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Stertor and Stridor
Abstract
The flow of air from the upper to lower respiratory tracts is relatively quiet in the normal patient at rest. However, abnormal sounds may result from obstructive upper airway disease. These sounds are audible without a stethoscope. Their presence and, in particular, their persistence, suggests that a diagnostic work‐up for the patient is indicated. Stertor and stridor are two abnormal sounds that result from upper airway partial or complete obstruction. These sounds are not distinguished based upon where they originate in the respiratory cycle: either can be inspiratory or expiratory. Rather, stertor and stridor are distinct because of their pitch. The low‐pitched sound that is associated with stertor suggests that flaccid tissue is vibrating throughout the respiratory cycle. This occurs routinely in brachycephalic patients that have elongated soft palates: although their skulls are foreshortened, the reduction in soft tissue structures is not proportional. This additional tissue bulges into the airway lumen, creating resistance to airflow. This forces the patient to increase respiratory effort to take in sufficient air. An elongated soft palate is just one structural abnormality that is associated with brachycephalic airway syndrome. Affected patients may also experience the additive effects of having stenotic nares, with or without everted laryngeal saccules. As compared to stertor, which sounds like a snore, stridor is a high‐pitched sound that results from rigid tissue vibrations. It is typically associated with laryngeal or tracheal disease. Laryngeal paralysis and tracheal collapse are two common presentations in companion animal practice.
Despite efforts of veterinarians and breeders, brachycephalic obstructive airway syndrome (BOAS) is still a common problem in pugs, underlining the need for objective tests to identify and prevent breeding with affected dogs. In the current study, a submaximal, treadmill-based fitness test was evaluated as a tool to identify signs of airway obstruction not recognisable under rest conditions. In addition to this, different body conformation and measurements were assessed regarding their association with BOAS. A total of 62 pugs and 10 mesocephalic dogs trotted with an individual comfort speed on a treadmill for 15 min. Before and during the examination, dogs were examined for signs of respiratory distress, and a functional BOAS grading was applied. The influence of body conformation on BOAS grading was tested in a univariable and multivariable logistic regression model. During exercise, more respiratory noises were observed, and existing respiratory noises became more apparent in comparison to when at rest. In the multivariable logistic regression model, no factor had a statistically significant influence on BOAS classification. Submaximal fitness testing helped to identify signs of respiratory distress not apparent under resting conditions, and could be a valuable addition for identifying dogs with BOAS. Performing testing on a treadmill facilitates continuous observation of the patients, and enables standardisation of the test regarding the test environment, as well as provides an uninterrupted, steady workload.
Performing the Small Animal Physical Examination offers an easy-to-follow guide to successfully executing a thorough physical exam in cats and dogs. With practical tips for ensuring that the exam goes smoothly and facilitates diagnostic and therapeutic recommendations, the book provides a comprehensive manual for examining canine and feline patients in sickness and in health. Nearly 1,000 color photographs demonstrate the individual components of the physical exam and provide picture matching for identification and diagnosis of abnormal findings. Divided into separate sections for the cat and dog, the book tracks the logical progression of an exam beginning with initial observations about the patient and how the patient interacts with the environment. Subsequent chapters cover the in-depth examination of each body system. Performing the Small Animal Physical Examination is an essential resource for veterinary and veterinary technology students, recent veterinary graduates, and veterinary technicians. • Provides comprehensive, practical information on the physical examination in small animal patients • Presents nearly 1,000 color photographs with step-by-step details of the procedures and principles • Offers advice on preparing the examination room, useful tips, and concrete guidance for examining each body system • Outlines a systematic, in-depth approach to the initial examination in dogs and cats • Supports new and experienced veterinarians and veterinary technicians alike in performing a thorough basic exam
Stenotic nares and elongated soft palates seem to be the initiating events of brachycephalic syndrome in dogs. As a result of increased negative pressure during inspira-tion, the soft tissues of the upper airway are sucked into the lumen, aggravating the condition. The most common signs of brachycephalic syndrome are stress and heat intolerance, inspira-tory stridor, and asphyxia. Severely affected animals are prone to life-threatening attacks. Sur-gical corrections include wedge resection of stenotic nares, shortening of the soft palate, and removal of laryngeal saccules. B rachycephalic breeds tend to have respiratory problems that come under the term brachycephalic syndrome. The typical anatomic abnormalities are stenotic nares, enlarged tonsils, elongated soft palate, everted lateral saccules of the lar-ynx, narrowed rima glottidis, and collapse of the larynx and trachea. 1 These findings occur singularly or in various combinations and degrees in each dog. These abnor-malities narrow the lumen of the upper respiratory tract, thereby restricting breath-ing, which often leads to asphyxiation and collapse during excitement or heat result-ing from the weather or activity. This article provides a review of the predisposition and anatomic and pathophysiologic particularities of the respiratory tract in connec-tion with brachycephalic syndrome.
