External Parasites:Mange

Mange is a parasitic disease of the skin caused by one of two mites, either Sarcoptes scabiei or Demodex phylloides. Sarcoptic mange (sometimes called scabies) is by far the most common and important because it is irritating and uncomfortable for the pig, causing it to rub and damage the skin which becomes unsightly. It significantly depresses growth rate and feed efficiency.

The mite spreads directly from pig to pig, either by close skin contact or contact with recently contaminated surfaces. If pigs are housed in groups, there is increased opportunity for spread. The mite dies out quickly away from the pig, under most farm conditions, in less than five days. This is an important factor in control. If a herd is free from mange, it is one of the easiest of diseases to keep out because it can only be introduced by carrier pigs. However, once it is introduced it tends to become permanently endemic unless control measures are taken.

The common signs are ear shaking and severe rubbing of the skin against the sides of the pen. Approximately three to eight weeks after initial infection, the skin becomes sensitized to the mite protein and a severe allergy may develop with very tiny red pimples covering the whole of the skin. These cause intense irritation and rubbing to the point where bleeding may occur. Head shaking is a common symptom and hairs are often rubbed away leaving bare patches. The incubation period to the appearance of clinical signs is approximately three weeks although it may be several months before signs are noticed in large pig populations, particularly in feeder pigs housed in pens with solid partitions.

After the acute phase, thick lesions develop on the ear, along the sides of the neck, the elbows, the front parts of the hocks, and along the top of the neck. Persistent skin irritation with small red spots on the skin developing into thickened areas suggests the presence of disease. The skin of pigs can also be examined at slaughter for evidence of the small red pimples. Herds with active disease always show a high level of grade 2 or grade 3 lesions. Diagnosis is confirmed by demonstrating the presence of the mite. To do this scrapings are taken from suspicious lesions on the skin and particularly inside the ears. Mange mites, which are rounded in shape and only 0.5mm in length, may be just visible to the naked eye. However to positively identify the mite, the scrapings should be examined microscopically. Injectable ivermectin products are a readily available, highly effective treatment for mange.
Info from: Morris Vet Clinic

Kidneyworms

The kidneyworm, Stephanurus, is a short (1 inch), stout, black and white worm found in the fat around the kidney and sometimes in the kidney. Mature infections are found primarily in sows, since it takes nine months to one year after infection before eggs are produced by adult kidneyworms. Because infection occurs in and around the kidneys, eggs are passed in the urine.

Wooded lots and shaded farrowing pens often become contaminated areas where larvae hatch from eggs and enter the soil. Pigs may become exposed to infective larvae by ingestion, skin penetration and ingestion of infected earthworms. Larvae then move from the small intestine and eventually into the liver, where they remain for two to four months.

Other organs such as the lungs and spleen may also be infected. From the liver, larvae migrate to areas around and in the kidneys and even into back muscle. Most of the damage is found in the liver, which becomes heavily scarred, and in nearby muscle tissue. Outbreaks have occurred in southern Missouri with both breeding stock and market-weight pigs involved

Threadworm

This tiny intestinal worm, Strongyloides, occurs commonly in baby pigs. The adults (females only) are practically microscopic and live in the wall of the small intestine. Microscopic eggs are passed in the feces of pigs as young as 4 days of age. Farrowing pens, dirt lots and pastures become contaminated; larvae that are hatched may be ingested in water and feed or may penetrate skin. Most importantly, these infective larvae may be passed in sow colostrum so that infection takes place at first nursing. Prenatal infections can also occur. Heavy infections may cause intensive scouring in neonatal pigs, resulting in acute dehydration. Protective immunity develops rapidly in pigs not overwhelmed by this early infection.