There are numerous means to control parasites of dogs, cats, livestock and other domestic animals without synthetic chemicals (i.e. insecticides, tickicides, louisicides, wormers, etc., also called antiparasitic drugs or parasiticides).
The major options are the following:
- Biological control. Consists in using natural enemies of the parasites, i.e. other living organisms (other insects, fungi, bacteria, viruses, etc.) that naturally attack the parasites.
- Vaccines. Usually contain biologically produced antigens, (i.e. complex molecules, mostly proteins) that stimulate the organism of the host to produce antibodies againts the parasite. These antibodies act very specifically on certain vital processes of the parasites that eventually kill them.
- Medicinal plants. May contain naturally produced chemicals that are more or less lethal or repellent to parasites.
This section explains these three options.
There is quite some confusion regarding terms such as "biological", "bio-something", "natural", "non-chemical", "ecologic", "eco-friendly", sustainable", etc. used in many media, particularly in advertising. The use of medicinal plants can be considered as "natural", at least to some extent, but not as "non-chemical", because what kills or repels parasites in the plants are chemical molecules. A more detail discussion is included in each specific article.
There is one common feature to all non-chemical means when compared with the chemical means, i.e. with the use of antiparasitic drugs. Non-chemical means are usually less effective, less blunt, less crushing than chemical means. Many of them "help to control" the parasites, but are often not enough to completely control them, particularly where they are abundant (e.g. in endemic regions). Non-chemical control is often the "soft" approach, whereas chemical control is often the "hard" approach. Each pet owner or livestock producer has to decide what fits better to his needs.
Besides these non-chemical methods, physical means (e.g. electric traps against flies) and management measures (avoiding conditions that are favorable for parasite infestation or development) are often a must to keep parasites under control, e.g. good waste management in livestock operations (will reduce the number of flies or the transmission of worms), reducing or eliminating hiding places for parasites (e.g. to control red chicken mites), etc. The parasite-specific articles in this site indicate which physical means and management measures are particularly recommended in each case.