Salmonellosis in horses usually causes diarrhoea, but the bacteria can cause more severe illness and even death in foals and adults. Horses may be infected and not show signs of disease, and these horses can shed the bacteria, contaminate environment and infect other horses, animals and humans. The bacteria are easily spread and difficult to control and eradicate. However, good general hygiene and management techniques can help prevent problems in horses. The common symptoms seen in sick horses are profuse foul-smelling dark diarrhoea and colic symptoms. The horses may have toxins and bacteria in the blood stream (sepsis) and this can lead to purple membranes, toxic shock, bleeding disorders and death. In foals sepsis is more common, and the bacteria are quickly spread to many organs in the body, and death is highly likely. Salmonella can also cause abortions.
The best way a stable can protect against Salmonella is to pay strict attention to cleanliness, prevent overcrowding, and limit possible exposure. It is important to remove potentially infected manure from stables and paddocks. The environment can quickly and extensively be contaminated by horses with salmonellosis because the diarrhoea and bacteria therein can diffuse into cracks or stalls, contaminate watering devices, bedding and equipment. Effective mechanical cleaning and disinfection are necessary to minimize bacteria in the environment. The bacteria can also easily be transmitted by the horse care-takers. Consider working with infected horses last, and using separate equipment and clothing. The horse trailer may have been infected by transportation of horses shedding bacteria and should be thoroughly mechanically cleaned and disinfected.
The most important treatment for a horse with salmonellosis is good supportive care and fluid therapy. The horses quickly get dehydrated with electrolyte and acid/base disturbances. It is important to rapidly contact a veterinarian in cases of diarrhoea in horses, since the horse is very sensitive to disturbances in the stomach flora. Fluids and electrolytes are crucial, and may be given intra-venous and oral. Anti-inflammatory drugs can minimize the inflammation in the gut, make the horse feel better, and possibly prevent laminitis. The use of antimicrobial drugs for adult horses with salmonellosis remains controversial. The antibiotics may likely kill good gut bacteria that ferment and digest feed, and sterilizing the gut in horses is not good. Supplements to promote and support a good gut bacterial flora may be of value. Horses that have diarrhea for more than 10 days are at high risk of dying due to the damage to the large intestines.
World Health Organization
Center of Disease Control and Prevention, USA
US Food and Drug Administration, Bad Bug Book.
US Morbidity and Mortality Weekly Reports on Salmonella
European Public Health Agency-Assessment of sources for foodborne Salmonella
Salmonella infections associated with reptiles
European Center for disease prevention and control EFSA-ECDC report on trends and sources of zoonoses in the European Union in 2007