaches in their diagnostic and therapeutic approach to a stable dog with suspected tracheal collapse and believe evaluating for comorbid disorders is important. A description of a typical diagnostic approach and knowledge of realistic treatment goals will assist the general practitioner managing dogs with stable tracheal collapse. Additionally, gaps between current practices established via this survey and data supporting those practices exist, specifically concerning the use of antibiotics and nonopioid medications for cough, representing areas for further study.

Sub-Antimicrobial Dosage Scheme of Doxycycline for the Chronic Treatment of Bronchiectasis in a Dog

A 9-month-old German shepherd dog was examined because of a chronic cough, exercise intolerance and labored breathing, as well as recurrent episodes of lethargy with anorexia. Multifocal severe bronchiectasis and neutrophilic bronchitis was found with thoracic computed tomography and cytology of bronchoalveolar lavage fluid, respectively. While oral azithromycin was administered, clinical signs were absent. However, stopping azithromycin lead repeatedly to presumed bacterial pneumonia within 1–2 months. With sub-antimicrobial dosed oral doxycycline (initially 1.5 mg/kg once daily for 3 months, then 0.7–0.5 mg/kg once daily for 6 months), the dog remained free from clinical signs. Bronchiectasis is characterized by marked irreversible bronchial dilation. Accumulation of intraluminal mucopurulent material and neutrophilic inflammation cause chronic cough and recurrent bacterial pneumonia. For therapy, life-long oral antibiotics are recommended. Chronic antibiotic administration, however, can select resistant bacterial strains. Though both azithromycin and doxycycline possess anti-inflammatory effects, doxycycline has these off-target properties at a sub-antimicrobial dose. In this report, a chronic sub-antimicrobial dose of doxycycline resulted in the resolution of chronic cough, exercise intolerance and labored breathing, and prevented recurrence of suspected bacterial pneumonia in the long-term in a dog with severe bronchiectasis. Beneficial effect of doxycycline is probably related to its anti-inflammatory effects rather than its antimicrobial properties.

Aerodigestive Disease in Dogs

Aerodigestive disorders (AeroDs) in people encompass a wide range of clinical syndromes, reflecting the complex relationship between the respiratory and digestive tracts. In veterinary medicine, aspiration is used interchangeably with aspiration pneumonia. Although aspiration pneumonia is a common disorder in dogs, it does not reflect the breadth of AeroDs. Unfortunately, AeroDs rarely are investigated in veterinary medicine because of lack of clinical recognition, limitations in available diagnostics, and the fact that AeroDs may be caused by occult digestive disease. Recognizing patients with AerodD represents an area of significant clinical importance that may provide additional areas of clinical intervention.

Canine Chronic Bronchitis: An Update

Chronic bronchitis is a syndrome defined by cough on most days for at least 2 months for which no specific cause can be identified. Older small breed dogs are most commonly affected, but bronchitis can also be documented in midsized and larger breed dogs. Diagnostic testing includes physical examination, laboratory testing, radiography, and airway evaluation via bronchoscopy, cytology, and culture. Treatment is directed at reducing exposure to irritants, reducing airway inflammation, and controlling cough.

Presumptive Development of Fibrotic Lung Disease From Bordetella bronchiseptica and Post-infectious Bronchiolitis Obliterans in a Dog

A 7-month-old Miniature Poodle acquired from a pet store developed cough and subsequently respiratory distress compatible with Bordetella bronchiseptica infection. Partial but incomplete resolution of clinical signs and thoracic radiographic/computed tomographic imaging lesions were noted with use of susceptibility-guided antimicrobials. Additionally, a concern for an infectious nidus led to left cranial lung lobectomy at 9 months of age. Histopathology predominantly revealed polypoid and constrictive bronchiolitis obliterans (i.e., small airway disease). Intermittent antimicrobial administration over the next 5 years failed to blunt progressive clinical signs. At 8 years, necropsy confirmed severe airway-centered interstitial fibrosis. This pattern of fibrosis was strongly suggestive of underlying small airway disease as the trigger. In retrospect, post-infectious bronchiolitis obliterans (PIBO), a syndrome in young children caused by pulmonary infections but not yet recognized in pet dogs, likely initiated a pathway of fibrosis in this dog. In dogs with risk factors for community-acquired pathogens such as Bordetella bronchiseptica, PIBO is a differential diagnosis with development of severe, persistent respiratory signs incompletely responsive to appropriate antimicrobials. Untreated PIBO may lead to airway-centered interstitial fibrosis. Future study is required to determine if targeted therapy of PIBO could alter the course of end-stage pulmonary fibrosis.

Bronchoscopy, Imaging, and Concurrent Diseases in Dogs with Bronchiectasis: (2003-2014)

Background

Bronchiectasis is a permanent and debilitating sequel to chronic or severe airway injury, however, diseases associated with this condition are poorly defined.

