MUSTANG MANAGEMENT CONTRACEPTIVE PRIMERThis is not a debate on which is the best method of controlling wild horse numbers. These are simply the facts. It is clear science is far from perfect but research and observation can serve to give us an idea, a general sense of something which can compel us to look for more answers and continue research, preferably as humanely and as compassionately as possible. This is also not a debate as to whether mustangs should be classified as a native species in North America, returned native species, indigenous or invasive. They are here, with limited resources, and they are our responsibility.
Porcine Zona Pellucida (PZP): The compound PZP, which is short for Porcina Zona Pellucida, is derived from sow ovaries. When the pigs are slaughtered for the meat industry, the excess tissue not used for the food industry is either discarded or utilized for non-consumption purposes. Some tissue used for research and others for the preparation of drugs. Heparin is a potent anticoagulant given to almost every patient who has had surgery followed by an overnight stay in the hospital, to prevent the formation of blood clots. Heparin is derived from pig intestines. Insulin, given to diabetics, was originally made from cow, pig, and even whale pancreases. Currently there are still some available that contain animal products, although there are genetically modified human insulins and insulin analogs that are not animal based (http://iddt.org/about/gm-vs-animal-insulin).
“For contraceptive treatment to be an effective management tool, it usually needs to be reversible (Kirkpatrick & Turner 1991). A long term study of feral horses showed that PZP was reversible even when females were treated for several years (Kirkpatrick & Turner 2002). However some females appeared not to return to full fertility after long-term PZP treatment and similar side effects were seen with GNRH treatments in deer (e.g. Miller et al. 2000a). Consequently, most wildlife contraceptives are reversible, or have minimal impact after prolonged use.” (Gray & Cameron, 2010).