Role of Water Medication in swine Deworming | Dechra UK

Worm Infestation in Pigs

The Parasite


Ascaris suum is the most common worm causing milk spot liver. As clinical signs are subtle, pigs may not show any signs of disease, the growth rates may be reduced, and may be more susceptible to other (respiratory) infections.

  • Excretion with the faeces of eggs that are very resistant
  • In the environment, eggs pass from non-infective, non-embryonated to infective, embryonated eggs
  • Swallowing of infective eggs
  • Larvae from the eggs travel through the digestive mucosa and move to the liver, causing white spots
  • Larvae migrate up through the lungs and are swallowed
  • Larvae become adult worms in the gut and start producing eggs

Swine deworming - worm infestation diagram

Importance of parasite cycle

Eggs are resistant to desiccation, heat, and cold, and can remain viable in the soil for up to 10 years under favourable conditions.

The total interval between the intake of embryonated eggs from the environment and the re-excretion of new eggs (prepatent period) is six weeks. This interval form the basis for an adequate deworming programme.

Liver milk spot lesions are a red flag. Larvae of embryonated eggs migrate through the liver and lungs before growing into adult worms in the gut. This migration causes damage in the liver (milk spots) and in the lungs (coughing, secondary bacterial infections e.g. Mycoplasma and A. pleuropneumoniae)

Why invest in a good deworming

  • Worm infestations have a negative impact on an average daily profit and feed conversion.
  • Not only does this lead to increased feed costs but also pig carcasses will have lower lean meat, resulting in lower value.
  • Less will also be paid due to milk spotted livers, or even nothing in severe cases.
  • Finally, worm infections can pave the way for respiratory infections leading to mortality and/or additional treatment cost.