Spontaneous pulmonary interstitial emphysema, pneumomediastinum and cervical subcutaneous emphysema secondary to the Macklin effect in dogs with no clinical signs: 12 cases.

Pneumomediastinum denotes the presence of gas within the mediastinum and generally occurs by leakage of air from an aerated viscus that traverses or abuts the mediastinal plane. The Macklin effect has been described in several veterinary studies and describes gas tracking along the perivascular interstitium following alveolar rupture causing interstitial emphysema, pneumomediastinum and subsequently cervical subcutaneous emphysema. This retrospective case series describes incidental spontaneous pulmonary interstitial emphysema, pneumomediastinum and cervical subcutaneous emphysema secondary to the Macklin effect in dogs with no related clinical signs. Twelve dogs were identified from the author's institution, of which 75 % were Sighthounds (Greyhounds, Whippets or Lurchers). Pulmonary interstitial emphysema had a predominantly paravascular distribution, although in some cases a parabronchial distribution was also identified. We conclude that incidental pulmonary interstitial emphysema, pneumomediastinum and secondary cervical subcutaneous emphysema can be incidental, presumed secondary to the Macklin effect and that Sighthound breeds may be overrepresented.

Application of collagen matrix (DuraGen®) to reduce subcutaneous emphysema in canine dorsal rhinotomy.

This retrospective case study aimed to evaluate the efficacy of collagen matrix (DuraGen®) in preventing subcutaneous emphysema, a common complication following dorsal rhinotomy. Six client-owned dogs diagnosed with nasal masses using computed tomography were included in this study. Dorsal rhinotomy was performed, and a collagen matrix was used to seal bone defects before fixation of the nasal bone flap. Following collagen matrix application, all dogs recovered without notable complications. These findings suggest that the collagen matrix is a reliable and safe intervention for mitigating subcutaneous emphysema after dorsal rhinotomy.

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.

Iatrogenic gas embolism in a juvenile loggerhead sea turtle (Caretta caretta).

A mild pneumocoelom was diagnosed by computed tomography in a stranded juvenile loggerhead sea turtle (Caretta caretta). After gas extraction by ultrasound-guided puncture, the animal did not improve and was subjected to hyperbaric oxygen therapy (HBOT). After HBOT, the turtle developed marked subcutaneous emphysema and was found dead the following morning. Gross lesions included a distended right atrium with numerous gas bubbles within the epicardium, gas bubbles in the hepatic, gastric and mesenteric veins, a small gas-filled bulla in the left lung and diffuse haemorrhages in the encephalon. Histological lesions included gas-like emboli in the lumen of the right atrium with myocardial necrosis, gas-like emboli in the lumina of intestinal, pulmonary and renal blood vessels and severe meningeal haemorrhages. From a forensic pathology perspective, the subcutaneous emphysema of immediate onset after HBOT and the greater severity of the histological lesions in blood vessels, heart, lung and brain differentiate this case from other cases of gas embolism in turtles due to incidental capture. Two factors contributed to this outcome: the existence of a probably unresolved pneumocoelom and the application of HBOT without an initial diagnosis that accurately indicated its use. Therefore, as in human medicine, the use of HBOT in sea turtles with lung lesions and pneumocoelom is discouraged. This is the first description of an iatrogenic gas embolism in a sea turtle.

The successful use of a subcutaneous catheter in the management of severe subcutaneous emphysema in a dog with laryngeal crush injury and tracheostomy tube placement.

OBJECTIVE: To describe the placement of a subcutaneous catheter in a dog for the management of severe subcutaneous emphysema secondary to severe laryngeal crushing injury and temporary tracheostomy tube placement. CASE SUMMARY: A 6-year-old male neutered Kelpie suffered a severe laryngeal crushing injury following a dog attack. Case management included the placement of a temporary tracheostomy tube due to severe respiratory compromise and inspiratory dyspnea associated with the crush injury. During hospitalization, the patient developed severe subcutaneous emphysema, pneumomediastinum, and a pneumothorax as a complication of the laryngeal crushing injury and temporary tracheostomy. A subcutaneous catheter was placed to manage the recurrent subcutaneous emphysema while the tracheostomy stoma healed. Five months posttrauma, the dog returned to normal with mild stridor during excitement and while panting. NEW OR UNIQUE INFORMATION PROVIDED: This is the first report in veterinary medicine describing the use of a subcutaneous catheter for the management of subcutaneous emphysema secondary to laryngeal crush injury and temporary tracheostomy tube placement.