Objective

To evaluate results of diagnostic tests used to document bronchiectasis and to characterize underlying or concurrent disease processes.

Animals

Eighty‐six dogs that had bronchoscopy performed and a diagnosis of bronchiectasis.

Methods

Retrospective case series. Radiographs, computed tomography, and bronchoscopic findings were evaluated for features of bronchiectasis. Clinical diagnoses of pneumonia (aspiration, interstitial, foreign body, other), eosinophilic bronchopneumopathy (EBP), and inflammatory airway disease (IAD) were made based on results of history, physical examination, and diagnostic testing, including bronchoalveolar lavage fluid analysis and microbiology.

Results

Bronchiectasis was diagnosed in 14% of dogs (86/621) that had bronchoscopy performed. Dogs ranged in age from 0.5 to 14 years with duration of signs from 3 days to 10 years. Bronchiectasis was documented during bronchoscopy in 79/86 dogs (92%), thoracic radiology in 50/83 dogs (60%), and CT in 34/34 dogs (100%). Concurrent airway collapse was detected during bronchoscopy in 50/86 dogs (58%), and focal or multifocal mucus plugging of segmental or subsegmental bronchi was found in 41/86 dogs (48%). Final diagnoses included pneumonia (45/86 dogs, 52%), EBP (10/86 dogs, 12%) and IAD (31/86 dogs, 36%). Bacteria were isolated in 24/86 cases (28%), with Streptococcus spp, Pasteurella spp, enteric organisms, and Stenotrophomonas isolated most frequently.

Conclusions and Clinical Importance

Bronchiectasis can be anticipated in dogs with infectious or inflammatory respiratory disease. Advanced imaging and bronchoscopy are useful in making the diagnosis and identifying concurrent respiratory disease.

Accuracy of a computed tomography bronchial wall thickness to pulmonary artery diameter ratio for assessing bronchial wall thickening in dogs

Computed tomography is increasingly being used in veterinary medicine to evaluate animals with pulmonary signs such as coughing, tachypnea, and exercise intolerance, however, a quantitative measure of bronchial wall thickening has yet to be validated in veterinary medicine. Canine chronic bronchitis is a disease that is characterized histologically by thickening of the bronchial walls. Thoracic CT images of 16 dogs with chronic bronchitis and 72 dogs presenting for conditions unrelated to cough were evaluated. A ratio comparing the bronchial wall thickness to the adjacent pulmonary artery diameter was obtained in the right and left cranial and caudal lung lobes. There was no significant difference in dogs with chronic bronchitis or unaffected dogs between the left and right hemithorax, patient weight, patient age, image slice thickness, or CT machine used. Dogs with chronic bronchitis were found to have a significantly greater ratio than unaffected dogs (P < 0.001). The ratios in the cranial lung lobes were found to be significantly greater than the caudal lung lobes in both chronic bronchitis and unaffected dogs (P < 0.001). A receiver operating characteristic curve of the ratios in the cranial lung lobes had an area under the curve of 0.912, indicating high accuracy in predicting for bronchial wall thickening. A ratio of ≥ 0.6 in the cranial lung lobes was found to have a sensitivity of 77% and specificity of 100% in predicting for the presence of chronic bronchitis, and we propose using this cut-off as supportive of bronchial wall thickening on CT.

Canine chronic bronchitis

Chronic bronchitis is a syndrome defined by cough on most days for at least 2 months where no specific cause can be identified. Older small breed dogs are most commonly affected, but bronchitis is also documented in midsized and larger breed dogs. Diagnostic testing includes physical examination, laboratory testing, radiography, and airway evaluation via bronchoscopy, cytology, and culture. Treatment is directed at reducing exposure to irritants, reducing airway inflammation, and controlling cough.

Approaches to canine health surveillance

Effective canine health surveillance systems can be used to monitor disease in the general population, prioritise disorders for strategic control and focus clinical research, and to evaluate the success of these measures. The key attributes for optimal data collection systems that support canine disease surveillance are representativeness of the general population, validity of disorder data and sustainability. Limitations in these areas present as selection bias, misclassification bias and discontinuation of the system respectively. Canine health data sources are reviewed to identify their strengths and weaknesses for supporting effective canine health surveillance. Insurance data benefit from large and well-defined denominator populations but are limited by selection bias relating to the clinical events claimed and animals covered. Veterinary referral clinical data offer good reliability for diagnoses but are limited by referral bias for the disorders and animals included. Primary-care practice data have the advantage of excellent representation of the general dog population and recording at the point of care by veterinary professionals but may encounter misclassification problems and technical difficulties related to management and analysis of large datasets. Questionnaire surveys offer speed and low cost but may suffer from low response rates, poor data validation, recall bias and ill-defined denominator population information. Canine health scheme data benefit from well-characterised disorder and animal data but reflect selection bias during the voluntary submissions process. Formal UK passive surveillance systems are limited by chronic under-reporting and selection bias. It is concluded that active collection systems using secondary health data provide the optimal resource for canine health surveillance.

