Neil Townsend

Equine paranasal sinus disease: A long-term study of 200 cases (1997–2009): Treatments and long-term results of treatments

REASONS FOR PERFORMING STUDY There is limited objective information available on the treatment and the long-term response to treatment of the different types of equine sinus disease. OBJECTIVES To document the treatments and long-term response to these treatments in 200 cases of equine sinus disease (1997-2009). METHODS The treatments of horses affected with subacute primary sinusitis (n = 52); chronic primary sinusitis (n = 37); dental sinusitis (n = 40); sinus cyst (n = 26); traumatic (n = 13); dental-related oromaxillary fistula (n = 8); sinus neoplasia (n = 10); mycotic sinus disease (n = 7); and intrasinus progressive ethmoid haematoma (n = 7) and the long-term response to these treatments were retrospectively reviewed. RESULTS Treatments evolved throughout the study and latterly were as conservative as possible, including sinoscopic lavage and standing sinusotomy, with a maxillary sinusotomy approach preferred for the mainly mature horses treated in this study. Removal of intrasinus inspissated pus, including transendoscopically (by sinusotomy and via existing sinonasal fistulae), was the main treatment for chronic primary sinusitis and sinonasal fistulation was seldom performed latterly. Attempted oral extraction of infected cheek teeth, even if unsuccessful, facilitated subsequent dental repulsion, resulting in few post operative problems. Sinus cyst removal carried an excellent prognosis. Except for cases of sinus neoplasia (only 22% cured), an excellent long-term response to treatment (91% fully cured, 7% partially cured) was obtained for all other types of sinus disease following a median of one treatment. CONCLUSIONS More conservative treatments, including removal of intrasinus inspissated pus by sinoscopy, pre-existing sinonasal fistula or sinusotomy, are effective for chronic primary sinus disease. Standing sinusotomy, mainly using a small maxillary site, was suitable for most cases of sinus disease in mature horses.

Investigation of the sensitivity and specificity of radiological signs for diagnosis of periapical infection of equine cheek teeth

REASONS FOR PERFORMING STUDY Radiography is commonly used for the diagnosis of equine cheek teeth (CT) infection but, to our knowledge, no study to date has evaluated the relative values of individual specific radiographic signs when making a diagnosis. OBJECTIVES To investigate the sensitivity and specificity of individual radiographic signs identified from the literature for the diagnosis of CT apical infection using a retrospective case-control study. METHODS Cropped radiographs taken using computed radiography of 41 apically infected CT and 41 control CT were independently blindly evaluated by 3 clinicians for the presence of 12 predetermined radiographic signs associated with CT apical infection. A final diagnosis of either noninfected or infected was made. Sensitivity and specificity were calculated for the presence or absence of each radiographic sign for each clinician. Uni- and multivariable conditional logistic regression were used to determine strength of association of the 12 radiographic signs with apical infection. RESULTS Median sensitivity and specificity for the diagnosis of CT apical infection were 76 and 90%, respectively. Periapical sclerosis, clubbing of one or 2 roots, degree of clubbing and periapical halo formation had the highest sensitivities (73-90%), with moderate specificity (61-63%). Multivariable conditional logistic regression revealed that severity of periapical sclerosis and extensive periapical halo were strongly associated with CT apical infection. CONCLUSIONS The presence of periapical sclerosis and formation of a periapical halo were strongly associated with CT apical infection. Computed radiography appears to have a higher sensitivity but similar specificity to previously published results using film radiography to detect CT apical infection. POTENTIAL RELEVANCE These findings may aid practitioners when interpreting radiographs of equine CT as to the relative significance of their findings.

Evaluation of the long-term oral consequences of equine exodontia in 50 horses.

The aims of this study were to objectively evaluate and quantify the process of post-extraction cheek teeth (CT) dental drift in horses, and to report on associated disorders of CT wear and long-term periodontal health. Fifty horses that had CT oral extraction because of apical infection were prospectively re-examined and a full oral examination, including measurements of some dental parameters, was performed. Narrowing of the extraction space was noted in all cases with complete closure occurring in 18% of horses. The rate of dental drift was calculated as 15.7% of extraction space/year (range 4-50%) and was not associated with the age at extraction (P=0.78) or frequency of dental care since extraction (P=0.48). There was a significant negative relationship between the rate of dental drift and the duration of time since extraction (P=0.008). Overgrowths were present on the opposite CT row in 98% of horses, including opposite the extracted CT and on the Triadan 06s and 11s. No significant difference was noted in either the number of diastemata (P=0.9) or periodontal disease score (P=0.8) between the extraction and the contralateral cheek tooth rows.

Complications of Equine Oral Surgery

The vast majority of equine oral procedures are dental-related and, unless great care is taken, almost all such procedures have the potential to cause marked short- or long-term damage to other oral structures. This review of the more common complications of oral surgery begins at the rostral oral cavity with procedures of the incisors, and then moves caudally to deal with complications related to procedures of wolf teeth and cheek teeth, including salivary duct disruption and dental sinusitis. Finally, complications associated with maxillary and mandibular fractures are discussed.

