Canine Pyothorax: Comparison of Culture and Susceptibility Results to the BSAVA PROTECT ME Poster and Other Published Recommended Antimicrobial Use Guidelines

The most common bacterial isolates in dogs with pyothorax include mixed anaerobes, Enterobacteriaceae (especially Escherichia coli), Pasteurella spp., Streptococcus spp., and Staphylococcus spp. A fluoroquinolone with amoxicillin (±clavulanate) or a fluoroquinolone with clindamycin are the most commonly recommended empirical antimicrobials whilst pending bacterial culture of the pleural effusion. The aim of this study is to review and compare the pleural effusion culture and antimicrobial susceptibility results to the PROTECT ME poster and other published antimicrobial use guidelines. The medical records of 53 dogs diagnosed with pyothorax between 2014 and 2020 at two veterinary referral centres were reviewed. Information, including culture and susceptibility results, was assessed. Antimicrobial susceptibility panels varied; susceptibility to a particular antibiotic was calculated as a percentage of isolates tested against the same antibiotic. A total of 30 of 53 dogs (57.7%) had a positive pleural fluid culture. The most common isolates were Pasteurella species (23.3%), Escherichia coli (23.3%), and mixed anaerobes (20%). From the aerobic isolates, 73-83% were susceptible to a fluoroquinolone, 14/19 (74%) to amoxicillin, and 20/22 (91%) to potentiated amoxicillin. Resistance to clindamycin was documented in 9/13 (69%) aerobic isolates, with all Gram-negative bacteria (9/9) being resistant. The combination of potentiated amoxicillin with marbofloxacin would have been appropriate in most of the dogs (75-92.9%). This study shows a high rate of resistance to clindamycin, which is not a suitable option for monotherapy and may be less effective in combination therapy compared to potentiated amoxicillin.

Therapy of Pyothorax in Cats via Small-Bore Thoracostomy Tube in Terms of Efficacy, Complications and Outcomes

Simple Summary

With this study we present our therapeutic strategy for cats with purulent fluid accumulation in the thorax. In addition to the systemic administration of antibiotics, the aim of the therapy is always the drainage of the purulent fluid from the thorax. For this purpose, we use a particular small-bore chest drain. The first aim of our study is to assess the efficacy and complication rate of our drainage. The second objective is to evaluate two treatment groups regarding their disease outcomes. We were able to show that our small-bore chest drain is similarly effective to the traditionally used large-bore drains. At the same time, we had a very low drain-associated complication rate. We detected no difference between the treatment groups and, thus, no effect on survival by early placement of bilateral drains into the thoracic cavity or lavage of the thoracic cavity with a heparinised solution. Our study supports the theory that drainage of purulent fluid from the thoracic cavity in cats can be performed with small-bore drains with good results and minimal risk of complications.

Abstract

First-line therapy for cats with pyothorax consists of intravenous antibiotics, drainage of the septic pleural effusion and closed-chest lavage. Large-bore thoracostomy tubes are traditionally used for drainage, but case series indicate a comparable efficacy using small-bore tubes. In this retrospective study, we describe a new technique of sheath-guided small-bore (6 F) thoracostomy tubes in cats with pyothorax and evaluate their efficacy and complications. Additionally, we compare outcomes between two treatment groups. Placement and use of the small-bore thoracostomy tubes described here has a low complication rate of 4% (3/67 tubes), and 53% (24/45) of the cats could be treated with thoracostomy tubes and closed-chest lavage according to the protocol. The success rate is reduced by 18% (8/45) due to deaths caused mainly by sepsis, 16% (7/45) due to structural diseases requiring surgery and a further 14% (6/43) due to lavage failures that could only be cured after additive therapy (thoracotomy or fibrinolysis). The long-term prognosis was very good, with a survival rate one year after discharge of 94% (30/32). We detected no effect on survival by early placement of bilateral thoracostomy tubes or closed-chest lavage with a heparinised solution. In conclusion, therapy of pyothorax with small-bore thoracostomy tubes is as successful as therapy with large- or medium-bore tubes.

