Researchers who explored an intriguing condition that can affect horses with head stitches say there appear to be several potential triggers.
Facial suture exostosis, suture periostitis, suture separation, or suturitis, is a not-so-uncommon condition that should be considered when investigating the potential cause of equine facial swelling, the study team said.
The condition involves excessive bone growth. Affected horses gradually develop a firm, non-painful swelling in the frontal region of the head. The exact location of the swelling is dependent on the facial suture or sutures affected.
New bone formation is often bilateral, symmetric and extends toward the eye.
The problem is usually diagnosed from clinical signs and x-rays. Because of the complex three-dimensional anatomy of the head and the difficulties in interpreting x-rays due to the overlapping of several bony structures, CT scans offer a better image of the problem.
Denis Verwilghen and his fellow researchers, in a just-published study in the journal Veterinary Sciences, noted that while several case reports have been published, no large case series is available.
The study team collected data on cases from multiple centres on horses with suture exostosis in the facial region. Information regarding breed, age, gender, history, imaging findings, initiated treatment, response to treatment and follow up was recorded.
One hundred and five cases of various breeds were reported. Analysis revealed the cases could be grouped into four entities: 45 developed following sino-nasal surgery, 23 following trauma, seven with underlying sinus pathology, and 25 were of unknown cause.
Treatment consisted of removal of bone fragments, surgical debridement, plate fixation, antimicrobial and anti-inflammatory drugs, or no treatment.
The authors found that while the initial localized pain arising from the problem faded within a few days or weeks, resolution or reduction of the swelling was obtained in most cases after three to 18 months.
The causes and progression of the condition differed in the cases investigated.
Identification of an underlying cause, particularly the presence of a bone fragment and infection, is important to speed up resolution, they said. Both needed to be ruled out before concluding that a cause could not be established.
Among the study horses, 39 developed weepy eyes and 35 had a nasal discharge.
The researchers, discussing their findings, said any type of head trauma or “stress” to the suture lines, leading to instability of the cranial sutures and any inflammatory reaction in the region, could lead to the development of the condition.
They noted that previous research seems to suggest that suture lines represent a patent way for inflammation to travel across. It is therefore not unusual for the insult, infection or bone fragment to be located on one side of the face yet the reaction of the suture line to be present bilaterally.
“The suture line seems to be able to act as a highway for infection and inflammation.”
The authors noted that earlier reports on suture exostosis describe the condition as non-painful. However, in the current series, many horses in the acute phase of the condition were reported to be painful at palpation.
They said that treatment should also focus on providing pain relief, either systemically or locally.
In conclusion, they said it was clear from the case series that conservative or medical management of these cases will rarely lead to full clinical resolution of the problem.
“Spontaneous disappearance was reported in a number of cases within a six-month timeframe (except one case where it took 1.5 years), therefore initiating surgical treatment in idiopathic cases (those of unknown cause) could be delayed until after this timeframe.”
The case series also highlights the importance of the presence of bone fragments in the occurrence of suture exostosis, and the need for their removal to speed up recovery
The study team comprised Verwilghen, Jack Easley, Timo Zwick, Maggy Uhlhorn, Sigrid Grulke, Hubert Simhofer, Neil Townsend, Oliver Liyou, Fabrice Bodeus, Davide Danilo Zani, Lieven Vlaminck, Chris Pearce, Carsten Staszyk and Astrid Bienert-Zeit, from a range of institutions.
Verwilghen, D.; Easley, J.; Zwick, T.; Uhlhorn, M.; Grulke, S.; Simhofer, H.; Townsend, N.; Liyou, O.; Bodeus, F.; Zani, D.D.; Vlaminck, L.; Pearce, C.; Staszyk, C.; Bienert-Zeit, A. Equine Suture Exostosis: A Review of Cases from A Multicenter Retrospective Study. Vet. Sci. 2022, 9, 365. https://doi.org/10.3390/vetsci9070365