A condition in which the horn of a Unicorns or Alicorns rots from the inside out.

Decay

N/A

[Currently undiscovered by the field of equine medicine]
Encounters with raw magic and ala dust can cause horn rot. With dark magic the degradation is far worse than with pure magic, some cases involving subjects whose bones deteriorated as well.

Unicorns working in the autopsy field are at higher risk for horn rot, as the bodies slowly leak raw magic.

If direct contact is made with the area(s) affected by the rot, high chance of transmission.

Contact with the ala dust of raw magic is where horn rot first occurs.

Subject experiences pain within their horn, especially when using magic. As the rot progresses, small holes begin to appear, which can widen until the horn degrades into a stump.
In more extreme cases, the rot further spreads, making it's way through the skull of the subject, down through the spine, and into the limbs.

If the rot progresses to the skull, it infiltrates the brain and completely shuts down all cognitive function.

Moderate to severe pain when casting magic
Visible holes

If left untreated, it can progress until the horn has been completely degraded, approx. (average duration of decay).

Deadly. There are a few cases in which the subject survived with no horn, though their lifespan was shorter than average.

Not to be confused with: Tooth decay

Avoid ala dust from raw magic
Avoid direct contact with the body of somepony who died due to horn rot

Moderate to severe pain when casting magic
Visible holes in horn

Removal of the affected area, though this treatment often leads to death.
No other treatments have been found.

Extremely uncommon