CT findings, management and short-term outcome of dogs with pyothorax: 101 cases (2010 to 2019)

OBJECTIVES

To describe diagnosis, CT findings, management and short-term outcome of a large population of canine pyothorax cases.

METHODS

Retrospective analysis of 101 canine pyothorax cases at two UK referral centres. Medical records and CT images were reviewed. Dogs were included if pre- and post-contrast CT was performed within 48 hours of presentation.

RESULTS

CT abnormalities included pleural thickening (84.1%), pannus (67.3%), pneumothorax (61.4%), mediastinal effusion (28.7%), pulmonary (13.8%) and mediastinal (7.9%) abscessation, foreign body presence (7.9%), foreign body tracts (6.9%) and pneumonia (6.9%). Seventy-one percent of dogs were managed surgically, of which 90.2% survived, and 29% were managed medically, of which 72.4% survived. Overall mortality was 14.8% and 86.6% of these dogs died within 48 hours of admission. All dogs with evidence of a foreign body on CT underwent surgery.

CLINICAL SIGNIFICANCE

Mortality in our population was low and most dogs that died did so within 48 hours of hospitalisation, regardless of management type.

Short- and long-term outcome in cats diagnosed with pyothorax: 47 cases (2009-2018)

OBJECTIVES

The aims of this retrospective study were to report the short- and long-term outcome in cats treated for pyothorax and to identify prognostic indicators as well as determine recurrence rate.

METHODS

Medical records from April 2009 to August 2018 were retrospectively reviewed. Cases were included if a diagnosis of pyothorax was confirmed via cytology and/or culture of pleural fluid. Cats diagnosed with or suspected of having other thoracic diseases and cats with no evidence of pleural effusion were excluded from the study.

RESULTS

Fifty-five cats met the inclusion criteria. Eighty five percent (n=47) cats underwent medical management with thoracostomy tubes, pleural lavage and broad-spectrum antibiotics. Fifteen percent (n=5) cases failed medical treatment and underwent thoracotomy. Twenty eight percent (n=13) did not survive to hospital discharge. Short-term survival (14 days) was achieved in 72% (n=34). Long-term follow-up was available for 31 of 34 with a long-term survival rate of 68% (n=30). The recurrence rate was 6% (n=2).

CONCLUSION

For cats with pyothorax that survive to discharge the prognosis is excellent and the condition is associated with a low recurrence rate.

The use of small-bore wire-guided chest drains for the management of feline pyothorax: A retrospective case series

Background:

Pyothorax in cats is routinely managed, at least initially, with thoracic tube placement associated with systemic antimicrobial administration. Traditionally, large-bore trocar-type thoracostomy tubes have preferentially been used for the drainage of thick material from the pleural space. In recent years, the use of small-bore wire-guided thoracic drains has increased in both small animals and in humans. Few studies have highlighted the efficacy of small-bore wire-guided thoracostomy tubes.

Aim:

The purpose of this study was to describe the use of small-bore wire-guided thoracostomy tubes in feline pyothorax in terms of efficacy, safety, and outcome.

Methods:

Cats with pyothorax managed with small-bore thoracostomy tubes (SBTTs) (2015–2018) were retrospectively studied. The number of drains inserted, the need for anesthesia and analgesia for chest tube placement and maintenance, and related major and minor complications were reviewed. Clinical data, diagnostic results, treatment, and outcome were recorded.

Results:

Ten cats were enrolled. Thoracostomy tube placement was unilateral in 7/10 cats, despite the presence of bilateral effusion in 9/10 cats, and required sedation (8/10) or anesthesia (2/10). Three cats experienced minor complications during the chest tube insertion, including self-limiting pneumothorax (1/3) and malpositioning (2/3). One cat had a major complication (non-functional malposition) requiring reposition of the drain. Pain management was adequately achieved using opioids (8/10) or opioids plus nonsteroidal anti-inflammatory drugs (2/10). Partial chest tube occlusion occurred in three cases and it was resolved with lavage. In one case, the occlusion was complete, requiring drain removal. Three out of 10 cats were treated medically, combining thoracostomy tubes and antibiotics, while 7/10 cats underwent surgery. All the cats survived.