To determine the prevalence of individual anatomic components of brachycephalic airway obstructive syndrome (BAOS), including everted tonsils, and analyze the frequency with which each component occurs with 1 or more other components of BAOS in brachycephalic dogs.
Retrospective case series.
90 dogs with BAOS.
Medical records were reviewed for signalment, clinical signs at time of admission, historical and physical examination findings, BAOS components found on laryngoscopic examination of the pharynx and larynx, surgical procedures performed, and perioperative complications.
English Bulldogs (55/90 [61%]), Pugs (19/90 [21%]), and Boston Terriers (8/90 [9%]) were the most common breeds with BAOS. The most common components of BAOS were elongated soft palate (85/90 [94%]), stenotic nares (69/90 [77%]), everted laryngeal saccules (59/90 [66%]), and everted tonsils (50/90 [56%]). Dogs most commonly had 3 or 4 components of BAOS, with the most common combination being stenotic nares, elongated soft palate, everted laryngeal saccules, and everted tonsils. Dogs with stenotic nares were significantly more likely to have everted laryngeal saccules (50/69 [72%]), and dogs with everted laryngeal saccules were significantly more likely to have everted tonsils (39/59 [66%]). Postoperative surgical complications occurred in 12% (10/83) of dogs that received corrective surgery. No specific BAOS component made dogs more likely to have complications.
The prevalence of components of BAOS in brachycephalic dogs of this study differed from that reported previously, especially for everted tonsils. Thorough examination of the pharynx and larynx is necessary for detection of BAOS components.
Two lateral nasal glands appear to provide a large part of the water for evaporative cooling in the panting dog; their function is analogous to that of sweat glands in man. Each gland drains through a single duct which opens about 2 centimeters inside the opening of the nostril. This location may be essential to avoid desiccation of the nasal mucosa during thermal panting. The rate of secretion from one gland increased from 0 to an average of 9.6 g (gland . hour)(-1) as air temperature was increased from 10 degrees to 50 degrees C. Evaporation of the fluid from the paired glands could account for between 19 and 36 percent of the increase in respiratory evaporation associated with thermal panting. The fluid secreted by the gland was hypoosmotic to plasma.
Panting is the major avenue of evaporative cooling in dogs exposed to heat and/or exercise. We found modulation of evaporation was achieved by varying the paths of airflow during inhalation and exhalation. The direction of airflow through the nose and mouth was determined by measuring pressure changes and temperature at the openings of one nostril and the mouth in three dogs (av. weight 22 kg). Rates of oxygen consumption and respiratory evaporation were measured simultaneously. Three patterns of panting were observed as the demand for respiratory evaporation increased: (I), inhalation and exhalation through nose; (II), inhalation through nose, exhalation through nose and mouth; and (III), inhalation through nose and mouth, exhalation through nose and mouth. Pattern I was observed in resting dogs when ambient temperature was below 26 degrees C and when animals ran at slow speeds in the cold (e.g. 0.8 m . s(-1) at 10 degrees C). Patterns II and III were observed when dogs rested quietly at ambient temperatures above 30 degrees C and during exercise except when dogs ran slowly at very low temperatures. Patterns II and III rarely occurred independently for long periods of time. Instead, there was normally a continual oscillation between the two. The proportion of the time that the dog used Pattern III instead of Pattern II increased as temperature and/or speed were increased; but the correlation between rate of respiratory evaporation and the percentage of time Pattern III was utilized was weak (r2=0.63).
Animals presenting with brachycephalic syndrome suffer from multilevel obstruction of the airways as well as secondary structural collapse. Stenotic nares, aberrant turbinates, nasopharyngeal collapse, soft palate elongation and hyperplasia, laryngeal collapse, and left bronchus collapse are being described as the most common associated anomalies. Rhinoplasty and palatoplasty as well as newer surgical techniques and postoperative care strategies have resulted in significant improvement of the prognosis even in middle-aged dogs.
