Downloaded from http://veterinaryrecord.bmj.com/ on June 17, 2015 - Published by group.bmj.com
Research
Research EDITORIAL
Surgical or medical management of pyothorax in dogs? K. C. L. Lee A clearly defined optimal strategy for the management of pyothorax in dogs, a recurrent and potentially fatal disease, remains elusive. Not only is it an uncommon diagnosis; it is also likely to have a multifactorial aetiology that is often difficult to determine with certainty in an individual dog without an invasive procedure and, even then, the aetiology often remains a mystery. So while there is an easily accessible veterinary literature on pyothorax dating back to the 1960s, the majority, if not all, of these publications are case reports, case series and retrospective reviews, which are compromised to different degrees by varying case presentation, diagnostic techniques and treatment strategies. Pyothorax is defined by the presence of a septic neutrophilic exudate within the pleural cavity, and diagnosis is based on cytological examination and/or culture of pleural fluid or histopathology and/or culture of the pleura. It commonly presents as dyspnoea (with or without cough), lethargy and pyrexia. Mixed bacterial infections are common. In a study of bacteria isolated from pleural fluid from 51 dogs, obligate anaerobes were isolated from 60 per cent of samples, and a mixture of obligate anaerobes and facultative
K. C. L. Lee, MA, VetMB, PhD, CertSAS, DipECVS, MRCVS, Department of Clinical Sciences and Services, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA e-mail: [email protected]
anaerobes from 44 per cent (Walker and others 2000). The most common anaerobes isolated were Peptostreptococcus anaerobius, Bacteroides species and Fusobacterium species, and aerobes isolated were Actinomyces species, Pasteurella species, Escherichia coli and Streptococcus canis. Therefore, empirical antibiotics chosen for canine pyothorax should have activity against anaerobic and facultative bacteria, be distributed into the pleural space and have low toxicity. Walker and others (2000), recommend the beta lactams ceftizoxime, clindamycin and metronidazole. Cytological and histopathological descriptions of pleural samples often report ‘filamentous bacteria’. In dogs these could represent Gram-positive Actinomyces species and Nocardia species, or Gram-negative Bacteroides species. The route of entry of bacteria into the pleural space often remains undefined. Reported modes of entry include: inhalation with a foreign body (Frendin 1997, Robertson and others 1983, Demetriou and others 2002, Rooney and Monnet 2002); escape from a pulmonary abscess (Demetriou and others 2002); oesophageal tear associated with bone foreign body or parasites (Hamir 1986, Trinterud and others 2014); penetrating wound or thoracic trauma (Piek and Robben 2000, Doyle and others 2009); and iatrogenic introduction following thoracic surgery (Meakin and others 2013). The presence of plant material is the most frequently reported cause of pyothorax in dogs. Actinomyces species are commonly implicated in this aetiology (Frendin 1997, Pelle and others 2000). Iatrogenic infections raise the possibility
June 14, 2014 | Veterinary Record | 605
Downloaded from http://veterinaryrecord.bmj.com/ on June 17, 2015 - Published by group.bmj.com
Research of nosocomial multiantibiotic resistant bacteria, as seen in over 50 per cent of cases in one report (Meakin and others 2013). In addition, Nocardia is a ubiquitous soil-borne bacterium and may enter the pleural cavity by inhalation or direct extension from a skin wound, but culture from popliteal lymph nodes in a dog with pulmonary lesions raises the possibility of haematogenous spread (Marino and Jaggy 1993). The common reported histopathological finding, where available, is pyogranulomatous pleuritis of predominantly the mediastinal pleura (Frendin 1997, Pelle and others 2000). Pyothorax in dogs treated with antibiotics alone or no treatment is often fatal, and the primary complication of different treatments is recurrence (Robertson and others 1983, Frendin 1997, Pelle and others 2000). Management strategies are broadly categorised as surgical or medical (Holmberg 1979). The simplest successful form of medical management is reported by Johnson and Martin (2007) in 15 dogs: a single ultrasound-guided thoracocentesis to remove pleural fluid followed by a minimum of six weeks of systemic antibiotics. Before treatment, thoracic ultrasound and radiography ruled out pulmonary, mediastinal and pleural masses in all dogs. Antibiotics were continued until two weeks after no abnormalities were seen on thoracic radiography. They reported 100 per cent success with a mean follow-up of 27 months. Frendin (1997) added twice daily drainage of the pleural cavity via indwelling