Answer: Unfortunately I am unable to quickly locate any information specific to bittersweet (Celastrus) toxicity although my mother always told me it was deadly poisonous! You might want to check with your veterinarian. In some cases these old wives tales are not true (Poinsettia in fact is not as toxic as we have all been lead to believe although its sap is certainly an irritant and it will cause stomach upset if parts of the plant are eaten) but then and again many very common plants are very poisonous. For this reason it is a good idea to keep plants away from pets (and children) and to teach them not to eat any plant material other than that given them expressly to eat. While the plant itself may not be poisonous it is always possible it has been sprayed or treated with something that is poisonous or potentially so -- you just never know. In other words, I would be very cautious because it is better to be safe than sorry.
For general reference however you might find the following
two web sites about poisonous plants interesting: Poisonous
plants in Canada (many grow here as well)
http://www.ansci.cornell.edu/plants/plants.html from Cornell
University. This second site includes links to more poisonous plant information including some specifically oriented for animals.
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