Implementation of the Surgical Apgar Score in Laboratory Animal Science: A Showcase Pilot Study in a Porcine Model and a Review of the Literature.

INTRODUCTION: In an attempt to further improve surgical outcomes, a variety of outcome prediction and risk-assessment tools have been developed for the clinical setting. Risk scores such as the surgical Apgar score (SAS) hold promise to facilitate the objective assessment of perioperative risk related to comorbidities of the patients or the individual characteristics of the surgical procedure itself. Despite the large number of scoring models in clinical surgery, only very few of these models have ever been utilized in the setting of laboratory animal science. The SAS has been validated in various clinical surgical procedures and shown to be strongly associated with postoperative morbidity. In the present study, we aimed to review the clinical evidence supporting the use of the SAS system and performed a showcase pilot trial in a large animal model as the first implementation of a porcine-adapted SAS (pSAS) in an in vivo laboratory animal science setting. METHODS: A literature review was performed in the PubMed and Embase databases. Study characteristics and results using the SAS were reported. For the in vivo study, 21 female German landrace pigs have been used either to study bleeding analogy (n = 9) or to apply pSAS after abdominal surgery in a kidney transplant model (n = 12). The SAS was calculated using 3 criteria: (1) estimated blood loss during surgery; (2) lowest mean arterial blood pressure; and (3) lowest heart rate. RESULTS: The SAS has been verified to be an effective tool in numerous clinical studies of abdominal surgery, regardless of specialization confirming independence on the type of surgical field or the choice of surgery. Thresholds for blood loss assessment were species specifically adjusted to >700 mL = score 0; 700-400 mL = score 1; 400-55 mL score 2; and <55 mL = score 3 resulting in a species-specific pSAS for a more precise classification. CONCLUSION: Our literature review demonstrates the feasibility and excellent performance of the SAS in various clinical settings. Within this pilot study, we could demonstrate the usefulness of the modified SAS (pSAS) in a porcine kidney transplantation model. The SAS has a potential to facilitate early veterinary intervention and drive the perioperative care in large animal models exemplified in a case study using pigs. Further larger studies are warranted to validate our findings.

Does Sex Matter in Liver Surgery? Comparison of Severity Assessments between Female and Male Rats after Partial Hepatectomy: A Pilot Study.

INTRODUCTION: Current animal-based biomedical research, including studies on liver function and disease, is conducted almost exclusively on male animals to mitigate confounding effects of the estrous cycle. However, liver diseases afflict both men and women, so translational research findings should also be applicable to female patients. This pilot study investigated sex differences in objective and subjective severity assessment parameters in rats following 50% partial hepatectomy. MATERIALS AND METHODS: This study was performed using Wistar Han rats, in which measurements of body weight, spontaneous motor activity in the open field (OF) (movement distance, movement velocity, rearing frequency), and fecal corticosterone metabolites were conducted at baseline and at multiple times after partial hepatectomy. Subjective postsurgical severity assessments were conducted using modified score sheets. Blood parameters such as leukocyte count and serum aspartate aminotransferase, as well as estrogens and testosterone were measured from samples obtained during partial hepatectomy and at sacrifice. In addition, the amount of resected liver tissue was measured at partial hepatectomy, and the proliferated liver was weighed at sacrifice. RESULTS: Fecal corticosterone metabolite concentrations differed significantly between males and females at baseline and following hepatectomy. Also, leukocyte counts and estrogen concentrations were significantly different between sexes before partial hepatectomy. Alternatively, there were no sex differences in severity assessments, body weight changes, and behavior in the OF at any measurement time point. Liver weight was significantly different in males and females at the time point of partial hepatectomy and sacrifice. CONCLUSION: The results of this pilot study suggest that males and females respond similarly following partial hepatectomy. Examination of both sexes is very important for translation to humans, where both men and women suffer from liver disease. Furthermore, the use of both sexes in animal-based research would improve the utilization of the animal breeding in terms of the 3 Rs. However, due to some limitations, larger scale investigations including a broader spectrum of pathophysiolological, behavioral, and pharmacokinetic measures are planned.