Historical and clinical features of 200 cases of equine sinus disease

The historical and clinical findings in 200 referred cases of equine sinus disease were reviewed retrospectively. Univariable and multivariable analyses were performed to detect significant differences in historical or clinical features between various categories of sinus disease. The causes of sinus disease were classified as subacute primary (less than two months duration) (n=52), chronic primary (more than two months duration) (n=37), dental (n=40), sinus cyst (n=26), traumatic (n=13) or mycotic sinusitis (n=7), sinus neoplasia (n=10), dental-related oromaxillary fistula (n=8) and intrasinus progressive ethmoid haematoma (n=7). The majority of sinus disorders were of chronic duration at the time of referral and most (including 97 per cent of chronic primary sinusitis cases) had not responded to previous antibiotic therapy and/or sinus lavage in some cases. Clinical signs included unilateral nasal discharge in most cases, including purulent or mucopurulent discharge in all horses with primary, dental and mycotic sinusitis. Haemorrhagic nasal discharge was a feature of traumatic sinusitis and intrasinus progressive ethmoid haematomas. Firm facial swellings and nasal airflow obstruction were features of sinus cysts and neoplasms. Ipsilateral lymphadenitis was a more prominent feature of sinus disease with active infections such as primary, dental or mycotic sinusitis.

A Tangential Radiographic Projection for Investigation of the Equine Temporomandibular Joint

OBJECTIVE To (1) describe a tangential radiographic projection of the equine temporomandibular joint (TMJ) and (2) optimize the radiographic angle and determine its use in standing sedated horses. STUDY DESIGN Descriptive study. ANIMALS Cadaveric equine skulls (n=11); 8 horses with a history of quidding or headshaking. METHODS Tangential radiographic projections were taken of a TMJ of a cadaveric skull before and after intra-articular injection of radiographic contrast. Additional tangential radiographic projections were taken after TMJ dissection and placement of a wire along the articular surface of the mandibular condyle. Subsequently, 3 tangential radiographs were taken of both TMJs of 10 skulls at 75 degrees , 70 degrees , and 65 degrees to the dorsal plane (Rt/Le15Cd70D-Le/RtRVO). Each of the 3 images for each TMJ was ranked by 4 observers who were unaware of the projection angle. Interobserver variation was calculated using a Friedman analysis of variance and significance of the most prevalent angle with a 1-sample repeated measures test. Tangential radiographic projections of both TMJs were then taken of 8 standing sedated horses. RESULTS Tangential radiographic projections allowed the lateral half of the TMJ to be viewed without superimposition of other structures and the anatomic orientation was determined. A 70 degrees projection to the dorsal plane was ranked as significantly better than other views (P<.001). There was no significant interobserver variation and the technique was safely performed in standing sedated horses with excellent image quality obtained. CLINICAL RELEVANCE Tangential radiography of the TMJ may complement and add to information obtained from clinical examination and ultrasonography before referral for more advanced imaging techniques.

Trephination of the Equine Rostral Maxillary Sinus: Efficacy and Safety of Two Trephine Sites

OBJECTIVE To examine 2 rostral maxillary sinus (RMS) trephine sites for safety and efficacy using skulls of horses of varying age. STUDY DESIGN Descriptive study. ANIMALS Cadaveric equine skulls (n=40). METHODS Two RMS trephination sites (rostral, caudal) were made in each skull. Radiographic projections using markers at each site were used to determine if sites were within the RMS and directly overlying a cheek tooth. Sinusotomy in 14 skulls was used to determine correlation between radiographic and anatomic location of trephine sites, and of the rostrolateral aspect of the maxillary septum. Age-related risk of trephine site being directly over a cheek tooth was determined using logistic regression. RESULTS Trephine site was within the RMS in 98% of skulls using the rostral portal and 68% using the caudal portal. The rostral site was over a cheek tooth in 18% of skulls compared with 10% using the caudal site. There was a significant negative relationship between the trephine site overlying a tooth and horse age for rostral (P=.02) and caudal (P=.03) sites. The radiographic appearance of the maxillary septum correlated to the rostrolateral portion of the septum in 12 of 14 skulls that had sinusotomy. CLINICAL RELEVANCE The rostral RMS trephine portal is more reliable than the caudal site for entering the RMS. Horses <or=5 years are at high risk for the trephine site overlying a cheek tooth and we advise that RMS trephination in this age group be performed with radiographic guidance.

