A Case Study Comparison Of Two Preclinical Studies Utilizing Traditional Versus Modified Methods For Surgical Closing And Post-Operative Treatment For Muscle Biopsy Sites In Nonhuman Primates

By Katherine Irby, David Benedict, Brett Megrath, and Julie Forget

Muscle biopsy in nonhuman primates is a specialized procedure used to collect samples for diagnosing or monitoring diseases and assessing biodistribution in tissue. However, it carries inherent risks of post-operative complications such as dehiscence and infections, primarily due to animal movement, grooming, and environmental conditions in group housing. Traditionally, the procedure involves using absorbable sutures to close the muscle and skin, with optional surgical adhesive for the skin. Standard post-operative care includes administering a nonsteroidal anti-inflammatory drug, limiting social contact, performing daily surgical site observations, and potentially administering antibiotics if signs of infection arise. However, changes in study designs, including multiple sample collections and housing animals in corrals instead of cages, led to higher rates of complications and introduced confounding variables to toxicology studies.

To address these issues, modifications were made to the post-operative care procedure, aimed at reducing single housing duration, allowing the surgical site to withstand more activity (including grooming), and minimizing complications. In the updated method, absorbable sutures were used to close both the muscle and skin, with the addition of surgical staples and optional surgical adhesive for the skin to reduce the risk of dehiscence. Following the procedure, animals received a prophylactic, long-acting antibiotic and a nonsteroidal anti-inflammatory drug globally. These modifications allowed animals to return to social housing immediately, and resulted in a significant reduction in post-operative complications, including dehiscence, discharge, and site swelling, which decreased from 7% of biopsy sites to less than 1%. Additionally, this approach eliminated the need for revision surgeries and reduced the impact of inconsistent antibiotic administration on study results.