Farm Ireland
Independent.ie

Thursday 27 July 2017

Salmonella can be deadly for animals and humans

Peadar O Scanaill

The busy period has arrived for farmers and vets alike as the calving season is well under way. I was attending a Charolais cow a few weeks ago when a rather strange thing happened.

It was a cold, wet evening with a chilly wind. A cow in a pen beside us suddenly lay down and stretched flat out and began groaning. We dealt with the cow calving quite promptly and directed our attention to the collapsed cow. A hundred things went through my mind and every treatment possible was given to the cow. Despite all our efforts, the cow was dead by 4pm the next day.

The one outstanding sign that directed our thinking was how toxic her membranes looked. With the sudden and dramatic loss of such a valuable animal, a post-mortem was necessary to get to the root of the problem.

A very severe and extensive enteritis was discovered when we opened up the carcass and samples were taken to be sent to the lab.

In fairness to the staff at the regional veterinary laboratory, they could not have been more helpful or accommodating. The lab was about to close but the vet on duty stayed back and opened up for me to receive the samples. Civil servants can come in for some criticism at certain times, but the staff at the Dublin lab deserve full marks.

A diagnosis of acute salmonellosis was made and, sure enough, when we did a trawl over the entire farm, we could see the likely source.

Salmonella is a bacterium that can build up on any farm as the winter months creep on. It is normally a housing disease and it can strike any farm despite the best efforts of all concerned. There is a vaccine available, and any farm that has come through a salmonella outbreak will use the vaccine as a routine prevention for many years to follow. Footbaths at entry and exit points of any shed for personnel entering and leaving is a first line of defence.

Good, deep bedding and minimising faecal contamination in water troughs and feeding areas are all part of a prevention programme.


Salmonella can easily spread to humans, so every care should be taken to wash hands and wear protective clothing on the farm. Good wash-down facilities are vital and general hygiene is the order of the day.

I find that slightly brighter lights in a winter shed helps to show up the areas of dirt or wet, and go a long way towards prompting a farmer to clean up the dark corners.

Vaccinated cows will pass on good immunity in the colostrum, so ensuring adequate feeding of colostrum becomes a vital link in the chain of prevention. Antibiotics must always be the last line of defence and, if at all possible, should be avoided unless completely necessary. The reason for this lies in the fact that humans can die from a salmonella infection.

The medics tell us that, more and more often, they are meeting strains of this bacteria that are resistant to all antibiotics.

The development of 'super bugs', as they are commonly known, is a big problem in human medicine. Because of this, the medical profession would like it if we were not to use the class of antibiotics that are actually most effective in salmonella infections. The fear is that the more we expose the bacteria to antibiotics in our animals, the more likely the doctors will find resistant bacteria endangering human life.

So the points to note with regards to the farm control of salmonella are as follows:

- Good hygiene in farm sheds;

- Deep clean dry bedding where possible;

- Clean feed areas and wash water troughs;

- Footbaths at entrance and exit of sheds;

- Avoid mixing very young stock with older batches;

- Use vaccination programme correctly;

- Feed adequate 'primed' colostrum in first few hours of the calf's life;

- Wear protective clothing and wash down regularly and thoroughly.

Peadar ó Scanaill is a vet in Garristown, Dublin, and is a member of the food animal group of Veterinary Ireland. Email hq@vetireland.ie Tel: 01 4577976

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