In Sweden the time post-weaning until slaughter is often divided into two stages (apart from the immediate post-weaning period) where the pigs first have a growth period, often in one facility, and then before slaughter, a fattening period. Diarrhea in the later part of the growing – and during the fattening period can have different etiologies. Samples for bacteriological culture should therefore
be taken from pigs with diarrhea, with the exception of wasting pigs. Pigs that exhibit blood stained or bloody diarrheas should always be sampled because of the possibility of dysentery. Brachyspira spp. and Lawsonia intracellularis may each cause clinical problems but are often found in mixed cultures. To arrive at the correct diagnosis and treatment the clinical symptoms should be supported by autopsy results and bacteriological culture or PCR. A sensitivity test should be included in the diagnostic package. Rapid changes in the feed type or composi- tion may lead to diarrhea, often caused by E. coli. Parasites with predilection sites in the large bowels may also cause diarrheas in these stages of the pig’s life.
In all cases of diarrhea the animals shall be offered fluids, preferably with electrolytes. Infections of the large bowels are often caused by Brachyspira spp. and the only effective antimicrobials are pleuromutilins and possibly tylosin. If B. hyodysenteriae is identified the aim should be to sanitize the herd. In the case of Lawsonia intracellularis-infections the drug of choice is tylosin. Chlortetracycline is an alternative but should not be used unless supported by a bacteriological culture result. Lawsonia intracellularis is generally sensitive to tiamulin, but use
of this antibiotic should be reserved for treatment of Brachyspira spp. Infections caused by L. intracellularis may be treated with pleuromutilins only when there are no other alternatives as uncritical use increases risk of development of anti- microbial resistance.
Trimethoprim/sulfa (T/S) is the drug of choice for cases of diarrhea caused by
E. coli. In case of non-responders to T/S use of some other antibiotic should be supported by bacterial culture and results of a sensitivity test.
Good hygiene, a warm environment and high quality feed are important when moving pigs to new facilities. Rearing pigs in batches with cleaning and disinfec- tion of the stalls and sufficient time to let the floors etc dry, reduces the bacterial load and leads to a favorable climate in the cubicles. With increasing age the pigs are less dependent on added heat. In the summer excess heat may lead to decreased hygiene in cubicles as the pigs search for cooler resting places.
If Brachyspira hyodysenteriae is found in a herd a sanitation program should be started. Sanitation comprises emptying, cleaning, disinfecting and drying out barns. All parent animals should be treated with tiamulin before returning to the cleaned and dried barns. Animals destined for slaughter or sale should not be allowed to return to the barns. The sanitation needs to be thorough and should preferably be done in the summertime. It is advantageous to, at the same time, intensify elimination of rodents.
Sanitation aimed at eradicating Lawsonia intracellularis and Brachyspira pilosicoli may be contemplated, but is costly and difficult to do. The risk of reinfection is high because of incomplete sanitation or reintroduction of the infections through purchase of new animals. A live vaccine against Lawsonia is available on the market.