APPROACH TO RESPIRATORY DISTRESS Peer Reviewed

Approach to Respiratory Distress in Dogs & Cats

Claire R. Sharp, BSc, BVMS (Hons), MS, CMAVA, Diplomate ACVECC Tufts University

Managing dogs and cats in respiratory distress Cooling Measures is a multifaceted effort that involves stabilizing Animals with upper airway obstruction, such patients prior to determining a defi nitive diagnosis. as those with laryngeal paralysis, may become Fortunately, respiratory distress—no matter what hyperthermic due to the increased work of the cause—requires somewhat standardized . Because of the airway obstruction, these interventions during initial stabilization. animals are unable to effectively pant, resulting in inability to thermoregulate and dissipate heat. As INITIAL STABILIZATION such, cooling hyperthermic patients in respiratory One of the benefits of initial stabilization is that distress is an important component of initial it provides the practitioner time to consider stabilization, and can be accomplished by: Minimizing the appropriate diagnostic and subsequent • Administering room temperature IV fluids Stress • Covering the patient with wet towels therapeutic approach. Dogs and cats with • Putting a fan on the patient respiratory distress Oxygen Supplementation • Applying alcohol to the axilla, inguinal area, and feet. are often fragile and Initial stabilization of a patient in respiratory Active cooling should stop once the patient’s can decompensate distress generally involves provision of oxygen temperature reaches 103°F to avoid precipitating rapidly. Initial hypothermia. evaluation should be supplementation, with or without patient sedation. performed rapidly, • The most common type of oxygen Thoracocentesis with minimal stress supplementation provided is use of an oxygen Initial stabilization may also include thoracocentesis, if to the patient. cage with a high fraction of inspired oxygen (FiO ) Often, one of the 2 severe respiratory distress is secondary to pleural space (eg, 40%–60%); a face mask or flow-by oxygen best fi rst steps is disease, such as pneumothorax or pleural effusion. from a hose can also be used. to place the animal • In more extreme cases, animals in respiratory distress in an oxygen cage INITIAL DIAGNOSTIC APPROACH and allow it to relax, may require emergency intubation, higher FiO (eg, 2 Diagnostic approach to a patient in respiratory considering it has 100%), and provision of positive pressure ventilation distress should consider the patient’s signalment and usually been through in order to provide adequate respiratory stabilization. history as well as the broad anatomic differential a stressful car • Particularly in cases of upper airway obstruction, ride and changed diagnoses of dyspnea (Table 1, page 54). the practitioner may need to ensure a patent environments (home airway by intubation or tracheostomy (if oral to car to clinic) that Signalment can exacerbate intubation is not possible). Clues in the patient’s signalment are common. distress. For example: Sedation • Upper airway obstruction due to Sedation with careful monitoring and, if necessary, brachycephalic airway disease is a common intubation and ventilation can be extremely useful in cause of respiratory distress in brachycephalic animals that have become anxious due to dogs, such as English bulldogs. and/or . In some patients, especially • Cardiogenic is a common cause dogs with upper airway obstruction, stabilization of respiratory distress in small breed dogs with may require sedating the animal by administering chronic valvular disease (eg, mitral endocardiosis), some form of anesthetic induction agent; then such as Cavalier King Charles spaniels. clearing the oral cavity of obstructing material (eg, • Lower airway obstruction associated with is secretions or foreign material in a animal) a common cause of respiratory distress in cats, with prior to intubation or tracheostomy. certain breeds, such as the Siamese, overrepresented.

