Rod shaped gram negative bacteria which are intracellular parasites and some of which may cause disease. They are spread through the consumption of faeces or faecally contaminated material and can cause severe watery diarrhoea, fever and lethargy in both foals and adult horses (Salmonellosis). The bacteria can spread between horses and to horses from other animals, birds, or humans. Humans can be infected from horses with Salmonellosis. Salmonella may inhabit the intestine of healthy horses and cause disease only when the horse is stressed by travel, surgery, or other disease. Some horses, probably around 1%, may shed salmonella long term. Treatment of acute Salmonellosis requires appropriate antibiotics and possibly fluid replacement therapy under veterinary supervision.