Congenital lobar emphysema concurrent with pneumothorax and pneumomediastinum in a dog

Leakage pressures of partial and total lung lobectomies performed with thoracoabdominal staplers in cadaveric dogs

OBJECTIVE

To compare leakage pressures of stapled partial and total lung lobectomies using thoracoabdominal (TA) staplers in canine cadaveric specimens.

STUDY DESIGN

Ex vivo experimental study.

SAMPLE POPULATION

A total of 29 lung lobes from six canine cadavers.

METHODS

Lower respiratory tracts were harvested from canine cadavers >15 kg. Lung lobes were randomized to groups: total lobectomy with a TA30-V3 (TL-30), partial lobectomy with two TA30-V3 cartridges in a wedge configuration (PL-30), and partial lobectomy with a TA60-3.5 mm (PL-60). The leakage pressure (pressure at which air bubbles were first seen from submerged tissue) was assessed, and groups were compared.

RESULTS

All nine PL-30 and all nine PL-60 sites leaked at median pressures of 10 cm H2O (range 10-15) and 18 cm H2O (range 10-20), respectively. Only 1/11 TL-30 site leaked during testing at a pressure of 22 cm H2O. PL-30 and PL-60 sites were more likely to leak at 20 (OR: 437; 95% CI: 7.9-24 171; p = .003) and 30 (OR: 133; 95% CI: 4.8-3674.2; p = .003) cm H2O compared to TL-30 sites, and the leakage pressure was greater for TL-30 as compared to PL-30 (marginal effect: -46.14; 95% CI: -55.9 to -36.38; p < .001) and PL-60 (marginal effect: -41.2; 95% CI: -51.73 to -30.67; p < .001) sites. PL-60 leakage pressures were greater than those of PL-30 (marginal effect: 4.94; 95% CI: 1.43-8.44; p = .006).

CONCLUSION

In canine cadaveric lung, total lobectomies with a TA30-V3 were less likely to leak at physiological pressures than partial lobectomies with either TA30-V3 or TA60-3.5 mm staplers.

CLINICAL SIGNIFICANCE

These results suggest a greater potential risk for air leakage at physiologically relevant pressures following partial as compared to total lobectomies with the TA stapling devices and techniques used commonly in veterinary surgery.

Air leak syndrome in animals: definition and pathogenesis

Air leak syndrome (ALS) is described in human medicine as a constellation of clinical disorders including pneumomediastinum, pneumopericardium, pulmonary interstitial emphysema, pneumothorax, pneumoperitoneum, pneumoretroperitoneum and subcutaneous emphysema. The pathogenesis of ALS depends on the anatomy of the mediastinum and its associations with thoracic, abdominal and cervical connective tissues, as well as a physical phenomenon referred to as the Macklin effect. Various animal species develop diverse combinations of these lesions, although ALS has not been recognized in animals. However, this term aids pathologists in addressing this disease compilation. The aim of this retrospective study is to illustrate examples of ALS in animals by arbitrarily selecting 13 cases in dogs, cats, pinnipeds, sea otters and harbour porpoises. ALS can be classified into three groups based on aetiology: iatrogenic, secondary or spontaneous. Iatrogenic ALS was diagnosed in two cats with tracheal laceration following endotracheal intubation. Secondary ALS was identified in two dogs, one with acute respiratory distress syndrome and the other due to grass awn migration. Secondary ALS in pinnipeds was diagnosed following severe pulmonary parasitism, uraemic pneumonia and oesophageal perforation. The other marine mammals developed ALS following trauma. Spontaneous ALS was also diagnosed in one cat and one dog without any apparent predisposing causes.

Local outbreak of spontaneous pneumothorax secondary to paragonimosis in southwestern Ontario dogs