Risk factors for surgical site infection following laparotomy: Effect of season and perioperative variables and reporting of bacterial isolates in 287 horses

Reasons for performing study: Surgical site infection (SSI) is an important cause of post operative morbidity following laparotomy. Objectives: To investigate risk factors for SSI, including effect of season and surgery performed outside normal working hours, and to report bacterial isolates and antimicrobial resistance patterns. Study design: Retrospective cohort study. Methods: Data were obtained from horses that had undergone exploratory laparotomy over a 3‐year period (2010–2013) in a UK hospital population. SSI was defined as any purulent or serous discharge from the laparotomy incision of >24 h duration that developed during hospitalisation. Multivariable logistic regression was used to identify associations between pre‐, intra‐ and post operative variables and altered likelihood of SSI. Results: Surgical site infection developed in 73/287 (25.4%) horses during hospitalisation. Horses of greater bodyweight (odds ratio [OR] 1.002, 95% confidence interval [CI] 1.0002–1.005, P = 0.03), increased packed cell volume (≥48%) on admission (OR 3.03, 95% CI 1.32–6.94, P = 0.01), small intestinal resection (OR 2.27, 95% CI 1.15–4.46, P = 0.02) and post operative colic (OR 2.86, 95% CI 1.41–5.79, P = 0.003) were significantly associated with increased likelihood of SSI in a multivariable model. SSI was also significantly more likely to occur during winter (OR 3.84, 95% CI 1.38–10.70, P = 0.01) and summer (OR 5.63, 95% CI 2.07–15.3, P = 0.001) months in the model. Three‐layer closure of the incision was protective (OR 0.31, 95% CI 0.16–0.58, P<0.001) compared to 2‐layer closure. There was no effect of surgery being performed outside normal working hours (P = 0.5). The most common bacterial isolates were Escherichia coli (59.5%), Enterococcus spp. (42.4%) and Staphylococcus spp. (25.4%). Penicillin resistant isolates accounted for 92% (96/104) of isolates while 18% (21/119) of isolates were gentamicin resistant. Conclusions: Laparotomy during winter and summer months was associated with increased likelihood of SSI but there was no effect of surgery performed outside normal working hours. This information assists in identifying horses at high risk of SSI and informing development of preventive strategies.

Partial Ostectomy of the Dens to Correct Atlantoaxial Subluxation in a Pony

OBJECTIVE To report a surgical technique that allows decompression and anatomic re-alignment for management of subluxation of the atlantoaxial articulation. STUDY DESIGN Clinical report. ANIMALS Four-year-old Welsh Section B pony gelding. METHODS Attempts at closed reduction of subluxation of the atlantoaxial articulation under general anesthesia were unsuccessful, so a ventral surgical approach allowing partial ostectomy of the dens of the axis was used to facilitate reduction. RESULT Recovery from surgery was uneventful and the pony remained comfortable without neurologic deficits. Both neck stiffness and ataxia resolved. Radiographic examination at 5 days and 6 months postoperatively showed normal anatomic position of the dens of the axis and stabilization of the atlantoaxial joint. CONCLUSION Partial ostectomy of the dens using a ventral approach can be used to facilitate reduction of atlantoaxial subluxation.

Prevalence of oro-dental pathology in a working horse population in Egypt and its relation to equine health

Reasons for performing study: Oro‐dental disease can have a significant impact on equine welfare. Objectives: To determine the prevalence of oro‐dental disease and to identify risk factors for oro‐dental disorders and poor body condition scores (BCS) in a working horse population in Egypt. Study design: Cross‐sectional survey. Methods: Oro‐dental examination was performed on 450 working horses in 2 Egyptian provinces. Horse and management historical data were collected and horses were assigned to no/mild, moderate and severe dental disease categories based on findings on examination. Multivariable logistic regression and generalised additive models were used to identify risk factors for oral mucosal injuries and very poor/poor BCS, and to explore the relationship between age and different oro‐dental disorders. Results: Oro‐dental disease was common, with 45.3% and 8.4% of horses considered to have moderate and severe oro‐dental disease, respectively. None of these horses had previously undergone any form of proper dental examination and treatment by trained personnel. Oral mucosal injuries (64.2%) and sharp enamel points (79.8%) were most common. Oral mucosal injuries were significantly associated with increasing age (odds ratio (OR) 1.1, 95% confidence interval (CI) 1.01–1.1, P = 0.03), focal dental overgrowths (OR 2.4, 95% CI 1.4–4.0, P = 0.002) and sharp enamel points (OR 6.3, 95% CI 3.5–11.0, P<0.001). Very poor and poor BCS were significantly associated with severe dental disease (OR 2.6, 95% CI 1.2–5.8, P = 0.02), horses aged 16–30 years (OR 3.5, 95% CI 1.7–7.0, P = 0.001), height (OR 0.9, 95% CI 0.9–0.97, P = 0.001) and packed cell volume (OR 0.9, 95% CI 0.85–0.95, P<0.001). Conclusions: There is a need for education of working horse‐owners in Egypt about the importance of oro‐dental disease and for greater availability of veterinarians with suitable training and equipment to perform dental prophylaxis and treatment. Even simple dental prophylaxis could have a significant impact on the health and welfare of this population of working horses.