Technical note: A technique for multiple liver biopsies in neonatal calves

Our objective was to develop a rapid and safe liver biopsy technique that c ould be repeated on multiple occasions in individual neonatal calves. A pil ot study was performed to verify the efficacy of sedation and restraint pro cedures and to evaluate different biopsy instruments. Following the pilot e xperiment, a biopsy trocar was fabricated and an experiment was conducted u sing this procedure. Liver biopsies were performed in neonatal calves on d 4, 9, 15, 21, and 28 of life to evaluate the effect of vitamin A intake on liver vitamin A concentrations. On these days, a single injection of ceftio fur sodium was administered i.m. 1 to 2 h prior to the procedure. Calves we re lightly sedated with xylazine and placed on a surgical table in left-lat eral recumbency. The right caudo-thoracic area was clipped and scrubbed wit h an iodophor agent. Following administration of a local anesthetic (lidoca ine), a small incision was made in the skin between the 12th and 13th ribs approximately 15 cm from the dorsal midline. The biopsy trocar was inserted through the body wall and peritoneum and introduced into the liver parench yma, and a liver sample was collected. Following the biopsy, the cutaneous incision was sutured and an antiseptic agent was applied to prevent infecti on. An i.m. injection of an analgesic was administered 1 h following the pr ocedure to alleviate postsurgical discomfort. Most calves were able to stan d within 2 h after the biopsy. The entire procedure, which could be perform ed by a single individual, usually required about 20 min from initial sedat ion until skin closure, Although liver samples of up to 500 mg were obtaine d, most samples weighed 75 to 150 mg (wet weight). A total of 156 liver bio psies were performed on 33 calves. Complications due to the biopsy procedur e were observed in only two calves. Therefore, this procedure can be useful for studies designed to monitor changes in liver composition or enzyme act ivities over time.