Spontaneous Pneumothorax in a Dog Secondary to Dirofilaria Immitis Infection

Abstract

Abstract.A 5-year-old female spayed Labrador Retriever dog was referred to the Louisiana State University Veterinary Teaching Hospital for treatment of pneumothorax. Thoracic radiographs and computed tomography showed spontaneous pneumothorax, thoracic lymphadenopathy, pulmonary hypertension, and multifocal pulmonary bulla lesions. At surgery, numerous adult nematodes protruded from the parenchyma of the left caudal and accessory lung lobes and pulmonary arteries. On histopathology, multiple adult filarid nematodes were observed within the pulmonary blood vessels. Broad foci of necrosis of the pulmonary parenchyma were present. The tunica intima of the pulmonary arteries was markedly thickened by intimal fibrosis and medial hypertrophy. The final diagnosis was severe Dirofilaria immitis infection that resulted in pulmonary vascular lesions and focally extensive infarcts of the pulmonary parenchyma with bulla formation and rupture causing spontaneous pneumothorax. The dog received antibiotic and steroid therapy, as well as adulticide treatment, and recovered.

Clinical assessment of heartworm‐infected Beagles treated with a combination of imidacloprid/moxidectin and doxycycline, or untreated

“…Spontaneous pneumothorax has been described in dogs with naturally occurring heartworm disease, in which the cause was suspected to be pulmonary parenchymal infarction with subsequent bulla formation and rupture, or rupture of a secondary bacterial abscess. [25][26][27][28] One necropsy-based study of n = 15 naturally-infected heartworm-positive dogs, all dying because of acute, severe respiratory distress and collapse, found that pulmonary lesions leading to pneumothorax were confined almost exclusively to the dorsal, peripheral margin of the right caudal lung lobe, and were characterized as "pulmonary cavities" or scarring emphysema with perforation and formation of a bronchopleural fistula. 26 A previous study evaluating pathologic changes in dogs with heartworm disease, before and after adulticidal treatment, noted a clinically insignificant increase in circulating basophil concentration and decrease in circulating platelet concentration during infection, as well as a transient increase in monocytes, eosinophils, and ALP.…”

“…Longitudinal evaluation of the nontreated control group illustrates that this model was associated with radiographically detectable changes in the cardiopulmonary system, although most radiographic abnormalities were mild or mild‐to‐moderate in severity, with the exception of pneumothorax. Spontaneous pneumothorax has been described in dogs with naturally occurring heartworm disease, in which the cause was suspected to be pulmonary parenchymal infarction with subsequent bulla formation and rupture, or rupture of a secondary bacterial abscess 25‐28 . One necropsy‐based study of n = 15 naturally‐infected heartworm‐positive dogs, all dying because of acute, severe respiratory distress and collapse, found that pulmonary lesions leading to pneumothorax were confined almost exclusively to the dorsal, peripheral margin of the right caudal lung lobe, and were characterized as “pulmonary cavities” or scarring emphysema with perforation and formation of a bronchopleural fistula 26 .…”

Feline secondary spontaneous pneumothorax: A retrospective study of 16 cases (2000–2012)

“…Surgical management results in lower reoccurrence and mortality rates (3% and 12%, respectively) in comparison to nonsurgical management via thoracocentesis or thoracostomy tube placement (50% and 53%, respectively) . Other less common causes of canine spontaneous pneumothorax include pulmonary abscesses, bacterial pneumonia, neoplasia, migrating foreign bodies, parasitic infections (eg, Dirofilaria immitis , Paragonimus westermani , Filaroides osleri , tapeworm), chronic obstructive pulmonary disease, congenital pulmonary cysts, mycotic granulomas and pulmonary thromboemboli . The prognosis is less favorable for dogs with diffuse lung disease for which complete surgical resection is not an option .…”

Pneumothorax in a dog caused by necrotizing pneumonia secondary to heatstroke

“…Previously reported etiologies of pneumothorax in dogs include neoplasia, pulmonary abscess, lung parasitism, migrating foreign body, pulmonary thromboembolism, and pneumonia . Pneumothorax secondary to thromboembolism in dogs is rare and generally involves chronic underlying processes (eg, Dirofilaria immitis infection and hyperadrenocorticism) . Necrotizing pneumonia or pneumothorax secondary to heatstroke have not been reported in dogs.…”

“…6,7 Pneumothorax secondary to thromboembolism in dogs is rare and generally involves chronic underlying processes (eg, Dirofilaria immitis infection and hyperadrenocorticism). 7,8 Necrotizing pneumonia or pneumothorax secondary to heatstroke have not been reported in dogs. This case report describes a life threatening delayed complication of acute severe illness in a dog that experienced a full recovery following aggressive medical and surgical intervention.…”