Objective
To report complications, long-term outcome, and disease progression in dogs with extrathoracic tracheal collapse treated by surgical placement of commercially available extraluminal rings. Study DesignRetrospective case series. AnimalsDogs (n=23). Methods
Medical records (2002-2011) of dogs treated with extraluminal rings for extrathoracic tracheal collapse were reviewed. Owner interviews, conducted at >10 months postoperatively, determined response to surgery, progression of clinical signs after surgery, and frequency of medication administration. Long-term re-evaluation (>10 months after surgery) was offered for surviving dogs, including radiographs and tracheoscopy if indicated. ResultsOf 23 dogs, 22 survived to discharge after surgery. Clinical signs improved in all dogs at 2 weeks after surgery and at long-term re-evaluation. Fourteen dogs (65%) required no medical management for respiratory signs after surgery. Four dogs (17%) were diagnosed with laryngeal paralysis at some point after surgery, but only 9% were diagnosed within 48hours of the surgery. Additional rings were placed between previously placed rings in 2 dogs, and 1 dog was treated with an endoluminal stent for intrathoracic tracheal collapse. Three dogs had clinical signs consistent with progression of tracheal collapse. Based on owner questionnaire, all owners were satisfied with surgical outcome. Conclusions
Treatment of severe cervical tracheal collapse with commercially-available extraluminal ring placement leads to an overall improvement in quality of life and good long-term results, with about one-third of dogs requiring continued medical management. Most dogs do not have clinical signs consistent with disease progression after surgery.
The purpose of this retrospective study was to assess risk factors and complications affecting postoperative outcome of dogs with laryngeal paralysis treated by either unilateral arytenoid lateralization (UAL) or bilateral ventriculocordectomy (VCC). Medical records of all dogs having either UAL or VCC between 2000 and 2011 were analyzed. Twenty-five dogs had VCC and 20 dogs had UAL. The overall postoperative complications rates for VCC and UAL were similar (52% and 60%, respectively; P = .0887). Dogs that had UAL were more likely to have acute postoperative respiratory distress and aspiration pneumonia (P = .0526). Dogs with VCC were more likely to have chronic postoperative respiratory distress and aspiration pneumonia (P = .0079). Revision surgery was required in 6 dogs (24%) following VCC and 2 dogs (10%) following UAL. Sex, breed, presenting complaint, type of service provided, and concurrent diseases were not significantly associated with higher risk of either death or decreased survival time postoperatively with either procedure. Overall postoperative complication rates, required revision surgeries, and episodes of aspiration pneumonia were similar in dogs undergoing UAL and VCC surgeries. Dogs that had VCC appeared to have an increased risk of lifelong complications postoperatively compared with UAL; therefore, VCC may not be the optimal choice for treatment of laryngeal paralysis.
Objective
To (1) describe a modification of conventional unilateral cricoarytenoid lateralization (UCAL), called less-invasive unilateral cricoarytenoid lateralization (LI-UCAL) for treatment of idiopathic laryngeal paralysis (LP); (2) report clinical outcome of LI-UCAL; and (3) describe the effect of early discharge after surgery.Study DesignRetrospective clinical study.AnimalsDogs (n = 22).Methods
Medical records (January 2009 to October 2011) of dogs diagnosed with idiopathic LP that had LI-UCAL were reviewed. Signalment, clinical signs, laboratory tests, imaging, concurrent medical conditions, information from the anesthesia record, and hospitalization time were documented. Follow-up was obtained by direct examination, questionnaire, and review of medical records from referring veterinarians.ResultsDogs included in the study had variable degrees and duration of respiratory distress before surgery. Median surgery time was 32 minutes. Median hospitalization was 6 hours, and median follow-up was 427 days. Long-term respiratory function, as reported by owners at last follow-up, improved in 95.5% of dogs after surgery; exercise tolerance improved by 90%. Major complications included death secondary to aspiration pneumonia (9%), aspiration pneumonia from which dogs recovered within 3 days after administration of antimicrobials (9%), and development of right-sided laryngeal collapse that required right sided LI-UCAL (4.5%). At long-term follow-up, 95.5% of owners were satisfied with the surgical outcome.ConclusionLI-UCAL is a feasible surgical technique and resulted in improvement of clinical signs related to LP. Calm recoveries without adverse effects such as respiratory distress were associated with early discharge. LI-UCAL could be considered an alternative to conventional UCAL.
The purpose of this study was to evaluate the prevalence of intranasal mucosal contact points in brachycephalic and normocephalic dogs. In total, 82 brachycephalic dogs (42 pugs and 40 French bulldogs) were evaluated by rhinoscopy for their intranasal mucosal contact and 25 normocephalic dogs were evaluated as a control group. Of those, 162 brachycephalic nasal cavities were evaluable and 140 had contact between intranasal structures (87%). Intraconchal and septoconchal mucosal contact points were the most commonly detected sites of contact. French bulldogs had a significantly higher prevalence of mucosal contact and had 3 mean contact points compared with 1.7 mean contact points per nasal cavity in pugs. Septal deviations were present in 62% of brachycephalic dogs. In the control group, mucosal contact points were present in only 7 of 50 nasal cavities (14%), and septal deviations occurred in 16% of those cases. Contact point average was 0.1 in large and 0.3 in small normocephalic dogs. Intranasal mucosal contact was identified as a common and previously unreported problem in brachycephalic dogs. Numerous contact points reduce the lumen of the intranasal passageways and indicate potential intranasal obstruction. Affected dogs might benefit from removal of obstructing conchae, potentially using laser-assisted turbinectomy.
