Rotaviral Diarrhoea The HAF RESEARCH data show that this year the most commonly diagnosed cause of calf diarrhoea was rotavirus infection.
Clinical Signs
- Calf over 4 days old, usually younger than three weeks
- Sudden onset pale yellow, pasty diarrhoea, sometimes with mucous and blood flecks
- Calves are dull and reluctant to drink
- Diarrhoea usually lasts 4 to 8 days
- Can become severely dehydrated, especially if mixed infections
Diagnosis
- Clinical signs are not enough to make a diagnosis
- Examination of faeces for presence of virus. However it is important to remember that rotavirus is found in healthy calves, so examination of faeces from more than one calf is necessary
- Diagnosis depends on an accurate history, clinical signs, and proper specimen collection and submission to a laboratory
Treatment
- Oral fluids are the most important line of treatment. They prevent dehydration, correct acidosis, and lost salts. The best electrolytes are far more than just a salt and glucose solution. Ask your veterinarian for advice as to the which oral fluid to use.
- The best method of administration of oral fluids is allowing the calf to drink the electrolyte solution naturally, as electrolyte given by stomach tube may be deposited in the rumen and remain there, delaying absorption. If the calf is not drinking, stomach tubing is indicated. If the calf collapses then intravenous fluids should be given
- Antibiotics: The use of antibiotics to treat calf diarrhoea is controversial, particularly if rotavirus is the main cause. Antibiotics will not kill the virus, but they can reduce secondary bacterial infection. Antibiotics are probably best used when the calf does not respond well to oral fluids
- Other drugs. There is little evidence that the myriad of compounds used to treat diarrhoea have any significant economic benefit
Prevention
Prevention is the key
Hygiene: This is vital, with disinfection between calves being essential. Keeping calves in hutches outside can significantly reduce the incidence of diarrhoea, probably because the rotation of calves around the field prevents the build-up of pathogens.
Colostrum: Early immunity in new-born farm animals depends almost entirely on their obtaining antibodies via colostrum. The transfer of colostral antibodies is the single most important form of protection of the new-born calf. Although the calf is capable of responding to virus infection, such responses are delayed and often ineffective. Thus ensuring that the calf receives sufficient colostrum (at least two litres within six hours) is vital in the control of calf diarrhoea. However, this protection lasts for only three to four days, so only reduces rather than eliminates rotaviral diarrhoea. Continued colostrum feeding can extend this period and thus reduce the risk of rotaviral diarrhoea.
Vaccination: Vaccines are available for giving to the dam to increase the amount of rotavirus antibodies in the colostrum. The levels of antibodies in the colostrum of vaccinated calves are high enough to result in a protection period of at least seven days if given within 12 hours of birth. For farms with a severe rotaviral problem, continued feeding of colostrum from vaccinated dams can extend this period still further.