thoracostomy tubes or catheters to this schedule. Antimicrobial therapy was continued for a minimum of six weeks. Criteria for duration of thoracic drainage are not reported, but success was reported in five of six dogs with a follow up of at least 3.5 years. Piek and Robben (2000) considered the further addition of pleural lavage. They reported on nine dogs with very welldefined pyothorax and a very consistent treatment schedule. The pleural cavity was irrigated three to four times daily with 10 to 20 ml/kg of crystalloids until lavage fluid retrieved contained no intracellular bacteria. Thoracic drainage was continued until the volume of pleural fluid retrieved was less than 3 to 5 ml/kg/day and there was no significant pleural fluid detectable on thoracic radiographs. All dogs received systemic antibiotics for at least four weeks until thoracic radiographs were normal. They reported 100 per cent success with follow-up of at least six months in eight dogs. Surgical management comprises exploratory thoracotomy with pleural drainage, and search for the source of the infection which, if identified, is removed. If no source is found, all accessible abnormal tissues are surgically resected; these may include lung lobes, the mediastinal pleura, 606 | Veterinary Record | June 14, 2014
and sections of the pericardium and diaphragm. Surgery also involves open pleural lavage. A thoracostomy tube is additionally placed at the end of surgery in some reports. In a study summarised on p 607 of this issue of Veterinary Record, Trinterud and others (2014) report on 12 dogs that underwent exploratory median sternotomy due to diagnosis of pyothorax in six, suspicion of intrathoracic foreign body on diagnostic imaging studies in three, draining sinus in one, and pleural or mediastinal masses in two. They report a consistent surgical approach in all dogs, with resection of all accessible grossly abnormal tissues within the thorax. While pyothorax was only confirmed in six dogs preoperatively, foreign bodies were found in resected tissues in five cases and positive tissue cultures were obtained in three. They report success in 11 dogs, with a minimum follow up of six months. The case series described above provides a good description of individual management strategies for confirmed or suspected cases of pyothorax and potential success rates. However, case selection bias is a concern and these reports do not provide definitive algorithms for how to choose between management strategies. At least two retrospective studies have attempted to compare medical versus surgical management strategies. They have the inherent problems of retrospective studies, that is, lack of consistency, in particular with respect to treatment and lack of randomisation to treatment strategy. Rooney and Monnet (2002) reported on 26 dogs with confirmed pyothorax, which had not received previous treatment. Medical management included thoracic drainage and lavage for at least two days with systemic antibiotics. Surgical management involved exploratory median sternotomy with resection of all accessible grossly abnormal tissues. A definitive cause for infection (plant foreign body) was found in only one case. Medical management alone was used in seven dogs and resulted in freedom from disease in an estimated two dogs at six months and one year. Surgical management was used in 19 dogs (including 12 initially treated medically) and resulted in freedom from disease in an estimated 16 dogs at six months and 15 dogs at one year, suggesting superiority of surgery over medical management in apparent ‘idiopathic’ pyothorax. Boothe and others (2010) reported on 46 dogs with confirmed pyothorax treated with three protocols: single thoracocentesis and systemic antibiotics; thoracostomy tube placement with or without lavage, plus systemic antibiotics; and surgical management with thoracostomy tube placement with or without lavage, plus systemic antibiotics. Some of these cases also received intrapleural heparin due to
its potential to prevent pleural adhesion formation. Overall, one year survival rate was 63 per cent with no difference between treatment groups. These retrospective studies highlight treatment failure in a significant percentage of dogs with pyothorax. It is now time for the veterinary community to embark upon a prospective study to determine the best management strategy for these challenging cases. This will probably involve algorithms to move between medical and surgical plans depending on the response to treatment. We need to start by designing fixed protocols for both surgical and medical management with the evidence we have already from case series such as that by Trinterud and others and by data that can be obtained from modern advances in critical care and diagnostic imaging in veterinary medicine.