Tracheal and airway collapse (bronchomalacia) are common causes of chronic cough in middle-aged to older dogs where weakening of cartilage within the respiratory system leads to narrowing of airways, coughing, wheezing, and other secondary effects. Successful treatment involves correct identification of the problem, recognition of concurrent problems, and appropriate medical therapy. Surgical and noninvasive treatment options are becoming readily available, and it is important to understand indications for such procedures.
Brachycephalic airway syndrome is a common finding in brachycephalic breeds. A combination of primary and secondary changes can progress to life-threatening laryngeal collapse. Early recognition of primary anatomic abnormalities that include stenotic nares, elongated soft palate, and hypoplastic trachea would allow the clinician to make early recommendations for medical and surgical management, which can improve the quality of life in affected animals.
A 7-year-old male terrier was referred with a 3-week history of coughing, anorexia, lethargy, and weight loss to the clinic
of small animals at the University of Tehran, Iran. On physical examination, cataracts were present in the eyes, nasal mucopurulent
discharge, cyanotic mucous membrane, respiratory distress, tachypnoea, and increased abdominal expiratory effort were revealed,
and a honking, productive cough was elicited on tracheal palpation. Auscultation of the trachea and lung fields revealed stertor
and inspiratory wheeze, respectively. Hematologic findings included leukocytosis, characterised by neutrophilia with left
shift, and normocytic, normochromic anaemia. Radiographic examination showed an alveolar pattern, especially in the medial
lobe of the right lung. No other abnormality was found on radiographic examination. Bacteriological study on tracheal and
lung specimens was performed, and Bordetella bronchiseptica was detected from the tracheal specimens. Based on the clinical history, physical examination, and bacteriological data,
infectious tracheobronchitis (kennel cough) was diagnosed. Because of the severe respiratory distress and worsening of the
clinical signs, further investigation and treatment were rejected by the owner, and the dog was euthanized. At necropsy, the
trachea was collapsed along its entire length, and the tracheal membrane was loose and floppy. Probably, the presence of a
concurrent tracheal infection with B. bronchiseptica (kennel cough) has been a triggering factor that caused clinical signs of tracheal collapse which developed in this dog.
Management of respiratory distress involves careful consideration of the history, physical examination, and diagnostic testing. Supplemental oxygen is useful. Urgent procedures, such as intubation, thoracococentesis, or tracheostomy, may be required. The prognosis is dependent on the underlying disease, but is often favorable. This article reviews the approach, differential diagnoses, and the approach to management for dogs and cats with respiratory distress.
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.
Objective − To describe clinical respiratory parameters in cats and dogs with respiratory distress and identify associations between respiratory signs at presentation and localization of the disease with particular evaluation between the synchrony of abdominal and chest wall movements as a clinical indicators for pleural space disease.
Design − Prospective observational clinical study.
Setting − Emergency service in a university veterinary teaching hospital.
Animals − Cats and dogs with respiratory distress presented to the emergency service between April 2008 and July 2009.
Interventions − None.
Measurements and Main Results − The following parameters were systematically determined at time of admission: respiratory rate, heart rate, temperature, type of breathing, movement of the thoracic and abdominal wall during inspiration, presence of stridor, presence and type of dyspnea, and results of thoracic auscultation. Abdominal and chest wall movement was categorized as synchronous, asynchronous, or inverse. Diagnostic test results, diagnosis, and outcome were subsequently recorded. Based on the final diagnoses, animals were assigned to 1 or more of the following groups regarding the anatomical localization of the respiratory distress: upper airways, lower airways, lung parenchyma, pleural space, thoracic wall, nonrespiratory causes, and normal animals. One hundred and seventy-six animals (103 cats and 73 dogs) were evaluated. Inspiratory dyspnea was associated with upper airway disease in dogs and expiratory dyspnea with lower airway disease in cats. Respiratory noises were significantly associated and highly sensitive and specific for upper airway disease. An asynchronous or inverse breathing pattern and decreased lung auscultation results were significantly associated with pleural space disease in both dogs and cats (P<0.001). The combination is highly sensitive (99%) but not very specific (45%). Fast and shallow breathing was not associated with pleural space disease. Increased or moist pulmonary auscultation findings were associated with parenchymal lung disease.