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History and the potential for cardiogenic pulmonary edema History can also be extremely useful; for example: or pleural effusion. • History of blunt trauma (eg, hit by a car) should In general, breathing patterns help narrow the list prompt concern for pulmonary contusions, of differential diagnoses (Table 1). For example, pneumothorax, diaphragmatic hernia, or flail chest. upper airway obstruction is associated with inspiratory • In cats, a history of is consistent with dyspnea and an externally audible noise. In contrast, asthma, while in dogs, a cough might suggest lower airway obstruction tends to be associated with tracheobronchial disease, interstitial lung disease, expiratory dyspnea and , with the wheeze or pulmonary edema. generally just audible on thoracic with a , rather than externally audible. Physical Examination Examining a patient with respiratory distress Diagnostic Tests should involve: Extensive diagnostics should not be performed until 1. Initial observation: Consider breathing pattern, the patient has been stabilized as much as possible, a presence of externally audible noise with breathing, brief physical examination has been performed, and any signs of trauma, or abdominal distension the practitioner has localized the disease to the most 2. Lung auscultation: likely anatomic location (Table 1). Diagnostic tests »» Increased adventitial lung sounds (eg, , may subsequently involve: , harsh lung sounds) are associated with • Blood analysis: Screening blood tests, blood gases lower airway and pulmonary parenchymal disease • Imaging: Thoracic ultrasound, including focused »» Decreased lung sounds, in an animal with assessment with sonography for trauma, triage, and respiratory distress, are associated with pleural tracking (tFAST); thoracic radiographs; thoracic space disease. computed tomography (CT); or echocardiography 3. Cardiac auscultation: A murmur, gallop, or other • Respiratory fluid analysis: Bronchoalveolar arrhythmia may indicate underlying cardiac disease lavage, thoracocentesis

Dogs and cats with respiratory distress can be classified into 8 disease categories, some of which are Categories of associated with distinct breathing patterns observed during physical examination.1,2 These categories Respiratory include both primary respiratory diseases and secondary causes of respiratory difficulty. Diagnostic approach is determined by the category of disease causing respiratory distress. Disease Table 1. Anatomic Classification: Causes of Respiratory Distress DISEASE EXAMPLES BREATHING PATTERN CATEGORY 1. Upper Airway • Brachycephalic airway disease • Inspiratory dyspnea Obstruction • Laryngeal paralysis • Externally audible noise (eg, stertor, ) 2. Lower Airway • Asthma • Expiratory dyspnea Obstruction • Wheeze (audible with stethoscope) 3. Pulmonary • Pneumonia • Not consistent; may be rapid, shallow, or Parenchymal Disease • Interstitial lung disease both, and have both inspiratory and expira- • Pulmonary edema tory components • Pulmonary contusions 4. Vascular • Pulmonary thromboembolism • Not specific 5. Pleural Space Disease • Pneumothorax • Inspiratory dyspnea, rapid , • Pleural effusion or generalized paradoxical breathing • Reduced lung sounds on auscultation 6. Flail Chest • Focal paradoxical breathing 7. Abdominal Distension • Ascites • Inspiratory dyspnea • Organomegaly 8. Look-alike Diseases • Not specific

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• Airway examination: Upper airway examination, Clinical Signs tracheobronchoscopy Characteristic signs in patients with an upper airway • Drug trials: Such as bronchodilators, diuretics, obstruction include inspiratory distress and an and corticosteroids. externally audible noise associated with breathing (eg, stertor, stridor). Tracheal disease is usually associated UPPER AIRWAY OBSTRUCTION with a cough. Etiology Upper respiratory tract obstruction involves a Initial Stabilization mechanical or functional obstruction of the upper Initial stabilization and therapy may involve: (large) airways (ie, the pharynx, larynx, or trachea). • Oxygen administration/securing an airway: Nasal disorders are not considered in this article as Generally administered by face mask (if tolerated), the animal should always be able to open its mouth flow-by oxygen, or oxygen cage, with intubation and breathe, preventing the development of dyspnea or tracheostomy performed if needed even if the nasal cavity is obstructed. • Sedation: Achieved with anxiolytic drugs, such Specific causes of upper airway obstruction include: as acepromazine or dexmedetomidine, or sedative • Naso-oropharyngeal disorders, including polyps analgesics, such as butorphanol (Table 2) (especially in cats), masses, and foreign bodies • Cooling: Many dogs with upper airway • Severe head trauma that results in bone fractures obstructions become hyperthermic due to inability (especially nasal, jaw, and palatine fractures) and to dissipate heat through their upper airways; associated hemorrhage and swelling the goal is to reduce body temperature to at least • Laryngeal disorders, including laryngeal 103°F, while avoiding hypothermia paralysis, laryngeal collapse, laryngeal masses (eg, • Corticosteroids: Breathing against an obstruction neoplasia, abscesses, granulomas), and laryngeal can result in marked edema of the upper airway inflammation soft tissue; therefore, anti-inflammatory doses of • Tracheal diseases, including tracheal collapse, tracheal corticosteroids (eg, dexamethasone SP, 0.15 mg/kg foreign body, tracheal stenosis, stricture, tracheal tear, IV single dose or Q 24 H) can be considered. or tracheal mass (either intra- or extraluminal) • Brachycephalic airway disease, which involves Diagnostic Approach a combination of primary and secondary anatomic Once the patient is stable, diagnostic tests can be pursued. abnormalities of the upper airways, including Upper airway examination. Examination is stenotic nares, an elongated soft palate, everted performed after preoxygenation under sedation. At laryngeal saccules, laryngeal edema and/or collapse its most basic, examination may involve inspection and, in some breeds (eg, English bulldog), a of the oropharynx and larynx with a laryngoscope; hypoplastic trachea. in patients with suspected tracheal disease, it

