Calf scour (diarrhoea) can be caused by one or more of the following agents:
Independent surveys have consistently shown that the vast majority of scours are caused by either viruses or cryptosporidia. In these cases antibiotics have no effect. However, vaccines are available to prevent scours caused by rotavirus, coronavirus, E.coli and Salmonella spp. The vaccines are normally administered to the dam between 12 and 3 weeks prior to calving. In the case of Salmonella vaccines, these can also be administered to healthy calves from 3 weeks of age.
As yet it is not possible to prevent scours caused by cryptosporidia, which, because of the success of vaccination against the viruses, has now become the single biggest cause of calf scour.
Scour in calves occurs because the calf is unable to maintain a correct balance between fluid intake (absorption) and fluid loss, with fluid loss greatly exceeding the fluid absorbed. The one inevitable effect of scour, regardless of its cause, is dehydration due to the loss of excessive amounts of fluid. Electrolytes (e.g. sodium, potassium, bicarbonate) are also lost in large quantities. In severe cases of scour, dehydration and electrolyte loss lead to a number of other damaging effects such as a reduction in blood circulation, acidosis, impaired kidney function, and even death.
Dehydration is responsible for much of the setback associated with scour whatever its cause, and consequently rehydration therapy is the most appropriate initial treatment for scour. If bacterial infections are associated your veterinary surgeon will probably decide to use an appropriate treatment.
For relatively mild cases, oral rehydration therapy (e.g. with Effydral) will often reverse the dehydration and the electrolyte imbalances. In severe cases of dehydration some animals may need additional intravenous rehydration therapy. In such cases consult your veterinary surgeon.
Effydral is available from veterinary surgeons, co-ops, pharmacists and licensed merchants.