Necrotizing mycotic vasculitis with cerebral infarction caused by Aspergillus niger in a horse with acute typholocolitis.

This study presents a case of an 18-year-old Morgan mare that suffered from cerebral infarction caused by Aspergillus niger necrotizing mycotic vasculitis. The horse, initially presented with diarrhea and depression, progressed to severe health complications and ultimately died. A postmortem examination revealed multiple affected areas in the body and irregularities in the brain tissue.

Clinical Presentation of the Horse

• This Morgan mare was brought to the Veterinary Medical Teaching Hospital at the University of Illinois with symptoms including watery diarrhea, depression, and difficulty in swallowing (dysphagia).
• Upon examination, the horse was found to be severely dehydrated and depressed with incapability to swallow, although no clinical signs of diarrhea were currently present.
• Other vital signs including respiratory and heart rates, and body temperature were found to be normal.
• After initiating fluid therapy, the mare presented severe watery diarrhea and its indication of mental depression and difficulty in swallowing continued. It showed lack of coordination in its movements as well.
• The horse died four days after being admitted to the hospital.

Postmortem Findings

• In examination after death, signs of an acute cerebral infarction in the right cerebral hemisphere, acute necrotizing typhlocolitis, and different types of hemorrhages were found.
• Additionally, the autopsy revealed issues with the pituitary gland and adrenal cortices, including enlargement, congestion, and necrosis along with hemorrhage.
• A closer look at the brain tissue revealed areas of coagulative necrosis, along with hemorrhage, inflammation of the blood vessels (vasculitis), and blood clot formation (thrombosis).
• Upon further histological examination, many fungal hyphae were present in the arterial walls and throughout the necrotic tissue.

Identification of Aspergillus Niger

• An immunohistochemical analysis was performed to determine the cause of the mycotic vasculitis and infarction in the brain.
• This study revealed Aspergillus niger, a common fungus in the environment, as the etiologic agent responsibile for these conditions.
• Notably, both bacteria culture and additional immunohistochemical testing of the colon and cecum could not identify any specific pathogens.

In summary, this case study illustrates a rare instance of Aspergillus niger causing necrotizing mycotic vasculitis and cerebral infarction in a horse. As such, it adds to the body of veterinary knowledge, potentially aiding in future cases involving similar symptoms and pathogens.