Conclusions − Cats and dogs with pleural space disease can be identified by an asynchronous or inverse breathing pattern in combination with decreased lung sounds on auscultation.
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.
Collapsed trachea was repaired by total ring prostheses in 20 miniature breed dogs. The average duration of respiratory disease prior to surgery was two years. Prior to surgery, 90% of the dogs coughed. Fifteen had episodes of dyspnea and/or cyanosis. Laryngeal paralysis was diagnosed preoperatively in six dogs. Common isolates from preoperative pharyngeal cultures included Bordetella bronchiseptica, Pseudomonas aeruginosa, and Escherichia coli. Radiographs of the trachea helped establish a diagnosis in only 59% of the dogs. Tracheoscopy confirmed the diagnosis in all cases. Pulmonary interstitial disease and biventricular or right ventricular cardiac enlargement were common radiographic findings. Surgery follow-up ranged from four months to four years. At the time of follow-up, most dogs coughed less, breathed better, were more active, and had fewer episodes of tracheobronchitis. Eighty-five percent of the owners felt their dog responded well to the surgery. A grading system for collapsed trachea is described.
To identify the type and frequency of tracheostomy tube complications, and to determine factors associated with these complications, and with poor outcome.
A database search for dogs undergoing temporary tube tracheostomy was performed. The medical records were scrutinised. The signalment, respiratory disease history, diagnosis, surgery, type and frequency of tube care procedures, type of complications and outcome were recorded.
Forty-two records were found. Complications occurred in 36 of 42 (86%) cases. Bulldogs were more likely to dislodge the tube than other breeds (P=0·0376), and cases with three or more complication types underwent more routine care procedures than those with fewer complications (P=0·0370). Thirty-four of 42 (81%) dogs had a successfully managed tracheostomy tube and survived until tube removal, or elective euthanasia without significant tube complications. Bulldogs were also significantly (P=0·0376) more likely to have an unsuccessful tube outcome, as were dogs experiencing severe bradycardia during treatment (P=0·0176). Dogs with unsuccessful tube outcome were significantly (P=0·0331) younger than dogs with successful tube outcome.
Tracheostomy tubes in dogs have a high complication rate but a good outcome in most dogs. Careful management may improve the outcome of dogs with tracheostomy tubes, especially bulldogs and dogs exhibiting bradycardia during treatment.
To identify combined laryngeal paralysis and collapse in small dogs and describe postoperative outcome after arytenoid lateralization.
Case series.
Small nonbrachycephalic breed dogs with laryngeal paralysis and collapse (n = 6).
Medical records of small breed dogs with airway problems and undergoing laryngeal surgery (January–December 2008) were reviewed. Dogs with combined laryngeal paralysis and laryngeal collapse (LPLC) had arytenoid lateralization. The immediate, 4 week and 6 month postoperative outcomes were described.
Direct visual laryngeal exam under a light plane of anesthesia revealed bilateral failure of arytenoid and vocal fold movement and concurrent bilateral medial folding with contact of the cuneiform processes in all dogs. None of the dogs had intra- or immediate postoperative complications after arytenoid lateralization. Two dogs required a 2nd contralateral procedure. Follow-up after 6 months revealed marked improvement in clinical signs related to upper airway obstruction, but all dogs continued to have mild respiratory noise.
Concurrent laryngeal paralysis and collapse should be considered as part of the differential diagnosis for small, nonbrachycephalic dogs with upper airway disease. Arytenoid lateralization resulted in improvement of clinical signs related to obstructive airway disease.
Many surgical options have been described to treat various aspects of canine brachycephalic airway syndrome (BAS). This article describes the surgical management, postoperative care, and prognosis of this condition. The pathophysiology and medical therapy of BAS are described in a companion article.
Canine brachycephalic airway syndrome is a progressive disease that affects many brachycephalic dogs. This article describes the components of this syndrome and focuses on acute emergency management and long-term conservative management of these patients. Surgical management is described in a companion article.
Objective— To evaluate the effects of various drugs and drug combinations conventionally used for anesthesia on arytenoid cartilage motion during laryngoscopy in normal dogs.
Study Design— Experimental study.
Animals— Six large breed healthy dogs with no previous history of respiratory dysfunction.
Methods— Each dog was randomly assigned to a different injectable anesthetic protocol once weekly for 6 weeks, then in the 7th week all dogs were anesthetized with isoflurane. Videolaryngoscopy was performed and recorded starting immediately after induction until dogs could no longer be safely restrained for endoscopy. Video was digitized and 3 still images ofmaximalinspiration and expiration from the first 15 seconds (induction) and the last 15 seconds (recovery) were captured and imported into an image analysis software program. The height andarea of the laryngeal ostium were measured in pixels. Normalization of the glottal gap areawasperformed using the formula (normalized glottal gap area (NGGA)=area in pixels/height2). ANOVA was performed on the NGGA of images collected at inspiration and expiration during induction and recovery. Fischer's exact test was performed when significance (P<.05) wasfound.
