Compassion Fatigue, Euthanasia Stress, and Their Management in Laboratory Animal Research.

This review is designed to assist both individuals and organizations involved in animal-based research to understand and appreciate the importance and potential risks of compassion fatigue and euthanasia stress. We reviewed current literature regarding compassion fatigue and euthanasia stress as they relate to the laboratory animal science community. Definitions, recognition, and mitigation steps are clarified. We offer educational and mitigation advice and present needs for future research on these topics that is related directly to the laboratory animal science community.

Anomaly in aortic arch alters pathological outcome of transient global ischemia in Rhesus macaques.

We investigated a non-human primate (NHP) transient global ischemia (TGI) model which was induced by clipping the arteries originating from the aortic arch. Previously we demonstrated that our TGI model in adult Rhesus macaques (Macaca mulatta) results in marked neuronal cell loss in the hippocampal region, specifically the cornu Ammonis (CA1) region. However, we observed varying degrees of hippocampal cell loss among animals. Here, we report for the first time an anomaly of the aortic arch in some Rhesus macaques that appears as a key surgical factor in ensuring the success of the TGI model in this particular NHP. Eleven adult Rhesus macaques underwent the TGI surgery, which involved 10-15-minute clipping of both innominate and subclavian arteries. Animals were allowed to survive between 1 day and 28 days after TGI. Because of our experience and knowledge that Japanese macaques exhibited only innominate and subclavian arteries arising from the aortic arch, macroscopic visualization of these two arteries alone in the Rhesus macaques initially assured us that clipping both arteries was sufficient to produce TGI. During the course of one TGI operation, however, we detected 3 arterial branches arising from the aortic arch, which prompted us to subsequently search for 3 branches in succeeding TGI surgeries. In addition, we performed post-mortem examination of the heart to confirm the number of arterial branches in the aortic arch. Finally, in order to reveal the pathological effect of the aortic arch anomaly, we compared the hippocampal cell loss between animals found to have 3 arterial branches but had all or only two branches clipped during TGI operation. Post-mortem examination revealed that eight NHPs had the typical two arterial aortic branches, but three NHPs displayed an extra arterial aortic branch, indicating that about 30% of Rhesus macaques had 3 arterial branches arising from the aorta. Histological analyses using Nissl staining showed that in NHPs with the aortic arch anomaly clipping only two of three arterial branches led to a partial cell loss and minimal alteration in number of cell layers in the hippocampal region when compared with clipping all three branches, with the hippocampal cell death in the latter resembling the pathological outcome achieved by clipping the two arterial branches in NHPs displaying the typical two-artery aortic arch. The finding that 3 of 11 NHPs exhibited an extra arterial aortic branch recognizes this aortic arch anomaly in Rhesus macaques that warrants a critical surgical maneuver in order to successfully produce consistent TGI-induced hippocampal cell loss.

Hippocampal CA1 cell loss in a non-human primate model of transient global ischemia: a pilot study.

We exposed adult Rhesus (Macaca mulatta) to a transient global ischemia, which was induced by clipping the innominate and subclavian arteries that originated from the aortic arch. NHP1 received 20-min, while NHP2 and NHP3, were exposed to a 15-min transient global ischemia and were euthanized at day 1 (NHP1), day 5 (NHP2) or day 30 (NHP3) after ischemia, respectively. NHP1 displayed severe paralysis and rigidity, and intermittent convulsions over the next 24 h. Although histological examination of the brain revealed no detectable gross brain damage (i.e., swelling) and only minimal cell loss in the hippocampus, the acute survival time after surgery likely prevented the cerebral ischemia to fully develop and to be morphologically manifested. Nonetheless, the 20-min ischemia might have been too severe and caused a systemic multiple organ collapse that produced the abnormal behavioral symptoms. On the other hand, NHP2 and NHP3 which received 15-min ischemia only exhibited minor hindlimb paralysis. Indeed, by 48 h after ischemia, both animals appeared fully recovered with only fine motor deficits. Immunohistochemical examination revealed that NHP2 and 3, but not NHP1, had a marked neuronal cell loss in the hippocampal region, specifically the cornu Ammonis (CA1) region. The cell loss in these two ischemic NHP hippocampi was further confirmed by direct comparison with a normal Rhesus brain. These findings replicate the brain pathology seen in Japanese macaques exposed to the same ischemia model [T. Tsukada, M. Watanabe, T. Yamashima, Implications of CAD and DNase II in ischemic neuronal necrosis specific for the primate hippocampus, J. Neurochem. 79 (2001) 1196-1206; T. Yamashima, Implication of cysteine proteases calpain, cathepsin and caspase in ischemic neuronal death of primates, Prog. Neurobiol. 62 (2000) 273-295; T. Yamashima, Y. Kohda, K. Tsuchiya, T. Ueno, J. Yamashita, T. Yoshioka, E. Kominami, Inhibition of ischemic hippocampal neuronal death in primates with cathepsin B inhibitor CA-074: a novel strategy for neuroprotection based on calpain-cathepsin hypothesis, Eur. J. Neurosci. 10 (1998) 1723-1733; T. Yamashima, T.C. Saido, M. Takita, A. Miyazawa, J. Yamano, A. Miyakawa, H. Nishijyo, J. Yamashita, S. Kawashima, T. Ono, T. Yoshioka, Transient brain ischemia provokes Ca2+, PIP2 and calpain responses prior to delayed neuronal death in monkeys, Eur. J. Neurosci. 8 (1996) 1932-1944; T. Yamashima, A.B. Tonchey, T. Tsukada, T.C. Saido, S. Imajoh-Ohmi, T. Momoi, E. Kominami, Sustained calpain activation associated with lysosomal rupture executes necrosis of the postischemic CA1 neurons in primates, Hippocampus 13 (2003) 791-800]. The present minimally invasive transient global ischemia model using Rhesus shows many histopathological symptoms seen in human patients who experienced global ischemia, and should allow translational validation of experimental therapeutics for ischemic injury. Additional studies are warranted to reveal behavioral deficits associated with this ischemia model.