Today's Veterinary Practice

MAY-JUN 2018

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PEER REVIEWED 48 ASTHMATIC CAT: MANAGEMENT GUIDELINES expiration) combined with abnormalities on thoracic auscultation and an appropriate history can often provide enough information to guide emergent therapy. Cats with feline asthma typically present with expiratory respiratory distress (greatest effort on exhalation with or without abdominal push), and wheezes may be heard on thoracic auscultation. Therapy to stabilize patients in respiratory distress should be instituted, and specific therapy to address bronchoconstriction should be considered. Stabilization includes providing supplemental oxygen therapy and mild sedation to reduce anxiety. If possible, placement of an IV catheter is preferable to ensure emergency venous access; however, this may not be possible in all cases before stabilization. Oxygen therapy can be delivered via flow-by, face mask, or oxygen cage. Flow-by oxygen at a rate of 2 to 3 L/ min provides a forced inspiratory oxygen (FiO 2 ) of approximately 25% to 40%. A loose-fitting face mask with a similar flow rate is recommended. It is estimated that with a tight-fitting face mask, an FiO 2 of 50% to 60% can be obtained; however, loose-fitting face masks are recommended because of concerns of rebreathing carbon dioxide with tight-fitting masks. Oxygen cages can reach a higher FiO 2 than can either of the other options and allow for adjustment of the delivered FiO 2 . It is recommended that oxygen flow rate be adjusted to maintain an FiO 2 at 40% to 50%. It is also essential to monitor temperature and humidity levels within oxygen cages. A more detailed discussion of this can be found elsewhere. 1,2 These options may vary by patient depending on their stability and tolerability. Mild sedation to relieve anxiety is recommended if there are no contraindications based on history or clinical assessment. Butorphanol can be used with minimal risk, and if additional sedation is necessary, it can be combined with a low dose of a benzodiazepine. Bronchodilators for acute management are delivered via inhalation or injectable routes. Short-acting β2 agonists (eg, albuterol, terbutaline) are widely available and appropriate for "rescue" therapy. Administration of albuterol can be achieved via a metered-dose inhaler attached to an aerosol chamber with a face mask ( FIGURE 1 ) (Aerokat; trudellmed.com ) or as a nebulized solution ( TABLE 1 ). Terbutaline is also available in various forms but is most useful as an injectable medication in this scenario. Terbutaline (0.01 mg/kg) can be administered as a SC, IM, or IV injection ( TABLE 1 ). 3 When restraint for IV access is not possible until stabilization is achieved, SC or IM injection is preferable, and onset of action usually occurs within 15 minutes of injection. 3 Home Management Acute management also includes home treatment of acute asthma attacks that are not severe enough to warrant emergency presentation to a veterinary facility. Acute exacerbations may result from exposure to asthma triggers. This usually manifests as episodes of spasmodic coughing and increased expiratory effort. At-home care providers should be trained to deliver bronchodilator therapy during episodes involving increased respiratory effort. One option is the use of inhaled albuterol delivered via a metered-dose inhaler with an aerosol chamber attached. However, this works best when cats have been trained to accept the chamber and accompanying mask; some cats will not tolerate the apparatus. Alternatively, owners can be trained to administer a SC terbutaline injection during these events. In addition to managing FIGURE 1. A metered-dose inhaler attached to an aerosol chamber with a face mask (AeroKat). Cats with feline asthma typically present with expiratory respiratory distress (greatest effort on exhalation with or without abdominal push), and wheezes may be heard on thoracic auscultation.

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