In dogs, reasonable choices for sedation are however, it can produce undesirable effects, butorphanol, acepromazine, or dexmedetomidine, such as bradycardia and hypotension. Sedation for while butorphanol is the drug of choice in cats. Regardless of the chosen drug, in potentially Patients in Choice of drug(s) used for sedation/anxiolysis unstable patients, lower doses are given initially should be based on the individual drug’s and later increased as needed and tolerated by Respiratory properties, and relative risks versus benefits for the the patient. patient. For example: Distress • Butorphanol is a very safe and effective drug Table 2. at recommended doses; however, it is relatively Patients in Respiratory Distress: short acting (often only 1–2 hours) and cannot Sedative Drug Dosages easily be reversed. SEDATIVE DRUG DOSE RANGE • Acepromazine is also very effective; however, it may be more likely to produce undesirable Butorphanol 0.1–0.4 mg/kg IM or effects, such as hypotension; has a long duration IV Q 1–4 H, as needed of action (4–6+ hours); and cannot be reversed. Acepromazine 0.005–0.05 mg/kg IM or • Dexmedetomidine has the desirable quality IV Q 4–8 H, as needed of being reversible (with atipamezole) and titratable (given a short duration of action); Dexmedetomidine 0.01–0.1 mg/kg/H IV CRI

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may involve tracheobronchoscopy with a flexible Chronic . Lower airway disease bronchoscope or endoscope. in cats may also be associated with neutrophilic When evaluating laryngeal function as part of an inflammation (often referred to as chronic upper airway examination: bronchitis), or a combination of both eosinophilic • Take care to minimize the level of anesthesia to and neutrophilic inflammation.3 In dogs, preserve laryngeal function as best as possible bronchomalacia—seen in severe, end-stage, chronic • Consider using the respiratory stimulant bronchitis—can also cause lower airway obstruction. doxapram HCl (0.5–1.1 mg/kg IV) to stimulate laryngeal motion Clinical Signs • Carefully observe inspiration versus expiration to Characteristic signs in an animal with lower airway ensure that the larynx is abducting (increasing the obstruction usually include expiratory distress and, aperture of the rima glottis) on inspiration (rather sometimes, an expiratory grunt or push. These patients than on expiration as might occur with paradoxical may have an expiratory wheeze on thoracic auscultation motion in patients with laryngeal paralysis). and, less commonly, an externally audible wheeze. Cervical and thoracic radiographs are useful for patients with laryngeal or tracheal disease to detect Initial Stabilization masses and collapse. Initial stabilization and therapy usually involve: Fluoroscopy is useful for detecting dynamic • Oxygen supplementation: See recommendations upper airway collapse that may not be visible on in the Initial Stabilization section (page 53) standard radiographs. • Bronchodilator trial: Options for an acute bronchodilator trial include either: Management »» Inhaled albuterol (1 or 2 puffs from a metered Definitive management for upper respiratory tract dose inhaler with a spacer) obstruction is extremely varied, depending on the »» Single dose of terbutaline (0.01 mg/kg IM or SC).3 definitive diagnosis, and beyond the scope of this review. Bronchodilator therapy often results in rapid improvement in these patients (eg, within 5–15 minutes). LOWER AIRWAY OBSTRUCTION Etiology Diagnostic Approach Lower airway obstruction is associated with a Once the patient is stable, the diagnostic approach narrowed bronchial lumen, which can be caused by usually involves:3 varied pathophysiologic processes, including: • Thoracic radiographs: Lower airway disease • Bronchial inflammation with edema and hyperemia is classically associated with a bronchial of bronchial mucosa or bronchointerstitial pattern on thoracic • Bronchospasm radiographs. Additonally, air trapping in cats with • Bronchomalacia asthma may result in pulmonary hyperinflation • Mucus accumulation and a flattened diaphragm. • Acute anaphylactic reaction (uncommon). • Lower airway cytology: Eosinophilic In all of these conditions, the bronchial lumen inflammation (> 17% eosinophils) is characteristic tends to close early during expiration, while it is of feline asthma, while neutrophilic inflammation opened by radial traction from the lungs during is evident in dogs and cats with chronic bronchitis. inhalation. Therefore, expiratory dyspnea is a • Heartworm testing (ideally both antigen hallmark of lower airway obstruction. and antibody tests): Determines if heartworm associated respiratory disease is present in cats. Specific Diseases • Baermann fecal test: Evaluates for lungworm Feline asthma and chronic bronchitis in dogs and disease. cats are associated with accumulation of mucus in the lower airways that contributes to obstruction. Management Feline asthma. The classic disease in cats that Treatment of lower airway disease may involve causes lower airway obstruction is feline asthma, bronchodilators, corticosteroids and, potentially, the hallmarks of which are eosinophilic airway deworming in cats.4 See Treatment of Feline inflammation, reversible bronchoconstriction and, Lower Airway Disease (March/April 2014), ultimately, airway remodeling.3 available at tvpjournal.com.

