Myonecrosis and cutaneous infarction associated with Salmonella serovar Infantum infection in a horse.

This study investigates a case of Salmonella serovar Infantum infection in a horse, which resulted in oral ulcers, limb edema, weight loss, weakness, and eventually myonecrosis leading to the horse’s euthanization.

Case Presentation and Physical Examination

• The study examines a specific case of a 5-year-old Quarter Horse mare that showed symptoms of oral ulcers, limb edema (swelling due to fluid accumulation), weight loss, and weakness.
• The physical examination found a significant and widespread swelling on the left hind limb of the horse, and the horse was lame on the same limb.
• Further physical examination showed firm swellings, ranging between 2 and 15 cm in diameter. These comprised nodules, plaques, and discrete masses located on both sides of the neck, over the right shoulder and left elbow region, and on the caudoventral aspect of the abdomen.

Laboratory Findings

• Lab tests revealed hypoproteinemia (abnormally low levels of protein in the blood), neutrophilia (higher than normal neutrophil count), and hyperfibrinogenemia (excessive fibrinogen in the blood).
• Ultrasonographic scans of the left hind limb and masses indicated muscle edema, necrosis (cell death), and hemorrhage (blood loss).
• The histopathological examination of a biopsy sample from a subcutaneous mass showed necrotizing, suppurative myositis (inflammation and infection of the muscle with pus formation).

Final Diagnosis and Outcome

• The horse’s condition progressively worsened, leading to the difficult decision of euthanasia.
• Necropsy (postmortem examination) revealed myonecrosis (muscle tissue death), cutaneous infarcts (tissue death due to lack of blood supply), hepatic abscesses (pus-filled cavities in the liver), and cholangitis (inflammation of the bile ducts).
• Salmonella serovar Infantum bacteria were identified in cultures from liver and muscle lesions. As a result, a diagnosis of Salmonella myonecrosis was made.