Keep a watch out for Salmonella Dublin in beef suckler herds

Although only ten per cent of our diagnoses of Salmonella Dublin come from beef herds, on farms which experience an outbreak, it can have a significant impact on health and mortality rates during a calving season.

The last time we experienced a higher number of cases was in the spring of 2018 associated with cows and calves being housed together for longer than expected associated with bad weather and ‘the Beast from the East’. This year is similar but different hence bringing this to your attention. We have cases from a couple of farms being worked up at the moment that are suspicious.

In dairy herds, the clinical presentation is often confined to one age group within a herd, i.e. some herds experience predominantly abortions, others calf health issues and others diarrhoea in adult cattle. We have tended to find that in beef herds it can present within one herd with a range of presentations in a range of age groups. This likely reflects that beef herds are often more naïve and there is increased contact between different ages of cattle.

In beef suckler herds:

• 28% of the diagnoses were in adult cattle, of which 40% were abortions
• The abortion rate in affected herds ranged from 2% to 5% at the time of submission
• The only other clinical sign noted in adult cattle was diarrhoea
• 72% of the diagnoses were in calves less than six months of age
• The peak age of diagnosis was between one and four weeks of age, with 60% of calf diagnoses in this age group
• Mortality rates were high in calves, with up to 18% mortality at the time of submission

The clinical presentation in calves was more varied, as shown in the table below:

Control in dairy herds is aided by snatch calving, so control in beef herds can be more challenging. With 50% of calves and 80% of cows affected within a month of calving this period is critical for control. Some pointers are below:

• Hygiene of the calving pen becomes critical in beef herds to limit transmission from cow to calf and also between cows
• Carrier cows are more likely to shed around calving, and cows which become infected around calving have an increased risk of becoming a carrier, therefore maintaining infection within the herd
• Infection in beef herds tends to build up in the environment towards the end of the calving period, so either grouping cows by expected calving date if known, frequent bedding or using a separate area for the second half of the calving period will limit contamination. Avoid overstocking where possible
• Minimising the age spread of calves in a group will reduce spread from older, recovered calves. In the face of an outbreak, splitting the herd into smaller groups will reduce transmission
• Weather permitting, getting cattle outside as quickly as possible will help to limit transmission, assuming the grazing is clean
• If calving outside, avoid using the same pasture for the whole of the calving period

Many of the control measures are sound general advice which will help with the control of many neonatal calf diseases in the suckler herd.

If calf mortality or scour, respiratory or neurological problems are an issue for your beef herds this year, consider Salmonella Dublin as a possible cause. Diagnosis can be made at the time of the outbreak by culturing faeces, or post-mortem samples, or retrospectively using serology.

Posted by SRUC Veterinary Services on 17/04/2024