Case study: Treating asthma-associated spontaneous pneumothorax in a cat

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Toby is a 12-year-old Devon Rex who presented on 24 April 2019. His owners observed him acutely straining to defecate and breathing with distress so he was rushed into the Emergency Service.

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He had a peripheral history of a previous respiratory episodes two years prior where he underwent broncho-alveolar lavage testing which identified eosinophilic inflammation and a scant growth of Bergeyella zoohelcum. The bacteria was suspected to be a contaminant as it is common in the upper respiratory tract but can cause pneumonia if present in the lower respiratory tract. He was treated with doxycycline for three weeks, prednisolone 5mg SID for five days and went on an advocate trial in case of lungworm. He was commenced on fluticasone (1puff BID) and salbutamol (in attacks) which the owners were unable to administer at home. His owner reported that since 2017 he’d had no coughing or respiratory episodes at home. 

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On presentation, he had a HR 166 with muffled heart and lung sounds. He had pale pink mucous membranes and was tachypnoeic and hyper-salivating. He had a temperature of 39.0 degrees Celsius. Due to his respiratory distress, he was immediately treated with 0.3mg/kg of butorphanol then 0.2mg/kg diazepam IV before being placed in an oxygen cage. 

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When he was breathing more comfortably, complete biochemistry, electrolyte and haematology panels were performed including a proBNP which was found to be normal. Blood results were otherwise unremarkable. 

Radiographs were performed which identified severe airway disease, with a mild right-sided pneumothorax caused most likely by rupture of the lung tissue and possible air trapping and emphysematous change in the more cranial lung fields. There was a moderately severe diffuse bronchointerstitial pattern approaching alveolar change in the caudal lung lobes, with subjective hyperlucent areas in the cranial lung lobes. There was a flattened diaphragm and widened thorax which supported the presence of air trapping in this patient. No bullous lesions could be identified. There was gastric gas distension consistent with aerophagia. 

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From top: A dorsal view of Toby showing a mild right-sided pneumothorax; the left lateral X-ray and right lateral showed severe airway disease; the right lateral of Toby post-drainage

Thoracentesis was performed and 150mls air was drained from the right thorax. He was treated with terbutaline and dexamethasone. His respiratory pattern was more comfortable post drainage. 

Discussions took place with his owners regarding repeat BAL, bronchoscopy and CT. A conservative approach was adopted due to his current increased risk for general anaesthesia and owner’s preference. He remained hospitalised for three days and was discharged on 1 May on Doxycycline 10mg/kg SID PO, fluticasone 125ug two puffs twice daily, salbutamol 100ug one puff twice daily and prednisolone 10mg SID PO. The owners were counselled and taught how to use a spacer correctly.    

At the seven-day recheck, the owners were pleased with Toby’s progress and reported he was doing very well. His medications were deescalated with the view to maintain ongoing fluticasone long term.  

Secondary spontaneous pneumothorax can be the result of many different underlying lung pathologies but most commonly associated with asthma or neoplasia. In this case, the disease had an extensive nature, therefore surgical resection of the diseased lung tissue was not recommended. Due to the variety of different causes of spontaneous pneumothorax in cats, it is important to tailor a medical treatment plan to their specific cause.


Heather Russell BVSc (Hons) GPCert SAM, head veterinarian and clinical manager

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Heather graduated from Sydney University in 2002 and started in a mixed practice in the UK. In 2006, she completed a GP Certificate in small animal medicine. She began working in emergency hospitals in 2007 soon after completion of her certificate and discovered her love of emergency and critical care. On her return to Australia, she began working at Northside Emergency Veterinary Service in 2011 before taking over the role of clinical manager in 2015. She completed a Post graduate certificate in Emergency and Critical care with Melbourne University.

Heather was invited in 2016 and 2019 to be part of an expert panel on treatment of tick paralysis and has contributed to development of a protocol for general practitioners for management and treatment of this disease. Heather lives on the Northern Beaches of Sydney with her partner, two children and one year old Border Collie Flynn, who she expects will need foreign body surgery in the near future..

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