Conclusion:

SBTTs represent a safe and effective option for the initial management of feline pyothorax. In fact, mainly minor complications were reported during insertion and usage. The SBTTs were well tolerated by the cats with a satisfactory performance in terms of exudate drainage in most cases. The combined use of a small-bore thoracostomy drain together with the common practice of surgical treatment might have resulted in the successful management of the cases presented.

Canine and Feline Exudative Pleural Diseases

Exudative pleural diseases are a common cause of respiratory distress and systemic illness in dogs and cats. This article covers the pathophysiology, development, and classification of exudative pleural effusions. The most current diagnostic strategies, causes, imaging findings, and medical or surgical treatment options for select diseases are reviewed in detail.

Utility of bronchoscopy combined with surgery in the treatment and outcomes of dogs with intrathoracic disease secondary to plant awn migration

OBJECTIVE

To evaluate the diagnostic and therapeutic utility of bronchoscopy in dogs undergoing computed tomography (CT) and surgery for intrathoracic disease (pyothorax and pneumothorax) secondary to migrating plant awns (MPA) and to report outcomes in dogs that did and did not undergo bronchoscopy in addition to CT and surgery.

STUDY DESIGN

Retrospective case series.

ANIMALS

Thirty-seven client-owned dogs.

METHODS

Medical records from 2008 to 2017 were reviewed for dogs with documented MPA in the thoracic cavity treated with CT and surgery with or without bronchoscopy. Information regarding diagnostics, treatments, complications, and outcomes relating to hospitalization was evaluated.

RESULTS

At least one abnormal lung lobe was identified by CT in all dogs. Bronchial abnormalities were identified with bronchoscopy in 21 of 22 dogs (95.4%) with available reports. Agreement between CT and bronchoscopy findings ranged from 50% to 81.8%, depending on lung lobe. Thirty-six dogs had one or more lung lobes surgically removed. Thirty-seven MPA were retrieved via bronchoscopy in 10 of 27 (37%) dogs, and 39 MPA were retrieved at surgery in 26 of 37 (70.3%) dogs. Actinomyces spp. were cultured from surgical samples in 7 of 33 (21.2%) dogs. Thirty-five of 37 (94.6%) dogs survived to discharge.

CONCLUSION

Migrating plant awns were successfully retrieved via bronchoscopy. Agreement between CT findings and bronchoscopy was inconsistent, so there may be roles for both modalities. Short- and long-term survival was excellent in this cohort.

CLINICAL SIGNIFICANCE

Bronchoscopy may allow for diagnostic and therapeutic advantages compared with CT in dogs with endobronchial MPA. Actinomyces spp appear to be variably present in surgically acquired bacterial cultures in dogs with MPA.

Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE): Domain 5-Discontinuation of anticoagulant therapy in small animals

OBJECTIVES

To systematically evaluate the evidence supporting the timing and mechanisms of permanent or temporary discontinuation of antiplatelet or anticoagulant medications in small animals DESIGN: Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality (poor, fair, or good), and development of consensus on conclusions via a Delphi-style survey for application of the concepts to clinical practice.

SETTINGS

Academic and referral veterinary medical centers.

RESULTS

Databases searched included Medline via PubMed and CAB abstracts. Two specific courses of inquiry were pursued, one focused on appropriate approaches to use for small animal patients receiving antiplatelet or anticoagulant drugs and requiring temporary discontinuation of this therapy for the purposes of invasive procedures (eg, surgery), and the other aimed at decision-making for the complete discontinuation of anticoagulant medications. In addition, the most appropriate methodology for discontinuation of heparins was addressed.