References
BOOTHE, H. W., HOWE, L. M., BOOTHE, D. M., REYNOLDS, L. A. & CARPENTER, M. (2010) Evaluation of outcomes in dogs treated for pyothorax: 46 cases (1983-2001). Journal of the American Veterinary Medical Association 236, 657-663 DEMETRIOU, J. L., FOALE, R. D., LADLOW, J., MCGROTTY, Y., FAULKNER, J. & KIRBY, B. M. (2002) Canine and feline pyothorax: a retrospective study of 50 cases in the UK and Ireland. Journal of Small Animal Practice 43, 388-394 DOYLE, J. L., KUIPERS VON LANDE, R. G. & WORTH, A. J. (2009) Intra-thoracic pyogranulomatous disease in four working dogs. New Zealand Veterinary Journal 57, 346-351 FRENDIN, J. (1997) Pyogranulomatous pleuritis with empyema in hunting dogs. Zentralbl Veterinarmed A 44, 167-178 HAMIR, A. N. (1986) Oesophageal perforation and pyothorax associated with Spirocerca lupi infestation in a dog. Veterinary Record 119, 276 HOLMBERG, D. L. (1979) Management of pyothorax. Veterinary Clinics of North America: Small Animal Practice 9, 357-362 JOHNSON, M. S. & MARTIN, M. W. (2007) Successful medical treatment of 15 dogs with pyothorax. Journal of Small Animal Practice 48, 12-16 MARINO, D. J. & JAGGY, A. (1993) Nocardiosis. A literature review with selected case reports in two dogs. Journal of Veterinary Internal Medicine 7, 4-11 MEAKIN, L. B., SALONEN, L. K., BAINES, S. J., BROCKMAN, D. J., GREGORY, S. P., HALFACREE, Z. J., LIPSCOMB, V. J. & LEE, K. C. (2013) Prevalence, outcome and risk factors for postoperative pyothorax in 232 dogs undergoing thoracic surgery. Journal of Small Animal Practice 54, 313-317 PELLE, G., MAKRAI, L., FODOR, L. & DOBOSKOVACS, M. (2000) Actinomycosis of dogs caused by Actinomyces hordeovulneris. Journal of Comparative Pathology 123, 72-76 PIEK, C. J. & ROBBEN, J. H. (2000) Pyothorax in nine dogs. Veterinary Quarterly 22, 107-111 ROBERTSON, S. A., STODDART, M. E., EVANS, R. J., GASKELL, C. J. & GIBBS, C. (1983) Thoracic empyema in the dog: a report of twenty-two cases. Journal of Small Animal Practice 24, 103-119 ROONEY, M. B. & MONNET, E. (2002) Medical and surgical treatment of pyothorax in dogs: 26 cases (1991-2001). Journal of the American Veterinary Medical Association 221, 86-92 Trinterud, T., Nelissen, P., Caine, A. R. & White, R. A. S. (2014) Mediastinectomy for management of chronic pyogranulomatous pleural disease in dogs. Veterinary Record doi:10.1136/vr.101932 WALKER, A. L., JANG, S. S. & HIRSH, D. C. (2000) Bacteria associated with pyothorax of dogs and cats: 98 cases (1989-1998). Journal of the American Veterinary Medical Association 216, 359-363
doi: 10.1136/g3817
Downloaded from http://veterinaryrecord.bmj.com/ on June 17, 2015 - Published by group.bmj.com
Surgical or medical management of pyothorax in dogs? K. C. L. Lee Veterinary Record 2014 174: 605-607
doi: 10.1136/vr.g3817 Updated information and services can be found at: http://veterinaryrecord.bmj.com/content/174/24/605
These include:
References Email alerting service
This article cites 14 articles, 0 of which you can access for free at: http://veterinaryrecord.bmj.com/content/174/24/605#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
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Research
Research EDITORIAL
Surgical or medical management of pyothorax in dogs? K. C. L. Lee A clearly defined optimal strategy for the management of pyothorax in dogs, a recurrent and potentially fatal disease, remains elusive. Not only is it an uncommon diagnosis; it is also likely to have a multifactorial aetiology that is often difficult to determine with certainty in an individual dog without an invasive procedure and, even then, the aetiology often remains a mystery. So while there is an easily accessible veterinary literature on pyothorax dating back to the 1960s, the majority, if not all, of these publications are case reports, case series and retrospective reviews, which are compromised to different degrees by varying case presentation, diagnostic techniques and treatment strategies. Pyothorax is defined by the presence of a septic neutrophilic exudate within the pleural cavity, and diagnosis is based on cytological examination and/or culture of pleural fluid or histopathology and/or culture of the pleura. It commonly presents as dyspnoea (with or without cough), lethargy and pyrexia. Mixed bacterial infections are common. In a study of bacteria isolated from pleural fluid from 51 dogs, obligate anaerobes were isolated from 60 per cent of samples, and a mixture of obligate anaerobes and facultative