Subcutaneous emphysema and pneumomediastinum following orbital blowout pathological fracture in a cat with nasal lymphoma: a case report.

BACKGROUND: Subcutaneous emphysema and pneumomediastinum are rare complications associated with orbital blowout pathological fracture. CASE PRESENTATION: A 7-year old, castrated male Abbysinian cat presented with anorexia, lethargy, nausea, eyelid swelling, nasal discharge, and sneezing. Based on the clinical and diagnostic work-up, the cat was diagnosed with T cell high-grade nasal lymphoma associated with orbital pathological fracture due to the tumour invasion. After chemotherapy, the cat showed massive subcutaneous emphysema from frontal region to abdomen and pneumomediastinum due to orbital blowout pathological fracture. As the nasal mass decreased in volume; the air had moved from the maxillary sinus to the subcutaneous region and the mediastinum through fascial planes in the head and neck region. CONCLUSIONS: This is a first case report of a massive subcutaneous emphysema and pneumomediastinum due to an orbital blowout pathological fracture following chemotherapy in feline nasal lymphoma in veterinary medicine.

Use of an equine compression suit to manage a deep axillary wound in a horse.

PURPOSE: To describe the use of an equine compression suit to manage a deep axillary wound in a Thoroughbred filly with bilateral pneumothorax. CASE SUMMARY: A 2-year-old Thoroughbred filly was referred for management of a deep wound to the left axilla. Packing and bandaging of the area were initially attempted, but this became repeatedly dislodged, and bandaging was discontinued. The filly subsequently developed widespread subcutaneous emphysema, and the wound was slow to granulate. Acute onset respiratory distress occurred 11 days after admission, secondary to bilateral worsening pneumothorax, and required placement of a chest drain. A commercially available equine compression suit was then successfully used to hold a primary dressing in place. This resulted in a marked improvement in the subcutaneous emphysema and pneumothorax. Wound granulation subsequently progressed well, and the filly was discharged from the clinic on day 36. UNIQUE INFORMATION PROVIDED: This case report highlights the potential applicability of a compression suit as an alternative to a stent to effectively prevent entry of air and successfully manage axillary wounds in the horse. It was also noted how delayed the progression of a pneumothorax can be after inadequate bandaging of a deep wound in the axillary region. The compression suit provided an alternative means of securing a dressing onto an awkwardly placed wound and may be useful in locations other than the axilla.

Cervical tracheal rupture with persistence of a pseudotrachea in a dog.

A dog was examined because of acute onset of respiratory distress following a cervical dog bite. Physical examination revealed a deep ventral cervical bite wound associated with localized mild subcutaneous emphysema. Thoracic radiographs showed moderate pneumomediastinum. Medical management consisting of oxygen therapy, antibiotics, and anti-inflammatories was initiated. After 2 days, respiratory distress suddenly worsened. Tracheoscopy showed a discontinuity between the tracheal rings of the cervical trachea; however, the inner tracheal wall appeared intact. Computed tomography scan revealed a ~3-cm complete rupture of all layers of the trachea. Surgical resection and anastomosis of the trachea were performed successfully. Follow-up 15 days after surgery showed complete resolution of respiratory signs, as well as subcutaneous emphysema. A mild ventral angulation of the trachea at the surgical site was noticed on thoracic radiographs. This is the first case report of a pseudotrachea in a dog. Persistence of a pseudotrachea may initially result in only minor clinical signs responsive to medical therapy despite tracheal rupture. In the presence of a pseudotrachea, tracheal rupture may be difficult to identify with tracheoscopy alone. Therefore, CT scan should be proposed in every patient with suspected tracheal trauma. Key clinical message: This case report highlights the importance of including a tracheal rupture in the differential diagnosis of cervical subcutaneous emphysema, even if the amount is small and not associated with significant respiratory signs. The presence of a pseudotrachea may result in less severe clinical signs than expected based on the actual degree of tracheal injury; however, the clinical status may rapidly deteriorate and become life-threatening. This case report also underlines the importance of a CT scan as a complement to tracheoscopy, which may not be sufficient to identify a tracheal rupture in the presence of a pseudotrachea.

