Background: No large study has examined the treatment and response to treatment of horses with sinonasal disease confirmed by computed tomography (CT). Objectives: Report the treatment and response to treatment of referred cases of equine sinonasal disease. Study design: Retrospective case series. Methods: Data were collected from 19 equine hospitals on 1600 CT-confirmed cases of sinonasal disease. Results: Surgical sinus treatments were performed under sedation in 78.4%, under general anaesthesia in 11.0% and the remaining cases did not have surgical sinus treatments. Sinoscopic debridement with maxillary septal bulla fenestration was performed in 754 horses, under sedation in 605 horses and under general anaesthesia in 139 cases. Nasofrontal and maxillary sinusotomies were performed in 324 and 93 cases, respectively, under sedation in 302/417 cases (72.4%) and general anaesthesia in 115/417 (27.6%). Sinoscopic lavage was performed in 711 cases, usually following other procedures. Sinoscopic treatment was associated with a higher likelihood of cure, and nasofrontal sinusotomy with a lower likelihood of cure, but more difficult cases may have had more sinus osteotomies. Primary, dental and mycotic sinusitis had the highest complete cure rate (all over 79%), while sinus neoplasia (7.3%) and PEH (40.4%) had the lowest cure rates. A total of 592 cheek teeth extractions (including 323 Triadan 09s) were performed in 488 horses with dental sinusitis, including by oral extraction (n=478, 80.4%). Oral extraction was associated with the highest likelihood of complete cure (84.5%), while standard repulsion and surgical buccotomy had the lowest likelihoods of cure (78.6% and 66.7% respectively). Overall response to treatment was available for 926 cases, showing 645 horses (69.7%) cured, 156 (17.0%) partially cured, and 125 (13.5%) not cured. Main limitations: This was a retrospective study. Data on treatments and response to treatments were not available for all cases.

Background: The diagnosis of equine sinonasal disorders has been greatly enhanced by the use of computed tomographic (CT) imaging Objectives: Report the causes of equine sinonasal disease in a large number of referred cases, all of which underwent CT imaging. Study design: Retrospective case series. Methods: Data were collected from 19 equine hospitals on cases of sinonasal disease they had examined, all of which underwent CT imaging. Results. Sinusitis was unilateral in 1457 cases and bilateral in 143. Dental sinusitis due to apical infection was the most common cause of sinusitis (n=693; 43.3% of cases). Other causes were primary sinusitis (n=329; 20.6%), sinus cyst (n=178; 11.1%), progressive ethmoid haematoma (PEH) (n=100; 6.3%), traumatic sinusitis (n=90; 5.6%), sinus neoplasia or suspect neoplasia (n=86; 5.4%), other non-neoplastic sinus growths (n=11; 0.6%), mycotic infection (n=65; 4.1%), sinus pneumocele (n=5; 0.3%), oro-nasal fistulae related sinusitis (n=4; 0.25%), sinus mucocele (n=2; 0.13%), facial suture infection (n=1;0.06%) cases. Sinus tumours and PEH had a significantly lower likelihood of cure than all other diagnoses. Facial swelling was more common with sinus cysts, tumours, trauma and mycosis than other diagnoses. Nasal malodour was most common with dental sinusitis. Nasal airflow obstruction was most common with sinus cysts, PEH and tumours. Empyema of the nasal conchal bullae was least common with sinus cysts, PEH, trauma and tumours (less purulent types of sinusitis). More severe grades of hyperostosis were associated with sinus cysts and tumours. Main limitations: This was a retrospective study, and no histology was performed in some cases.

