Lice
Haematopinus suis
The stationary ectoparasites of the pig with a worldwide incidence are mange mites (Sarcoptes scabiei var. suis) and hog lice (Haematopinus suis). The introduction of mange mites and lice into a clean herd usually occurs as a result of purchasing infested stock. Transmission within the herd takes place by contact from pig to pig.
The service boar plays an important role in the transmission chain. Both mange and louse infestation can be described as typical factorial diseases which are favoured by malnutrition, inadequate management and high performance such as pregnancy and lactation. Under modern management systems with a high livestock density, ectoparasites can cause substantial economic losses and jeopardise the profitability of pig rearing and breeding.
Biology
The hog louse, Haematopinus suis, is up to 6 mm long and lives on the skin of the pig; sites of predilection are parts of the body where the skin is delicate such as throat, inside of the thighs, and skin folds. Their legs are equipped with strong terminal claws for attaching themselves to the bristles. Every day the females deposit 2-6 yellowish-white eggs (nits) approximately 1 mm long to the bristles with a water-resistant glue-like substance. After 12-18 days the 1st larval stages hatch (Fig. 5). The entire life cycle is completed in 20-29 days.
Clinical Findings
Hog lice suck blood approximately 6 times daily, each time feeding on a different site. The numerous bites and the crawling lice cause intense pruritus. Scratching can lead to skin lesions. The pruritus and the resultant restlessness interfere with feed con-sumption and conversion. This causes reduced production and stunted growth.
Economic losses
Infestation with hog lice causes production losses in sows and stunted growth in piglets, stores and fatteners. Blood loss and irritation due to the intense itching in severe louse infestation lead to reductions in weight gains which amount to 50 g/animal/day. Hog lice are transmitters of a variety of diseases caused by viruses, rickettsiae or bacteria. Severe infestation with hog lice damages the hides.