”Three-week” diarrhea is associated with bacteria - mainly E. coli, parasites – mainly Isospora suis or viruses – such as rotavirus, but also other infectious agents have been found. Isospora suis and rotavirus are also found in animals without clinical symptoms.
Post-weaning diarrhea is generally found 5 to 14 days after weaning and is often associated with E. coli. Symptoms vary from subclinical infections to per-acute disease with fatal outcome. Oedema disease is a per-acute disease during this period and is caused by vero-toxin producing E. coli. Oedema disease is often fatal and piglets sometimes die without displaying any symptoms due to the rapid progres- sion of the disease.In order to get an etiological diagnosis of diarrheas in this time period the clini- cian in charge is recommended to perform autopsies, if possible, and to obtain a bacteriological diagnosis, including a test for sensitivity. If oedema disease is suspected it should be stated on the referral form.
”Three-week” diarrhea – for treatment of E. coli-related diarrheas, please see piglet diarrhea above. There are no effective therapies for viral diarrheas except feeding electrolyte solutions. Herd health problems caused by I. suis should be treated by initiating preventive measures, see above.
Post-weaning diarrhea – if diarrhea is found in a litter of newly weaned pigs the first action is to withdraw or drastically reduce the feed for the next 24 hours.
The amount of feed should then gradually be restored to the desired amount. Electrolytes should be served to reduce the risk of dehydration and to compen- sate for the loss of feed. It is recommended to add peat to the bedding in order to normalize gut peristalsis and to improve hygiene. If the diarrhea cannot be cured through these initial measures individual pigs may be treated with Trimethoprim/sulfa parenterally. Another antibiotic may be chosen if supported by bacterial diagnosis and a sensi- tivity test.
If more than 10 % of litters are treated annually with antibiotics a herd health investigation should be initiated. In severe cases, and when a large proportion of the herd is affected, group therapy may be indicated, see Strategies for group treatment.
The process of weaning is stressful for the young pig. Age and weight at weaning is of great importance. A prolonged period for suckling is indicated for those litters that are born late in the farrowing batch. Other positive factors are good hygiene, proper heating and good quality feed of correct composition.
The principle of “all-in-all-out” to reduce bacteria load and enable cleaning, disinfection and drying of floors should result in good, clean conditions in the cubicles. If the herd suffers repeatedly from post-weaning diarrhea Zink oxide may be mixed into the feed, see Strate- gies for group treatment.
General preventive measures, including composition of feed, are of particular importance to prevent oedema disease. The course of the disease may be so rapid that the pigs die before therapy can be administered and the prognosis may be unfavorable even with treatment. Vaccinating against oedema disease has been tried in Sweden but with limited success.