K. C. L. Lee, MA, VetMB, PhD, CertSAS, DipECVS, MRCVS, Department of Clinical Sciences and Services, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA e-mail: [email protected]
anaerobes from 44 per cent (Walker and others 2000). The most common anaerobes isolated were Peptostreptococcus anaerobius, Bacteroides species and Fusobacterium species, and aerobes isolated were Actinomyces species, Pasteurella species, Escherichia coli and Streptococcus canis. Therefore, empirical antibiotics chosen for canine pyothorax should have activity against anaerobic and facultative bacteria, be distributed into the pleural space and have low toxicity. Walker and others (2000), recommend the beta lactams ceftizoxime, clindamycin and metronidazole. Cytological and histopathological descriptions of pleural samples often report ‘filamentous bacteria’. In dogs these could represent Gram-positive Actinomyces species and Nocardia species, or Gram-negative Bacteroides species. The route of entry of bacteria into the pleural space often remains undefined. Reported modes of entry include: inhalation with a foreign body (Frendin 1997, Robertson and others 1983, Demetriou and others 2002, Rooney and Monnet 2002); escape from a pulmonary abscess (Demetriou and others 2002); oesophageal tear associated with bone foreign body or parasites (Hamir 1986, Trinterud and others 2014); penetrating wound or thoracic trauma (Piek and Robben 2000, Doyle and others 2009); and iatrogenic introduction following thoracic surgery (Meakin and others 2013). The presence of plant material is the most frequently reported cause of pyothorax in dogs. Actinomyces species are commonly implicated in this aetiology (Frendin 1997, Pelle and others 2000). Iatrogenic infections raise the possibility
June 14, 2014 | Veterinary Record | 605
Downloaded from http://veterinaryrecord.bmj.com/ on June 17, 2015 - Published by group.bmj.com
Research of nosocomial multiantibiotic resistant bacteria, as seen in over 50 per cent of cases in one report (Meakin and others 2013). In addition, Nocardia is a ubiquitous soil-borne bacterium and may enter the pleural cavity by inhalation or direct extension from a skin wound, but culture from popliteal lymph nodes in a dog with pulmonary lesions raises the possibility of haematogenous spread (Marino and Jaggy 1993). The common reported histopathological finding, where available, is pyogranulomatous pleuritis of predominantly the mediastinal pleura (Frendin 1997, Pelle and others 2000). Pyothorax in dogs treated with antibiotics alone or no treatment is often fatal, and the primary complication of different treatments is recurrence (Robertson and others 1983, Frendin 1997, Pelle and others 2000). Management strategies are broadly categorised as surgical or medical (Holmberg 1979). The simplest successful form of medical management is reported by Johnson and Martin (2007) in 15 dogs: a single ultrasound-guided thoracocentesis to remove pleural fluid followed by a minimum of six weeks of systemic antibiotics. Before treatment, thoracic ultrasound and radiography ruled out pulmonary, mediastinal and pleural masses in all dogs. Antibiotics were continued until two weeks after no abnormalities were seen on thoracic radiography. They reported 100 per cent success with a mean follow-up of 27 months. Frendin (1997) added twice daily drainage of the pleural cavity via indwelling thoracostomy tubes or catheters to this schedule. Antimicrobial therapy was continued for a minimum of six weeks. Criteria for duration of thoracic drainage are not reported, but success was reported in five of six dogs with a follow up of at least 3.5 years. Piek and Robben (2000) considered the further addition of pleural lavage. They reported on nine dogs with very welldefined pyothorax and a very consistent treatment schedule. The pleural cavity was irrigated three to four times daily with 10 to 20 ml/kg of crystalloids until lavage fluid retrieved contained no intracellular