Activated clotting time and heparin administration in Sprague-Dawley rats and Syrian golden hamsters.

To determine the activated clotting time (ACT) in rats and hamsters from our colony and to evaluate the response of this parameter to different heparin doses in these species, ACTs were measured using a Medtronic HemoTec ACT measurement system in samples obtained by intracardiac puncture from normal, nonanticoagulated, anesthetized rats and hamsters. Another groups of animals received different intravenous boluses of heparin to determine the dose needed to maintain ACT values > 480 sec for at least 30 min. The ACT (mean +/- SEM) was 48.0 +/- 2.17 sec for the 50 rats sampled and 42.5 +/- 2.35 sec for the 48 hamsters. Rats required a bolus of 1200 IU/kg intravenous heparin to maintain an ACT > 480 sec for 30 min; hamsters required 1000 IU/kg heparin for the same effect. We concluded that compared with humans, rats and hamsters from our colony have short ACTs and low sensitivity to heparin, in terms of the dose needed to reach a target ACT as well as the time required to sustain it. Further the ACT values in these animals showed great variability.

Some studies on the experimental infection of golden hamsters with Taenia solium.

Golden hamsters were infected orally with viable cysticerci of Taenia solium obtained from infected pigs. After two weeks of infection implanted scolices of about 4 mm were found in exactly the same number as the number of ingested cysticerci. At six weeks 66% of the ingested cysticerci were found as implanted tapeworms (average size: 5.7 cm). At ten weeks 16% of the ingested cysticerci were found as implanted tapeworms (average size: 5.8 cm). At 14 weeks no tapeworms were found. Skin tests with taenia extracts were positive after 9 weeks of infection peaked at 12 and 14 weeks and declined afterwards becoming negative after 27 weeks. Skin test with cysticercus extracts were weaker, peaked at 8 and 10 weeks, were very low after 12 weeks and became negative after 16 weeks. Histological studies in the attachment site at the small intestine showed at 2 weeks a cellular infiltrate formed by macrophages, epithelioid cells and some plasma cells, there was very little alteration of epithelium. At 6 and 8 weeks the epithelium was damaged and necrotized. At 17 and 19 weeks the lesion started to resolve. We conclude that the golden hamster can be used to reproduce in the laboratory at least part of the life cycle of Taenia solium.