Bacterial infection before and after stent placement in dogs with tracheal collapse syndrome

Assessment of the circulating inflammatory mediator interleukin-8 in dogs with tracheal collapse

Objective

Tracheal collapse (TC) is an obstructive respiratory disorder in dogs that can affect lifespan and quality of life. Systemic inflammation has been identified in other obstructive airway conditions in dogs and humans. We hypothesized a systemic pro-inflammatory state exists in dogs with TC.

Animals

Dogs with TC (TC, n = 15) and healthy, non-affected controls (C, n = 15), were prospectively enrolled.

Procedure

Signalment and body condition score (BCS) were recorded for all dogs. For TC dogs, cough duration, pharyngeal collapse, bronchial collapse, and previous stent placement were recorded. Plasma samples were banked at -80°C and batch-analyzed for interleukin-8 (IL-8). Differences between groups were evaluated.

Results

Yorkshire terriers were overrepresented in the TC group. The TC group was older than the C group and had a higher BCS. Interleukin-8 was significantly greater in the TC compared to the C group. Interleukin-8 was not correlated with age sex, BCS, breed, cough duration, pharyngeal collapse, bronchial collapse, or stent placement.

Conclusion and clinical relevance

Increased plasma IL-8 concentration supports the presence of systemic inflammation in canine TC. Dogs with TC were older than controls, with a higher BCS, but this did not account for the increased IL-8. Further investigation of IL-8 as a potential biomarker for monitoring TC progression and therapeutic response is warranted.

A systematic review and meta-analysis of prevalence of complications after tracheal stenting in dogs

BACKGROUND

Stenting has become popular to treat tracheal collapse in dogs, but complications might arise and negatively affect treatment outcome.

OBJECTIVES

Determine the overall prevalence of complications of tracheal stenting in dogs.

METHODS

A bibliographic search was performed of publications from 2000 to 2020. Studies were assessed for quality of evidence and measured prevalence of the 8 most commonly reported complications after tracheal stenting in dogs (stent fracture, stent migration, relapsing collapse, granuloma formation, tracheobronchial infections, and early, late, and clinically relevant late cough). Random effects meta-analyses were used to estimate pooled complications prevalence.

RESULTS

Fifteen studies met inclusion criteria. Cough (early: 99%; 95% confidence interval [95% CI]: 95%-100%, late: 75%; 95% CI: 63%-85%, and clinically relevant: 52%; 95% CI: 42%-61%), tracheobronchial infections (24%; 95% CI: 14%-35%), and granulomas (20%; 95% CI: 11%-30%) were common after tracheal stenting. Stent fractures (12%; 95% CI: 5%-20%), relapsing collapse (10%; 95% CI: 5%-15%), and stent migration (5%; 95% CI: 1%-9%) were less frequent. Significant heterogeneity among studies was identified for the estimated prevalence of stent fracture, granulomas, infections, and late cough.

CONCLUSIONS AND CLINICAL IMPORTANCE

Tracheal stenting in dogs is associated with a high risk of coughing and a moderate risk of tracheobronchial infections and granuloma formation. Because most complications will impact a dog's quality of life, owners must be informed that tracheal stenting is a second-line procedure that does not necessarily alleviate the need for medical treatment and frequent follow-up visits. Additional studies are warranted to identify the risk factors of these complications.

Antimicrobial and Antiproliferative Coatings for Stents in Veterinary Medicine-State of the Art and Perspectives

Microbial colonization in veterinary stents poses a significant and concerning issue in veterinary medicine. Over time, these pathogens, particularly bacteria, can colonize the stent surfaces, leading to various complications. Two weeks following the stent insertion procedure, the colonization becomes observable, with the aggressiveness of bacterial growth directly correlating with the duration of stent placement. Such microbial colonization can result in infections and inflammations, compromising the stent's efficacy and, subsequently, the animal patient's overall well-being. Managing and mitigating the impact of these pathogens on veterinary stents is a crucial challenge that veterinarians and researchers are actively addressing to ensure the successful treatment and recovery of their animal patients. In addition, irritation of the tissue in the form of an inserted stent can lead to overgrowth of granulation tissue, leading to the closure of the stent lumen, as is most often the case in the trachea. Such serious complications after stent placement require improvements in the procedures used to date. In this review, antibacterial or antibiofilm strategies for several stents used in veterinary medicine have been discussed based on the current literature and the perspectives have been drawn. Various coating strategies such as coating with hydrogel, antibiotic, or other antimicrobial agents have been reviewed.

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.

Self-expanding tracheal stent placement in a cat with primary tracheal collapse

A 12-year-old mixed-breed spayed female cat presented with dyspnoea, open-mouthed breathing, and cyanosis that was difficult to control with medical pharmacotherapy; the cat was diagnosed with the primary tracheal collapse of the neck and chest regions. The diagnosis was confirmed by dynamic chest radiography, tracheal endoscopy, and computed tomography (CT). Tracheal endoscopy and CT showed dropsy of the dorsal membranous wall over most of the trachea. A self-expanding Nitinol cross-and-hook braided stent was placed along the entire tracheal lumen using surgical X-ray fluoroscopy. Bacterial cultures in the trachea were negative. Dyspnoea disappeared immediately after the endotracheal stent was implanted. Although the long-term prognosis remains under observation, the short- to medium-term prognosis was very good. These results suggest that stenting may be useful in the treatment of primary tracheal collapse in cats.

