Abstract:
There have been a number of advances in pig management in New Zealand in the last 20 years, which might have led to changes in pig parasitic infections.
Four hundred and ten pigs from North Island farms were examined after slaughter for the presence of the nematode Hyostrongylus rubidus in the stomach, and the management methods used on these farms were determined. Some work was carried out to determine the pathology and pathogenesis of the infection.
Changes in housing, from earth-floored sties and open paddocks to clean, solid or mesh-floored buildings, and increased use of anthelmintics has led to a reduction in the percentage of pigs infected compared to earlier studies. A change in feed from milk to grain appeared to have little effect on the prevalence of the infection. A higher prevalence of H. rubidus was found in older pigs.
Ulceration of the gastric mucosa was seen in a minority of cases, but the most frequently encountered pathological effects were thickening of the mucosa and production of copious amounts of mucus. It was concluded that H. rubidus is capable of causing serious pathogenic effects, especially in the presence of secondary stress producing factors.