bacteria. Thoracic drainage was continued until the volume of pleural fluid retrieved was less than 3 to 5 ml/kg/day and there was no significant pleural fluid detectable on thoracic radiographs. All dogs received systemic antibiotics for at least four weeks until thoracic radiographs were normal. They reported 100 per cent success with follow-up of at least six months in eight dogs. Surgical management comprises exploratory thoracotomy with pleural drainage, and search for the source of the infection which, if identified, is removed. If no source is found, all accessible abnormal tissues are surgically resected; these may include lung lobes, the mediastinal pleura, 606 | Veterinary Record | June 14, 2014
and sections of the pericardium and diaphragm. Surgery also involves open pleural lavage. A thoracostomy tube is additionally placed at the end of surgery in some reports. In a study summarised on p 607 of this issue of Veterinary Record, Trinterud and others (2014) report on 12 dogs that underwent exploratory median sternotomy due to diagnosis of pyothorax in six, suspicion of intrathoracic foreign body on diagnostic imaging studies in three, draining sinus in one, and pleural or mediastinal masses in two. They report a consistent surgical approach in all dogs, with resection of all accessible grossly abnormal tissues within the thorax. While pyothorax was only confirmed in six dogs preoperatively, foreign bodies were found in resected tissues in five cases and positive tissue cultures were obtained in three. They report success in 11 dogs, with a minimum follow up of six months. The case series described above provides a good description of individual management strategies for confirmed or suspected cases of pyothorax and potential success rates. However, case selection bias is a concern and these reports do not provide definitive algorithms for how to choose between management strategies. At least two retrospective studies have attempted to compare medical versus surgical management strategies. They have the inherent problems of retrospective studies, that is, lack of consistency, in particular with respect to treatment and lack of randomisation to treatment strategy. Rooney and Monnet (2002) reported on 26 dogs with confirmed pyothorax, which had not received previous treatment. Medical management included thoracic drainage and lavage for at least two days with systemic antibiotics. Surgical management involved exploratory median sternotomy with resection of all accessible grossly abnormal tissues. A definitive cause for infection (plant foreign body) was found in only one case. Medical management alone was used in seven dogs and resulted in freedom from disease in an estimated two dogs at six months and one year. Surgical management was used in 19 dogs (including 12 initially treated medically) and resulted in freedom from disease in an estimated 16 dogs at six months and 15 dogs at one year, suggesting superiority of surgery over medical management in apparent ‘idiopathic’ pyothorax. Boothe and others (2010) reported on 46 dogs with confirmed pyothorax treated with three protocols: single thoracocentesis and systemic antibiotics; thoracostomy tube placement with or without lavage, plus systemic antibiotics; and surgical management with thoracostomy tube placement with or without lavage, plus systemic antibiotics. Some of these cases also received intrapleural heparin due to
its potential to prevent pleural adhesion formation. Overall, one year survival rate was 63 per cent with no difference between treatment groups. These retrospective studies highlight treatment failure in a significant percentage of dogs with pyothorax. It is now time for the veterinary community to embark upon a prospective study to determine the best management strategy for these challenging cases. This will probably involve algorithms to move between medical and surgical plans depending on the response to treatment. We need to start by designing fixed protocols for both surgical and medical management with the evidence we have already from case series such as that by Trinterud and others and by data that can be obtained from modern advances in critical care and diagnostic imaging in veterinary medicine.