Rupture trachéale cervicale avec persistance d'une pseudotrachée chez un chien. Un chien a été présenté pour une dyspnée aiguë modérée consécutive à des morsures cervicales par un autre chien. L'examen clinique révéla une plaie cervicale ventrale profonde associée à un emphysème sous-cutané localisé léger. Les radiographies thoraciques ont montré un pneumomédiastin modéré. Un traitement médical consistant en une oxygénothérapie, des antibiotiques et des anti-inflammatoires a été initié. Après deux jours, la dyspnée s'aggrava brutalement. Une trachéoscopie révéla une discontinuité entre les anneaux trachéaux malgré la persistance d'une paroi trachéale interne intègre. L'examen par tomodensitométrie montra une rupture trachéale cervicale complète dans toute son épaisseur, sur 3 cm de long. Une chirurgie de résection-anastomose de la trachée a été réalisée avec succès.Il s'agit de la première description de pseudotrachée chez un chien. La persistance d'une pseudotrachée peut initialement ne provoquer que des signes cliniques mineurs, notamment un emphysème sous-cutané léger et une dyspnée répondant au traitement médical, malgré une lésion trachéale en réalité importante. Par conséquent, un examen par tomodensitométrie de la trachée doit être envisagé chez tous les patients pour lesquels un traumatisme trachéal est suspecté.Message clinique clé :Ce cas souligne l'importance d'inclure une rupture trachéale dans le diagnostic différentiel de l'emphysème souscutané cervical, et cela même s'il n'est présent qu'en petite quantité et associé à faibles signes cliniques respiratoires. La persistance d'une pseudotrachée peut entraîner des signes cliniques moins importants qu'une rupture trachéale complète, cependant l'état respiratoire de l'animal peut rapidement s'aggraver et devenir une urgence vitale.Ce cas souligne de plus l'importance de l'examen par tomodensitométrie en complément de la trachéoscopie, qui peut parfois s'avérer insuffisante pour le diagnostic des ruptures trachéales, en particulier en présence d'une pseudotrachée.(Traduit par les auteurs).

Fatal non-traumatic gas gangrene caused by Clostridium perfringens type A in a Siberian Husky dog.

An 8-y-old, castrated male Siberian Husky dog was admitted to an emergency clinic with acute collapse and severe swelling of both forelimbs, ventral thorax, and axillary region. The clinical assessment, with laboratory tests and radiologic investigation, confirmed severe subcutaneous emphysema and multi-organ failure. The animal died while receiving emergency treatment. On postmortem examination, Clostridium perfringens was isolated from the subcutaneous fluid and the effusion from the thoracic and abdominal cavities. Relevant histopathology findings included subcutaneous emphysema and multi-organ perivascular and intravascular, intralesional myriad 0.5-3-µm gram-positive rod bacteria, with no associated inflammation. Whole-genome sequencing and phylogenetic analysis identified C. perfringens type A. Virulence genes detected included cpa (alpha toxin), cadA (v-toxin), colA (collagenase A), nagH (hyaluronidase), nanH, nanI, nanJ (sialidases), and pfoa (perfringolysin). These virulence genes have previously been reported to act synergistically with alpha toxin in C. perfringens-mediated gas gangrene.

Pneumoperitoneum as an uncommon complication after an axillary laceration in a horse.