CONCLUSIONS

To better define specific patient groups, a risk stratification characterization was developed. It is recommended to continue anticoagulant therapy through invasive procedures in patients at high risk for thrombosis that are receiving anticoagulant therapy, while consideration for discontinuation in patients with low to moderate risk of thrombosis is reasonable. In patients with thrombosis in whom the underlying cause for thrombosis has resolved, indefinite treatment with anticoagulant medication is not recommended. If the underlying cause is unknown or untreatable, anticoagulant medication should be continued indefinitely. Unfractionated heparin therapy should be slowly tapered rather than discontinued abruptly.

Diagnosis and management of pyothorax in a domestic ferret (Mustela putorius furo)

OBJECTIVE

To describe the diagnosis, management, and outcome of pyothorax in a domestic ferret (Mustela putorius furo).

CASE SUMMARY

A domestic ferret was evaluated for a history of lethargy, anorexia, and pyrexia. Pleural effusion was detected with radiography and ultrasonography, and a diagnosis of pyothorax was made following cytologic evaluation of pleural fluid. Bilateral thoracostomy tubes were placed for thoracic drainage and lavage, and the ferret was treated with intravenous crystalloid fluids, antimicrobials, and analgesics. Bacterial culture of the pleural fluid yielded Fusobacterium spp. and Actinomyces hordeovulneris. This treatment protocol resulted in resolution of pyothorax, and a positive clinical outcome.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first reported case of successful management of pyothorax caused by Fusobacterium spp. and A. hordeovulneris in a ferret.

Video-assisted thoracic surgery for the management of pyothorax in dogs: 14 cases

OBJECTIVE

To report the perioperative findings and outcome of dogs undergoing video-assisted thoracic surgery (VATS) for the management of pyothorax.

DESIGN

Multi-institutional, retrospective study.

ANIMALS

Client-owned dogs (n = 14).

METHODS

Medical records of dogs with pyothorax managed via VATS were reviewed for signalment, history, clinical signs, clinicopathological findings, diagnostic imaging results, surgical variables, bacterial culture and sensitivity results, post-operative management and outcome. VATS was performed after placing a paraxyphoid endoscopic portal and 2-3 intercostal instrument portals. VATS exploration was followed by one or more of the following: mediastinal debridement, tissue sampling, pleural lavage, and placement of a thoracostomy tube.

RESULTS

Two dogs (14%) required conversion from VATS to an open thoracotomy to completely resect proliferative mediastinal tissue. These dogs had severe pleural effusion on preoperative thoracic radiographs and one had severely thickened contrast-enhancing mediastinum on preoperative computed tomography (CT). The cause of pyothorax was identified as a penetrating gastric foreign body (n = 2), migrating plant material (n = 2), and idiopathic (n = 10). The median follow-up time was 143 days (range, 14-2402 days). All dogs were discharged from the hospital and their clinical signs resolved. One patient had recurrence of a pyothorax requiring revision surgery 17 months postoperatively.

CONCLUSION

VATS allows minimally invasive treatment of uncomplicated canine pyothorax. Preoperative thoracic CT may help identify candidates for VATS among dogs with pyothorax.

Antimicrobial use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases

Respiratory tract disease can be associated with primary or secondary bacterial infections in dogs and cats and is a common reason for use and potential misuse, improper use, and overuse of antimicrobials. There is a lack of comprehensive treatment guidelines such as those that are available for human medicine. Accordingly, the International Society for Companion Animal Infectious Diseases convened a Working Group of clinical microbiologists, pharmacologists, and internists to share experiences, examine scientific data, review clinical trials, and develop these guidelines to assist veterinarians in making antimicrobial treatment choices for use in the management of bacterial respiratory diseases in dogs and cats.

A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats

OBJECTIVE

To review the current literature in reference to the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats.

