Worms can have a negative influence on the condition of a pigeon negative , no birds will reach top form. Moderate worm infestations will have more symptoms such as weight loss, bad moult, diarrhea, and fatigue and to throw a little down. It can also negatively affect fertility. Hairworms are mor damaging for pigeons than roundworms. It is recommended in case of a worms to always treat the pigeons. It is recommended that the pigeon is treated again between 8 days and three weeks after the first treatment. There are several anthelmintics available. Worm Capsules (one capsule per pigeon) for individual treatment, worm liquid (8 ml per 2 liters drinking water) or Worm Powder for couple therapy. It is recommended to burn the lofts.This is the only effective method to kill eggs in the lofts. After a few days of treatment a vitamin preparation can be given. Farvisol for example.