What is Salmonella?

Salmonella is a bacterium that can cause severe diarrhoea in foals and adult horses. 

There are many types of salmonella, but the most common one in horses is Salmonellatyphimurium, an organism that can also affect cattle and humans.1

The most obvious sign of salmonella is debilitating diarrhoea, which can prove deadly.1 Dehydration also results.1

The infection can cause septicaemia – bacterial blood infection that can spread to multiple organs and lead to death – particularly in foals.1

Signs of septicaemia include:

  • High fever
  • Dullness and depression
  • Bacterial spread to other organs
  • Possible death within 24 to 48 hours

Salmonella typhimurium infection is spread easily, either directly or indirectly.1

  1. Horse-to-horse contact – some horses can transmit the bacteria even if they have no signs of illness themselves1
  2. Shared tools, equipment and water buckets1
  3. Foals can become infected while nursing if their mother has released bacteria in her faeces1

Minimising risk

In addition to vaccination, strict hygiene practices and limiting the possibility of exposure to infection are the best ways to protect against salmonella.1

  • Get rid of faeces as soon as possible to avoid exposure to the bacteria.1
  • Isolate any horse or foal that has symptoms.1
  • If you have a sick horse, make sure you don’t spread the infection – always wash your hands after touching the horse, and ensure you don’t walk through watery faeces and then track it around your property.1
  • Don’t be tempted to move any horses that were in contact with the sick horse – they may be incubating the bacteria so you may be spreading the disease to otherwise unaffected horses. Instead, move the sick horse, disinfect its stall and closely monitor the others.1

You can help protect your foals and mares by ensuring they are vaccinated with Equivac® EST. The vaccine aids in the control of diseases caused by Salmonella typhimuriuminfection.

Your foal can get this vaccination from 4 months of age. Initially, your foal will need a second dose after 4 weeks, and if still under 12 months old, it should be followed by a booster dose 6 months after the second dose. Protection can then be maintained with annual boosters.

Equivac® EST can also help protect your pregnant mares, even if they have not been previously vaccinated, provided the first vaccine is administered at least 10 weeks before foaling– ask your vet for details.

For more details about Equivac® EST and correct dosing information, visit the Products section of this site. 


  1. Salmonella in Horses. The Horse, May 2005. Available online: Accessed 26/8/13.

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