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Equine Health Resource

Suture Line Periostitis

Synonyms: Suture Ostitis

Although it may be surprising, the equine (and any vertebrate) skull is actually made up of separate bones that are joined by a slightly flexible junction called a bone suture. These junctions allow very slight movement of the bones as the head grows, allowing growth of the brain and other internal structures. A human baby’s fontanelle is a large suture and allows rapid change in skull size in the very young growing human.

In horses, abnormal development of skull sutures can result in hard swellings on the head. This condition is not fully understood.

Suture line periostitis is more common in young horses but can develop in mature horses. In the cases I have seen, the presumed reason for the appearance of these swellings has been a traumatic episode. In younger horses they may result from trauma, congenital or nutritional causes.

If they occur at the suture near the eye, the swelling can cause blockage of the naso-lacrimal duct (the tube that normally carries tears through the bone to the nostril) and result in tearing. It can also cause swelling of the tissues around the eye.

These bumps usually are not painful. The most common appearance is a horizontal ridge of hard swelling on the forehead between the eyes or down the side of the face in front of the eye.

Diagnosis involves ruling out other conditions that result in head swelling. This involves careful physical examination, dental exam, and head radiographs. The appearance of suture line periostitis is typically different than Nutritional Secondary Hyperparathyroidism (“Big Head” or “Bran” Disease) but there is some overlap in appearance, so that condition needs to be carefully considered and ruled out.

There is no treatment for this condition. Over time, these bumps usually smooth out and become less obvious.


  • Could this condition result from a nutritional deficiency?
  • Did a traumatic injury to the head possibly cause this condition?

    Any management that reduces a horse's likelihood of having an accident reduces the likelihood of formation of this condition.

    Nutritional Secondary Hyperparathyroidism ("Big Head" or "Bran" Disease) is a separate condition and must be treated with nutritional change. That said, it is always critical to ensure that your horse is eating a balanced diet.

    Author: Doug Thal DVM Dipl. ABVP


    Verwilghen. "Help Doc: My horse turned into Frankenstein." Department of Large Animal Sciences, Faculty of Health and Medicine, University of Copenhagen, Denmark.


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