CHARACTERIZATION OF SEVERE SMALL AIRWAY DISEASE IN A PUPPY USING COMPUTED TOMOGRAPHY

A young Golden Retriever dog developed severe respiratory distress following an initial clinical diagnosis of infectious tracheobronchitis. Severe expiratory flow limitation, associated with exertional respiratory distress and hypoxemia was present. Thoracic images obtained with conventional radiography were characterized by hyperinflation and abnormal bronchial and alveolar patterns. Computed tomography was performed and in conjunction with pulmonary functional changes was diagnostic of small airway disease. The dog was treated with a variety of antibiotics, anti-inflammatory agents, and antitussives, but the clinical signs worsened and the puppy was euthanized. Pathologic examination confirmed severe small airway disease, with emphysema and bronchiolitis.     

Severe bronchoconstriction after bronchoalveolar lavage in a dog with eosinophilic airway disease

Bronchoalveolar lavage (BAL) is considered to be a safe procedure in humans and other animals. However, in some instances, potentially life-threatening complications can arise. In this clinical report, a dog with eosinophilic airway disease that underwent a BAL and subsequently became profoundly dyspneic during the recovery period is described. The dyspnea was severe enough to warrant mechanical ventilation for almost 24 hours. Several anti-inflammatory and bronchodilatory medications were also used. The dog was successfully weaned off the ventilator and made a full recovery. On the basis of radiographic findings and clinical response to treatment, we believe the dog had acute exacerbation of eosinophilic airway disease and severe bronchoconstriction secondary to the BAL. Caution should be exercised when performing a BAL if there is suspicion of a reactive airway disease.     

Coma and respiratory failure due to moxidectin intoxication in a dog

Objective: To describe the clinical consequences following ingestion by a dog of a moxidectin‐containing equine deworming product. Few reports exist concerning the treatment and outcome of severe moxidectin toxicity. Treatment, known factors influencing intoxication, and prognosis are reviewed. Case summary: A 10‐month‐old female Border Collie ingested an unknown quantity of a moxidectin‐containing equine deworming product several hours before presentation. Severe neurological signs subsequently developed and included: ataxia, seizures, coma, and respiratory failure. The dog was treated with supportive care including intravenous fluids, activated charcoal, and positive pressure ventilation. Normal spontaneous respiration returned in 34 hours and the patient was discharged 58 hours after ingestion. Full recovery occurred within 1 week of intoxication. New information provided: This report describes moxidectin intoxication and associated respiratory failure in a dog that required mechanical ventilation. The dog's recovery was rapid. Despite severity of signs, the prognosis for patients with moxidectin intoxication is good with appropriate supportive care.     

Laryngeal collapse in seven brachycephalic puppies

OBJECTIVES: To document the histories, clinical findings, and management of seven puppies with laryngeal collapse occurring secondarily to brachycephalic airway syndrome. METHODS: Seven brachycephalic puppies aged between 4.5 and six months underwent surgery for management of brachycephalic airway syndrome following presentation for exercise intolerance and increased respiratory noise and effort. RESULTS: Stenotic nares of varying severity and an elongated soft palate were common to all dogs. All dogs had tracheal hypoplasia and this was severe in four dogs. Laryngeal collapse was present in all dogs. Two dogs had stage I, four dogs stage II, and one dog stage III laryngeal collapse. The dog with stage III laryngeal collapse and one dog with stage II laryngeal collapse died. There was no apparent association between the changes evident on thoracic radiographs or the degree of tracheal hypoplasia and postoperative outcome. CLINICAL SIGNIFICANCE: The development of severe secondary laryngeal changes in dogs aged six months or less supports the suggestion that immature brachycephalic dogs should undergo assessment and, if indicated, surgery as soon as any clinical signs of BAS are apparent.     

