Death of a horse infected experimentally with Anaplasma phagocytophilum.

This study follows the path of a 19-year-old horse that was part of a larger group that was intentionally infected with Anaplasma phagocytophilum, the bacteria responsible for equine granulocytic ehrlichiosis. Despite having similar clinical signs and lab findings as the others, this horse suffered widespread internal bleeding and vasculitis in its kidneys, leading to its sudden death two days after symptoms first emerged.

Study Overview

• This particular research focuses on a group of six horses that were experimentally infected with the bacterium Anaplasma phagocytophilum. The purpose of the study was to observe and document the pathogenesis, or disease development, of equine granulocytic ehrlichiosis – a bacterial disease common in horses.
• One of the horses in the experiment, a 19-year-old, exhibited similar clinical signs and lab results as the other horses, but unexpectedly died after only two days of expressing disease symptoms.

Clinical Signs and Laboratory Findings

• The clinical signs and lab findings observed in the horses were similar with all infected horses. No information is provided on what these signs were or how they were similar to previous reports of this disease.
• The unexpected turn of events came when a 19-year-old horse suddenly died after only showing clinical signs for two days. This was a speedy and unforeseen progression for a horse that was behaving similarly to the others in the study.

Postmortem Examination

• The ensuing postmortem examination on the deceased horse revealed widespread internal hemorrhaging (bleeding), and inflammation (vasculitis) and clotting in the blood vessels (thrombosis) in the horse’s kidneys.
• These findings were consistent with a condition known as disseminated intravascular coagulation (DIC). DIC is a serious disorder where the proteins that control blood clotting become overactive. This results in small blood clots developing throughout the bloodstream, blocking small blood vessels and using up all available clotting proteins, potentially leading to severe bleeding.

Relevance to Human Health

• This observation is significant because the same clinical progression has previously been noted in humans infected with what is presumed to be the same bacterium. It is known as human granulocytic ehrlichiosis in humans.
• This could potentially provide valuable insights into how this bacterium operates in different organisms and may inform future treatments for both humans and horses infected with this bacterium.