A study was undertaken to determine the pressor and toxic effects of etoposide, an antineoplastic agent, when administered IV in 0.9% sodium chloride solution (0.4 mg of etoposide/ml) over a 30-minute period to dogs at a dosage of 40 mg/m2 of body surface. On day 1, 6 adult German Shorthaired Pointers were anesthetized with halothane, and blood pressures were measured via a femoral artery catheter before, during, and after the etoposide was administered. Systolic, diastolic, and mean blood pressures of each dog increased significantly (P less than 0.01) within 30 minutes after initiation of etoposide infusion. On day 3, when the dogs were not anesthetized, etoposide was again administered to each dog, using the same dosage. Each dog developed a moderate to severe cutaneous reaction characterized by moderate to severe pruritus, urticaria, and swelling of the head and extremities that began during the second infusion of etoposide. These same cutaneous reactions were seen on day 30, when etoposide was administered to 3 of the previously treated dogs and 2 previously untreated Beagles. We concluded that the administration of the commercial preparation of etoposide is likely to cause a significant reduction in blood pressure of anesthetized dogs, and that the drug is likely to induce a moderate to severe cutaneous reaction when administered to unanesthetized dogs.

A commerical radioimmunoassay kit designed for measuring gastrin in human serum was validated for use with equine serum. This nonextraction, double-antibody procedure uses an antiserum with broad specificity for molecular forms of gastrin. Synthetic human gastrin (G17-I) was added to pooled equine serum, and the observed assay values were compared with the mass added. Recovery was 99 to 115% in the gastrin concentration range of 40 to 640 pg/ml. Dilutions of postprandial serum with serum from fasted horses were assayed, and the inhibition curves were compared with those of the human gastrin kit standards, using a log-logit transformation. The slopes of the sample dilution plots were not significantly different from the slopes ofthe standard curves. Ethylenediamine tetraacetate and heparin adversely affected the assay, resulting in lower assayed gastrin concentration values. The intra-assay coefficient of variation (n = 10) was 3.8%, and the interassay coefficient of variation (n = 6) was 11.2%. The assay sensitivity, as reported by the manufacturer, is 8 pg/ml. Gastrin concentrations in serum from fasted horses ranged from undetectable values (less than 8 pg/ml) to 17.5 pg/ml, and peaked at a mean value (n = 6) of 70 pg/ml 3 hours after feeding. Serum cortisol values monitored during the postprandial blood collection period were in the normal range for horses.