Lacerations of the axillary region occur frequently in horses. Typical complications caused by entrapment of air in the wound during locomotion are subcutaneous emphysema, with consecutive pneumomediastinum and pneumothorax. In this case report, the clinical, radiographic and laboratory diagnosis and management of these complications after an axillary laceration that finally resulted in pneumoperitoneum are described. A 1-year-old Hannoveranian was presented with a pre-existing axillary laceration of unknown duration and subcutaneous emphysema in the surrounding tissue. Due to extensive tissue loss, attempts to adequately close the wound surgically and by packing with sterile dressing material were unsuccessful. Despite stall confinement and tying of the horse, subcutaneous emphysema was progressive and pneumomediastinum as well as pneumothorax was developed. These complications were monitored radiographically. On day 5 after admission, signs of air accumulation were detected on radiographs craniodorsally in the peritoneum and a pneumoperitoneum was diagnosed. Repeated thoracentesis with a teat cannula to gradually evacuate the thoracic cavity was used in combination with nasal oxygen insufflation to treat global respiratory insufficiency. Subcutaneous emphysema and all other complications resolved progressively and the horse was discharged from the hospital 21 days after admission when the axillary wound was adequately filled with granulation tissue. The wound healed fully 1 month later and the horse did not develop long-term complications within the following year. To the authors´ knowledge, the development of pneumoperitoneum including its radiographic monitoring following an axillary laceration has not been described in horses previously.

Survey of current trends in the management of traumatic subcutaneous emphysema in dogs.

BACKGROUND: Subcutaneous emphysema (SCE) is a common occurrence in emergency veterinary practice, but published information regarding treatment and management strategies is lacking. This study examined trends in diagnostic and treatment recommendations. STUDY DESIGN: An internet-based survey with cross-sectional analysis. There were 129 respondents: board-certified and nonboard-certified veterinarians in private practice and university settings. KEY FINDINGS: Significant differences in the choice of diagnostics and treatment were found based on the etiology and severity of SCE and between respondent groups. Computed tomography (CT) was selected more frequently for SCE resulting from blunt or penetrating traumas by the board-certified veterinarians practicing in a teaching hospital (VTH group; P < 0.001). All veterinarians were more likely to select tracheobronchoscopy as part of their workup for SCE as a result of endotracheal intubation trauma (P = 0.0093 [penetrating traumas]; P = 0.0002 [blunt force traumas]). Intermittent SC drainage and ventral cervical exploratory surgery were more likely to be chosen as treatments when SCE was classified as severe generalized (P < 0.0001). SIGNIFICANCE: There is significant variation in the treatment of SCE in veterinary medicine as well as associated diagnostics to determine severity and treatment options. Further studies are indicated to determine the optimal approach and provide guidance to clinicians.

Thoracic radiographic features of fatal paraquat intoxication in eleven dogs.

BACKGROUND: Paraquat (1,1-dimethyl-4,4-bipyridinium dichloride) is a toxic herbicide. Accidental ingestion of paraquat in animals and humans causes respiratory failure and death. AIM: To describe the radiographic features of confirmed paraquat intoxication in a group of dogs and determines whether any identified features can facilitate this diagnosis. METHODS: Eleven dogs diagnosed with paraquat intoxication were selected from two institutions between November 2014 and August 2019 comprising five males (all intact) and six females (one intact and five spayed). The mean age was 3.9 ± 2.9 (SD) years and their mean weight was 11.6 ± 5.0 kg. The tentative diagnosis was confirmed through analysis of their urine samples using a colorimetric assay (paraquat concentation 0.39 µg/ml ranging from 0.19-0.65 µg/ml), and their clinical signs were reviewed. Thoracic radiographs were evaluated for the presence of pneumomediastinum, lung patterns (interstitial or alveolar) and their locations (caudodorsal, cranioventral, diffuse, or symmetrical), subcutaneous emphysema, pneumoretroperitoneum, and pneumothorax. RESULTS: The most common clinical signs were dyspnea (11/11, 100%) and anorexia (9/11, 82%). Pneumomediastinum (10/11, 91%) and symmetrically increased lung opacity (7/11, 65%) were the most common radiographic features. Pneumothorax (3/11, 27%), pleural effusion (3/11, 27%), subcutaneous emphysema (2/11, 18%), and pneumoretroperitoneum (1/5, 20%) were the less common findings. None of the dogs survived. CONCLUSION: Pneumomediastinum and diffuse or symmetrical interstitial or alveolar lung patterns are the most common radiographic features in dogs with paraquat intoxication. CLINICAL RELEVANCE: In countries where this herbicide is not banned, paraquat intoxication should be considered if dogs with no history of trauma present with pneumomediastinum.