Results— Within each protocol, laryngeal motion (defined as change in NGGA) at induction was not significantly different from laryngeal motion measured at recovery. Additionally, no significant differences were found in arytenoid motion immediately after induction when anesthetic protocols were compared. Arytenoid motion before recovery was significantly greater with thiopental when compared with propofol (P=.046), ketamine+diazepam (P=.0098), acepromazine+thiopental (P=.0021), and acepromazine+propofol (P=.0065). No significant difference in arytenoid motion was seen immediately after induction or before recovery when acepromazine+butorphanol+ isoflurane and thiopental were compared.
Conclusion— We concluded that intravenous thiopental given to effect is the best choice for assessing laryngeal function in dogs. Dogs premedicated with acepromazine with or without opioids that require further anesthetic restraint for laryngoscopy should be anesthetized with isoflurane administered by mask.
Clinical Relevance— Misdiagnosis of laryngeal paralysis during laryngoscopy can be avoided by selecting the anesthetic regimens with the least effect on arytenoid motion.
Acquired laryngeal paralysis (LP) is an important cause of upper airway obstruction in dogs. We hypothesize that LP may be part of a generalized polyneuropathy complex. Electro-diagnostic studies were performed in six dogs, and histopathological studies of muscle and nerve biopsies were obtained from 11 dogs diagnosed with acquired LP. Abnormalities in electrodiagnostic procedures were consistent with a generalized polyneuropathy. Loss of large-caliber nerve fibers and axonal degeneration were identified in nerve biopsies, and neurogenic atrophy was observed in muscle specimens. Abnormalities in electrodiagnostic studies and histopathology provide evidence that LP may be part of a generalized polyneuropathy. Establishing a diagnosis of a more involved disease process is relevant for long-term prognosis.
This focused resource covers all medical conditions that affect cats. Using a unique problem-based approach, it provides essential information for assessing presenting symptoms, reaching a differential diagnosis, and selecting the appropriate course of treatment for feline patients. A consistent format makes it easy to find information related to key signs and possible causative factors (graded to indicate how common each is), diagnosis, differential diagnosis (including tests where appropriate), treatment, prognosis, and prevention (where applicable) for each clinical condition. Unique problem-based approach discusses how to make a problem-based diagnosis. Concise, logical format makes this resource ideal for quick reference in the clinical setting. Covers every condition likely to be encountered in cats worldwide. Features a strong international contributor list of feline experts from North America, UK, Europe, and Australia A comprehensive drug formulary lists all drug treatments available for cats. A separate chapter on drugs in cats lists the problems veterinarians might encounter due to differences in feline metabolism.
To compare esophageal function in dogs with idiopathic laryngeal paralysis (ILP) to age and breed matched controls; to determine if dysfunction is associated with aspiration pneumonia over 1 year; and to compare clinical neurologic examination of dogs with ILP at enrollment and at 1 year.
Prospective controlled cohort study.
Dogs with ILP (n=32) and 34 age and breed matched healthy dogs.
Mean esophageal score was determined for each phase of 3 phase esophagrams, analyzed blindly. After unilateral cricoarytenoid laryngoplasty, dogs with ILP were reexamined (including thoracic radiography) at 1, 3, 6, and 12 months. Neurologic status was recorded at enrollment, 6 and 12 months.
Esophagram scores in dogs with ILP were significantly higher in each phase compared with controls, most notably with liquid (P<.0001). Dysfunction was more pronounced in the cervical and cranial thoracic esophagus. Five dogs that had aspiration pneumonia during the study had significantly higher esophagram scores than dogs that did not develop aspiration pneumonia (P<.02). Ten (31%) ILP dogs had generalized neurologic signs on enrollment and all ILP dogs developed neurologic signs by 1 year (P<.0001). Conclusions- Dogs with ILP also have esophageal dysfunction. Postoperative aspiration pneumonia is more likely in dogs with higher esophagram scores. Dogs with ILP will most likely develop generalized neuropathy over the course of 1 year.
Esophagrams and neurologic examinations should be performed on all dogs with ILP.
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.
Bronchomalacia is common in dogs with tracheal collapse, is associated with inflammatory airway disease, and is poorly documented radiographically.
One hundred and fifteen dogs admitted for evaluation for respiratory disease and examined by bronchoscopy.
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.
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.
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.