Use of successive dynamic videoendoscopic evaluations to identify progression of recurrent laryngeal neuropathy in three horses

CASE DESCRIPTION: 3 racehorses were evaluated because of poor performance or abnormal noise originating from the upper portion of the respiratory tract. CLINICAL FINDINGS: During maximal exercise, initial dynamic videoendoscopy of the upper respiratory tract revealed complete arytenoid cartilage abduction in 2 horses and incomplete but adequate abduction of the left arytenoid cartilage in 1 horse. Subsequent exercising endoscopic evaluation revealed severe dynamic collapse of the left arytenoid cartilage and vocal fold in all 3 horses. TREATMENT AND OUTCOME: 2 horses were treated with prosthetic left laryngoplasty and raced successfully. One horse was retired from racing. CLINICAL RELEVANCE: Idiopathic laryngeal hemiplegia can be a progressive disease. Successive dynamic videoendoscopic upper airway evaluations were used to confirm progression of left laryngeal hemiplegia in these 3 horses. Videoendoscopy of the upper respiratory tract during exercise should be considered as part of the clinical evaluation of horses with signs of upper respiratory tract dysfunction.     

Complications and Long-term Results after Partial Laryngectomy for the Treatment of Idiopathic Laryngeal Paralysis in 45 Dogs

Forty-five dogs with severe respiratory signs caused by idiopathic, acquired laryngeal paralysis were treated by partial laryngectomy. The predominant postoperative complications were coughing in 28 dogs and pneumonia in 15 dogs. Eight dogs required a second operation to alleviate persistent or recurrent upper airway obstruction. Results of surgery were considered excellent in 11 dogs (25%), good in 18 dogs (40%), fair in 6 dogs (13%), and poor in 10 dogs (22%). Poorer results were obtained by surgical residents than by more experienced surgeons. Death in the immediate postoperative period was related to pneumonia (8 dogs) and laryngeal collapse (1 dog). Nine dogs died later of respiratory disease. Although partial laryngectomy is effective for the treatment of laryngeal paralysis, it is not recommended because of the high incidence of postoperative complications.     

Tracheal Collapse and Bronchomalacia in Dogs: 58 Cases (7/2001–1/2008)

Background: Tracheobronchomalacia is diagnosed in people by documentation of a reduction in airway diameter during bronchoscopy. While tracheal collapse in the dog has been well described in the literature, little information is available on bronchomalacia in the dog. Hypotheses: Bronchomalacia is common in dogs with tracheal collapse, is associated with inflammatory airway disease, and is poorly documented radiographically. Animals: One hundred and fifteen dogs admitted for evaluation for respiratory disease and examined by bronchoscopy. Methods: Case‐controlled, observational study. Dogs examined and having a bronchoscopic procedure performed by a single operator were separated into groups with and without visually identified airway collapse. Clinical parameters and bronchoalveolar lavage findings were compared between groups. Radiographs were reviewed in masked fashion to assess the sensitivity and specificity for detection of bronchomalacia. Results: Tracheobronchomalacia was documented in 50% of dogs examined, with tracheal collapse in 21% and bronchomalacia in 47%. In dogs with bronchomalacia, collapse of the right middle (59%) and left cranial (52%) lung lobes was identified most commonly. Dogs with bronchomalacia were significantly more likely to display normal airway cytology and to have mitral regurgitation and cardiomegaly than dogs without airway collapse (P < .05). Radiographs were insensitive for detection of airway collapse. Conclusions and Clinical Importance: Bronchomalacia was identified more commonly than tracheal collapse in this population of dogs, and documentation required bronchoscopy. This study could not confirm a role for airway inflammation in bronchomalacia, and further studies are required to determine the role of cardiomegaly in the disorder.     

