Anthelmintics are chemical compounds which can be used to expel parasitic worms from the body. Known as helminths, parasitic worms can be found all over the world and in a wide range of animal species, with some jumping between species while others confine themselves to infecting a single species. Animals with parasitic worms in their bodies can experience a variety of symptoms related to the parasite including intestinal discomfort, weight loss, abdominal bloating, and signs of malnutrition such as hair loss.
These drugs can work in one of two ways. Vermicides kill helminths while vermifuges stun them so that they become disoriented, and in both cases the worms can be expressed from the body once the medications are administered because the worms are no longer able to function as they normally do. There are a wide range of anthelmintics on the market which cover a variety of species of worm. In addition to pharmaceutical drugs, there are also natural compounds which can sometimes be used in the treatment of worms.
Animals on pasture tend to be prone to being infected and reinfected with worms, and may be administered dewormers as a prophylactic treatment before they are actively infected. Likewise, pets can be prone to developing worms because they ingest them from fleas during grooming or from prey during hunting. Pet owners are usually encouraged to use flea control to eliminate problems associated with fleas, including worms, and anthelmintics can be administered if pets experience parasitism. Pet owners should be aware that medications used for flea control in dogs often contain ingredients unsafe for cats, and it is important to make sure that a drug is species-appropriate before administering it.
The dosage of these drugs is very important. Many anthelmintics can be dangerous when taken in dosages which are too high, and drugs are not suitable for all organisms just because they work in some. Drugs used on humans, for example, are not necessarily safe for dogs. It is also usually necessary to have an examination to determine which kind of worm is involved so that appropriate medication can be prescribed.
In the farming community, there are concerns that routine use of anthelmintics could contribute to the development of drug resistant worms. After a deworming, usually some worms or eggs are left behind. Over repeated treatments, this can inadvertently result in the selection of resistant individuals who can then pass their resistance on to their descendants, making it harder to treat parasites in farm animals.
