FieldDxStephanurus dentatus kidney infestationClinical signs, differential diagnosis, treatment and prevention in pigs.
Overview
A parasite of wild, feral and outdoor pigs in warm climates, usually subclinical but able to impair growth and productivity. Stephanurus dentatus, a stout worm 2-4.5 cm long that lies in pairs along the ureters, perirenal fat and kidney after larvae migrate through the liver.
Clinical signs
- Poor growth when worms are numerous.
- Liver cirrhosis, scarring, portal vessel thrombosis and necrosis from larval migration.
- Possible kidney and lung damage.
- Eggs in the urine when worms are in the kidney or ureter-linked cysts.
- Economic loss mainly from organ condemnation.
Predisposing factors
- Outdoor or extensive rearing, and wild or feral populations.
- Warm tropical and subtropical areas.
- Eggs in urine become infective in 3-5 days; larvae enter through the skin or by ingestion, and earthworms may act as paratenic hosts.
- Larvae are killed by cold below 5°C, drying and sunlight; confined pigs are not considered at risk.
Treatment
Ivermectin given subcutaneously is effective against the kidney worm; the parasite is of little concern in confined pig production and mainly affects backyard or free-range herds.
Drugs mentioned: Ivermectin
Prevention
1. A gilts-only breeding programme, replacing older boars with clean-herd boars. 2. Rearing on concrete or in confinement for sanitation. 3. Anthelmintics such as ivermectin, doramectin or fenbendazole, repeated at 4-6 months. 4. In the US, feed-based drugs need a Veterinary Feed Directive.
Source
MSD Veterinary Manual — Swine Kidney Worm Infection (accessed 2026-08-12)
MSD Veterinary Manual — Swine Kidney Worm Infection (accessed 2026-10-29)
Condensed and attributed, never reproduced whole. Open the full entry in the app.