Treatment of a dog with severe baclofen intoxication using hemodialysis and mechanical ventilation

Objective: This case report describes the successful management of a dog with coma and respiratory depression due to severe baclofen intoxication. Case summary: A Doberman Pinscher mixed breed dog ingested 500 mg (20 mg/kg) of baclofen. Signs of severe intoxication included coma and profound respiratory muscle weakness. The dog was supported with positive pressure ventilation and treated with one session of hemodialysis. Weaning from the ventilator was achieved within 4 hours of hemodialysis, and recovery from coma occurred over the following 12–36 hours. The dog regained full neurologic function and was normal at discharge following 3 days of hospitalization. New or unique information provide: Severe central nervous system depression and respiratory depression due to baclofen intoxication can be life threatening. In addition to other supportive care, hemodialysis may hasten recovery and ventilatory support may be essential to achieve a positive outcome. With successful treatment, toxicity can be decreased and the associated life‐threatening central nervous system and ventilatory depression can resolve. Prognosis for return of normal function is excellent.     

Tracheal collapse in the dog - is there really a role for surgery? A survey of 100 cases

One hundred dogs with clinical signs associated with tracheal collapse were examined over a four-year period. The symptomatic state of tracheal collapse was found to have a multifactorial aetiology. Factors linked with the onset of clinical signs included cardiomegaly, pulmonary oedema, respiratory infection, endotracheal intubation, the presence of a smoker in the household, allergic respiratory disease and obesity. Medical or conservative management resulted in long term resolution of signs (greater than 12 months) in 71 per cent of cases while a further 4 per cent were successfully managed by upper airway surgery. Tracheal reconstruction was performed for the minority of non-responsive cases (11 per cent) in which no other medical condition could be identified. Only half of these dogs (5 per cent) remained asymptomatic long term. The importance of identifying and eliminating the factors implicated in initiating the symptomatic state of tracheal collapse is emphasised. Suppression of these exciting causes should be considered as the therapeutic priority and surgery should be reserved only for those dogs which do not respond to conservative management.     

Alternating one lung ventilation using a double lumen endobronchial tube and providing CPAP to the non-ventilated lung in a dog

Introduction This case report describes the anaesthetic management of exploratory thoracoscopy and alternating one lung ventilation (OLV) in a dog with a pulmonary bulla, and the application of continuous positive airway pressure (CPAP) to the non‐ventilated lung for preventing and treating hypoxia. Case history A 6‐year‐old, male castrated Border collie was scheduled for exploratory thoracoscopy to investigate spontaneous pnemothorax that had not resolved with repeated suction. Specific requirements for the thoracoscopy were alternating OLV to allow the surgical access to the right middle lobe and its removal, and the examination of the left hemithorax to rule out the presence of other lesions. Diagnosis and management Selective lung ventilation was performed with a double lumen endobronchial tube (DLT), inserted under endoscopic guidance. After a short period of two lung ventilation during preparation of the surgical field, alternating OLV was performed, combining CPAP, provided to the non‐ventilated lung via a Mapleson D breathing system, and positive end‐expiratory pressure (PEEP) applied to the ventilated lung. Left OLV occurred first and resection of the right middle pulmonary lobe was successfully performed; right OLV followed to allow the examination of the left hemithorax. Discussion and conclusions The combination of CPAP and PEEP resulted in a satisfactory intra‐operative management of hypoxemia. Alternating OLV can be performed successfully by using a DLT. CPAP, commonly employed in human medicine, should be considered an important tool in the anaesthetic management of OLV in small animals.     

The recognition and treatment of the intermediate syndrome of organophosphate poisoning in a dog

Objective: To discuss a new clinical presentation of organophosphate toxicity called the intermediate syndrome in a dog. Case summary: A mixed breed dog presented with generalized weakness, hypoventilation and hypoxemia. The weakness was most marked in the thoracic limbs, cervical and respiratory muscles. The history revealed a likely exposure to an organophosphate compound. The other dog in the household demonstrated mild clinical signs of organophosphate toxicity. A blood cholinesterase level was markedly reduced. Therapy included placement of a tracheostomy tube and mechanical ventilation. The dog gradually improved over the following 8 days but had persistent cervical ventroflexion for a total of 4 weeks. New or unique information provided: Organophosphate toxicity can present as a paralysis following the acute cholinergic crisis. The muscular weakness predominantly affects the thoracic limb and neck muscles but cranial nerve deficits can also occur. Dogs can die from the associated respiratory depression. Oxime therapy is indicated in the treatment of this syndrome.     