Assessing the severity of laparotomy and partial hepatectomy in male rats-A multimodal approach.

This study assessed the postoperative severity after three different visceral surgical interventions in rats by using objective parameters pertaining to various disciplines. The objective was to evaluate whether the degree of severity increases with the invasiveness of the intervention and whether this is in accordance with the EU Directive 2010/63. 136 adult male WistarHan rats were assigned to three groups: Sham-laparotomy (Sham) [7 days post-surgical survival time]; 50% partial hepatectomy (PH); 70% PH [PH groups with 1, 3, or 7 days post-surgical survival times]. Post-surgical severity assessment was performed via several multimodal assessment tools: I) model-specific score sheet focusing on body weight, general condition, spontaneous behavior, and the animals' willingness to move as well as on wound healing; II) Open Field tests evaluating the total distance and velocity an animal moved within 10 minutes and its rearing behavior during the test; III) telemetric data analyzing heart rate and blood pressure; and IV) analysis of blood (AST, ALT, and hemogram) and fecal samples (fecal corticosterone metabolites). Significant differences among the experimental groups and models were observed. We demonstrated that the Open Field test can detect significant changes in severity levels. Sham-laparotomy and removal of 50% of the liver mass were associated with comparable severity (mild-moderate); the severity parameters returned to baseline levels within seven days. Removal of 70% of the liver tissue seemed to be associated with a moderate severity grade and entailed a longer recovery period (>7 days) for complete regeneration. We recommend the use of Open Field tests as part of multimodal objective severity assessment.

Re-Sterilisation of Single-Use Telemetric Devices.

Implantable telemetric transponders for contactless measurement of physiological parameters are often used in animal-based research. After explantation, single-use devices cannot be re-implanted because of non-validated functionality and necessary re-sterilisation. This is disadvantageous because the battery life would enable a second implantation cycle in another animal. To save costs and time taken for the manufacturer's refurbishing process, we validated and implemented a re-sterilisation protocol for single-use transponders using hydrogen peroxide gas. The described protocol was established with models, i.e., for large (n = 7) and small (n = 3) animals, of telemetric device from 2 different manufacturers (Data Science International and EMKA). All transponders, prepared according to the protocol, were previously implanted subcutaneously in the flank of pigs or rats for a duration of 21 days. Our investigations demonstrate that disinfection only is not sufficient against bacterial contamination and that sterility can only be achieved by additional gas sterilisation with hydrogen peroxide. Furthermore, re-implantation of the re-sterilised transponders into pigs caused neither undesired tissue reactions along the transponder nor impairment of the measured values when compared to the first implantation and after necropsy in 4 cases. We were able to demonstrate that, using our protocol, re-implantation of reprocessed single-use telemetric devices can be performed without compromising transponder quality.

Severity assessment using three common behavioral or locomotor tests after laparotomy in rats: a pilot study.

The aim of this pilot study was to evaluate whether behavioral or locomotor tests (Open Field (OF), rotarod (RR), and CatWalk (CW)) can help assess the severity of laparotomy in rats.The new EU Directive (2010/63/EU) mandates severity assessment in experiments involving animals. However, validated and objective methods are needed to relate trial-specific monitoring results to the degree of distress caused to individual animals. Therefore, we focused on non-invasive or minimally invasive, simple, and convenient severity assessment methods in a surgical model.To evaluate surgical severity in this model, we compared moving velocity among three commonly used behavioral test methods (OF, RR, and CW) after midline laparotomy within postoperative 7 days.In this study, 30 adult male Wistar Han rats (n = 10 per test) were trained in their assigned test method and subsequently subjected to surgery. Severity scoring was performed daily using a modified score sheet developed previously. In addition, blood and fecal samples were collected to analyze surgical and postoperative corticosterone metabolite levels. We found significant differences among the experimental groups in terms of the analyzed parameters. In this context, the OF test was found to be the most suitable method for severity assessment after laparotomy in rats.