Diseases caused by Salmonella bacteria are some of the most important diseases found in cattle. Not because they are very common or because infection causes high disease and death rates, but because all salmonellae found in cattle can potentially spread to humans.
A wide range of salmonellae have been isolated from cattle in the UK, most of them only occasionally. The most common type of Salmonella affecting cattle in the UK is currently Salmonella Dublin.
S. Dublin causes a wide range of diseases in cattle, not just diarrhoea.
Disease in Adult Cattle
- Fever, dullness, decreased appetite and milk drop
- Severe bloody (and often watery) diarrhoea with blood, mucus and casts
- Death occurs in around 75% of affected animals if they are not treated.
- Abortion due to S. Dublin is the most commonly diagnosed cause of abortion in UK laboratories.
Disease in Calves
This is much more variable. It is usually seen in calves between two and six weeks of age. However, because the disease can be slow to resolve, older infected calves can be seen.
Clinical signs include
Pasty diarrhoea, which becomes bloody and watery with an offensive odour
- Calves become dehydrated, collapse and die
- Calves may also die suddenly with no previous diarrhoea
- Pneumonia, stiffness, joint-ill and meningitis are also seen
Control of Salmonella
Diagnosis in affected adults is relatively easy, as large numbers of bacteria are found in faeces (or in aborted calves). In calves a proper post mortem examination is much more useful.
Control and Prevention
In infected herds, infected animals must be separated and isolated away from the rest of the animals.
Ensure that infected cows do not come into contact with calving cows, as they have the highest risk of infection.
Also, ensure that milk from ill cows is not fed to calves, or do not consume unpasteurised milk from infected or in contact cows.
Hygiene is essential.
Clear out and disinfect all calving boxes thoroughly and if you have infected calves clean and disinfect calf pens.
If possible use temporary facilities to allow bacterial numbers to decline even further.
Vaccines are available, however once S. Dublin has entered a herd, vaccination alone will not control the spread of infection. Good husbandry and hygiene is essential if control is to be achieved.
Two injections spaced 3 weeks apart, the second injection should be given at least 3-4 weeks prior to the high risk period (Calving). This ensures adequate protection at time of risk and provides good maternal antibodies to the calf via the colostrum.
Healthy calves can be vaccinated from 3 weeks of age, and require 2 injections spaced 2-3 weeks apart.
An annual booster is required consisting of a single injection at least 2 weeks prior to the 'at risk' period. Ideally 3-4 weeks prior to calving.
Please contact one of our vets if you require any more information or you wish to discuss a vaccination protocol tailored to your individual farm requirements.