A horse with a suture line exostosis on the forehead

Horses and Unicorns

Today on rounds, we had the opportunity to meet this lovely lady. She had a lump on her forehead which had been there for a month. What do you think it is?

IMG_0147 A horse with a suture line exostosis on the forehead

This lump is called suture periosteitis or suture line exostosis. It is an inflammation of the suture lines of the nasofrontal bone of the skull and can often occurs in youngsters. Quite often the cause of this is unknown. In some cases the cause can be trauma. It is usually non painful and usually settles with time.

Could this be the origin of the unicorn 😉 as some of these masses can get very large and some young horses can have a horned appearance.

This condition or a related condition can occur in humans as the image below shows. No one is sure why they occur but it is thought some type of irritation to the line joining the bones in the skull occurs.

A lump on the skull of a human behind the ear

1 thought on “Horses and Unicorns

  1. Valerie Kenyon

    My 21 year old gelding has recently been diagnosed with this condition. He’s had it about two months and I think the lumps are getting bigger. He doesn’t seem bothered by it. Is further investigation needed? I’ve been wondering about the supplements in his diet and whether he is consuming too much calcium. Is this likely? Many thanks for an opinion.

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