Secretoglobin and Transferrin Expression in Bronchoalveolar Lavage Fluid of Horses with Chronic Respiratory Disease.

BACKGROUND: Lower expression of secretoglobin and transferrin has been found in the bronchoalveolar lavage fluid (BALF) of a small number of horses with experimentally induced signs of recurrent airway obstruction (RAO) compared to healthy controls. HYPOTHESIS/OBJECTIVES: Secretoglobin and transferrin BALF expression will be similarly decreased in horses with naturally occurring clinical signs of RAO and in horses with experimentally induced clinical signs of RAO as compared to healthy controls and intermediate in horses with inflammatory airway disease (IAD). ANIMALS: Recurrent airway obstruction-affected and control horses were subjected to an experimental hay exposure trial to induce signs of RAO. Client-owned horses with a presumptive diagnosis of RAO and controls from the same stable environments were recruited. METHODS: Pulmonary function and BALF were evaluated from control and RAO-affected research horses during an experimental hay exposure trial (n = 5 in each group) and from client-owned horses (RAO-affected horses, n = 17; IAD-affected horses, n = 19; healthy controls, n = 5). The concentrations of secretoglobin and transferrin in BALF were assessed using Western blots. RESULTS: Naturally occurring and experimentally induced RAO horses had similar decreases in BALF transferrin expression, but secretoglobin expression was most decreased in naturally occurring RAO. Secretoglobin and transferrin expression were both lower in BALF of RAO-affected horses than in IAD-affected and control horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Secretoglobin and transferrin expression is decreased in BALF of RAO-affected horses after both experimental and natural exposure. Secretoglobin and transferrin likely play clinically relevant roles in the pathophysiology of RAO, and may thus be used as biomarkers of the disease.

Effects of N-butylscopolammonium bromide on lung function in horses with recurrent airway obstruction.

BACKGROUND: Equine recurrent airway obstruction (RAO) is characterized by airway inflammation, bronchoconstriction, and increased mucus production in the airways. Anticholinergic drugs like atropine induce bronchodilatation and rapid improvement in lung function. N-butylscopolammonium bromide (NBB) is an anticholinergic drug used to relieve spasmodic colic in horses, but its effect on airway smooth muscle is unknown. OBJECTIVE: To evaluate the effect of NBB on clinical signs and lung function of RAO-affected horses. ANIMALS: Nine horses diagnosed with RAO. METHODS: Double-blind, placebo-controlled, randomized crossover trial. Horses were challenged with moldy hay until a maximum change in transpulmonary pressure (∆P(L) (max) ) > 15 cm H(2) O was achieved. NBB (0.3 mg/kg) or placebo (0.9% saline) was administered IV. Clinical scores and lung function were recorded at baseline and then periodically after treatment administration. Horses were allowed a 6-week washout before administration of opposite treatments. RESULTS: Clinical score at 10 and 30 minutes (8.7 ± 2.8 and 8.7 ± 3.2, respectively) after NBB administration was significantly lower than baseline (10.8 ± 2.4). NBB administration resulted in a significant decrease in ∆P(L) (max) (baseline: 35.1 ± 6.9 cm H(2) O) starting 2 minutes after administration (16.3 ± 6.6 cmH(2) O) with a maximum decline observed at 10 minutes (13.5 ± 7.1 cm H(2) O). ∆P(L) (max) values between 60 and 120 minutes after NBB administration were not different from placebo. CONCLUSION AND CLINICAL IMPORTANCE: N-butylscopolammonium bromide is a potent bronchodilator, reaching maximum effect 10 minutes after intravenous administration. This effect dissipates within 1 hour of drug administration.

Efficacy and safety of sound wave treatment of recurrent airway obstruction in horses.

BACKGROUND: One proposed nonmedical therapy for recurrent airway obstruction (RAO) in horses is a handheld acoustic device that propels sound waves from the nose down the tracheobronchial tree where it is intended to dislodge mucous and relax bronchospasm, permitting clearance of mucoid secretions. OBJECTIVE: To evaluate the effectiveness and safety of this device when used as per the manufacturer's recommendations as a treatment for RAO. ANIMALS: Nine adult horses previously diagnosed with RAO. METHODS: Prospective, cross-over clinical trial. Horses were exposed to a dusty environment until airway obstruction developed as defined by standard lung mechanics (SLM). Horses were randomly assigned to receive either acoustic therapy or a sham treatment for 4 weeks while being maintained in this environment. Horses were evaluated by clinical scores, SLM, and forced expiration regularly for 4 weeks. The opposite treatment was administered after a washout period. RESULTS: Seven horses received the treatment; 9 received the sham. There were no changes (P>.05) in clinical score, maximal change in transpulmonary pressure (ΔPLmax), lung resistance (RL), or the forced expiratory flow rate averaged over the last 75-95% of expiration (FEF75-95%) over the study period. The device was determined to be safe, although several minor adverse effects were noted, including head tossing, coughing, and chewing during treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Treatment with this device did not improve clinical signs or lung function in horses with RAO kept in a dusty environment. Currently accepted treatments, including environmental management and medical therapy, should be recommended.