Today's Veterinary Practice

MAY-JUN 2018

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49 MAY/JUNE 2018 ● TVPJOURNAL.COM FEATURES these events when they occur, clients must know to contact their veterinarian when asthmatic cats experience these events regularly or the frequency of these events increases. This can indicate that the disease is poorly controlled and that long-term management must be adjusted, or that a secondary or concurrent condition must be addressed. LONG-TERM MANAGEMENT The main goals of long-term management include reducing airway inflammation and airway resistance. Although many therapies have been investigated, the mainstays for accomplishing these goals remain glucocorticoids and bronchodilators. This section discusses therapeutic mainstays as well as therapies that have shown promise in experimental models of feline allergic asthma. Anti-inflammatory Therapy Addressing airway inflammation is an essential component of therapy in feline allergic asthma. Glucocorticoids are the first-line therapy to accomplish this and are potent anti-inflammatory agents. Oral glucocorticoids, such as prednisolone, are widely available and inexpensive, which makes them an ideal first choice for many patients. Results of studies that used prednisone (2 mg/kg q24h) in cats with experimentally induced allergic asthma indicate that oral glucocorticoids reduce eosinophilic airway inflammation. 4,5 However, a retrospective study evaluating high-dose oral steroid therapy (prednisone/prednisolone, 2 mg/kg q24h ) in cats with naturally occurring chronic lower airway disease indicated that clinical signs may resolve in some cats while airway inflammation persists.6 Persistent inflammation is clinically relevant because it can lead to airway remodeling. Unfortunately, without repeating airway sampling (eg, bronchoalveolar lavage), there is no way to identify patients with persistent inflammation, and repeat sampling is not clinically feasible in most cases. Therefore, this simply needs to be considered in therapeutic decision-making. Another method for administering glucocorticoids to feline patients is via a metered-dose inhaler with an attached aerosol chamber and face mask, as mentioned earlier. Inhaled glucocorticoids are an attractive option for cats that will not tolerate administration of oral medication. With appropriate training with the aerosol chamber and mask, most cats tolerate the device quite well. Additionally, cats with concurrent medical conditions for which systemic steroids are undesirable (eg, diabetes mellitus) and cats requiring long-term steroid administration may benefit from inhaled glucocorticoid therapy. A study evaluating the effect of fluticasone on the hypothalamic-pituitary-adrenal axis (HPAA) in cats showed no suppression of the axis with 3 available doses (treatment q12h with 44 μg per actuation, 110 μg per actuation, or 220 μg per actuation).7 This study also found that all 3 doses were equally efficacious for reducing eosinophilic airway inflammation in experimentally induced allergic asthma. This latter finding could allow for significantly reduced cost associated with inhaled fluticasone therapy. Another study evaluated inhaled budesonide (400 μg q12h) in cats, and although the agent did suppress the HPAA in some cats, no clinical manifestations of glucocorticoid side effects were noted.8 Inhaled budesonide improved clinical signs and reduced airflow limitation; however, this study did not assess airway inflammation.8 Finally, the successful use of cyclosporine for the management of feline asthma was reported in a single case report in which glucocorticoids were contraindicated because of concurrent diabetes mellitus and severe heart disease.9 Treatment with cyclosporine in this case resolved clinical signs and airway inflammation.9 Although further study is needed with this therapy, it may be a useful alternative in complex cases in which steroids are contraindicated. TABLE 1 Bronchodilator Characteristics DRUG ROUTE DOSE FREQUENCY Albuterol Metered-dose inhaler 1 puff 3,24 q30min for up to 4–6 h Nebulized 0.5 mL of 2.5 mg/3 mL solution (preservative free) in 3.5 mL saline 24 q6–24h Terbutaline SC, IM, IV 0.01 mg/kg 3 Theophylline PO 15 mg/kg 3 q24h

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