Effect of topical cyclopentolate alone or combined with phenylephrine in healthy horses.

OBJECTIVE: Evaluate the effect of repeated doses of topical 1% cyclopentolate hydrochloride alone and in combination with topical 2.5% phenylephrine on pupil diameter (PD), tear production (STT-1), intraocular pressure (IOP), digestive function (gut motility and feces production), and heart rate (HR). ANIMAL STUDIED: Six healthy mares. PROCEDURES: In a prospective, randomized, controlled, and crossover design study, the left eye of six healthy mares was administered 0.2 mL of cyclopentolate alone and in combination with 0.2 mL of phenylephrine. The drugs were administered 3 times a day for 1 day, twice a day for 1 day, and then once a day for 2 days, as commonly used in practice. Daily and two days after the last topical drug administration, HR, digestive auscultation, feces production, STT-1, IOP, and PD were recorded. RESULTS: The cyclopentolate alone significantly increased the horizontal and vertical PD of the treated eye from day 2 to day 6 (p < .0001) compared with the baseline value. The combination with topical phenylephrine did not have any additional effect on mydriasis compare with the cyclopentolate alone. The other ocular and digestive parameters were not affected by repeated doses of cyclopentolate alone or combined. CONCLUSIONS: Repeated administration of cyclopentolate alone or combined with phenylephrine induce a significant mydriasis for at least 48 h after the last administration in normal horses' eyes, and do not affect STT-1, IOP, digestive function, and HR. The phenylephrine combined with the cyclopentolate did not potentiate the pupil dilation when compared with cyclopentolate alone in healthy horses.

Airway remodeling in horses with mild and moderate asthma.

BACKGROUND: There is a remodeling of the central airways in horses with severe asthma but whether a similar process occurs in horses with the mild or moderate asthma (MMA) is unknown. OBJECTIVES: To evaluate lesions affecting the central airways of horses with MMA. ANIMALS: Twelve horses with MMA and 8 control horses. METHODS: Case-control retrospective study of horses classified as MMA affected or controls based on history and bronchoalveolar lavage fluid cytology. Endobronchial biopsies were analyzed using histomorphometry and a semiquantitative histologic scoring system. RESULTS: Histomorphometry identified epithelial hyperplasia (47 µm2 /µm [34-57 µm2 /µm]; P = .02), a thickened lamina propria (166 µm [73-336 µm]; P = .04), and smooth muscle fibrosis (42% [33%-78%]; P = .04) in horses with MMA when compared to controls horses (24 µm2 /µm [21-80 µm2 /µm]; 76 µm [36-176 µm]; and 33% [26%-52%], respectively). The semiquantitative score results indicated, in horses with MMA, the presence of epithelial hyperplasia (7 of the 12 horses with MMA and only 1 of the 8 control horses had a score of 1/1), and submucosal inflammatory leucocytes in the central airway (11 of the 12 horses with MMA and only 4 of the 8 control horses had a score ≥ 1/2). CONCLUSIONS AND CLINICAL RELEVANCE: Tissue remodeling of the bronchial lamina propria, epithelium, and smooth muscle was present in horses with MMA.