Three dogs were diagnosed with spontaneous pneumothorax and referred to the Ontario Veterinary College Health Sciences Centre for management. The 3 dogs were diagnosed with secondary spontaneous pneumothorax due to paragonimosis. The diagnosis was made by visualization of adult trematodes during surgical exploration with histopathological confirmation in 1 dog, and detection of trematode eggs via fecal sedimentation in the other 2 dogs. Two of the dogs developed unusual additional lesions, including hemoabdomen, muscle abscess, and abdominal adhesions. These were suspected to be secondary to aberrant fluke larval migration. All 3 dogs lived within a relatively small geographical area of Ontario and were hospitalized between December 2021 and March 2022. Each dog survived to discharge with surgical or medical management of the pneumothorax and treatment with a prolonged course of fenbendazole. Key clinical message: Paragonimosis should be considered as a differential diagnosis for canine spontaneous pneumothorax in areas where Paragonimus kellicotti is, or may be, endemic, or in dogs that have travelled to endemic areas - particularly if the patient has a history of cough or potential exposure to freshwater crayfish. Routine anthelmintic treatment does not prevent infection and standard fecal floatation methods may not detect the eggs. Therefore, diagnostic testing should include a fecal sedimentation test and thoracic radiographs to screen for P. kellicotti.

Case report: Treatment of congenital lobar emphysema with lung lobectomy in a puppy

An 11-week-old, sexually intact female Catahoula Leopard dog was evaluated for a multiple-week history of exercise intolerance and intermittent periods of respiratory distress. Thoracic radiographs revealed a markedly hyperinflated right lung field, with compression of the surrounding lung lobes. Thoracic computed tomography further localized the hyperinflation to the right middle lung lobe, with suspicion of congenital lobar emphysema. A right intercostal thoracotomy with right middle lung lobectomy was performed successfully. Histopathology results confirmed bronchial cartilage hypoplasia with marked emphysema and pleural fibrosis. The puppy recovered from surgery uneventfully and was discharged from the hospital without any postoperative complications. At 18 months postoperatively, the dog was clinically normal with no return of respiratory distress. This case report describes successful surgical treatment of a large breed puppy with the uncommonly reported condition of congenital lobar emphysema.

Congenital Lobar Emphysema in a Kitten with Concomitant Hiatal Hernia and Nutritional Secondary Hyperparathyroidism

A 2 mo old domestic shorthair kitten was presented for acute respiratory distress and severe ambulatory difficulties. Thoracic radiography revealed hyperinflation of the left cranial lung lobe and a mass with soft-tissue/gas opacity in the caudal mediastinum, leading to the suspicion of congenital lung lobe emphysema and hiatal hernia. Decreased bone radiopacity and suspected pathological fractures were also present. Complete clinicopathological analyses showed significant ionized hypocalcemia and suspicion of secondary hyperparathyroidism related to an inadequate diet. Lung lobectomy and reduction of the hiatal hernia following a median sternotomy and a cranial laparotomy were performed. IV and oral supplementation of calcium led to a full recovery and improvement in the kitten's walking. A histopathological analysis revealed pulmonary emphysema associated with hypoplastic and irregular bronchial cartilage. Congenital lobar emphysema is a rare disease in both humans and animals. This is the first veterinary report describing a kitten affected by congenital lobar emphysema combined with a hiatal hernia and additionally complicated by secondary nutritional hyperparathyroidism with a good long-term outcome.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Nonproliferative and Proliferative Lesions of the Dog

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions) Project (www.toxpath.org/inhand.asp) is a joint initiative of the societies of toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in most tissues and organs from the dog used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions, lesions induced by exposure to test materials, and relevant infectious and parasitic lesions. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

Spontaneous Pneumothorax: Pathophysiology, Clinical Presentation and Diagnosis

Spontaneous pneumothorax, which may have an acute or insidious onset in dogs and cats, results in respiratory difficulty and has the potential to be life threatening.^1-3 Dogs commonly develop spontaneous pneumothorax due to bullae or blebs, while cats typically have underlying inflammatory disease, like feline allergic airway disease. Urgent therapeutic intervention is essential in animals with respiratory distress. The recommended therapeutic strategies are typically different in each of these species due to underlying etiology. The first part of this review article will focus on physiology, clinical presentation, and diagnosis of spontaneous pneumothorax in dogs and cats. Advances in diagnostics, especially the recent utility of point of care ultrasound, will be discussed. The second part of the series will provide an overview of therapeutic options and management of patients with spontaneous pneumothorax, as well as information on prognosis.

Imaging findings in 14 dogs and 3 cats with lobar emphysema

Background

Lobar emphysema in dogs and cats is caused by bronchial collapse during expiration and subsequent air trapping. Congenital causes such as bronchial cartilage defects or acquired causes such as compressive neoplastic lesions have been reported. Morbidity results from hyperinflation of the affected lung lobe and compression of adjacent thoracic structures.

