Submitted to: Laboratory Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1998
Publication Date: N/A
Interpretive Summary: In order to further understand the manner in which stress responses are regulated in domestic animals, it is necessary to collect serial blood samples to determine stress hormone profiles. It is also imperative that the procedure used to collect these blood samples does not induce a stress response in the animals. To date, the two primary blood collection protocols utilized for neonatal pigs require either jugular catherization via a surgical "cutback" procedure or venipuncture which are both stressful for the animal. Thus, we have developed a nonsurgical, minimally invasive cannulation technique which allows jugular vein catheter placement in the neonatal pig without causing extended discomfort or stress. The procedure is rapid (approximately 10 min/pig) and relatively simple, requiring only minimal anesthesia for immobilization of the pig during the procedure. Routinely, 2 wk old piglets are standing in their pens within 15-20 min from initiation of the procedure. Piglets recover rapidly from the procedure and display no clinical indications of pain or discomfort. Basal serum concentrations of cortisol, a standard indicator of stress and/or discomfort, are normal within an hour of completing the procedure. Stress is limited to the initial immobilization of the piglets. With this technique of cannulation, we routinely maintain catheter blood flow for 2 d, and oftentimes for as long as 5 d. Implementing this new cannulation technique in research programs will reduce the pain and discomfort that piglets normally experience due to other blood sampling techniques. This information will be of use to individuals in academia, government and industry who have a research interest in neonatal pigs which requires the collection of multiple blood samples within a short period.
Technical Abstract: In the neonatal pig, jugular catheterization has previously required surgical placement of a catheter into the jugular vein. While this "cutback" method of jugular vein cannulation has been effectively used for years in neonatal pigs, there are several drawbacks to this approach. First, surgical placement of a jugular catheter requires the piglets be anaesthetized and the jugular vein exposed for ligation. Exposure of the jugular vein requires a 4 cm incision through the skin. Residual pain and soreness associated with retraction of the superficial and cutaneous muscle layers undoubtedly remain for several days following the procedure. Post operative inflammation and pain prevent monitoring of endocrine profiles in a stress free condition. Secondly, the "cutback" procedure requires rigorous post surgical care to prevent general infection and septicemia which will inevitably alter research results. Therefore, we developed a nonsurgical method for jugular catheterization of the neonatal pig which allows collection of serial blood samples without exposing the piglets to extended periods of stress or discomfort. Thirty-two 2 wk old piglets were cannulated using this procedure and blood samples collected over a 3 hr period. Basal serum concentrations of cortisol, a standard indicator of stress and/or discomfort, are asymptomatic within an hour of completing the procedure (mean = 23.85 +/ 2.85 ng/ml). With this technique of cannulation, we routinely maintain catheter patency for 2 d, and oftentimes for as long as 5 d. Incorporating this new cannulation procedure into research programs which require multiple blood samples over short time periods will aid in reducing animal stress and discomfort, and will allow monitoring of endocrine hormones in a more homeostatic state.