The Effects of Mycophenolate on the Formation of Granulation Tissue Post-operatively in Canine Tracheal Stent Patients (2014-2020)

Objectives: To determine if mycophenolate mofetil reduces the incidence and severity of granulation tissue in-growth in canine tracheal stent patients. Study design: Randomized clinical trial. Animals: 111 dogs from the hospital population. Methods: Client-owned dogs that received an endoluminal self-expanding tracheal stent for canine tracheal collapse between 2014 and 2020 were randomly assigned into one of two treatment groups. Control group medication protocol consisted of prednisone 0.5 mg/kg PO BID/SID/EOD × 30 days, hydrocodone 0.25 mg/kg PO TID × 30 days, and cefovecin 8 mg/kg SQ post-placement. Mycophenolate group medication protocol was identical to the control group medication protocol with the addition of mycophenolate mofetil 10 mg/kg PO BID × 30 days, SID for life. Recheck tracheoscopy was performed at 1, 3, and 6 months post-stent placement. Presence and severity of granulation tissue were determined by tracheoscopy and were recorded as a percentage of tracheal lumen obstruction by blinded evaluators (none present, <25%, >25-50%, and >50%). Results: At none of the three time points was there a statistically significant difference in grade between controls and those receiving mycophenolate (p = 0.467, p = 0.330, and p = 0.410). Conclusions and Clinical Significance: Our results suggest that mycophenolate can be safely given to these patients but do not support that its administration will reduce the incidence and severity of granulation tissue. Although a difference was observed in the severity of granulation tissue between the two groups, loss to follow-up may have influenced conclusions. A larger study would be warranted to further evaluate the effect of mycophenolate on the development of granulation tissue.

Lower airway collapse: Revisiting the definition and clinicopathologic features of canine bronchomalacia

Bronchomalacia (BM) is an inconsistently defined term in dogs, impairing understanding of clinical presentation, therapeutic response and prognosis. Herein the authors propose to clarify the definition of canine bronchomalacia (CBM) as regional to diffuse dynamic airway collapse of segmental and/or subsegmental bronchi with associated clinical signs due to airflow limitation. In contrast to tracheal collapse, mainstem bronchial collapse, and in some cases lobar collapse, CBM requires advanced imaging. Common co-morbid conditions (e.g., chronic bronchitis, mitral valve degenerative disease, etc.) should be identified during a comprehensive diagnostic evaluation. Current empiric treatments advocated in absence of clinical trials documenting efficacy in the dog warrant evaluation, as some (e.g., bronchodilators) may have detrimental effects in certain types of airway collapse in humans. There is no direct treatment for CBM, as defined above, but non-specific therapies and targeted treatment of co-morbid disease may improve clinical signs and quality of life. In this manuscript, the authors provide a review of the different types of airway collapse focusing on CBM, reviewing their definition and etiology, proposing a classification scheme, and discussing clinical signs, diagnostic testing, and treatment. Future studies should focus on both improving understanding of the etiology and natural disease progression of CBM and treatment trials.

Bacterial infection before and after stent placement in dogs with tracheal collapse syndrome

Background

Dogs with tracheal stents often have positive airway bacterial cultures. The pathogenicity of these organisms and risk factors for infection have not been investigated.

Objective

Describe bacterial infection in dogs with tracheal collapse before and after tracheal stent placement.

Animals

Fifty‐three client‐owned dogs.

Methods

Retrospective review of medical records of dogs receiving tracheal stents with thoracic radiographs, tracheoscopy, and endotracheal lavage.

Results

There was no difference between the overall prevalence of dogs with positive bacterial cultures before (31/38; 82%) or after stent placement (24/31; 77%) (P = .67). An increased number of geriatric (17/28; 61%) and traditional‐type collapse (TTC) (16/26; 62%) dogs had positive pathogenic airway infections before stent placement, compared to young (8/25; 32%; P = .04) and malformation‐type collapse (MTC) dogs (9/27; 33%; P = .04). After tracheal stent placement, geriatric dogs had a 52% reduction in pathogenic bacteria infection frequency (P = .02) and dogs with TTC had a 56% reduction in pathogenic bacteria infection frequency (P = .01). Significant risk factors for pathogenic infection included a history of pneumonia (OR = 3.6; 95% CI, 0.28‐43.36) and cardiac disease (OR = 1.25; 95% CI, 0.16‐9.92) in geriatric dogs, and hepatomegaly in young dogs (OR = 1.5; 95% CI, 0.12‐19.44).

Conclusions and Clinical Importance

Tracheal stent placement does not increase the overall rate of pathogenic bacterial infection in dogs with tracheal collapse and can decrease the rate of subsequent pathogenic infections in geriatric dogs and dogs with TTC that require tracheal stenting. Airway culture and cytology should be performed in all dogs undergoing tracheal stent placement.