Clean-catching urine from pigs: A method for collecting quality specimens for urinalysis and microbiological culturing in a laboratory environment

Urine is an important biological specimen for assessing various metabolic functions and drug clearance. In urinary tract infection research, urine is particularly important as urinary bacterial titres constitute the main diagnostic outcome for assessing the course of infection. Collecting uncontaminated urine samples from pigs can be done by bladder catheterization or suprapubic bladder aspiration, which are both laborious and invasive procedures that require the need for anaesthesia. To improve animal welfare and optimize urine sampling protocols, we developed a method of clean-catching midstream urine specimens from pigs during spontaneous micturition. The quality of urine specimens collected by clean-catch, bladder catheter and suprapubic bladder aspiration were compared using microbiological culturing. We show that urine specimens collected by clean-catch are only minimally contaminated by skin- and vaginal-commensals with no influence on urinary bacterial titres during ongoing infection. In conclusion, we describe a method in which spontaneous micturition can be prompted in pigs, facilitating fast and reliable collection of quality specimens suitable for microbiological culturing. The method supersedes the need for anaesthesia, which not only represents a considerable refinement in terms of animal welfare but also facilitates more frequent collection of specimens that can enhance the scientific outcome of experimental animal studies in pigs.