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PULMONARY PARENCHYMAL DISEASE receiving broad spectrum empiric antibiotics as Etiology soon as possible.7 Pulmonary parenchymal diseases affect the terminal and respiratory bronchioles, interstitium, alveoli, Diagnostic Approach and vasculature. These diseases include pneumonia, Once the patient is stable, if cardiogenic pulmonary pulmonary edema, interstitial lung disease, pulmonary edema is suspected, firstline diagnostics should include: neoplasia, and others. Examples of pulmonary • Thoracic radiographs parenchymal diseases are listed in Table 3. • Echocardiography. When it is unclear whether the etiology is primary Clinical Signs cardiac versus primary respiratory disease, other Characteristic signs in an animal with pulmonary diagnostics can be performed, including: parenchymal disease often include abnormally loud • Measurement of serum NT-pBNP (aminoterminal breathing sounds on thoracic auscultation, such as pro B-type natriuretic peptide)—a biomarker harsh lung sounds, crackles, and wheezes. Patients associated with atrial stretch, which is increased with cardiogenic pulmonary edema may also have in dogs and cats with clinically significant heart obvious cardiac abnormalities on auscultation, such disease; in cats, this test can be performed in a as a murmur or arrhythmia.5 point-of-care fashion but, in dogs, is only available Animals with infectious causes of pulmonary as a reference laboratory test at this time. parenchymal disease (eg, pneumonia) may have a • Airway cytology (depending on radiographic fever; however, fever has only been reported in about abnormalities identified). ¹⁄8 of dogs and ¼ of cats with pneumonia, making it Further diagnostics for interstitial lung disease an unreliable abnormality.6 may include: • Thoracic CT Initial Stabilization • Lung biopsy. Initial stabilization and therapy usually involve: If a solitary lung mass is identified close to the chest • Oxygen supplementation: See recommendations wall, percutaneous fine needle aspiration or biopsy in the Initial Stabilization section (page 53) may be an ideal diagnostic modality. Additionally, • Diuretic: Depending on index of suspicion for surgical removal via lung lobectomy may be both cardiogenic pulmonary edema, a furosemide trial dose diagnostic and therapeutic. may be administered (typically, 2–4 mg/kg IV, IM) • Antibiotics: If there is a high index of suspicion Management for pneumonia (eg, history of vomiting, Treatment for pulmonary parenchymal diseases depends regurgitation, fever), the patient should begin entirely on the underlying disease. However, regardless of the underlying cause, judicious fluid therapy is usually Table 3. appropriate to prevent exacerbation of extravascular Classification & Examples of Pulmonary lung water and potential diffusion impairment. Parenchymal Diseases Intravenous fluid therapy is generally absolutely CLASSIFICATION EXAMPLES contraindicated in animals with heart failure; rather, diuretic therapy is a mainstay of treatment. Pneumonia • Infectious (viral, bacterial, parasitic, fungal) Specific therapeutic approaches include: • Aspiration • Cardiogenic pulmonary edema: Diuretic therapy and other cardiac drugs Pulmonary edema • Cardiogenic • Noncardiogenic • Microbial pneumonia: Antimicrobial administration and supportive care; adjunct Interstitial lung • Idiopathic pulmonary diseases fibrosis therapies, such as nebulization and coupage, • Eosinophilic bronchopneu- may be considered. Empirical antimicrobial drug mopathy choices depend somewhat on patient stability. • Heartworm disease Animals that present in respiratory distress Pulmonary neoplasia • Primary generally warrant broad spectrum coverage with • Metastatic parenterally administered antibiotics, such as: Traumatic pulmonary • Pulmonary contusions »» Monotherapy with a potentiated parenchymal injury aminopenicillin, such as ampicillin + sulbactam