The United Kingdom pedigree-dog industry has faced criticism because certain aspects of dog conformation stipulated in the UK Kennel Club breed standards have a detrimental impact on dog welfare. A review of conformation-related disorders was carried out in the top 50 UK Kennel Club registered breeds using systematic searches of existing information. A novel index to score severity of disorders along a single scale was also developed and used to conduct statistical analyses to determine the factors affecting reported breed predisposition to defects. According to the literature searched, each of the top 50 breeds was found to have at least one aspect of its conformation predisposing it to a disorder; and 84 disorders were either directly or indirectly associated with conformation. The Miniature poodle, Bulldog, Pug and Basset hound had most associations with conformation-related disorders. Further research on prevalence and severity is required to assess the impact of different disorders on the welfare of affected breeds.
To describe the signalment, history, clinical signs, surgical technique, and outcome for cats with laryngeal paralysis that had arytenoid lateralization.
Case series.
Cats with laryngeal paralysis (n=10).
Medical records (1996-2002) for cats with laryngeal paralysis that had arytenoid lateralization were reviewed for signalment, history, clinical signs, degree of paralysis, cause, concurrent medical conditions, surgical technique, and outcome. Follow-up information was obtained from owners or referring veterinarians.
Of 10 cats, 9 had bilateral and 1 had unilateral laryngeal paralysis. Arytenoid lateralization were unilateral (n=7), bilateral (1), and staged bilateral procedures (2), 10 days and 3 years apart, respectively. Postoperatively, 1 cat had persistent inspiratory noise because of minimal enlargement of the rima glottidis and 2 cats required a temporary tracheostomy for management of laryngeal swelling. Three cats developed aspiration pneumonia and died 4, 7, and 150 days after surgery; all 3 had bilateral (simultaneous or staged) procedures. Of the 7 remaining cats, 4 were alive at follow-up and 3 had died of causes unrelated to arytenoid lateralization. The calculated mean survival time for all 10 cats was 406 days (median, 150 days; range, 4-1825 days).
Arytenoid lateralization was effective at enlarging the rima glottidis and reducing signs of airway obstruction in most cats.
Unilateral arytenoid lateralization is a feasible option for the surgical management of cats with marked clinical signs; however, bilateral procedures should be avoided or at least performed with considerable caution because of the apparent risk for aspiration pneumonia.
This retrospective study reports the presence and incidence of nasal turbinates in the nasopharynx (nasopharyngeal turbinates) in a population of brachycephalic dogs and cats exhibiting signs of upper respiratory disease. Medical records were reviewed for 53 brachycephalic dogs and 10 brachycephalic cats undergoing upper airway endoscopy. Nasopharyngeal turbinates were identified in 21% of brachycephalic animals, including 21% of dogs and 20% of cats. Pugs accounted for 32% of all dogs in the study population and 82% of dogs with nasopharyngeal turbinates. The presence of nasopharyngeal turbinates may play a role in upper airway obstruction in the brachycephalic airway syndrome.
A multi-institutional retrospective study of 103 dogs in which hypoplasia of the trachea was diagnosed was conducted. Bulldogs (55%) and Boston Terriers (15%) were most commonly affected. Age at diagnosis ranged from 2 days to 12 years, with a median of 5 months. Hypoplasia of the trachea was diagnosed more frequently in males (66%) than females (34%). Congenital anomalies in dogs with hypoplasia of the trachea included elongated soft palate (n = 44), stenotic nares (n = 23), cardiac defects (n = 12), and megaesophagus (n = 10). Ratios between tracheal lumen diameter and depth of the thoracic inlet or width of the third rib did not correlate with dyspnea. Of 42 dogs reexamined greater than 6 months after diagnosis, 25 (60%) were clinically normal. The remaining 17 were dyspneic and 15 (88%) had concurrent respiratory or cardiovascular disease that could account for their clinical signs. Hypoplasia of the trachea appears to be tolerated well in the absence of concurrent respiratory or cardiovascular disease.
The range of clinical syndromes and the pathophysiology of respiratory disorders in brachycephalic animals are presented. The problem of deciding which patients require surgical management is reviewed in the light of recent studies and the author's clinical experience. Newer information from related disorders in humans suggests that serious problems can be subclinical and difficult to diagnose. The index of suspicion and guidelines for providing surgical relief to veterinary patients may need to undergo revision.
The understanding of the mechanisms of dog and cat airway disease is in its infancy, because the clinical tools necessary to measure airway function in patients have not been readily available. The advent of lung function computers that can rapidly analyze flow-volume loops and calculate Cdyn and RL will make it easier to evaluate airway function in disease and to detect the effects of the newer specific receptor blockers. In the not-too-distant future, measurements of lung function will be used to prove the efficacy of new therapeutic agents for canine and feline airway disease and to guide the clinician in the use of these agents.
