HERD HEALTH
PIH-61
pork industry
handbook
COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA
Rotaviral Diarrhea in Pigs
Authors
Edward H. Bohl, Ohio State University,
O.A.R.D.C., Wooster, Ohio
James G. Lecce, North Carolina State University
Reviewers
Edward O. Haelterman, Purdue University
Ralph Vinson, Oneida, Illinois
Recently, a group of viruses known as rotaviruses has been found to be a frequent cause of diarrhea in the young of many different animals and man. In 1976, a porcine rotavirus was first reported as a cause of diarrhea in pigs. Since then, only limited information has become available about rotaviral diarrhea in pigs; thus, this report will be incomplete in many respects. However, since infections are very widespread and common in swine, especially infecting young pigs, this fact sheet is included in the Pork Industry Handbook.

The Cause
Rotaviruses have been isolated from different species of animals besides pigs. At least 2 other types, a bovine (calf) rotavirus and a human rotavirus, can also infect and cause diarrhea in pigs? however, there have been no reports of pigs being naturally infected with the bovine or human rotavirus. The name "rota", which is Latin for “wheel,” comes from the wheel-like appearance of the virus when seen through an electron microscope. Rotaviruses have been difficult to grow in the laboratory, and this has delayed the recognition of and the research findings on rotaviral diarrhea.

Clinical Signs and Epidemiology
Suckling Pigs. Rotaviral diarrhea has been reported in 1- to 6-week-old suckling pigs, but is probably most common in pigs about 3 weeks of age. It appears that rotavirus is one of the principal causes of a widespread and common type of diarrhea that has been variously referred to as white scours, milk scours or 3-week scours. Some veterinarians and pork producers believe that white scours occurs when pigs ingest more milk than they can digest, which often takes place in litters of high milk-producing sows at about 3 weeks of age. Suckling pigs under 1 week
of age seldom have rotaviral diarrhea, apparently because they have obtained sufficient immunity from nursing their mother. Rotaviral diarrhea has not been reported in pigs over 8 weeks of age.

The diarrhea is characterized by a white or yellow stool which, at the onset, is liquid; but after a few hours or a day, it becomes creamy and then pasty before returning to normal. The duration of diarrhea may be for only a few hours to several days. Vomiting occurs much less frequently than it does in transmissible gastroenteritis (TGE). In most cases, pigs remain active and lose little, if any, weight. Present information suggests that rotaviral infection in many pigs results in either no clinical signs of disease or only a mild disease characterized by a shortterm diarrhea. However, field observations indicate that the severity of the disease and the death rate are increased by concurrent infections with pathogenic Escherichia coli (colibacillosis) or TGE virus, by inadequate intake of immune milk, and by stress such as chilling. The disease is more severe in younger pigs. Diarrhea is more profuse and, thus, more noticeable in pigs that ingest a large amount of milk.
Outbreaks of rotaviral diarrhea will often be first observed in farrowing or nursery units in 3- to 4-week-old pigs. As the disease spreads, younger pigs are increasingly exposed to the virus and may experience diarrhea at 4 to 10 days of age.

In many respects, rotaviral diarrhea is similar to enzootic TGE (persistence of TGE infection in a herd). Sows are usually not sick in either disease. In enzootic TGE, the usual age for diarrhea is at 1 to 6 weeks of age, depending on management conditions, and the death loss may be from 0 to 20%. The duration of diarrhea is longer, and dehydration and death losses are greater in enzootic TGE than in rotaviral diarrhea.
Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U. S. Department of Agriculture Cooperating. H. G. Diesslin, Director, West Lafayette. IN, Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to its programs and facilities without regard to race, color, sex. religion, national origin, age or handicap.