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(30–50 mg/kg IV Q 6 H) or on radiographs (ie, a patient in ticarcillin + clavulanate (50 mg/ severe respiratory distress with kg IV Q 6 H) minimal abnormalities on thoracic »» Dual therapy with a beta-lactam radiographs) antimicrobial (eg, ampicillin, • Demonstration of focal hypolucency 30–50 mg/kg IV Q 6 H) and or vessel truncation enrofloxacin (5 mg/kg IV Q 24 H • Evidence of main pulmonary artery in cats; 10–20 mg/kg IV Q 24 H and/or right heart enlargement due in dogs) to pulmonary hypertension, a result »» Other antibiotic choices may also of significant PTE. be appropriate but are beyond the Echocardiography is also a useful scope of this article. diagnostic modality in cases of • Interstitial lung disease: These suspected PTE as it can document conditions are challenging to treat; pulmonary hypertension that often some are steroid responsive occurs secondary to PTE; detect • Pulmonary neoplasia: right-sided cardiomegaly and main Management depends on type, pulmonary artery dilation; and may location, and whether neoplasia is allow visualization of a thrombus in primary versus metastatic; surgery, the main pulmonary artery. chemotherapy, and radiation therapy Advanced imaging, such as CT are all considerations. angiography or, less commonly, a ventilation/perfusion lung scan with PULMONARY nuclear scintigraphy, are required to confirm the diagnosis.8,9 FIGURE. Thoracic radiograph demonstrating THROMBOEMBOLISM focal hypolucency in the right middle and Etiology caudal lung lobes associated with pulmonary \Causes of PTE are the same as Stabilization & Management thromboembolism; main pulmonary artery for any thromboembolic disease— Stabilization involves oxygen enlargement is also evident. Courtesy Dr. essentially abnormalities in Virchow’s supplementation, and treatment Carol Reinero triad, which include abnormalities requires anticoagulant drugs as well of blood flow (turbulence or as addressing the underlying disease. stasis), endothelial damage, and Therapies that can be used include: hypercoagulability. • Anticoagulants (unfractionated With PTE, it is critical to identify or low-molecular-weight heparin) and treat the underlying disease and/or antiplatelet drugs (eg, if it is not immediately apparent, clopidogrel) reduce risk of further so as to reduce the risk of further thrombus formation. Although the thromboembolic events. Theoretically, ideal antithrombotic strategy for Table 4. any systemic inflammatory state can dogs and cats with PTE is unknown, Diseases & Conditions That Predispose result in a systemic pro-coagulant state it is reasonable to combine low- Veterinary Patients to Hypercoagulability that predisposes the patient to PTE. molecular-weight heparin (eg, DISEASES Table 4 lists diseases and conditions dalteparin, 150 U/kg SC Q 12 H) Cardiac disease known to predispose veterinary with clopidogrel (approximately 2 Disseminated intravascular coagulation patients to hypercoagulability.8 mg/kg PO Q 24 H in dogs; 18.75 Heartworm disease mg/day in cats). Dalteparin dosing Hyperadrenocorticism Clinical Signs & Diagnostic should ideally be monitored by Immune-mediated hemolytic anemia Neoplasia Approach assessment of anti-Xa activity. Protein-losing enteropathy Diagnosis of PTE can be challenging. • Thrombolytic therapies, such as Protein-losing nephropathy While thoracic radiographs may be tissue plasminogen activator (tPA), Sepsis normal, indications of PTE include can also be administered; however, CONDITIONS (Figure): systemic administration of tPA is Exogenous corticosteroid administration • Degree of respiratory distress limited by adverse effects. Indwelling IV catheters out of proportion with changes • Sildenafil is often beneficial

