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Fifty-eight foals were divided into two groups for study of aspects of the clinical anesthetic management of foals and to characterize effects of halothane (n = 30) and isoflurane (n = 28) in foals. There were no significant differences (P greater than 0.05) in the demographics of the two groups. Results of hemograms and biochemical analysis of venous blood samples before and after anesthesia were either not influenced or only mildly (clinically unimportant) affected by either agent. Like adult horses, foals have an increased PaCO2 when anesthetized with inhaled anesthetics. We could detect no difference in the magnitude of increase in PaCO2 with either anesthetic. Anesthetic induction and recovery was most rapid with isoflurane. The quality of induction and recovery was similarly acceptable with either agent. Heart rate during isoflurane was not significantly different from conscious conditions but during halothane, heart rate was significantly less than control except at 91-120 min when statistical significance was not detected. These results support the clinical impression that foals can be safely and reliably anesthetized with either agent.

The ultrastructural, histochemical, and immunohistochemical characteristics of 12 classical signet ring cell Krukenberg tumors (CKT) and three tubular Krukenberg tumors (TKT) were evaluated and related to their possible influence on the ovarian stroma. In CKT, single signet ring cells predominated over lumen-forming cells and contained ultrastructural and histochemical characteristics similar to goblet cells in colonic and ovarian mucinous adenocarcinomas. In TKT, lumen-forming nonsecretory and secretory signet ring cells were prominent. Rare argentaffin cells were found in TKT but not in CKT. Cells in both CKT and TKT produced neutral and sialomucins. The stroma contained extracellular mucin, hypertrophied stromal fibroblasts and myofibroblasts, and in two cases stromal lutein cells with steroidogenic type ultrastructure. It appears that Krukenberg tumors are made up exclusively of intestinal type cells. Based on cell differentiation, TKT is better differentiated than CKT. Hypertrophy and hyperplasia of ovarian stromal cells may occur in response to malignant growth and/or the extracellular mucinous products of malignant cells and may play a role in the control of tumor invasiveness. None of the 15 cases were immunohistochemically positive for chorionic gonadotropin, placental lactogen, or luteinizing hormone. These hormones are suspected to be related to stromal luteinization in KT.