Introduction
The investigation of equine sino-nasal disease is restricted by the difficulty of radiographically imaging the complex equine skull with its many overlapping structures. However, computed tomographic (CT) imaging has allowed unparalleled opportunities to investigate equine sinonasal diseases, including by more accurately identifying the presence of dental sinusitis, identifying which sinus compartments and nasal conchal bullae are affected. Because sinonasal disorders are relatively uncommon, no single referral centre has enough cases to perform studies with a high statistical power to more fully investigate them. Consequently, it was proposed that a large number of equine clinics with CT facilities would be approached to hopefully obtain a large number of cases to complete such a study.

Materials and Methods
The aim was to document on an agreed Excel spreadsheet the clinical and CT findings of each case of sinus disease. A draft Excel spreadsheet was modified repeatedly, and a structured spreadsheet was eventually agreed on by several initial collaborators in January 2024. This agreed template consisted of 92 separate columns for different clinical or imaging findings, as outlined below. This new multicentre equine sinonasal disease study was performed by 20 referral centres (in the UK, Continental Europe, USA and Ireland) that had, or had access to equine CT Facilities. Each clinic was requested to provide the clinical and CT findings of 100 cases of equine sinonasal disease all of which had undergone head CT imaging. The questionnaire requested information on the following clinical and CT imaging topics.

History
Duration of sinus disease (weeks) Treatments prior to presentation for this current CT examination
- Antibiotics
- Duration of antibiotic therapy in weeks
- NSAIDs - Sinoscopic treatment
- Sinusotomy
- Tooth extraction ( Insert Triadan number)

Current Clinical Signs
- Unilateral nasal discharge
- Bilateral nasal discharge
- Nasal malodour (may be present without nasal discharge)
- Nasal airflow obstruction
- Facial swelling
- Submandibular lymphadenopathy
- Epiphora

Signalment
Age (to nearest year)

Breed
- Thoroughbred - Thoroughbred Cross
- Warmbloods (all breeds)
- Warmblood Cross - Standardbred - Quarter horses - Irish Draught - Irish Draught cross
- Other “sports horses”
- Clydesdale - Other Draught breeds
- Halfinger
- Friesian
- Icelandic Horses
- Fjords
- Arabians
- Coloured cobs
- Shetland ponies - Miniature horses
- Welsh pony
- Other breeds
- free text

Gender
- female
- male
- neutered male

Nasal Endoscopy
- Exudate at sino-nasal ostium (drainage angle)
- Middle meatus endoscopic changes (sinonasal fistula, inspissated exudate, bone sequestra, partial loss/distortion of nasal concha)
- Oro-nasal fistula Final Diagnosis - Primary Sinusitis
- Dental sinusitis
- Oro-maxillary fistula casued by a diastema
- Oro-maxillary fistula iatrogenic (following a prior dental extraction)
- Mycotic sinusitis
- Sinus cyst
- Progressive Ethmoid Haematoma (PEH)

Sinonasal Tumour
- Squamous cell carcinoma
- Adenocarcinoma
- Undifferentiated Carcinoma
- Adenomas
- Ameloblastoma/Ameloblastic carcinoma 
- Compound Odontoma
- Complex Odontoma
- Cementoma
- Osteosarcoma
- Osteoma
- Fibrosarcoma
- Ossifying Fibroma
- Haemangiosarcoma
- Undifferentiated sarcoma
- Other sinonasal tumour use free text
- Traumatic sinusitis
- Cause of sinusitis was not determined

Treatment
Performed under standing sedation | under general anaesthesia

Dental extraction
- Triadan number(s)
- Oral extraction (many cases will have this at initial attempts)
- Minimally invasive transbuccal technique
- Standard (surgical) transbuccal technique
- Minimally invasive (Steinmann pin) repulsion
- Standard Repulsion
- Dental segmentation utilised
- Extraction method not available

Sinusotomy
Nasofrontal flap | Maxillary flap

Sinoscopic treatment
Debridement and /or curettage and/or MSB | fenestration

Sinoscopic lavage
(will likely be additional to other treatments)

Transendoscopic sinus lavage per nasum
Utilising a fine endoscope via sinonsal ostium | via an existing sinonsal fistula

Surgical sinonasal fistulation Conservative treatment only
(i.e. Antibiotics/NSAIDs) Length of time since the above treatment to this survey (Spring 2024)

Total number of treatments
for the current sinus disorder (including treatments before the current CT)
- Not documented
- One treatment
- Two
- Three
- More than three treatments

Outcome
 - Not available/documented
- Cured
- Partially cured
- Not cured CT information
- Unilateral sinusitis
- Right side 
 Left side
- Bilateral sinusitis -start a new column (same case with number B) with all information separately recorded

Compartments involved
(i.e. contain exudate or mucosal swelling present)
- RMS affected
- VCS “
- CMS “
- Conchofrontal sinus affected
- Ethmoidal (middle nasal) sinus “
- Sphenopalatine sinus “

Ipsilateral ventral nasal conchal bulla abscess (i.e. bulla contains liquid or inspissated exudate)
Ipsilateral ventral nasal conchal bulla distorted/ruptured but contains no exudate (see guidelines for this criteria)
Ipsilateral dorsal nasal conchal bulla abscess (i.e. contains liquid or inspissated exudate)
Ipsilateral dorsal nasal conchal bulla distorted/ruptured but no exudate

Contralateral ventral nasal conchal bulla abscess (contains liquid or inspissated exudate)
Contralateral ventral nasal conchal bulla distorted/ruptured but contains no exudate (see guidelines for this criteria)
Contralateral dorsal nasal conchal bulla abscess (contains liquid or inspissated exudate)
Contralateral dorsal nasal conchal bulla distorted/ruptured but no exudate

Middle meatus and conchal have changes detected on CT (e.g., damaged or missing areas of nasal concha, sinonasal fistula, intra-nasal inspissated exudate or sequestra). Presence of swelling of sinus-related bones (including maxillary, nasal, and lacrimal bones, infraorbital canal, and maxillary septal bulla. Rhiannon suggests we use hyperostosis rather than osteitis as we are essentially measuring bone thickness and not bone inflammation

Grade (see guidelines below)
- Mild
- Moderate
- Marked

Non-Complicated Cheek Teeth Fractures
Presence of non-complicated (not involving pulp) cheek teeth fracture- in ipsilateral sinuses Insert its Triadan number(s) if present
Presence of non-complicated (not involving pulp) cheek teeth fracture - in contralateral sinuses. Insert its Triadan number(s) if present.

Ipsilateral apically or endodontically infected non-fractured tooth- believed to be the cause of the sinusitis. Insert its Triadan number if present - if more than one - insert additional Triadan numbers in this column.

Ipsilateral apically or endodontically infected fractured tooth - believed to be the cause of sinusitis - Insert its Triadan number if present – if more than one - insert additional Triadan numbers in this column.

Contralateral apically or endodontically infected non-fractured tooth Insert Triadan number if present – if more than one - insert additional Triadan numbers in this column Contralateral apically or endodontically infected fractured tooth- also include al midline infundibular caries -related fractured teeth in this category if present insert a Triadan Number if more than one - insert additional Tridan numbers in this column.

Contralateral fractured tooth ( eg slab fracture) without evidence of endodontic or apical changes Y/N. If present insert Triadan number(s) – if more than one - insert additional Tridan numbers in this column. A brief summary of the study which is undergoing statistical analysis will be presented.