Diarrhoea; pre-weaning occurs in pre-weaning piglets worldwide. Rotavirus infection and coccidiosis are the major causes of pre-weaning diarrhoea. Other agents such as E. coli may be involved as colostral protection wanes or when new strains are encountered and clostridia may colonise intestines damaged by other agents.
- Causes of Diarrhoea - pre-weaning >
- Effects of Diarrhoea - pre-weaning >
- Diagnosis of Diarrhoea - pre-weaning >
- Treatment & Control of Diarrhoea - pre-weaning >
- Medication/Vaccination for Diarrhoea - pre-weaning >
Causes of Diarrhoea - pre-weaning
Rotavirus infection and coccidiosis are the major causes of pre-weaning diarrhoea. Other agents such as E. coli may be involved as colostral protection wanes or when new strains are encountered and clostridia may colonise intestines damaged by other agents.
Transmissible Gastroenteritis and Porcine Epidemic Diarrhoea may also occur. Rotaviruses are double stranded RNA viruses with a characteristic wheel shaped appearance and can be classified by their viral proteins and nucleic acids into groups. Groups A, B C and E have been found in pigs Group A is usually the first to infect a piglet and is most common in pre-weaning diarrhoea.
Rotaviruses are relatively resistant, survive for 7-9 months at 18-20°C and are stable between pH 3 and 9. They may be cultured but require exposure to trypsin and agitation for continued subculture. Infection occurs in piglets which have not taken colostrum and when maternal antibody in milk declines from 2 weeks onwards.
Infection is oral and the virus replicates in the cells lining the middle small intestine from upper jejunum to lower ileum. Mature absorptive cells are shed and villous atrophy results. The resulting failure to absorb nutrients leads to diarrhoea containing virus particles. Recovery may be complete within 7 days.
Effects of Diarrhoea - pre-weaning
Pre-weaning diarrhoea is white or greyish because of the undigested milk present in the faeces and may occur in most litters from 14 days to 3 weeks or age or until weaning. Not all members of the litter develop diarrhoea. Some remain unaffected and others merely pass perfectly-formed white motions.
Affected piglets may be depressed, stop sucking and become reluctant to move. Vomiting may be seen. A few hours later, profuse diarrhoea develops and is white or yellow with floccules floating in a whey-like fluid, but may be grey in colour. Dehydration and rapid loss of condition may occur, but many affected piglets appear relatively normal. Appetite returns after 24-72 hours.
Clinical signs regress 4-6 days after infection but loose yellow faeces may persist for 7-14 days and the faeces of sucking pigs may remain whitish for a period after recovery. Thirty-three percent of affected young pigs may die in outbreaks where piglets do not have access to water, but mortality is usually much less and uncommonly exceed 1 piglet per litter.
Rotavirus diarrhoea may recur as immunity to one type does not prevent infection with others. The effects on growth rate range from nothing to at least 5 days to 25 kg.
Diagnosis of Diarrhoea - pre-weaning
Inspection of the pen floor, areas between slats, the vicinity of the drinker or the kerb of an outdoor pen reveals whitish or grey diarrhoea or white faeces. Bedding may make detection more difficult. Inspection of individual piglets may then be necessary.
Post-mortem examination of dead piglets confirms the presence of diarrhoea. The small intestines are thin walled with villous atrophy and filled with fluid, creamy contents. The large intestinal contents are fluid and creamy or greyish and there may be faecal staining on the perineum.
Rotavirus is the commonest cause, but is common in piglets of this age group regardless of the presence of diarrhoea. It can be identified in the faeces by the use of latex agglutination tests, user-friendly strip tests, demonstration of the particles by electron microscopy, confirmation of the presence of the RNA by polyacrilamide gel electrophoresis (which identifies it to group) and by nucleic acid methods such as the polymerase chain reaction. E. coli and the clostridia can be cultured from faecal samples, but confirmation of the presence of coccidia, TGE and PED may require the post-mortem examination of freshly killed piglets and careful examination of the mucosa.
Treatment & Control of Diarrhoea - pre-weaning
The severity of pre-weaning diarrhoea can be reduced markedly by the provision of piglet drinkers. If ion-replacement fluids can be administered through these drinkers and other husbandry factors such as environmental temperature corrected, mortality from this condition can be reduced further. Specific treatment depends upon the agents present.
There is no specific treatment for rotavirus, TGE or PED infection. Coccidiosis can be treated (but is best prevented) and those cases where E. coli and clostridia are important can be treated using oral antimicrobial dosers for 3-5 days.
Prevention depends upon the prevention of conditions such as coccidiosis by treatment and E. coli and clostridial infection by vaccination of the sow, ensuring that colostrum is ingested by the piglet.
Medication/Vaccination for Diarrhoea - pre-weaning
Vaccines have been produced which can immunise the sow against rotavirus and thus protect piglets by colostral immunity, but they are not available in all pig-keeping countries. Rotavirus survives in the environment, so infection may arise from environmental contamination. All-in, all-out husbandry should be practised in farrowing and rearing accommodation and should include a disinfection step using hypochlorite on clean surfaces and proprietary disinfectants such as a mixture of surfactant, organic acid, oxidising agents and buffers. Phenolic disinfectants are less effective.
