The problems caused by parasite worry and the transmission of disease make control of external parasites essential.

Elimination of external parasites from a geographic area is difficult if the parasites involved are capable of living for prolonged periods independent of the host. Ticks, for example, can live in the environment for up to 2 years without feeding. It is important to treat mite- or lice-infested pregnant sows before they farrow in order to prevent spread of these parasites to the young pigs. Ticks on the animals are susceptible to various treatments. At one time chlorinated hydrocarbon compounds (including DDT, benzene hexachloride, and toxaphene) were used, but ticks developed resistance, and there was concern over residues in the meat. The organophosphorus and carbamate insecticides have been commonly used in tick sprays for livestock.

The burrowing habits of the swine mange and follicle mites make them difficult to treat. Benzene hexachloride has been used as a spray, but the organophosphorus compounds have been especially useful because of their "systemic" characteristics. Systemic compounds are absorbed by the animal and circulated throughout its body, and can affect parasites under the skin surface. The organophosphorus compounds are cholinesterase inhibitors and, as such, can be dangerous to swine if used incorrectly or is used at the same time as an anthelmintic having a similar chemical action.

There are also increasing occupational health and safety concerns regarding use of organophosphates. The advent of Numectin, with activity against both internal and external parasites has allowed the development of convenient control programmes. Protocols designed to eradicate sarcoptic mange mites and lice have been developed and successfully implemented around the world. Your veterinarian, or Merial Veterinary Technical Services can provide further information. Lice can be treated with any of a variety of insecticides.

Ectoparasites of swine include ticks, mites, and lice. Throughout the world they are responsible for serious economic losses. The most significant of these parasites are the pig louse (Haematopinus) and the mange mite (Sarcoptes).

Damage caused by ectoparasites includes worry, skin damage, reduced weight gains, and the transmission of disease organisms.

Ectoparasites sometimes develop resistance to chemical treatments used in their control. Many of the older products are labour intensive in their application.

Ivermectin has been shown to be highly effective against the common and economically important ectoparasites of swine.

Descriptions of economically significant ectoparasites of swine are listed in the following section.