Rheological study of healthy chicken's pooled tracheobronchial secretions and its modification by mucolytics drugs.

The rheological properties of pooled tracheobronchial secretions (TBS) of chicken, including mucus, have not been characterized. Yet mucolytic drugs are frequently used in poultry medicine. To define such properties, TBS from healthy untreated and from chickens treated with various mucolytic drugs was studied. Three hundred, three-week-old Rhode Island Red chickens were divided into five groups, with three repetitions each (n = 20) as follows: ambroxol (GAmb), ethylene diamine dihydro-iodide (GEddi), carbocysteine (GCs), bromhexine (GBr), and an untreated control group (CG). Under anesthesia, samples of TBS were taken by gently flushing saline solution through the tracheobronchial tree, and rheological evaluations were made to determine viscosity, yield stress, and viscoelasticity by means of a rheometer using controlled efforts with a geometry system of concentric cylinders. It was found that TBS in the CG and in all treatments showed a non-Newtonian behavior (n < 1). TBS from all treatments possess yield stress (necessary force applied for a fluid to flow) and a pseudo-solid type behavior (viscoelastic test) as far as elasticity is concerned. TBS from treated animals revealed that yield stress was higher for the GBr and lowest for GAmb. Statistically significant differences in viscosity were observed among all treatments, including CG (P < 0.05). Considering yield stress, little effort would be required for respiratory cilia to displace TBS in ambroxol medicated chickens, followed by carbocysteine. Contrary to expectation, cilia from healthy chickens medicated with bromhexine or ethylene diamine dihydro-iodide, would require greater force to displace mucus as compared to untreated healthy birds.