References
BOOTHE, H. W., HOWE, L. M., BOOTHE, D. M., REYNOLDS, L. A. & CARPENTER, M. (2010) Evaluation of outcomes in dogs treated for pyothorax: 46 cases (1983-2001). Journal of the American Veterinary Medical Association 236, 657-663 DEMETRIOU, J. L., FOALE, R. D., LADLOW, J., MCGROTTY, Y., FAULKNER, J. & KIRBY, B. M. (2002) Canine and feline pyothorax: a retrospective study of 50 cases in the UK and Ireland. Journal of Small Animal Practice 43, 388-394 DOYLE, J. L., KUIPERS VON LANDE, R. G. & WORTH, A. J. (2009) Intra-thoracic pyogranulomatous disease in four working dogs. New Zealand Veterinary Journal 57, 346-351 FRENDIN, J. (1997) Pyogranulomatous pleuritis with empyema in hunting dogs. Zentralbl Veterinarmed A 44, 167-178 HAMIR, A. N. (1986) Oesophageal perforation and pyothorax associated with Spirocerca lupi infestation in a dog. Veterinary Record 119, 276 HOLMBERG, D. L. (1979) Management of pyothorax. Veterinary Clinics of North America: Small Animal Practice 9, 357-362 JOHNSON, M. S. & MARTIN, M. W. (2007) Successful medical treatment of 15 dogs with pyothorax. Journal of Small Animal Practice 48, 12-16 MARINO, D. J. & JAGGY, A. (1993) Nocardiosis. A literature review with selected case reports in two dogs. Journal of Veterinary Internal Medicine 7, 4-11 MEAKIN, L. B., SALONEN, L. K., BAINES, S. J., BROCKMAN, D. J., GREGORY, S. P., HALFACREE, Z. J., LIPSCOMB, V. J. & LEE, K. C. (2013) Prevalence, outcome and risk factors for postoperative pyothorax in 232 dogs undergoing thoracic surgery. Journal of Small Animal Practice 54, 313-317 PELLE, G., MAKRAI, L., FODOR, L. & DOBOSKOVACS, M. (2000) Actinomycosis of dogs caused by Actinomyces hordeovulneris. Journal of Comparative Pathology 123, 72-76 PIEK, C. J. & ROBBEN, J. H. (2000) Pyothorax in nine dogs. Veterinary Quarterly 22, 107-111 ROBERTSON, S. A., STODDART, M. E., EVANS, R. J., GASKELL, C. J. & GIBBS, C. (1983) Thoracic empyema in the dog: a report of twenty-two cases. Journal of Small Animal Practice 24, 103-119 ROONEY, M. B. & MONNET, E. (2002) Medical and surgical treatment of pyothorax in dogs: 26 cases (1991-2001). Journal of the American Veterinary Medical Association 221, 86-92 Trinterud, T., Nelissen, P., Caine, A. R. & White, R. A. S. (2014) Mediastinectomy for management of chronic pyogranulomatous pleural disease in dogs. Veterinary Record doi:10.1136/vr.101932 WALKER, A. L., JANG, S. S. & HIRSH, D. C. (2000) Bacteria associated with pyothorax of dogs and cats: 98 cases (1989-1998). Journal of the American Veterinary Medical Association 216, 359-363
doi: 10.1136/g3817
Downloaded from http://veterinaryrecord.bmj.com/ on June 17, 2015 - Published by group.bmj.com
Surgical or medical management of pyothorax in dogs? K. C. L. Lee Veterinary Record 2014 174: 605-607
doi: 10.1136/vr.g3817 Updated information and services can be found at: http://veterinaryrecord.bmj.com/content/174/24/605
These include:
References Email alerting service
This article cites 14 articles, 0 of which you can access for free at: http://veterinaryrecord.bmj.com/content/174/24/605#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