Bronchial stent placement in a dog with bronchomalacia and left atrial enlargement

A 13‐year‐old neutered male Maltese was referred for paroxysms of coughing and cyanosis, with radiographic evidence of bronchial disease and cardiomegaly. Investigation with echocardiography, bronchoscopy, fluoroscopy and bronchoalveolar lavage led to a diagnosis of myxomatous mitral valve degeneration with insufficiency, ISACHC class II heart failure and bronchomalacia with severe left mainstem bronchial collapse. Persistence of intractable cough despite medical therapy prompted placement of a stent in the left mainstem bronchus. Immediately after stent placement, severe pulmonary oedema developed, thought to be due to compression of the left atrium by the stent or acute lung injury related to stent placement. The dog recovered over a 3‐day period with diuretic therapy and positive end expiratory pressure ventilation. Subsequently, the dog died from congestive heart failure 102 days after stent placement, during which time occasional, self limiting coughing episodes occurred .     

Application of Airway Pressure Therapy in Veterinary Critical Care: Part I: Respiratory Mechanics and Hypoxemia

Over the past several decades, recognition of acute respiratory failure as the cause of death in patients suffering from various clinical conditions has prompted aggressiv investigation into the area of respiratory physiology and supportive respiratory care. With the evolution of emergency medicine and critical care services in both human and veterinary medicine, many patients previously considered unsalvageable due to the severity of their underlying disease are now being resuscitated and successfully supported, creating a new population of critically ill patients. Where only a decade ago these patients would have succumbed to their underlying disease, they now survive long enough to manifest the complications of shock and tissue injury in the form of acute respiratory failure. Investigation into the pathophysiology and treatment of this acute respiratory distress syndrom (ARDS) has facilitated increased clinical application of respiratory theerapy and machanical ventilation.¹ The purpose of this paper is to provide a basic review of respiratory mechanics and the pathophysiology of hypoxemia as they relate to airway pressure therapy in veterinary patients and to review the use of airway pressure therapy in veterinary patients This paper is divided into two parts; part I reviews respiratory mechanics and hypoxemia as they apply to respiratory therapy, while part II deals specifically with airway pressure therapy andits use in clinical cases.     

Treatment of unresectable hepatocellular adenoma in dogs with transarterial iodized oil and chemotherapy with and without an embolic agent: A report of two cases

Transarterial iodized oil with chemotherapy was evaluated in two dogs with large, surgically unresectable hepatocellular adenoma. A single cycle of therapy was used in each dog. Chemoembolic mixtures varied: doxorubicin emulsified with iodized oil radiographic contrast (case 1), doxorubicin and mitomycin C emulsified with iodized oil radiographic contrast (case 2). In addition, dog 2 underwent arterial embolization with polyvinyl alcohol granules. Response was assessed by computed tomography at 1 and 3 months after treatment. Superselective catheterization of the hepatic arterial branch supplying the tumour was not achieved in either case. In the immediate post‐operative period, both dogs developed mild clinical signs that may have been consistent with post‐embolization syndrome, but neutropenia and reduced liver function were not observed. Tumour response was minimal: stable disease at 1 month and progressive disease at 3 months was observed in both cases.     