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for reducing moderate to severe pulmonary Concurrent injuries, such as pulmonary contusions hypertension if documented on echocardiography. and pneumothorax, are common in dogs with fl ail chest and are generally the cause of respiratory PLEURAL SPACE DISEASE compromise, rather than the fl ail chest itself. Etiology Pleural space disease refers to abnormal Clinical Signs & Diagnostic Approach accumulations within the pleural space that impair Flail chest is usually visually obvious on examination, lung expansion on inhalation. These accumulations but radiographs are indicated to confi rm the nature can be associated with fl uid (ie, pleural effusion), of the rib fractures and allow assessment of severity of air (ie, pneumothorax), masses, or organs (ie, the underlying pulmonary parenchymal damage. Rib diaphragmatic hernia). fractures are extremely painful and may cause rapid, shallow breathing because big chest excursions cause Clinical Signs more pain than little breaths. Animals with pleural space disease may have: • Inspiratory distress Stabilization & Management • Rapid shallow breathing Management of fl ail chest is often supportive; the • Paradoxical breathing pattern in which the chest following should be provided: falls on inspiration and the abdomen expands • Oxygen supplementation, given the high rather than the chest rising with inspiration likelihood of underlying pulmonary contusions • Decreased lung sounds on thoracic auscultation. • Appropriate analgesia: » Usually in the form of systemic analgesia Diagnostic Approach (eg, pure mu-opioid agonists, such as Thoracic imaging is the mainstay of diagnosis. hydromorphone or fentanyl) ± local nerve In unstable patients, point-of-care ultrasound is blocks particularly useful to confi rm the presence of pleural » Intercostal nerve blocks can be performed in fl uid or air.10 Radiographs can also confi rm diagnosis dogs using 0.5% bupivacaine, with a total of 1 but ideally, in unstable patients, thoracocentesis to 4 mg/kg divided between sites (see Stabilization & Management) should be » If local anesthetic nerve blocks are used in cats, performed after ultrasound and prior to radiographs. dose reduction to prevent toxicity is important; If ultrasound is not available, thoracocentesis should generally, the total local anesthetic dose should be performed based on clinical suspicion, in order to not exceed 0.2 to 0.5 mg/kg in cats; particular stabilize the patient prior to obtaining radiographs. care should be taken to avoid inadvertent IV administration Stabilization & Management » Although use of nonsteroidal anti-infl ammatory Diaphragmatic In patients with pleural effusion or pneumothorax, drugs (NSAIDS) should be avoided in the Hernia: therapeutic thoracocentesis should result in initial stabilization and management of trauma emergency immediate improvement. Pleural fl uid can then patients, NSAIDs can be considered later in Management be submitted for analysis/cytology and, in cases the course of hospitalization once the patient is Patients with of pyothorax, bacterial culture (both aerobic and hemodynamically stable. diaphragmatic anaerobic culture). Additional supportive care may include: hernia usually Once therapeutic thoracocentesis has been • Patient positioning in lateral recumbency, with have a history of performed, the next step is addressing the underlying the flail segment facing downwards trauma; either disease. Specifi c discussion of treatment of underlying • Bandaging the chest to reduce movement of the acute, or at some time in the past. diseases is beyond the scope of this article. flail segment, although, extreme care must be taken Surgery via a ventral to avoid further impeding inspiration. midline laparotomy FLAIL CHEST Surgery is not indicated unless penetrating thoracic to replace the Etiology wounds are present, in which case an exploratory abdominal contents Flail chest refers to destabilization of a portion of the thoracotomy should be performed. Assuming unilateral in the abdomen rib cage, which occurs if there are rib fractures in 2 penetrating thoracic wounds, a lateral thoracotomy is and repair the torn diaphragm is different locations (proximal and distal) on the same performed to allow visualization of the affected thorax, indicated as soon rib(s). This condition often affects multiple ribs (at a lung lobectomy if necessary, and thoracic lavage, prior as possible. least 2 consecutive ribs), creating a fl ail segment.11 to closure with placement of a chest tube.

