On June 18, an 18-year-old Paint mare in Montgomery County, Maryland, tested positive for salmonellosis. The mare developed clinical signs on June 14, including fever, diarrhea, and systemic inflammatory response syndrome. She was referred to an equine hospital for evaluation and treatment under isolation protocol. 

Fecal samples collected upon hospital admission tested positive for Salmonella by PCR and culture. The mare has reportedly improved with treatment. Several other horses at the mare’s home farm have also been treated for fever, diarrhea, and/or colic over the past week. 

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Salmonellosis

Salmonellosis is a contagious and zoonotic bacterial infection caused by Salmonella spp, which causes enterocolitis. Clinically normal horses can transiently shed Salmonella, with shedding more common during: 

• Concurrent illness: antibacterial usage, physiological disturbance
• Stress: transportation, social, nutritional 
• Gastrointestinal disturbance: motility (especially colic), feed change

Clinical signs of salmonellosis include diarrhea, fever, lethargy, anorexia, colic, localized infection, sepsis and septic shock. Foals are commonly more seriously affected with profound systemic illness, including hemorrhagic diarrhea, pneumonia, meningitis, inflammation of growth plate and septic arthritis. 

Treatment of the severe form of salmonellosis is based on IV fluid and electrolyte replacement and efforts to control the host’s responses initiated by the systemic inflammatory response.

Prevention of salmonellosis is difficult, because the organism is present in the environment as well as in the feces of some healthy animals. Isolation and increased biosecurity are needed to prevent spread of the disease.