Quantitative and qualitative computed tomographic characteristics of bronchiectasis in 12 dogs

Bronchiectasis is an irreversible dilatation of the bronchi resulting from chronic airway inflammation. In people, computed tomography (CT) has been described as the noninvasive gold standard for diagnosing bronchiectasis. In dogs, normal CT bronchoarterial ratios have been described as <2.0. The purpose of this retrospective study was to describe quantitative and qualitative CT characteristics of bronchiectasis in a cohort of dogs with confirmed disease. Inclusion criteria for the study were thoracic radiography, thoracic CT, and a diagnosis of bronchiectasis based on bronchoscopy and/or histopathology. For each included dog, a single observer measured CT bronchoarterial ratios at 6 lobar locations. Qualitative thoracic radiography and CT characteristics were recorded by consensus opinion of two board-certified veterinary radiologists. Twelve dogs met inclusion criteria. The mean bronchoarterial ratio from 28 bronchiectatic lung lobes was 2.71 ± 0.80 (range 1.4 to 4.33), and 23/28 measurements were >2.0. Averaged bronchoarterial ratios from bronchiectatic lung lobes were significantly larger (P < 0.01) than averaged ratios from nonbronchiectatic lung lobes. Qualitative CT characteristics of bronchiectasis included lack of peripheral airway tapering (12/12), lobar consolidation (11/12), bronchial wall thickening (7/12), and bronchial lumen occlusion (4/12). Radiographs detected lack of airway tapering in 7/12 dogs. In conclusion, the most common CT characteristics of bronchiectasis were dilatation, a lack of peripheral airway tapering, and lobar consolidation. Lack of peripheral airway tapering was not visible in thoracic radiographs for some dogs. For some affected dogs, bronchoarterial ratios were less than published normal values.

Naturally occurring mutations in the canine CFTR gene

Naturally occurring cystic fibrosis (CF)-causing mutations in the CFTR gene have not been identified in any nonhuman animal species. Since domestic dogs are known to develop medical conditions associated with atypical CF in humans (e.g., bronchiectasis and pancreatitis), we hypothesized that dogs with these disorders likely have a higher expression rate of CFTR mutations than the at-large population. Temporal temperature-gradient gel electrophoresis (TTGE) was used to screen canine CFTR in 400 animals: 203 dogs diagnosed with pancreatitis, 23 dogs diagnosed with bronchiectasis, and 174 dogs admitted to clinics for any illness (at-large dogs). Twenty-eight dogs were identified with one of four CFTR missense mutations. P1281T and P1464H mutations occur in relatively unconserved residues. R1456W is analogous to the human R1453W mutation, which has approximately 20% of normal CFTR function and is associated with pancreatitis and panbronchiolitis. R812W disrupts a highly conserved protein kinase A recognition site within the regulatory domain. We conclude that naturally occurring CFTR mutations are relatively common in domestic dogs and can be detected with TTGE. No substantive differences in mutation frequency were observed between the at-large, pancreatitis, and bronchiectasis dogs.

Demographic and historical findings, including exposure to environmental tobacco smoke, in dogs with chronic cough

BACKGROUND

Controlled studies investigating risk factors for the common presenting problem of chronic cough in dogs are lacking.

HYPOTHESIS/OBJECTIVES

To identify demographic and historical factors associated with chronic cough in dogs, and associations between the characteristics of cough and diagnosis.

ANIMALS

Dogs were patients of an academic internal medicine referral service. Coughing dogs had a duration of cough>or=2 months (n=115). Control dogs had presenting problems other than cough (n=104).

METHODS

Owners completed written questionnaires. Demographic information and diagnoses were obtained from medical records. Demographic and historical data were compared between coughing and control dogs. Demographic data and exposure to environmental tobacco smoke (ETS) also were compared with hospital accessions and adult smoking rates, respectively. Characteristics of cough were compared among diagnoses.

RESULTS

Most coughing dogs had a diagnosis of large airway disease (n=88; 77%). Tracheobronchomalacia (TBM) was diagnosed in 59 dogs (51%), including 79% of toy breed dogs. Demographic risk factors included older age, smaller body weight, and being toy breed (P<.001). No association was found between coughing and month (P=.239) or season (P=.414) of presentation. Exposure to ETS was not confirmed to be a risk factor (P=.243). No historical description of cough was unique to a particular diagnosis.

CONCLUSIONS AND CLINICAL IMPORTANCE

Associations with age, size, and toy breeds were strong. TBM is frequent in dogs with chronic cough, but descriptions of cough should be used cautiously in prioritizing differential diagnoses. The association between exposure to ETS and chronic cough deserves additional study.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS AND CLINICAL RELEVANCE

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