Foramen magnum decompression with cranioplasty for treatment of caudal occipital malformation syndrome in dogs

Objectives— To describe a cranioplasty procedure used in conjunction with foramen magnum decompression (FMD) for the treatment of canine caudal occipital malformation syndrome (COMS), and to evaluate the clinical outcome. Study Design— Prospective clinical study. Animals— Dogs (n=21) with COMS diagnosed by magnetic resonance imaging (MRI). Methods— After FMD, titanium screws were placed around the perimeter of the foramen magnum defect and a skull plate fashioned from titanium mesh and polymethylmethacrylate was attached to the back of the skull, using the titanium screws as anchor posts. Follow‐up was obtained by direct examination by the authors, telephone interviews with owners and referring veterinarians, and a questionnaire sent to owners of surviving dogs designed to assign objective measures of response to surgical intervention. Surgical success was defined as improvement in ≥1 aspects of clinical dysfunction (e.g. scratching, pain) postoperatively. Owner‐assigned pre‐ and postoperative quality‐of‐life (QOL) scores (1–5) for surviving dogs were compared using a Wilcoxon's signed rank test for paired data (P≤.05). Results— No intraoperative complications occurred and postoperative complications were limited to transient worsening of a pre‐existing head tilt and ataxia in 1 dog, and the need for oral pain medication for 1–4 weeks in 3 dogs. Seventeen dogs (81%) had clinical improvement after surgery. Although clinical signs resolved in 1 dog, it died after being hit by a car, 5 months after surgery. One dog had no change in clinical signs; this patient's clinical signs were not severe and the owners had opted for surgery primarily to prevent progression of disease. Two dogs were euthanatized; 1 because of no improvement of severe clinical signs, and 1 because of sustained recurrence of apparent head and neck pain 7 months later. One dog required a dorsal laminectomy at a second site (C1/C2 vertebral level), 2 months later. Four dogs has transient “flare‐ups” of apparent head/neck pain 2–13 months later; all resolved with transient re‐institution of oral analgesic therapy. Further surgery at the FMD was not needed. Based on the returned questionnaires, there was an overall significant improvement in QOL scores. Conclusions— FMD with cranioplasty was well tolerated, with no intraoperative complications, and minor postoperative complications. Most dogs improved clinically, and none required further surgery at the original FMD site. Clinical Relevance— FMD with cranioplasty may be an effective surgical method of treating dogs with COMS and is well tolerated. Based on prior reports of FMD for this disorder, it appears that cranioplasty may reduce the rate of surgical failure caused by formation of compressive scar tissue at the FMD site in the short term. Results of this preliminary study support further evaluation of the cranioplasty procedure in a larger group of dogs over a more extended follow‐up period.     

Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia

OBJECTIVES: To describe clinical features of brachycephalic airway obstructive disease in dogs, the incidence of laryngeal collapse in dogs presenting for surgery and the outcome after surgery in dogs with laryngeal collapse. METHODS: Basic clinical details were reviewed retrospectively in 73 dogs. Presence of laryngeal collapse and short-term outcomes after surgery were determined for 64 dogs with complete medical records. Long-term outcomes were reviewed for 46 dogs by telephone survey between 19 and 77 months following surgery. RESULTS: Stenotic nares were present in 31 dogs (42.5 per cent), elongated soft palate in 63 (86.3 per cent) and everted laryngeal saccules in 43 (58.9 per cent). The most common breeds were the pug (19 dogs, 26 per cent), Cavalier King Charles spaniel (15 dogs, 20.5 per cent), British bulldog (14 dogs, 19.2 per cent) and Staffordshire bull terrier (4 dogs, 5.5 per cent). Laryngeal collapse was present in 34 of 64 (53 per cent) dogs. No dogs died perioperatively and only one dog was euthanased as a result of its respiratory disease three years after surgery. Telephone interviews indicated that 26 dogs (56.5 per cent) were much improved after surgery, 15 (32.6 per cent) had some improvement and 5 (10.9 per cent) showed no improvement. Signs that persisted after surgery were snoring during sleep (34 dogs, 73.9 per cent), stertor/stridor while conscious (23 dogs, 50 per cent), excessive panting (13 dogs, 28.3 per cent) and dyspnoea (10 dogs, 21.7 per cent). Long-term outcome was considered good, even in dogs with laryngeal collapse. CLINICAL SIGNIFICANCE: Laryngeal collapse is relatively common in dogs presented for surgical correction of brachycephalic airway obstructive disease. Dogs with severe laryngeal collapse often respond well to surgery. Clinical signs rarely resolve completely following surgery.     

