Ocular changes in a horse with gutturomycosis.

The research article discusses a case of a 7-year-old horse developing visual and locomotor disturbances, recurrent epistaxis and eventual blindness due to a spreading fungal granuloma in the guttural pouch which further affected the optic nerve and chiasma. Microscopic investigation revealed the cause to be an infection by fungus of the Aspergillus species.

Clinical Presentation and Symptoms

The horse under examination was afflicted with varied systemic and neurological disorders. Key symptoms included:

• Recurrent epistaxis, or nosebleeds – a common symptom of guttural pouch disease in horses.
• Locomotor disturbances – indicating that the horse’s motor functions were affected.
• Visual disturbances leading to blindness – a severe manifestation resulting from the fungal granuloma’s spread to the optic nerves and chiasma.

Pathological Findings and Spread of the Disease

The fungus originated in the guttural pouch, from where it extended to various parts of the horse’s brain and visual system. The disease progression can be summarized as follows:

• The inflammatory site in the guttural pouch gradually reached the intracranial segment of the right optic nerve and the region adjacent to the optic chiasma – a crucial area where optic nerves cross over.
• Microscopic observations revealed multiple foci of ischemic infarction – an event where insufficient blood flow leads to tissue death – in the retina, optic nerves, optic chiasma, and optic lobe. This essentially meant that the fungus was causing severe damage in key areas of visual perception and transmission.

Identification of the Causal Fungus

The researchers identified the fungus causing the inflammation and subsequent disorders as of the Aspergillus species. Mainly,

• The fungal elements in the guttural granuloma showed the morphologic characteristics of Aspergillus sp. This species is commonly found in the environment and known to cause infection in animals.
• Aspergillus spp. have previously been associated with guttural pouch mycosis in horses, making this finding consistent with past research.