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identifi ed based on a complete history, physical TABLE 5. examination, and screening laboratory tests. Thoracic Intra-abdominal Pathology That Results in radiographs can help defi nitively rule out underlying Signifi cant Abdominal Distension respiratory disease. Abdominal masses Since the increased respiratory effort associated Ascites with these conditions is not usually oxygen Gastric dilatation +/- volvulus responsive, management is aimed at treating the Hepatomegaly underlying disease. Late-term pregnancy Splenomegaly IN SUMMARY The mainstays of management of a patient in ABDOMINAL DISTENSION respiratory distress are: Etiology 1. Initial stabilization, including oxygen Signifi cant abdominal enlargement Table( 5) can supplementation and potentially sedation result in respiratory distress because it impedes 2. Characterization of the breathing pattern to thoracic expansion during inspiration. Dyspnea is localize the disease rarely a presenting sign, but is common in 3. Systematic approach to diagnostics and therapy these patients. based on identifying the anatomic location of the cause of respiratory distress. Clinical Signs & Diagnostic Approach Respiratory distress due to abdominal distension CT = computed tomography; FiO2 = fraction is usually visually obvious. Abdominal palpation of inspired oxygen; NSAID = nonsteroidal and imaging (ie, abdominal radiographs and/or anti-infl ammatory drug; PTE = pulmonary ultrasound) can help determine the underlying cause. thromboembolism

Stabilization & Management References Supplemental oxygen may provide some relief, but 1. Sharp CR, Rozanski EA. Physical examination of the treatment should be aimed at reducing the degree . Top Companion Anim Med 2013; 28:79- of abdominal enlargement. Reducing the abdominal 85. 2. Sigrist NE, Adamik KN, Doherr MG, et al. Evaluation of distension may be straightforward, such as with respiratory parameters at presentation as clinical indicators of abdominocentesis in the case of ascites, or more the respiratory localization in dogs and cats with respiratory complicated. For example, in the case of severe distress. J Vet Emerg Crit Care 2011; 21:13-23. hepatosplenomegaly in dogs with immune-mediated 3. Sharp CR. Feline lower airway disease: Presentation and diagnosis. Today Vet Pract 2013; 3:28-31,35. hemolytic anemia, nothing can be immediately done 4. Sharp CR. Treatment of feline lower airway disease. Today Vet other than treating the underlying cause and giving Practice 2014; 4:28-32. the patient time to recover. 5. Goutal CM, Keir I, Kenney S, et al. Evaluation of acute congestive heart failure in dogs and cats: 145 cases (2007- LOOK-ALIKE SYNDROMES 2008). J Vet Emerg Crit Care 2010; 20:330-337. 6. Kogan DA, Johnson LR, Jandrey KE, et al. Clinical, Apparent breathing diffi culty caused by non- clinicopathologic, and radiographic fi ndings in dogs with respiratory conditions can occur in association with aspiration pneumonia: 88 cases (2004-2006). JAVMA 2008; severe pain, acidosis (eg, Kussmaul respiration 233:1742-1747. associated with diabetic ketoacidosis), anemia, drug 7. Schulze HM, Rahilly LJ. Aspiration pneumonia in dogs: Treatment, monitoring, and prognosis. Compend Contin Educ administration (eg, opioids), shock, and hypotension. Pract Vet 2012; 34:E1. These diseases or conditions can generally be 8. Goggs R, Benigni L, Fuentes VL, et al. Pulmonary thromboembolism. J Vet Emerg Crit Care 2009; 19:30-52. 9. Goggs R, Chan DL, Benigni L, et al. Comparison of CLAIRE R. SHARP computed tomography pulmonary angiography and point-of- Claire R. Sharp, BSc, BVMS (Hons), MS, CMAVA, Diplomate ACVECC, care tests for pulmonary thromboembolism diagnosis in dogs. is senior lecturer at Murdoch University in Perth, Western Australia, and J Small Anim Pract 2014; 55:190-197. adjunct assistant professor at Tufts Cummings School of Veterinary 10. Lisciandro GR. Abdominal and thoracic focused assessment Medicine. Dr. Sharp received her BVMS from Murdoch University. with sonography for trauma, triage, and monitoring in small She completed a rotating small animal internship at Oklahoma State animals. J Vet Emerg Crit Care 2011; 21:104-122. University, and an internship and residency in small animal emergency 11. Olsen D, Renberg W, Perrett J, et al. Clinical management of and critical care at University of Missouri. fl ail chest in dogs and cats: A retrospective study of 24 cases (1989-1999). JAAHA 2002; 38:315-320

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