This is a complex condition, recognized primarily in brachycephalic breeds, that results in varying degrees of upper airway obstruction. The signs consist of respiratory distress, stridor, reduced exercise tolerance, and in more severe cases, cyanosis and collapse. The inherent anatomy of the brachycephalic skull contributes to the development of these signs. Such anatomic features include: a shortened and distorted nasopharynx, stenotic nares, an elongated soft palate, and everted laryngeal saccules. The increased negative pressure created in the pharyngolaryngeal region, as a result of these obstructing structures, ultimately results in distortion and collapse of the arytenoid cartilages of the larynx.
This article presents an overview of the clinical features of upper airway obstructive disorders. It includes more detailed discussions of certain common conditions such as brachycephalic airway syndrome, laryngeal paralysis, and upper airway obstruction due to trauma, foreign bodies, extraluminal masses, and tumours of the larynx and trachea.
Tracheas from 15 toy breed dogs with normal tracheas and 6 dogs with collapsed tracheas were examined histologically and histochemically. Tracheal cartilage was analyzed for chondroitin sulfate by means of alcian blue (CEC method) and for calcium with alizarin red S. Cartilage arcs from dogs with collapsed tracheas had areas that were apparently hypocellular, and some had other areas that appeared like fibrocartilage or fibrous tissue. Histochemically, collapsed tracheal cartilage had less chondroitin sulfate and calcium than did normal tracheal cartilage. Cartilage arcs from the collapsed tracheas were not uniformly affected to the same degree, and parts of a given tracheal arc appeared normal, whereas other parts had an abnormal histologic appearance.
In dogs which are panting due to a heat load, most of the respired air enters through the nose and leaves through the mouth.
Different patterns of flow are, however, possible. The unidirectional flow over the evaporative (nasal) surfaces is an important mechanism for regulating the amount of heat dissipated in panting.
Tracheas were removed from 8 average-sized (13 to 19 kg) dogs, 12 toy breed dogs, and 6 toy breed dogs with collapsed trachea. The tracheal arcs were counted whenever possible and measurements of the inner ventrodorsal and lateral diameters, lumen areas, cartilage and muscle thicknesses, and numbers of chondrocytes and muscle cells/0.1 mm2 were obtained from 3 regions. The regions were the 3rd ring caudal to the larynx, the region at the thoracic inlet, and the 2nd ring cranial to the carina. The 3 tracheal regions were compared with one another for all the variables in the 3 dog groups. All groups exhibited similar significant regional variations for tracheal diameters, lumen areas, and cartilage and muscle thicknesses. There were no significant differences between regions for chondrocyte and muscle cell counts. In the comparison of average dogs and normal toy breed dogs, the former had larger ventrodorsal tracheal diameters, lumen areas, and cartilage and muscle thicknesses. The measurements from the toy breed dogs with collapsed tracheas were smaller than those from the normal toy breed dogs. There were no significant differences in chondrocyte and muscle cell counts between average dogs and normal toy breed dogs.
Use of a CO2 laser to resect the soft palate in 6 dogs with elongated soft palate is described. The technique was rapid and uncomplicated; hemostasis was not a problem. Breathing was noticeably improved in all dogs immediately after surgery. Use of the CO2 laser represents a new option for surgical treatment of elongated soft palate in dogs.
To determine factors associated with long-term outcome in dogs with tracheal collapse treated with extraluminal polypropylene C-shaped stents.
Retrospective case series.
90 dogs.
Medical records of dogs with surgically treated tracheal collapse were reviewed. Follow-up was obtained either by recheck at the veterinary teaching hospital only (n = 10) or by telephone interviews with referring veterinarians and owners (n = 35), referring veterinarians alone (n = 23), or owners alone (n = 16). The chi 2 test was used to determine which factors were associated with long-term outcome.
11 breeds were represented. Yorkshire Terriers, Poodles, and Pomeranians were most common. Median age at the time of surgery was 6.8 years. Median weight was 2.9 kg. Severity of collapse ranged from grade II to grade IV. Dogs < 6 years old had more severe collapse than did dogs > or = 6 years old. Dogs > or = years old had more postoperative complications and a poorer longterm outcome than did dogs < 6 years old. 17 dogs required permanent tracheostomy, 10 within 24 hours after surgery.
Surgical placement of extraluminal polypropylene C-shaped stents was an effective method of attenuating clinical signs of tracheal collapse. Dogs < 6 years old had more severe tracheal collapse but did better after surgery than did dogs > or = 6 years old.