Computed tomographic findings in a Bluetick Coonhound with a longitudinal thoracic tracheal tear.

A 9-year-old intact male Bluetick Coonhound presented for progressive subcutaneous emphysema of 5 days' duration due to a suspected tracheal tear. Cervical computed tomography (CT) and thoracic CT were performed after failure to identify the tracheal tear with tracheoscopy. A longitudinal tracheal tear was identified starting 4.3 cm cranial to the tracheal bifurcation and extending caudally over a distance of 3.6 cm. Severe pneumomediastinum, subcutaneous emphysema, and retroperitoneal gas were also present. A follow-up CT 7 days postoperatively confirmed the successful repair of the tear with partial resolution of the presurgical secondary pathology and the patient recovered uneventfully.

Orbital and Subcutaneous Emphysema Following Enucleation and Respiratory Distress in a Japanese Chin.

A 7 yr old, neutered male Japanese chin presented to the Cummings School of Veterinary Medicine at Tufts University (CSVMTU) for evaluation of chronic unilateral orbital swelling that worsened following an episode of respiratory distress. The left eye had been enucleated 5 yr previously. Intermittent mild-to-moderate left orbital swelling had been noted by the owner since the initial surgery. Examination demonstrated a moderate-to-severe, soft, fluctuant swelling involving the left orbit with erythema of the overlying skin. Crepitus was noted over the occipital tuberosity. Computed tomography revealed a large volume of gas involving the left orbit. The gas extended caudally within the subcutaneous tissues to both hemimandibles, dorsal to the cranium, and partially surrounded the cranial neck. The presence of a mucosa-lined, air-filled space with a patent nasolacrimal duct was noted on orbital exploration. The lining was removed and the duct closed. Histopathology confirmed the presence of an epithelial lining. No recurrence of the swelling was observed on examination 8 wk after surgery. This is the first report documenting acute worsening of orbital swelling following an episode of respiratory distress. This case highlights the importance of addressing the nasolacrimal duct while performing an enculeation in a brachycephalic dog.

Airway injury associated with cervical bite wounds in dogs and cats: 56 cases.

OBJECTIVE: To investigate the frequency of airway injury and damage to other vital structures associated with cervical bite wounds in dogs and cats and the implications for management and outcome. METHODS: A retrospective search of electronic patient records was used to identify dogs and cats suffering cervical bite wounds that were presented to a large multidisciplinary veterinary hospital over a four year period. RESULTS: Complete records were available for 55 animals, with one animal suffering two separate injuries. Fourteen animals (25%) had injuries to vital structures, including airway injury in nine (17%) which was surgically confirmed and treated in six (11%). Airway injuries were associated with either subcutaneous or mediastinal emphysema in all affected animals. Other structures injured included the jugular vein, pharynx, oesophagus and spine. Airway injuries were treated with primary repair in five animals and a fasciomuscular patch in one. Temporary tracheostomy was performed in three animals. Median duration of hospitalisation was one day (0-19) with 53 animals (54 cases) (96%) surviving to discharge. Long-term follow-up (16-114 months) revealed that 43 of 49 animals were alive with six that died due to unrelated reasons. CLINICAL SIGNIFICANCE: Cervical bite wounds are associated with significant injury to vital structures. Up to 17% of animals may have injury to their airway. Identification and treatment of airway injury is vital and was associated with an excellent outcome in six animals.

Pneumomediastinum and subcutaneous emphysema in a cat associated with necrotizing bronchopneumonia caused by feline herpesvirus-1.

This report describes a 1-year-old cat with acute dyspnea. Thoracic radiography revealed a pneumomediastinum and severe subcutaneous emphysema. Lower airway surgical exploration was unable to determine the cause. At postmortem examination, acute necrotizing bronchopneumonia and fibrinonecrotic tracheitis due to feline herpesvirus-1 were diagnosed.