Background: No study has described the computed tomographic (CT) sinonasal findings in a large cohort of referred cases. Objectives: Report the CT imaging findings in cases of sinonasal disease referred for advanced imaging and treatment. Study design: Retrospective case series. Methods: Data were collected from 19 equine hospitals on referred cases of sinonasal disease, all of which had undergone CT imaging. Results CT imaging in 1600 cases of sinus disease showed unilateral sinusitis in 1457 and bilateral sinus disease in 143 cases. The findings in the 1457 unilateral cases and the initially affected side in the 143 bilateral cases (n=1600) (termed side A) showed the rostral maxillary sinus was affected in 1377/1600 horses (86.1%), with 74.8% of the ventral conchal, 67.7% caudal maxillary, 52.1% conchofrontal, 31.2% ethmoidal (middle conchal) and 28.6% of sphenopalatine sinuses affected. Fluid attenuation or distortion of the ventral nasal conchal bulla (NCB) was present in 21.3% and 39.3% of cases, respectively, and fluid attenuation or distortion of the dorsal NCB was present in 16.5% and 28.4% of cases, respectively. Hyperostosis (inflammatory thickening) of sinus-related bones was mild in 508 (35.5%), moderate in 283 (19.8%), severe in 124 (8.7%), and absent in 516 (36.1%) of 1431 CT records. A total of 659 non-fractured, apically infected cheek teeth and 200 fractured, apically infected teeth were found, with 52.2% of these involving the Triadan 09 position. Notably, examination of the normal contralateral sinuses in the 1457 horses with unilateral sinusitis revealed that 100 horses had CT evidence of 114 maxillary cheek apical infection within intact alveoli. This finding indicates that the presence of a tooth with CT evidence of endodontic/apical disease does not always result in sinus infection. Main limitations: This was a retrospective study with incomplete data available for some cases.

Background: Equine sinonasal disorders are significant diseases whose investigation and treatment have undergone significant changes over the past decade. No large study has described the signalments, pre-referral management, or the clinical and nasal endoscopic findings in such cases referred for advanced imaging and treatment. Objectives: Report the signalments, pre-referral management, and the clinical and nasal endoscopic findings of cases with sinonasal disease referred for advanced imaging and treatment. Study design: Retrospective case series. Methods: Data were collected from 19 equine hospitals on cases of sinonasal disease they had examined, all of which had undergone computed tomographic (CT) imaging. Results: 1600 cases met the requirements for the study, including 1457 cases of unilateral and 143 cases of bilateral (sinonasal disease) sinusitis. Most were chronic disorders with a mean duration of 17.9 weeks (s.d. 34.6 weeks), and 96 cases were over 12 months duration. The most common antimicrobials administered pre-referral were potentiated sulphonamides, followed by doxycycline and procaine penicillin. Pre-referral surgical treatments included maxillary cheek tooth extraction (n=234 teeth), sinoscopy (11.8% of cases), nasofrontal sinus osteotomy (5.2%) and maxillary sinus osteotomy (3.6%). Nasal airflow was obstructed in 14.9% of cases, and facial swelling was present in 26.9% of cases. Nasal endoscopy showed exudate at the sinonasal ostium in 65.8% of cases, and abnormalities, including inspissated exudate, sequestra and sinonasal fistulae, were present in the middle meatus in 44.6% of cases. Multivariable analysis showed the presence of the following variables at presentation were significantly associated with a decreased chance of complete cure: age greater than 12 years, sinonasal disease of greater than 8 weeks duration, prior nasofrontal sinusotomy, presence of facial swelling, epiphora, or bilateral nasal discharge. Main limitations: This was a retrospective study with complete data unavailable for some cases.

This article briefly reviews the causes of unilateral nasal discharge associated with sinonasal disease in the horse. Whilst, computed tomographic and radiographic imaging are often of great diagnostic value, clinical and nasal endoscopic examinations are the initial steps in investigating these disorders. This article reviews the use of oral examination and nasal endoscopy in the investigation of nasal discharge caused by sinonasal disease.

Due to the length of the reserve crown and roots of equine cheek teeth, especially in younger horses, their extraction (exodontia) can be a challenging procedure with the potential for many types of post-extraction complications to develop. The prevalence of post-extraction complications is greatly influenced by the exodontia technique used, with unacceptably high levels of complications with the traditional repulsion technique and conversely, low levels of complications with oral extraction performed by skilled operators. Recent objective studies on post-exodontia problems in horses have also highlighted some risk factors for the development of post-extraction problems including exodontia of rostral mandibular teeth in young horses, and exodontia of teeth with apical infections The recent recognition that some non-healing post-extraction equine alveoli suffer from a disorder very similar to dry socket in humans, may help clinicians to recognise, treat and possibly help prevent this disorder.