Objective

To describe patient characteristics and imaging findings in dogs and cats with lobar emphysema.

Animals

Fourteen dogs and 3 cats with lobar emphysema diagnosed by imaging findings were retrospectively identified from veterinary referral hospital populations over a 10‐year period.

Methods

Cases that included thoracic radiography, thoracic computed tomography (CT), or both were included. All images were reviewed by a European College of Veterinary Diagnostic Imaging diplomate. Relevant case information included signalment, clinical findings, treatment, and histopathology where available.

Results

Ten of 17 (59%) patients were presented for evaluation of dyspnea and 6 (35%) for coughing. Eleven (65%) patients were <3 years of age. The right middle lung lobe was affected in 12 cases (71%) and multiple lobes were affected in 7 cases (41%). Congenital lobar emphysema was suspected in 14 cases (82%).

Conclusion and Clinical Importance

Lung lobe hyperinflation, atelectasis of nonaffected lung lobes, mediastinal shift, and thoracic wall and diaphragmatic wall deformation were common findings. Lobar or multilobar emphysema should be considered in patients with dyspnea or coughing, particularly younger patients. Although radiography is useful, CT provides better detail. In older patients, acquired causes of bronchial compression should be considered.

Successful Treatment of Congenital Lobar Emphysema in Multiple Lung Lobes in an English Bulldog Puppy

A 5 mo old male intact English bulldog was evaluated at a veterinary referral hospital for acute respiratory distress and chronic difficulty breathing. Thoracic radiographs revealed multifocal pulmonary hyperinflation and hyperlucency suspected in the left caudal and accessory lung lobes. A thoracic computed tomography scan identified severe diffuse enlargement of the caudal subsegment of the left cranial lung lobe and the dorsal process of the accessory lung lobe, with parenchymal hypoattenuation, rounded margins, and thin pulmonary vessels. Based on clinical signs and imaging findings, he was diagnosed with suspect congenital lobar emphysema in multiple lung lobes. A median sternotomy was performed, which revealed a hyperinflated, emphysematous left cranial lung lobe (caudal subsegment) and accessory lung lobe for which two lung lobectomies were performed. The remaining lung lobes were small and atelectatic. Histopathology revealed bronchial cartilage hypoplasia and aplasia and findings consistent with congenital lobar emphysema. The puppy recovered well from surgical treatment of congenital lobar emphysema, requiring multiple lung lobectomies, with subsequent computed tomography-evidenced re-expansion of the remaining lung lobes 3 mo after surgery. The patient is still alive 1 yr after surgery with a normal activity level and no evidence of respiratory compromise.

Evaluation of a pre-tied ligature loop for canine total lung lobectomy

OBJECTIVE

To determine the ability of a pre-tied ligature loop (PLL) to create a seal against physiological airway pressures after total lung lobectomy and report outcomes in dogs requiring lung lobectomy.

STUDY DESIGN

Ex vivo experimental randomized study and clinical case study.

SAMPLE POPULATION

Thirty cadaveric canine lung lobes and 5 client-owned dogs.

METHODS

Thirty canine lung lobes from dogs weighing 22.5-35 kg were randomized to lobectomy with stapler, PLL, or suture ligation. After lobectomy, each bronchial stump was submerged in water, and the mainstem airway pressure was increased to 80 mm Hg. Leakage was compared between techniques. The PLL was subsequently used in 5 dogs (17-25 kg) with neoplastic disease requiring total lung lobectomy.

RESULTS

Two stapled and 4 sutured bronchial stumps leaked at supraphysiological pressures >15 mm Hg. One stapled bronchial stump failed at a physiological airway pressure (5 mm Hg). None of the PLL lobectomies leaked. The incidence of bronchial stump failures did not differ among techniques (P = .15). Lung lobectomy was performed successfully with the PLL in 5 clinical cases with no intraoperative or postoperative complications; median follow-up time was 6 months.

CONCLUSION

Bronchial ligation with the PLL reliably resisted physiological airway pressures and performed comparably to current standard techniques in cadavers. The PLL provided an adequate air and vascular seal in 5 clinical cases undergoing total lung lobectomy.

CLINICAL RELEVANCE

Pre-tied ligature loops provide an alternative method for total lung lobectomy in dogs.