External parasites

1. Lice

The louse is a small, flat, wingless insect parasite. There are several species of lice and most species are specific to a particular class of animal. Hog lice do not affect other animals or man. The hog louse (Haematopinus suds) grow up to 1/4 inch in length. Lice are endemic to all parts of the world. Diseased or poorly fed hogs (commonly true for free-ranging hogs) are more prone to lice than healthy hogs.

Life Cycle

Lice spend their entire life cycle on the host's body. They attach their eggs or nits to the hair near the skin where they hatch in about 2 weeks. Two weeks later the young females begin laying eggs, and after reproduction they die on the host. Lice do not survive more than a week when separated from a pig; but under favorable conditions, eggs clinging to detached hairs may continue to hatch for 2-3 weeks.

Prevention

It is practically impossible to prevent lice on swine. General sanitation and occasional treatment to keep the number of lice down seems to be the only practical suggestion. Prevent overcrowding in the herd.

Symptoms

Since lice are blood suckers they cause severe itching, restlessness, and a loss of condition in swine. Pigs may be seen scratching, rubbing, and gnawing at their akin as an indication of lice. Scabs and scaly skin can be seen in severe outbreaks.

Treatment

Spraying or dipping with anacricide is more effective with swine than dusting. Refer to the attached charts for dosage and names of typical acaracides to use.

2. Mites (Mange)

Kites produce a specific contagious disease known as mange (or scabies) These parasites are insect-like and almost invisible to the naked eye. Swine are most affected by the sarcoptic type of mites. With the exception of sarcoptic mites, mites are species-specific and do not normally live or reproduce on a different host. The sarcoptic mite will live on different species. The sarcoptic mite of horse and cow is transferrable to humans. There are 2 chief forms of mange: sarcoptic mange, caused by burrowing mites, and psoroptic mange, caused by mites that bite the skin and suck blood, but do not burrow. The sarcoptic form is most damaging, for in addition to their tunneling, they secrete an irritating poison. The irritation and blood sucking caused by mites retard growth and lower meat production. Mites exist in all parts of the world.

Life Cycle

The mites that attack swine breed exclusively on the bodies of their hosts. They will live for only 2-3 weeks when removed. The female mite which produces sarcoptic mange- the most severe form of scabies- lays from 10-25 eggs during the egg-laying period, which lasts about 2 weeks. At the end of another 2 weeks, the eggs have hatched and the mites have reached maturity. A new generation of mites may be produced every 15 days. The disease is most common when pigs are closely confined.

Prevention

The only sure means of prevention is to avoid contact with infected animals or pens.

Symptoms

Itching, scratching, lack of appetite, crusty or thick skin, and secondary skin infections.

Treatment

Lindane at a concentration of 0.05 to 0.1% or Malathion at 0.05%. Both should be mixed at these concentration with water when applying.

3. Ringworm

Ringworm is a contagious disease of the outer layer of skin. It is caused by microscopic molds or fungi (Trichophyton, Achorion, or Microsporon). All animals and man are susceptible. It is a fairly common parasite worldwide. It is less common in free-ranging hogs than those penned closely together because it is spread through contact.

Life Cycle

The period of incubation for this disease is about one week. The fungi form seed or spores that may live 18 months or longer in barns or pastures.

Prevention

Affected animals should be isolated. Everything that has been in contact with infected pigs should be disinfected (impossible at times).

Symptoms

This disease produces ugly round scaly areas almost devoid of hair around the eyes, ears, side of neck, and tail. It may form gray, powdery crusts that gradually increase in size. The pig will be discomforted by the disease, but the economic losses are so low that it may not warrant treatment.

Treatment

Tincture of iodine and alcohol can be used to clear up the infection. You may not find that the expense justifies the treatment.

4. Screwworm

Screwworms affect all types of livestock and will infect man if given the opportunity. They have been nearly eradicated in the U.S., but are still a problem in many other parse of the world, especially in subtropical ant tropical zones. In infested areas, it is one of the most bothersome parasites and can literally destroy herds of animals.

Life Cycle

The primary screwworm fly is bluish green in color, with three dark stripes on its back and reddish or orange color below the eyes. The fly generally deposits its eggs in shingle-like masse e on the edges or the dry portion of wounds. From 50 to 300 eggs are fait at one time, with a single female being capable of laying 3,000 eggs in a life time. Hatching of eggs occurs in 11 hours, and the young whitish worms (larvae or maggots) immediately burrow into the living flesh. There they are feed ant grow for a period of 4-7 days, shedding their skin twice during this period. When these larvae have reached their full growth, they assume a pinkish color, leave the wound, and drop to the ground, where they dig beneath the surface of the soil and undergo a transformation to the hart-skinned, dark-brown, motionless pupa. It is during the pupa stage that the maggot changes to the adult fly.

After the pupa has been in the soil from 7-60 days, the fly emerges from it, works its we, to the surface of the ground, and crawls up on some nearby object (bush, weed, etc.) to allow it wings to unfold and otherwise mature. Under favorable conditions, the newly emerged female fly becomes sexually assure and will la, eggs 5 days later. During wane weather, the entire life cycle is usually completed in 21 days, but under cold, unfavorable conditions the cycle we, take as many as 80 day.

Prevention

Keep the number of wounds on your pigs to a bare minimum. Screwworms must have access to a wound to be able to enter the pig.

Symptoms

Maggots burrowing in and around a wound producing a wound full of reddish-brown pus that almost completely covers the wound and larvae or maggots. The wound will drain continually. The pus will turn attract house and bow flies.

Treatment

All wounds should be treated with a smear or spray containing lindane, ronnel, or diphenylamine to prevent the invasion of tissue by fly larvae. If these are not available use a thick petroleum grease to cover the wound.

5. Ticks

Ticks are destructive blood-sucking parasites found in most, if not all, countries of the world. In tropical and subtropical zones they can severely damage the profit of an operation. They affect all warm blooded animals including man. After sucking blood they can survive long periods of time without a host. Ticks have been grouped into the "hard" and "soft" categories. Hard ticks have a more damaging effect on livestock.

Life cycle

There are one-host ticks, two-host ticks, and three-host ticks. With one-host ticks, the larva and nymph live on one host while the adult completes the cycle on a second host. In three-host ticks the engorged larva drops from the host and molts to the nymph on the ground. The nymph attaches to another animal (possibly of another species) engorges again, falls to the ground, and molts to the adult stage.

Hard Ticks:

The Cayenne tick is found on swine in Central & South America. The Bont tick (3 hoes) is found in southern Africa.

The Tropical Bont tick (3 hoes) is found in Eastern, Central, and West Africa. They are more common in the rainy season that the dry season.

Prevention

Avoid contact between your swine and wild animals. Avoid grazing swine in areas of brush that are infected with ticks. Remember that in addition to the blood losses to ticks and the resulting stunted growth, that ticks are vectors for many different bacterial and viral infections.

Symptoms

Ticks are commonly attached near the ears, neck, and flanks but can be found over the entire body during bad infestations. Most swine will tolerate a few ticks but become irritable as their numbers increase. They will rub, scratch, and gnaw at the site of infection. This in turn can cause irritated and raw skin which is prone to secondary infections. Most ticks can be readily seen by the naked eye.

Treatment

They can, in some cases, be removed by hand. If you practice this then be sure to check yourself out later to see if you have ticks. Treatment with acaricide washes is good for swine. Dusts will not reach all the ticks. A wash or spray could contain: 0.5% malathion or 0.05% lindane or rotenone.

Table 2-9

Handy Spray and DIP Guide for Control of Lice of Swine