Experimental Salmonella anatum infection in horses.

This study entails the effects of orally administered Salmonella anatum to horses, identifying four type of responses, all leading to excretion of the organisms. The severity of the symptoms and the dosage appeared correlated.

Overview of the Research

In this experimental research, Salmonella anatum, a bacterial organism, was orally administered to eight horses on eleven occasions, and the reactions were observed in regards to clinical, pathological, and laboratory findings. The study was essentially exploring the effects of Salmonella anatum infections in horses.

Clinical Observations

• Four distinct syndromes were noted based on various indicators like clinical and pathological changes. These include the asymptomatic syndrome where there were no noticeable symptoms, moderate clinical signs that came with or without changes in faecal consistency, a third characterized by fever, depression, and anorexia coupled with diarrhoeic faeces, and lastly, septicaemia, where diarrhoea and peripheral circulatory failure were observed.
• The severity of syndromes increased with the dosage of Salmonella anatum given, indicating a correlation between the administered dosage and effects.
• All subjects excreted the Salmonella anatum organisms, implying that this form of bacterial infection may be highly communicable among horses.

Laboratory Observations

• The researchers found that peak temperature generally came before the onset of diarrhoea by around one or two days.
• Changes in a horse’s faecal consistency appeared to be directly associated with the isolation of the Salmonella anatum organism.
• A significant increase in neutropaenia, a condition characterized by an abnormally low number of neutrophils, was observed with higher doses of the bacteria.
• Blood cultures were largely unsuccessful, with just one among 33 samples returning a positive result. This suggests that blood culture might not be the most effective means of detecting this type of infection.
• Despite some animals displaying a significant seroconversion consistent with the clinical reaction, the serological responses were determined as insignificant.

Use of Indomethacin and Autopsy Findings

• An attempt was made to moderate intestinal fluid secretion using indomethacin, a nonsteroidal anti-inflammatory drug (NSAID), but this was unsuccessful.
• The autopsy results, including both distribution and quantitation of positive cultures, closely reflected the type of syndrome that each horse had developed.
• The study confirmed the invasiveness of the organism by frequently recovering it directly from intestinal wall and draining lymph node samples.

Comparison of S. anatum and S. typhimurium

• The research concluded that Salmonella anatum appeared be of similar pathogenicity to Salmonella typhimurium in horses under experimental conditions.