Chronic bronchial dilatations in different colonies of laboratory rats

Bronchiectasis occurred naturally in 12-month-old spontaneously diabetic eSS male rats. The lungs of 3 and 6-month-old eSS rats were compared in eumetabolic eSS rats from three inbred lines consisting of inbred spontaneously diabetic eSS derived from IIM strain; these were compared with eumetabolic, outbred Wistar rats, paired by sex and age. Acrylic casts of bronchial tree were obtained after injection of a plastic substance. The casts were pruned to focus on the first four bronchial branchings. Diameter and volume of the conductive bronchial tree were determined using a binocular magnifier. Histological sections were obtained. All lines showed multiple bronchiectasis, mostly fusiform, bronchial dilatation and inflammatory response with lymphocytic infiltrates. These symptoms were much more severe in 180-day-old eSS males. Bacteria were isolated from the lungs in 70% of cases (n = 32), except in eSS rats. Pseudomonas spp. (38%) and Gram-positive cocci as coagulase-negative Staphylococcus spp. (20%) were detected. Neither pathogenic bacteria nor saprophyte fungi were found. Although all lines were affected, diabetes in eSS appears to be an aggravating factor.