Cervical injury following a horse kick to the head in two dogs

Two dogs were presented to North Carolina State University Veterinary Teaching Hospital following blunt trauma to the head delivered by a horse kick. On presentation, both dogs had resolving clinical signs directly related to the head trauma, but both also had compromise to their upper airway as a result of indirect injury to the soft tissues of the neck, visible on plain radiographs. One dog made a full recovery following a period of assisted ventilation. The other dog was euthanized at the request of the owner. These injuries illustrate the importance of evaluating the cervical spine and soft tissues of the neck following blunt trauma to the head.     

X‐linked CD40 ligand deficiency in a 1‐year‐old male Shih Tzu with secondary Pneumocystis pneumonia

An approximately 1‐year‐old male intact Shih Tzu dog was referred to a tertiary facility with a history of progressive tachypnea, increased respiratory effort, and weight loss over a 3‐month period that failed to improve with empirical antimicrobial treatment. Upon completion of a comprehensive respiratory evaluation, the dog was diagnosed with severe Pneumocystis pneumonia and secondary pulmonary hypertension. Clinical signs resolved and disease resolution was confirmed after completion of an 8‐week course of trimethoprim‐sulfonamide, 4‐week tapering dose of prednisone to decrease an inflammatory response secondary to acute die‐off of organisms, a 2‐week course of clopidogrel to prevent clot formation, and a 2‐week course of a phosphodiesterase‐5 inhibitor to treat pulmonary hypertension. Immunodiagnostic testing and genetic sequencing were performed to evaluate for potential immunodeficiency as an underlying cause for the development Pneumocystis pneumonia, and identified an X‐linked CD40 ligand deficiency.     

Mitigating the risk of airway obstruction during recovery from anaesthesia: The way is far from clear

All equine anaesthetists should take steps to mitigate the risk of anaesthetic‐related morbidities and mortalities where they can, and whilst some interventions against some of these are widely practiced, the number of approaches adopted by equine anaesthetists to mitigate the risk of airway obstruction suggests not only that the causes and severity of airway obstruction vary, but also that evidence for the superiority of any approach over another is limited. The limited evidence available suggests that the prevalence of severe airway obstruction in both the general and upper respiratory tract surgical equine populations is likely to be low, and that when cases do occur, rapid recognition and intervention often results in successful treatment. The above evidence considered with the understanding that pre‐emptively placing endotracheal or nasotracheal tubes in situ for recovery may only delay the recognition of some causes (e.g. laryngeal) of airway obstruction, alongside an awareness that this approach is not a benign risk‐free intervention, may lead some anaesthetists to re‐evaluate the perceived risk of respiratory obstruction and whether their chosen intervention will reduce that risk, potentially exacerbate it or introduce a further risk.     

Canine tracheal collapse

Tracheal collapse occurs most commonly in middle‐aged, small breed dogs. Clinical signs are usually proportional to the degree of collapse, ranging from mild airway irritation and paroxysmal coughing to respiratory distress and dyspnoea. Diagnosis is made by documenting dynamic airway collapse with radiographs, bronchoscopy or fluoroscopy. Most dogs respond well to medical management and treatment of any concurrent comorbidities. Surgical intervention may need to be considered in dogs that do not respond or have respiratory compromise. A variety of surgical techniques have been reported although extraluminal ring prostheses or intraluminal stenting are the most commonly used. Both techniques have numerous potential complications and require specialised training and experience but are associated with good short‐ and long‐term outcomes.