ETIOLOGY

Pyothorax, also known as thoracic empyema, is characterized by the accumulation of septic purulent fluid within the pleural space. While the actual route of pleural infection often remains unknown, the oral cavity and upper respiratory tract appear to be the most common source of microorganisms causing pyothorax in dogs and cats. In human medicine, pyothorax is a common clinical entity associated with bacterial pneumonia and progressive parapneumonic effusion.

DIAGNOSIS

Thoracic imaging can be used to support a diagnosis of pleural effusion, but cytologic examination or bacterial culture of pleural fluid are necessary for a definitive diagnosis of pyothorax.

THERAPY

The approach to treatment for pyothorax varies greatly in both human and veterinary medicine and remains controversial. Treatment of pyothorax has classically been divided into medical or surgical therapy and may include administration of antimicrobials, intermittent or continuous thoracic drainage, thoracic lavage, intrapleural fibrinolytic therapy, video-assisted thoracic surgery, and traditional thoracostomy. Despite all of the available options, the optimal treatment to ensure successful short- and long-term outcome, including the avoidance of recurrence, remains unknown.

PROGNOSIS

The prognosis for canine and feline pyothorax is variable but can be good with appropriate treatment. A review of the current veterinary literature revealed an overall reported survival rate of 83% in dogs and 62% in cats. As the clinical presentation of pyothorax in small animals is often delayed and nonspecific, rapid diagnosis and treatment are required to ensure successful outcome.

Pleural Space Disease

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Abnormalities within the pleural space may include pleural effusion, pneumothorax, or space-occupying soft tissue structures (diaphragmatic hernia, neoplasia).

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A diagnostic thoracocentesis may also prove therapeutic in severely affected patients.

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Fluid analysis and cytologic evaluation should always be performed on aspirates from a patient with newly diagnosed pleural effusion of unconfirmed etiology.

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Aerobic and anaerobic culture and susceptibility testing of suppurative effusions are imperative.

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Comparison of pleural fluid and serum triglyceride levels and cholesterol concentrations are necessary to confirm the diagnosis of chylothorax.

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Clinical evidence of cardiovascular shock often precedes dyspnea in patients with hemothorax.

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Tension pneumothorax, regardless of its origin, rapidly may be fatal. Immediate drainage via thoracocentesis or thoracostomy tube placement is required before taking thoracic radiographs.

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Clinical signs of a traumatic diaphragmatic hernia may be delayed; however, early detection and correction are important because perioperative outcome is worse in chronically affected patients.

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Tools such as ultrasonography, computed tomography (CT), and thoracoscopy are becoming increasingly available to aid in the diagnostic evaluation and treatment of pleural space disease.

Prevalence, outcome and risk factors for postoperative pyothorax in 232 dogs undergoing thoracic surgery

Objective

To determine the prevalence, outcome and risk factors for postoperative pyothorax in dogs undergoing thoracic surgery.

Methods

Case records were reviewed retrospectively to identify dogs with post thoracic surgery pyothorax, defined as septic neutrophilic inflammation within the pleural space based on cytology and/or a positive bacterial culture of pleural fluid. Those identified were reviewed for potential risk factors for postoperative pyothorax based on biological plausibility and previously published data. These potential risk factors were explored by multivariable logistic regression.

Results

Of 232 dogs undergoing thoracic surgery, 15 (6·5%) dogs developed pyothorax. Bacteria cultured included methicillin-resistant Staphylococcus aureus and multi-resistant Escherichia coli. Of these dogs, six died, four were euthanased and five were treated successfully. A diagnosis of idiopathic chylothorax [Odds Ratio (OR)=12·5, 95% Confidence Interval (CI)=2·7-58·5, P=0·001], preoperative intrathoracic biopsy (OR=14·3, 95% CI=1·7-118·7, P=0·014) and preoperative thoracocentesis (OR=11·2, 95% CI=1·6-78·2, P=0·015) were identified as independent risk factors for development of postoperative pyothorax.

Clinical Significance

Idiopathic chylothorax, intrathoracic biopsy and prior thoracocentesis are independent risk factors for postoperative pyothorax, which was associated with a 67% mortality rate.